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21 pages, 3403 KiB  
Review
Coordinated Actions of Neurogenesis and Gliogenesis in Nerve Injury Repair and Neuroregeneration
by Mei-Yu Chen, Cheng-Yu Chi, Chiau-Wei Zheng, Chen-Hung Wang and Ing-Ming Chiu
Int. J. Transl. Med. 2024, 4(4), 810-830; https://doi.org/10.3390/ijtm4040053 - 19 Dec 2024
Viewed by 313
Abstract
The failure of endogenous repair mechanisms is a key characteristic of neurological diseases, leading to the inability to restore damaged nerves and resulting in functional impairments. Since the endogenously regenerative capacity of damaged nerves is limited, the enhancement of regenerative potential of quiescent [...] Read more.
The failure of endogenous repair mechanisms is a key characteristic of neurological diseases, leading to the inability to restore damaged nerves and resulting in functional impairments. Since the endogenously regenerative capacity of damaged nerves is limited, the enhancement of regenerative potential of quiescent neural stem cells (NSCs) presents as a therapeutic option for neural diseases. Our previous studies have shown exciting progress in treating sciatic nerve injury in mice and rats using NSCs in conjunction with neurotrophic factors such as fibroblast growth factor 1 (FGF1). Additionally, a recently discovered neurotrophic factor, IL12p80, has shown significant therapeutic effects in sciatic nerve injury repair via myelinating oligodendrocytes. IL12p80 induces oligodendrocyte differentiation from NSCs through phosphorylation of Stat3. Therefore, it might be possible to alleviate the myelination defects of oligodendrocytes in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS), multiple sclerosis (MS), and even schizophrenia through the administration of IL12p80. These applications could shed light on IL12p80 and FGF1, not only in damaged nerve repair, but also in rectifying the oligodendrocytes’ defects in neurodegenerative diseases, such as ALS and MS. Finally, the synergistic effects of neurogenesis-induced FGF1 and myelination-induced IL12 might be able to supplant the need of NSCs for nerve repair and neuroregeneration. Full article
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<p>Transcriptional regulation of endogenous FGF1 expression in different tissues. The human FGF1 gene structure is schematically presented with a scale (kbp). Exons –1A, –1B, –1C, and –1D are the alternative exons generated using promoters A, B, C, and D, respectively [<a href="#B96-ijtm-04-00053" class="html-bibr">96</a>].</p>
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<p>GFP fluorescence permits the isolation and purification of F1B-positive brain cells from F1B-Tag transgenic mice. F1B-Tag/F1B-GFP(+) and F1B-Tag/F1B-GFP(−) cells were separated via fluorescence-activated cell sorting. The F1B-GFP(+) cells possess remarkable neurosphere-forming activity when compared with F1B-GFP(−) [<a href="#B96-ijtm-04-00053" class="html-bibr">96</a>]. Furthermore, F1B-GFP(+) cells could differentiate into neurons, astroglial cells, and oligodendrocytes, demonstrating their multipotent capacities [<a href="#B102-ijtm-04-00053" class="html-bibr">102</a>]. Thus, F1B-positive brain cells from F1B-Tag transgenic mice showed self-renewal and multipotent capacities [<a href="#B96-ijtm-04-00053" class="html-bibr">96</a>,<a href="#B102-ijtm-04-00053" class="html-bibr">102</a>].</p>
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<p>Assessment of functional recovery via walking track analysis, using the rat’s footprint areas as indices. A brief description is as follows: Preoperatively, the rats were trained to walk down a 150 × 8 cm track in a darkened enclosure. The sciatic functional index (SFI), which assessed the functional muscle reinnervation, was calculated based on the walking track analysis using the following equation: SFI = −38.3(PLF) + 109.5(TSF) + 13.3(ITF) − 8.8, where PLF (print length function) = (experimental PL − normal PL)/normal PL, TSF (toe spread function) = (experimental TS − normal TS)/normal TS (1st to 5th Toe), and ITF (inter-median toe spread function) = (experimental IT − normal IT)/normal IT (2nd to 4th Toe) [<a href="#B110-ijtm-04-00053" class="html-bibr">110</a>]. The footprinted area in the walking track analysis was further scanned and recorded with an image analysis system (Image-Pro Lite, Media Cybernetics, Rockville, MD, USA). The ratio of the experimental foot area/normal foot area was analyzed. The degrees of repair could be quantitated using SFI analyses, as described in our publication [<a href="#B97-ijtm-04-00053" class="html-bibr">97</a>].</p>
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<p>Sciatic functional index analyses of rats with transected sciatic nerves and treated with GFP-positive NSCs using PLA-grooved nerve conduits with FGF1 and NSCs. Cn: rats repaired using conduits alone (<span style="color:blue">△</span>); Cn+NSCs: rats repaired using conduits with NSCs (<span style="color:red">○</span>); Cn+FGF1: rats repaired using conduits with FGF1 (<span style="color:blue">▲</span>); Cn+FGF1+NSCs: rats repaired using conduits with FGF1 and NSCs (<span style="color:red">●</span>). Four rats were used in each group. The Cn+FGF1+NSCs group shows better functional recovery than any of the other three groups. The results indicate that using the treatment comprising stem cells, FGF1, and conduits is the best strategy for sciatic nerve injury repair in rats [<a href="#B97-ijtm-04-00053" class="html-bibr">97</a>].</p>
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<p>Diameters of regenerated sciatic nerve were increased with the administering of IL12. Four mice were used in each group. Mouse IL12p80 increases the diameter of a regenerated nerve up to 4.5-fold when NSCs or NSCs+IL12p80 were incorporated in the conduits, from 65 µm to 189 µm and 295 µm, respectively, at the medial section of the regenerated nerve. Mouse sciatic nerve injury repaired using conduits alone (<span style="color:red">■</span>); using conduits with NSCs (<span style="color:green">■</span>); using conduits with NSCs and IL12p80 (<span style="color:blue">■</span>) [<a href="#B114-ijtm-04-00053" class="html-bibr">114</a>].</p>
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<p>Enhancement of nerve regeneration in the sciatic nerve injury mouse model through the implantation of PLA conduits with NSCs and human IL12p80. (<b>A</b>–<b>D</b>) Staining of tissue sections with hematoxylin and eosin (H&amp;E) was carried out for the measurements of the sizes of the regenerated sciatic nerve in mice. “P” marks the proximal site of the residual sciatic nerves in mice, while “D” marks the distal site (“P” and “D” are 3.0 mm apart). (<b>E</b>–<b>H</b>). Immunohistochemical staining using anti-NF200 antibody (green) and anti-PZ0 antibody (red). Nuclei were stained with DAPI (blue). NF200 and PZ0 are the markers for nerve fibers and myelinating Schwann cells, respectively. Four mice were used in each group. Scale bars: (<b>A</b>–<b>D</b>), 1.0 mm; (<b>E</b>–<b>H</b>), 200 µm [<a href="#B133-ijtm-04-00053" class="html-bibr">133</a>].</p>
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33 pages, 1058 KiB  
Review
Mechanisms and Potential Benefits of Neuroprotective Agents in Neurological Health
by Burcu Pekdemir, António Raposo, Ariana Saraiva, Maria João Lima, Zayed D. Alsharari, Mona N. BinMowyna and Sercan Karav
Nutrients 2024, 16(24), 4368; https://doi.org/10.3390/nu16244368 - 18 Dec 2024
Viewed by 430
Abstract
The brain contains many interconnected and complex cellular and molecular mechanisms. Injury to the brain causes permanent dysfunctions in these mechanisms. So, it continues to be an area where surgical intervention cannot be performed except for the removal of tumors and the repair [...] Read more.
The brain contains many interconnected and complex cellular and molecular mechanisms. Injury to the brain causes permanent dysfunctions in these mechanisms. So, it continues to be an area where surgical intervention cannot be performed except for the removal of tumors and the repair of some aneurysms. Some agents that can cross the blood–brain barrier and reach neurons show neuroprotective effects in the brain due to their anti-apoptotic, anti-inflammatory and antioxidant properties. In particular, some agents act by reducing or modulating the accumulation of protein aggregates in neurodegenerative diseases (Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, Amyotrophic lateral sclerosis, and prion disease) caused by protein accumulation. Substrate accumulation causes increased oxidative stress and stimulates the brain’s immune cells, microglia, and astrocytes, to secrete proinflammatory cytokines. Long-term or chronic neuroinflammatory response triggers apoptosis. Brain damage is observed with neuronal apoptosis and brain functions are impaired. This situation negatively affects processes such as motor movements, memory, perception, and learning. Neuroprotective agents prevent apoptosis by modulating molecules that play a role in apoptosis. In addition, they can improve impaired brain functions by supporting neuroplasticity and neurogenesis. Due to the important roles that these agents play in central nervous system damage or neurodegenerative diseases, it is important to elucidate many mechanisms. This review provides an overview of the mechanisms of flavonoids, which constitute a large part of the agents with neuroprotective effects, as well as vitamins, neurotransmitters, hormones, amino acids, and their derivatives. It is thought that understanding these mechanisms will enable the development of new therapeutic agents and different treatment strategies. Full article
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<p>Neuroprotective effect of agents with their properties of anti-inflammatory, antioxidant, anti-apoptotic, modulating neuroplasticity and preventing the protein aggregation using different mechanisms of action. Upward arrows represent an increase in the activity or synthesis of the indicated molecules, whereas downward arrows indicate a decrease. (Created by Biorender at 14 November 2024; <a href="https://www.biorender.com" target="_blank">https://www.biorender.com</a>).</p>
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<p>Comparison of the total number of neuroprotective agents-related publications in the last five years.</p>
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16 pages, 1907 KiB  
Review
Dehydrated Human Amnion–Chorion Membrane as a Bioactive Scaffold for Dental Pulp Tissue Regeneration
by Sahng G. Kim
Biomimetics 2024, 9(12), 771; https://doi.org/10.3390/biomimetics9120771 - 18 Dec 2024
Viewed by 348
Abstract
The dehydrated human amnion–chorion membranes (dHACMs) derived from the human placenta have emerged as a promising biomaterial for dental pulp regeneration owing to their unique biological and structural properties. The purpose of this review is to explore the potentials of dHACMs in dental [...] Read more.
The dehydrated human amnion–chorion membranes (dHACMs) derived from the human placenta have emerged as a promising biomaterial for dental pulp regeneration owing to their unique biological and structural properties. The purpose of this review is to explore the potentials of dHACMs in dental pulp tissue engineering, focusing on their ability to promote cellular proliferation, differentiation, angiogenesis, and neurogenesis. dHACMs are rich in extracellular matrix proteins and growth factors such as TGF-β1, FGF2, and VEGF. They also exhibit significant anti-inflammatory and antimicrobial properties, creating an optimal environment for dental pulp regeneration. The applications of dHACMs in regenerative endodontic procedures are discussed, highlighting their ability to support the formation of dentin and well-vascularized pulp-like tissue. This review demonstrates that dHACMs hold significant potential for enhancing the success of pulp regeneration and offer a biologically based approach to preserve tooth vitality and improve tooth survival. Future research is expected to focus on conducting long-term clinical studies to establish their efficacy and safety. Full article
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<p>Schematic diagram illustrating the structure of the amnion–chorion membrane and its detailed extracellular matrix components. The diagram highlights the distinct layers of the membrane—amnion and chorion—showing their unique composition and the types of collagen fibers, proteoglycans, glycoproteins, fibronectin, and laminin.</p>
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<p>Cell homing-based pulp regeneration using dHACMs. dHACMs promote the recruitment of stem cells from the periapical tissue (e.g., stem cells of the apical papilla, bone marrow stem cells, periodontal ligament stem cells) and augment cellular events which are critical for pulp regeneration, such as angiogenesis, odontoblast differentiation, cell proliferation, and immunomodulation. Moreover, the membranes possess anti-inflammatory and antimicrobial properties and enhance wound healing and ECM remodeling through their function as a bioactive scaffold.</p>
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<p>Clinical case using dHACMs for pulp regeneration. (<b>A</b>) Preoperative radiograph showing the maxillary right central incisor with a periapical lesion. The tooth was diagnosed with previously initiated therapy and symptomatic apical periodontitis (<b>B</b>) Postoperative radiograph after root canal disinfection, placement of dHACMs, and restoration. (<b>C</b>) Three-month follow-up showing a reduction in size of the periapical lesion. (<b>D</b>) Fourteen-month follow-up showing the complete resolution of the periapical lesion and the complete root formation.</p>
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<p>Clinical case using dHACMs for vital pulp therapy. (<b>A</b>,<b>D</b>) Preoperative radiograph showing the mandibular left first molar with extensive caries involving the distal pulp horn. The tooth was diagnosed with symptomatic irreversible pulpitis and symptomatic apical periodontitis. (<b>B</b>,<b>E</b>) Postoperative radiograph after the removal of both caries and inflamed coronal pulp tissue, the placement of dHACMs, and restoration. (<b>C</b>,<b>F</b>) Three-month follow-up showing no periapical lesion. The tooth was negative to percussion and palpation and positive to electric pulp testing.</p>
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15 pages, 4094 KiB  
Article
Mossy Fiber Sprouting in Temporal Lobe Epilepsy: The Impact of Netrin-1, DCC, and Gene Expression Changes
by Melis Onay, Patrick N. Harter, Katherina Weber, Albrecht Piiper, Marcus Czabanka, Karl H. Plate, Thomas M. Freiman, Florian Gessler and Barbara Puhahn-Schmeiser
Biomedicines 2024, 12(12), 2869; https://doi.org/10.3390/biomedicines12122869 - 17 Dec 2024
Viewed by 428
Abstract
Background: Temporal lobe epilepsy (TLE) is the most common form of drug-resistant epilepsy, often associated with hippocampal sclerosis (HS), which involves selective neuronal loss in the Cornu Ammonis subregion 1 CA1 and CA4 regions of the hippocampus. Granule cells show migration and mossy [...] Read more.
Background: Temporal lobe epilepsy (TLE) is the most common form of drug-resistant epilepsy, often associated with hippocampal sclerosis (HS), which involves selective neuronal loss in the Cornu Ammonis subregion 1 CA1 and CA4 regions of the hippocampus. Granule cells show migration and mossy fiber sprouting, though the mechanisms remain unclear. Microglia play a role in neurogenesis and synaptic modulation, suggesting they may contribute to epilepsy. This study examines the role of microglia and axonal guidance molecules in neuronal reorganization in TLE. Methods: Nineteen hippocampal samples from patients with TLE undergoing epilepsy surgery were analyzed. Microglial activity (M1/M2-like microglia) and neuronal guidance molecules were assessed using microscopy and semi-automated techniques. Gene expression was evaluated using the nCounter Expression Profiling method. Results: Neuronal cell loss was correlated with decreased activity of the M1 microglial phenotype. In the CA2 region, neuronal preservation was linked to increased mossy fiber sprouting and microglial presence. Neuronal markers such as Deleted in Colorectal Cancer (DCC) and Synaptopodin were reduced in areas of cell death, while Netrin-1 was elevated in the granule cell layer, potentially influencing mossy fiber sprouting. The nCounter analysis revealed downregulation of genes involved in neuronal activity (e.g., NPAS4, BCL-2, GRIA1) and upregulation of IκB, indicating reduced neuroinflammation. Conclusions: This study suggests reduced neuroinflammation in areas of neuronal loss, while regions with preserved neurons showed mossy fiber sprouting associated with microglia, Netrin-1, and DCC. Full article
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<p>Subregions of healthy hippocampi (noHS) and sclerotic hippocampi (HS) stained with CD68. Activated microglia is recognizable by thickened and retracted branches. In the bar diagrams, bars and error bars indicate medians and IQR. (<b>A</b>) CA1 subregion of noHS. (<b>B</b>) CA1 subregion of HS. (<b>C</b>) CA2 subregion of noHS. (<b>D</b>) CA2 subregion of HS—here you can detect a significant overexpression of Iba-1. (<b>E</b>) CA3 subregion of noHS. (<b>F</b>) CA3 subregion of HS. (<b>G</b>) CA4 subregion of noHS. (<b>H</b>) CA4 subregion of HS. (<b>I</b>) Granule cell layer of noHS. (<b>J</b>) Granule cell layer of HS.</p>
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<p>The levels of DCC in noHS and HS hippocampal slices. (<b>A</b>) Expression of DCC in noHS. (<b>B</b>) Expression of DCC in HS revealing a loss of DCC in all subregions. (<b>C</b>) One-factorial analysis of DCC-positive stained area/tissue area mm<sup>2</sup> in HS and noHS. The semi-automatized analysis shows a significant downregulation of DCC in subregion CA2, CA3, CA4, and GCL in the sclerotic tissue. Bars and error bars indicate medians and IQR. * <span class="html-italic">p</span> &lt; 0.05; ** <span class="html-italic">p</span> &lt; 0.01; *** <span class="html-italic">p</span> &lt; 0.001.</p>
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<p>IHC staining of Netrin-1 in noHS and HS in hippocampal slices. (<b>A</b>) Expression of Netrin-1 in noHS (<b>B</b>) and in HS, displaying a loss of Netrin-1 in almost all subregions. (<b>C</b>) One-factorial analysis of Netrin-1-positive area/tissue area mm<sup>2</sup> in HS. A significant upregulation is detectable in the GCL region of HS. Bars and error bars indicate medians and IQR. ** <span class="html-italic">p</span> &lt; 0.01.</p>
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<p>Cell type analyses according to the expression of different cell type scores in noHS and HS. For the investigation, six samples were used per group. Each point represents a sample. Boxes, bars and error bars indicate medians and IQR. The score is calculated from the cell type abundances by taking the logarithm of the expression of the genes specific to the cell types. (<b>A</b>) Astrocytes score (<b>B</b>) Oligodendrocytes score—An increased oligodendrocytes score (genes that occur in oligodendrocytes) is detectable in the sclerosis but there are no significant differences. (<b>C</b>) Microglia score—Surprisingly, an increased number of genes encoding for macrophages in general is apparent, even though the results are not significant. (<b>D</b>) Activated microglia score—The genes specifically associated with activated microglia exhibit higher expression in the noHS group, although without a significant result.</p>
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<p>Differential levels of mRNAs and proteins between non-sclerotic (noHS) and sclerotic tissue (HS) are presented in volcano plots. (<b>A</b>) Differential levels of mRNAs and proteins involved in activated microglia. The largest differences were seen in the proteins NPAS4, FLT1, and BCL2, but none reached statistical significance. (<b>B</b>) Differential levels of cytokine mRNAs and proteins in HS and noHS. The highest differences were seen in VEGFA and FLT1, which, however, did not reach statistical significance. (<b>C</b>) Differential levels of mRNAs and proteins involved in vesicle trafficking. The highest differences are observed in NPAS4, ARC, KCNA1, and GRIA1; however, this did not reach statistical significance. (<b>D</b>) Differential levels of mRNAs involved in axon and dendrite structure in HS and noHS. The highest differences were seen in ARC, KCNA1, and GRIA1, again without reaching statistical significance.</p>
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<p>Exemplary scheme of the expression of signaling influenced by cAMP in HS. The pathway was created by the summarization of pathway scores, which were calculated on the principal component analysis of the pathway genes’ normalized expression (refer to the <a href="#sec2-biomedicines-12-02869" class="html-sec">Section 2</a> for details). The mRNAs, which were found to be downregulated are blue colored, whereas upregulated mRNAs are gold colored. Interestingly, the expression of IκB was upregulated, which, in turn, leads to reduced activity of NFκB, as the NFκB pathway is inhibited by IκB. This could be interpreted as a sign of reduced neuroinflammation.</p>
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17 pages, 3525 KiB  
Review
Harnessing the Antibacterial, Anti-Diabetic and Anti-Carcinogenic Properties of Ocimum sanctum Linn (Tulsi)
by Rakesh Arya, Hossain Md. Faruquee, Hemlata Shakya, Sheikh Atikur Rahman, Most Morium Begum, Sudhangshu Kumar Biswas, Md. Aminul Islam Apu, Md. Azizul Islam, Md. Mominul Islam Sheikh and Jong-Joo Kim
Plants 2024, 13(24), 3516; https://doi.org/10.3390/plants13243516 - 16 Dec 2024
Viewed by 604
Abstract
Ocimum sanctum Linn (O. sanctum L.), commonly known as Holy Basil or Tulsi, is a fragrant herbaceous plant belonging to the Lamiaceae family. This plant is widely cultivated and found in north-central parts of India, several Arab countries, West Africa and tropical [...] Read more.
Ocimum sanctum Linn (O. sanctum L.), commonly known as Holy Basil or Tulsi, is a fragrant herbaceous plant belonging to the Lamiaceae family. This plant is widely cultivated and found in north-central parts of India, several Arab countries, West Africa and tropical regions of the Eastern World. Tulsi is known to be an adaptogen, aiding the body in adapting to stress by harmonizing various bodily systems. Revered in Ayurveda as the “Elixir of Life”, Tulsi is believed to enhance lifespan and foster longevity. Eugenol, the active ingredient present in Tulsi, is a l-hydroxy-2-methoxy-4-allylbenzene compound with diverse therapeutic applications. As concerns over the adverse effects of conventional antibacterial agents continue to grow, alternative therapies have gained prominence. Essential oils (EOs) containing antioxidants have a long history of utilization in traditional medicine and have gained increasing popularity over time. Numerous in vitro, in vivo and clinical studies have provided compelling evidence supporting the safety and efficacy of antioxidant EOs derived from medicinal plants for promoting health. This comprehensive review aims to highlight the scientific knowledge regarding the therapeutic properties of O. sanctum, focusing on its antibacterial, anti-diabetic, anti-carcinogenic, radioprotective, immunomodulatory, anti-inflammatory, cardioprotective, neurogenesis, anti-depressant and other beneficial characteristics. Also, the extracts of O. sanctum L. have the ability to reduce chronic inflammation linked to neurological disorders such as Parkinson’s and Alzheimer’s disease. The information presented in this review shed light on the multifaceted potential of Tulsi and its derivatives in maintaining and promoting health. This knowledge may pave the way for the development of novel therapeutic interventions and natural remedies that harness the immense therapeutic potential of Tulsi in combating various health conditions, while also providing valuable insights for further research and exploration in this field. Full article
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<p><span class="html-italic">O. sanctum</span> L. (Tulsi) plant.</p>
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<p>The schematic diagram illustrates the different medicinal properties of <span class="html-italic">O. sanctum</span> L. (Tulsi). Each of these activities highlights the diverse therapeutic potential of Tulsi, making it a valuable nutraceutical agent in promoting health and managing different diseases. (Figure created with <a href="http://biorender.com" target="_blank">biorender.com</a>).</p>
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17 pages, 3493 KiB  
Article
Transfer RNA Levels Are Tuned to Support Differentiation During Drosophila Neurogenesis
by Rhondene Wint and Michael D. Cleary
Genes 2024, 15(12), 1602; https://doi.org/10.3390/genes15121602 - 15 Dec 2024
Viewed by 462
Abstract
Background/Objectives: Neural differentiation requires a multifaceted program to alter gene expression along the proliferation to the differentiation axis. While critical changes occur at the level of transcription, post-transcriptional mechanisms allow fine-tuning of protein output. We investigated the role of tRNAs in regulating gene [...] Read more.
Background/Objectives: Neural differentiation requires a multifaceted program to alter gene expression along the proliferation to the differentiation axis. While critical changes occur at the level of transcription, post-transcriptional mechanisms allow fine-tuning of protein output. We investigated the role of tRNAs in regulating gene expression during neural differentiation in Drosophila larval brains. Methods: We quantified tRNA abundance in neural progenitor-biased and neuron-biased brains using the hydrotRNA-seq method. These tRNA data were combined with cell type-specific mRNA decay measurements and transcriptome profiles in order to model how tRNA abundance affects mRNA stability and translation efficiency. Results: We found that (1) tRNA abundance is largely constant between neural progenitors and neurons but significant variation exists for 10 nuclear tRNA genes and 8 corresponding anticodon groups, (2) tRNA abundance correlates with codon-mediated mRNA decay in neuroblasts and neurons, but does not completely explain the different stabilizing or destabilizing effects of certain codons, and (3) changes in tRNA levels support a shift in translation optimization from a program supporting proliferation to a program supporting differentiation. Conclusions: These findings reveal coordination between tRNA expression and codon usage in transcripts that regulate neural development. Full article
(This article belongs to the Section RNA)
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<p>tRNA levels are largely constant between neuroblast-biased and neuron-biased brains, but variation exists for a subset of anticodon groups. (<b>A</b>) Hierarchically clustered heatmap showing the average expression level of 84 nuclear-encoded Drosophila tRNA genes (isodecoders). Counts were normalized to the Trimmed Mean of M-values (TMM). An X in the isodecoder name indicates that more than one gene encodes that particular isodecoder, and those genes are not distinguishable by mature tRNA sequence. (<b>B</b>) Volcano plot showing the relative isodecoder expression level for nuclear-encoded (cytosolic) and mitochondrial tRNA genes on the x-axis (fold change = average Neuroblast TMM/average Neuron TMM) and the false discovery rate <span class="html-italic">q</span>-value. tRNAs with a log2 fold change ≥ ±0.5 and <span class="html-italic">q</span>-value ≤ 0.1 are highlighted in red. **** denotes that Gly-GCC-1-X is off-scale, with a <span class="html-italic">q</span>-value &lt; 0.001. (<b>C</b>) Hierarchically clustered heatmap showing the average expression level (normalized to Trimmed Mean of M-values (TMM)) for 44 anticodon groups (isoacceptors). Differentially expressed isoacceptors (<span class="html-italic">q</span>-value &lt; 0.1) are highlighted in red.</p>
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<p>Codon optimality-mediated decay is similar in neuroblasts and neurons and correlates with the stability of functionally related mRNAs. (<b>A</b>) Codon stabilization coefficients (CSCs) were calculated using neuroblast-specific and neuron-specific transcriptome-wide mRNA decay measurements [<a href="#B24-genes-15-01602" class="html-bibr">24</a>]. (<b>B</b>) Gene ontology (GO) categories of mRNAs enriched with optimal codons or non-optimal codons. A total of 5169 neural transcripts (mRNAs present in neuroblast-biased and neuron-biased brains) were ranked by percent optimal codon content (defined by optimality in neuroblasts): the top 10% optimal codon enriched mRNAs (<b>left</b> panel) and the top 10% non-optimal codon enriched mRNAs (<b>right</b> panel) were used for GO analysis. The top five (ranked by adjusted <span class="html-italic">p</span>-value) non-redundant GO categories and corresponding adjusted <span class="html-italic">p</span>-values are listed. Neuroblast-specific and neuron-specific mRNA decay data [<a href="#B24-genes-15-01602" class="html-bibr">24</a>] for the transcripts within each GO category were used to calculate the average mRNA half-life. The number of transcripts in each GO category is listed to the right of the plot bars. Error marks are standard errors of the mean. The adjusted <span class="html-italic">p</span>-value is based on the Bonferroni correction.</p>
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<p>tRNA abundance correlates with codon-mediated mRNA decay in neuroblasts and neurons. (<b>A</b>) Scatter plots comparing tRNA isoacceptor abundance and codon stabilization coefficient (CSC) in each cell type (neuroblast data in the left panel, neuron data in the right panel). (<b>B</b>) Relationship between tRNA adaptation index (tAI) and CSC in each cell type (neuroblast data in left panel, neuron data in right panel). The effect size was measured by Cohen’s d and significance (<span class="html-italic">p</span>-value) was determined by Welch’s <span class="html-italic">t</span>-test. (<b>C</b>) Scatterplot comparing tAI_gene and mRNA half-life for 5169 transcripts present in neuroblast-biased and neuron-biased brains. (<b>D</b>) Heatmaps comparing differential tAI (left column) and differential CSC (right column). Only absolute D tAI values ≥ 0.2 are shown. Only CSCs that differed in category (optimal, neutral, non-optimal) are shown, according to the following criteria: optimal (CSC ≥ 0.01) in one cell type but neutral (0.01 &gt; CSC &gt; −0.01) or non-optimal (CSC ≤ −0.01) in the other.</p>
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<p>tRNA adaptation during neural differentiation supports distinct translation programs. (<b>A</b>) Hierarchically clustered heatmap showing neuroblast-specific and neuron-specific tAI_gene values for 5169 neural mRNAs. Three emergent patterns are outlined in colored boxes: green for high tAI_gene in neuroblasts and neurons (“shared high”, <span class="html-italic">n</span> = 517 mRNAs), tan for low tAI_gene in neuroblasts and neurons (“shared low”, <span class="html-italic">n</span> = 411 mRNAs), and blue for increased tAI_gene in neurons compared to neuroblasts (“neuron up”, <span class="html-italic">n</span> = 965 mRNAs). (<b>B</b>) Biological function gene ontology (GO) category enrichment in each of the tAI_gene groups identified in part A. The bar color matches the group color in part A. Up to ten of the most significantly enriched GO categories, with adjusted <span class="html-italic">p</span>-value ≤ 0.0001, are listed (fewer categories if the <span class="html-italic">p</span>-value cutoff was not met). Adjusted <span class="html-italic">p</span>-values are based on the Bonferroni correction. (<b>C</b>) Molecular function GO category enrichment for transcripts present in the “neuron morphogenesis”, “photoreceptor cell development”, and “peripheral nervous development” Biological GO categories shown in part B. The ten most significantly enriched Molecular GO categories for each group (neuron up, shared low) are listed. The adjusted <span class="html-italic">p</span>-value is based on the Bonferroni correction.</p>
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<p>mRNAs enriched in proliferation-associated codons are poorly adapted for translation by the post-differentiation tRNA pool. (<b>A</b>) Principal component analysis (PCA) on the normalized codon frequencies of 5169 mRNAs present in neuroblast-biased brains and neuron-biased brains. PCA captured a total variation of 23%, with 15% of the variance in principal component 1 (PC1). Unsupervised clustering by kmeans grouped the mRNAs into 5 clusters. (<b>B</b>) GO analysis of mRNAs within kmeans clusters at opposite ends of PC1: cluster 0 and cluster 4. (<b>C</b>) PCA plot from part A recolored with the Codon Adaptation Index (CAI) of each mRNA. (<b>D</b>) Scatterplot comparing CAI and the change in Supply Demand Ratio (SDR) between neurons and neuroblasts (DSDR = Neuron SDR—Neuroblast SDR). The Pearson R-value and the line of best fit show the inverse relationship between CAI and neuron-optimal SDR. (<b>E</b>) The 5169 neural mRNAs were ranked by ∆SDR (Neuron SDR—Neuroblast SDR) and the top 10% (increased SDR) and bottom 10% (decreased SDR) were subject to GO analysis. Significantly enriched GO categories with a Bonferroni adjusted <span class="html-italic">p</span>-value &lt; 10<sup>−5</sup> are listed.</p>
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14 pages, 2484 KiB  
Article
Identification of Stable Reference miRNAs for miRNA Expression Analysis in Adult Neurogenesis Across Mouse and Human Tissues
by Daniella Liana Levitis, Julia Si, Kushal Ravishankar, Michal Toborek and Minseon Park
Cells 2024, 13(24), 2060; https://doi.org/10.3390/cells13242060 - 13 Dec 2024
Viewed by 484
Abstract
Accurate normalization in miRNA studies requires the use of appropriate endogenous controls, which can vary significantly depending on cell types, treatments, and physiological or pathological conditions. This study aimed to identify suitable endogenous miRNA controls for neural progenitor cells (NPCs) and hippocampal tissues, [...] Read more.
Accurate normalization in miRNA studies requires the use of appropriate endogenous controls, which can vary significantly depending on cell types, treatments, and physiological or pathological conditions. This study aimed to identify suitable endogenous miRNA controls for neural progenitor cells (NPCs) and hippocampal tissues, both of which play crucial roles in neurogenesis. Using small RNA sequencing, we identified the most stable miRNAs in primary mouse NPCs and hippocampal tissues and accessed their stability using NormFinder analysis. Six miRNAs—miR-181d-5p, miR-93-5p, miR-103-3p, let-7d-5p, miR-26a-5p, and miR-125a-5p—demonstrated high stability and were evaluated for their suitability as endogenous controls across multiple experimental conditions. All selected miRNAs exhibited consistent expression in the NE-4C mouse cell line but not in ReNcells, a human cell line. For ReNcells, only miR-186-5p, one of the known reference miRNAs tested for comparison, showed stable expression. Notably, miR-103-3p and let-7d-5p were stably expressed in hippocampal tissues from both mouse and human samples but were absent in human brain pericytes, human brain microvascular endothelial cells, and SVG p12 cells, a human fetal glial cell line. This study is the first to identify optimal reference miRNAs for adult neurogenesis in both mouse and human samples, providing reliable options for miRNA normalization and improving the accuracy and reproducibility of miRNA expression analyses in neurogenesis research. Full article
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<p>Overview of Cq values obtained by RT-qPCR for NE-4C samples: (<b>A</b>) NE-4C mouse NPCs were treated with LPS (10 ng/ml), METH (100 µM), or PBS as a vehicle control for 2 h. Mean ± SD, N = 12 (4 per group). Dots shown in A represent mean raw Cq values for technical replicates of individual samples. Cq values for the indicated miRNAs from all groups were used for NormFinder stability analysis (#). (<b>B</b>–<b>I</b>) Group comparison of miRNA candidates for NE-4C samples. Data are presented as mean ± SEM, N = 4 per group.</p>
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<p>Overview of Cq values obtained by RT-qPCR for ReNcell samples: (<b>A</b>) Human NPCs (ReNcells) were treated with METH (100 µM), cultured in growth-factor-free media (a differentiation condition), or cultured in complete media (containing EGF and FGF, a proliferation condition) for 24 h. Data are presented as mean ± SD, N = 11–12 (3–4 per group). Dots represent mean raw Cq values for technical replicates of individual samples. Cq values for the indicated miRNAs from all groups were used for NormFinder stability analysis (#). (<b>B</b>–<b>G</b>) Group comparison of miRNA candidates for ReNcell samples. Data are presented as mean ± SEM, N = 3–4 per group. * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01.</p>
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<p>Overview of Cq values obtained by RT-qPCR for mouse hippocampal tissue samples: (<b>A</b>) C57BL/6 mice were exposed to chronic METH and infected with EcoHIV, followed by housing in wheel cages for voluntary running for 4 weeks. Total RNAs, including small RNA, were extracted from the dissected hippocampal tissues. Dots represent mean raw Cq values for technical replicates of individual samples. Cq values for the indicated miRNAs from all groups were used for NormFinder stability analysis (#). Data are presented as mean ± SD, N = 4 per group. (<b>B</b>–<b>I</b>) Group comparisons of miRNA candidates for mouse HP tissues. Data are presented as mean ± SEM, * <span class="html-italic">p</span> &lt; 0.05, ** <span class="html-italic">p</span> &lt; 0.01, *** <span class="html-italic">p</span> &lt; 0.005.</p>
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<p>Overview of Cq values obtained by RT-qPCR for human hippocampal tissue samples. (<b>A</b>) Total RNA, including small RNA, was extracted from post-mortem human hippocampal tissues from normal brains (N = 7) and stroke-affected brains (N = 3), obtained from the UM Brain Endowment Bank. Dots represent mean raw Cq values for technical replicates of individual samples. Cq values for the indicated miRNAs from all groups were used for NormFinder stability analysis (#). Data are presented as mean ± SD. (<b>B</b>–<b>I</b>) Group comparison of miRNA candidates for human HP tissues. Data are presented as mean ± SEM, * <span class="html-italic">p</span> &lt; 0.05.</p>
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<p>Overview of Cq values obtained by RT-qPCR for SVG p12 cells, HBMECs, and human pericytes: (<b>A</b>–<b>C</b>). Total RNA, including small RNA, was extracted from SVG p12 cells treated with LPS (1 or 2 µg/mL) for 2 h. A one-way ANOVA with Tukey’s multiple comparisons test was performed. N = 4 per group (mean ± SEM), * <span class="html-italic">p</span> &lt; 0.05 and ** <span class="html-italic">p</span> &lt; 0.01. (<b>D</b>–<b>F</b>) Total RNA was extracted from HBMEC-treated METH (100 µM) or HIV NL4-3 (60 ng/ml of p24) for 24 h. N = 4 per group (mean ± SEM), * <span class="html-italic">p</span> &lt; 0.05 and ** <span class="html-italic">p</span> &lt; 0.01. (<b>G</b>,<b>H</b>) Total RNA was extracted from human brain vascular pericytes treated METH (100 µM) or LPS (4 µg/mL) for 2 h. miR-103a-3p was not amplified under the same qPCR conditions. N = 4 per group (mean ± SEM).</p>
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20 pages, 3903 KiB  
Article
ACTH-like Peptides Compensate Rat Brain Gene Expression Profile Disrupted by Ischemia a Day After Experimental Stroke
by Ivan B. Filippenkov, Yana Yu. Shpetko, Vasily V. Stavchansky, Alina E. Denisova, Leonid V. Gubsky, Lyudmila A. Andreeva, Nikolay F. Myasoedov, Svetlana A. Limborska and Lyudmila V. Dergunova
Biomedicines 2024, 12(12), 2830; https://doi.org/10.3390/biomedicines12122830 - 13 Dec 2024
Viewed by 418
Abstract
Background: Ischemic stroke results from a disruption of cerebral blood flow. Adrenocorticotropic hormone (ACTH) serves as the basis for the creation of synthetic peptides as neuroprotective agents for stroke therapy. Previously, using RNA-Seq we first revealed differential expressed genes (DEGs) associated with ACTH(4–7)PGP [...] Read more.
Background: Ischemic stroke results from a disruption of cerebral blood flow. Adrenocorticotropic hormone (ACTH) serves as the basis for the creation of synthetic peptides as neuroprotective agents for stroke therapy. Previously, using RNA-Seq we first revealed differential expressed genes (DEGs) associated with ACTH(4–7)PGP (Semax) and ACTH(6–9)PGP peptides under cerebral ischemia conditions. Analysis was carried out at 4.5 h after transient middle cerebral artery occlusion (tMCAO) model in the ipsilateral frontal cortex of a rat brain. Methods: Here, we analyzed the penumbra-associated frontal cortex of rats and actions under the same peptides at 24 h after tMCAO using RNA-Seq. Results: 3774 DEGs (fold change > 1.5 and Padj < 0.05) were identified under ischemia conditions, whereas 1539 and 2066 DEGs were revealed under Semax and ACTH(6–9)PGP peptides at 24 h after tMCAO. Furthermore, both peptides significantly reduced expression distortions caused by ischemia for 1171 genes associated with immune and neurosignaling pathways. Concomitantly, there were 32 DEGs under ACTH(6–9)PGP versus Semax administration at 24 h after tMCAO. Besides, neurogenesis-, angiogenesis-, protein kinase- and growth factor-related DEGs were revealed under peptides action. Previously, we observed the neuroprotective effect of peptides at the histological level in rat brains at 24 h after tMCAO. Thus, here we demonstrate the transcriptome manifestation of this histological effect. Furthermore, comparison with previous data at the 4.5 h post-tMCAO time point showed that the pattern of peptide action on the transcriptome depends on the time elapsed after tMCAO. Conclusions: We revealed that the effect of ACTH(6–9)PGP was more similar to Semax than different from it a day after tMCAO. At this time point, ACTH-like peptides compensated rat brain gene expression profiles disrupted by ischemia. Thus, our results may be useful for selecting more effective structures for future anti-stroke drugs and appropriate post-stroke time points for their testing. Full article
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<p>Effect of ischemia, ACTH(6–9)PGP and Semax on the transcriptome of FC of rats 24 h after tMCAO. (<b>a</b>,<b>d</b>,<b>g</b>) Results of RNA-Seq analysis for IR24-f vs. SO24-f (<b>a</b>), IS24-f vs. IR24-f (<b>d</b>), IA24-f vs. IR24-f (<b>g</b>). The quantity of DEGs is indicated by the numbers in the diagram sectors. (<b>b</b>,<b>e</b>,<b>h</b>) Volcano plots show a distribution data between the IR24-f and SO24-f (<b>b</b>), IS24-f and IR24-f (<b>e</b>), IA24-f and IR24-f (<b>h</b>) groups. (<b>c</b>,<b>f</b>,<b>i</b>) The top 10 DEGs (Fold change &gt; 1.5; <span class="html-italic">Padj</span> &lt; 0.05) with the highest expression changes in IR24-f vs. SO24-f (<b>c</b>), IS24-f vs. IR24-f (<b>f</b>), IA24-f vs. IR24-f (<b>i</b>). The data are presented as the mean ± standard error of the mean (M ± SEM).</p>
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<p>The gene expression changes for different groups of ischemia, ACTH(6–9)PGP and Semax at 24 h after tMCAO. Venn diagrams represent RNA-Seq results obtained in comparisons between the IR24-f vs. SO24-f (<b>a</b>–<b>c</b>); IS24-f vs. IR24-f (<b>e</b>–<b>g</b>); IA24-f vs. IR24-f (<b>i</b>–<b>k</b>) groups in FC. All (<b>a</b>,<b>e</b>,<b>i</b>), upregulated (<b>b</b>,<b>f</b>,<b>j</b>), and downregulated (<b>c</b>,<b>g</b>,<b>k</b>) DEGs are shown. The top 10 DEGs (Fold change &gt; 1.5; <span class="html-italic">Padj</span> &lt; 0.05) among 1335 (<b>d</b>), 1753 (<b>h</b>) and 1286 (<b>l</b>) in the Venn diagram (<b>d</b>,<b>h</b>,<b>l</b>), respectively, featuring the highest fold changes in the IR24-f vs. SO24-f (<b>d</b>); IS24-f vs. IR24-f (<b>h</b>); IA24-f vs. IR24-f (<b>l</b>) comparison groups. The data are presented as M ± SEM.</p>
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<p>The RNA-Seq results for the IR24-f vs. SO24-f, IS24-f vs. IR24-f, IA24-f vs. IR24-f and IA24-f vs. IS24-f pairwise comparisons. (<b>a</b>) Venn diagrams present comparison of results between the IR24-f vs. SO24-f, IS24-f vs. IR24-f and IA24-f vs. IR24-f groups. The top 10 DEGs that lie within the intersection between the gene sets in the Venn diagram (<b>a</b>) and have the highest fold change in IR24-f vs. SO24-f (<b>b</b>). The top 10 DEGs that lie within the gene sets in the Venn diagram (<b>a</b>) among the overlapping section between IS24-f vs. IR24-f and IA24-f vs. IR24-f but not in the IR24-f vs. SO24-f pairwise comparisons (<b>c</b>). The data are presented as M ± SEM. (<b>d</b>) Hierarchical cluster analysis of all DEGs in IR24-f vs. SO24-f, IS24-f vs. IR24-f, IA24-f vs. IR24-f, where each row represents a DEG; n = 3 per group. Only those genes with cut-off &gt;1.5 and <span class="html-italic">Padj</span> &lt; 0.05 were selected recognized by significant.</p>
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<p>Signaling KEGG pathways associated with DEGs in the FC of rats 24 h after occlusion. DAVID (2021 Update) was used for pathway search in the IR24-f vs. SO24-f, IS24-f vs. IR24-f, IA24-f vs. IR24-f comparisons. (<b>a</b>) 3-set Venn diagram presents a comparison of DEG-related pathways in the IR24-f vs. SO24-f, IS24-f vs. IR24-f, IA24-f vs. IR24-f and IA24-f vs. IS24-f groups. The number on the chart segments indicates the numbers of annotations. (<b>b–d</b>) The most significant pathways in IR24-f vs. SO24-f (<b>b</b>), IS24-f vs. IR24-f (<b>c</b>), IA24-f vs. IR24-f (<b>d</b>) are presented. (<b>e</b>,<b>f</b>) Cluster analysis of overlapped signaling pathways associated with DEGs in IR24-f vs. SO24-f, IS24-f vs. IR24-f, IA24-f vs. IR24-f pairwise comparison. Pathways of inflammatory cluster (IC) (<b>e</b>) and neurotransmitter cluster (NC) (<b>f</b>) are presented. Each column represents a pairwise comparison and each row represents a signaling pathway (KEGG). The green bars represent the pathways with which the majority of upregulated genes are associated, and the red bars represent the pathways with which the majority of downregulated genes are associated. Only DEGs and pathways with <span class="html-italic">Padj</span> &lt; 0.05 were selected as significant, n = 3 of animals per group.</p>
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<p>The search for pathways that reflect gene expression effects of Semax and ACTH(6–9)PGP at 24 h after tMCAO in FC. (<b>a</b>) Venn diagram presents overlapped and unique DEG-related annotations in the IS24-f vs. IR24-f and IA24-f vs. IR24-f pairwise comparisons. Only pathways that have annotations with DEGs in IA24-f vs. IS24-f pairwise comparison are included. The number on the chart segments indicates the numbers of annotations. All pathways were grouped on three pathway clusters (PC1, PC2 and PC3) (<b>b</b>) The gene network of effects of ACTH(6–9)PGP and Semax peptides on transcriptome of FC at 24 h after tMCAO. In the scheme, 13 genes that are DEGs in the IA24-f vs. IS24-f are presented. These genes are grouped by three half rings of rectangles colored according to their differential expression in comparison groups. Each half ring includes the same 32 genes, but the color in the inner half ring indicates DEGs in the IA24-f vs. IS24-f, the color in the central half ring indicates DEGs in the IS24-f vs. IR24-f, and the colour in the outer half ring indicates the DEGs in IA24-f vs. IR24-f. Three pathway clusters (PC1, PC2 and PC3) are grouped in ovals. PC1 represents common pathways that lie within the intersection between the IA24-f vs. IR24-f and IS24-f vs. IR24-f pathway sets in the Venn diagram (<a href="#biomedicines-12-02830-f004" class="html-fig">Figure 4</a>a) and reflects effects of both peptides. PC2 represents unique pathways that lie within the pathway sets among the IS24-f vs. IR24-f but not among the IA24-f vs. IR24-f pairwise comparisons in the Venn diagram (<a href="#biomedicines-12-02830-f004" class="html-fig">Figure 4</a>a). PC3 represents unique pathways that lie within the pathway sets among the IA24-f vs. IR24-f but not among the IS24-f vs. IR24-f pairwise comparisons in the Venn diagram (<a href="#biomedicines-12-02830-f004" class="html-fig">Figure 4</a>a). The lines connecting the genes and pathways indicate association between them. The KEGG databases from DAVID v. 2021 were used to annotate all clustered pathways. Only DEGs and pathways with <span class="html-italic">Padj</span> &lt; 0.05 were selected as significant. The network was constructed using Cytoscape 3.9.2.</p>
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15 pages, 845 KiB  
Review
The Role and Mechanism of Metformin in the Treatment of Nervous System Diseases
by Hui Li, Ruhui Liu, Junyan Liu and Yi Qu
Biomolecules 2024, 14(12), 1579; https://doi.org/10.3390/biom14121579 - 10 Dec 2024
Viewed by 616
Abstract
Nervous system diseases represent a significant global burden, affecting approximately 16% of the world’s population and leading to disability and mortality. These conditions, encompassing both central nervous system (CNS) and peripheral nervous system (PNS) disorders, have substantial social and economic impacts. Metformin, a [...] Read more.
Nervous system diseases represent a significant global burden, affecting approximately 16% of the world’s population and leading to disability and mortality. These conditions, encompassing both central nervous system (CNS) and peripheral nervous system (PNS) disorders, have substantial social and economic impacts. Metformin, a guanidine derivative derived from a plant source, exhibits therapeutic properties in various health conditions such as cancer, aging, immune-related disorders, polycystic ovary syndrome, cardiovascular ailments, and more. Recent studies highlight metformin’s ability to cross the blood–brain barrier, stimulate neurogenesis, and provide beneficial effects in specific neurological disorders through diverse mechanisms. This review discusses the advancements in research on metformin’s role and mechanisms in treating neurological disorders within both the central and peripheral nervous systems, aiming to facilitate further investigation, utilization, and clinical application of metformin in neurology. Full article
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<p>The mechanism of metformin in the treatment of central nervous system diseases. Solid arrows represent facilitation; T-shaped arrows represent inhibition.</p>
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12 pages, 1291 KiB  
Review
Astrocytic Alterations and Dysfunction in Down Syndrome: Focus on Neurogenesis, Synaptogenesis, and Neural Circuits Formation
by Beatrice Uguagliati and Mariagrazia Grilli
Cells 2024, 13(24), 2037; https://doi.org/10.3390/cells13242037 - 10 Dec 2024
Viewed by 435
Abstract
Down syndrome (DS) is characterized by severe neurodevelopmental alterations that ultimately lead to the typical hallmark of DS: intellectual disability. In the DS brain, since the prenatal life stages, the number of astrocytes is disproportional compared to the healthy brain. This increase is [...] Read more.
Down syndrome (DS) is characterized by severe neurodevelopmental alterations that ultimately lead to the typical hallmark of DS: intellectual disability. In the DS brain, since the prenatal life stages, the number of astrocytes is disproportional compared to the healthy brain. This increase is due to a shift from neuron to astrocyte differentiation during brain development. Astrocytes are involved in numerous functions during brain development, including balancing pro-neurogenic and pro-gliogenic stimuli, sustaining synapse formation, regulating excitatory/inhibitory signal equilibrium, and supporting the maintenance and integration of functional neural circuits. The enhanced number of astrocytes in the brain of DS individuals leads to detrimental consequences for brain development. This review summarizes the mechanisms underlying astrocytic dysfunction in DS, and particularly the dysregulation of key signaling pathways, which promote astrogliogenesis at the expense of neurogenesis. It further examines the implications of astrocytic alterations on dendritic branching, spinogenesis and synaptogenesis, and the impact of the abnormal astrocytic number in neural excitability and in the maintenance of the inhibitory/excitatory balance. Identifying deregulated pathways and the consequences of astrocytic alterations in early DS brain development may help in identifying new therapeutic targets, with the ultimate aim of ameliorating the cognitive disability that affects individuals with DS. Full article
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<p>Schematic representation illustrating the neurons-to-astrocytes shift typical of the developing brain in Down syndrome (DS). (1) Hyperactivation of the Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway promotes astrocytic differentiation, a process influenced by multiple factors, including (2) hypersensitivity to interferon (IFN), (3) overexpression of dual specificity tyrosine-phosphorylation-regulated kinase-1A (DYRK1A), and (4) downregulation of repressor element-1 silencing transcription factor (REST). Additionally, upregulation of the Notch protein in DS (5), partially mediated by DYRK1A overexpression (3), increases the levels of Notch intracellular domain (NICD) (6), which translocates into the nucleus, further promoting astrocytic fate during differentiation. Moreover, NICD promotes the expression of HES1 (7), fostering gliogenesis through the suppression of pro-neurogenic signals. The reduction of the wingless-type MMTV integration site family (WNT)/β-catenin pathway observed in the DS brain (8) participates in the neuron-to-astrocyte shift. Furthermore, DS overexpression of DIRK1A (3) and HES1 (7) contribute to the reduction of the β-catenin pro-neurogenic pathway, which, in turn, promotes NICD signal further fostering astrogliogenesis. Plain arrows indicate the signaling direction, dotted arrows indicate the signaling reduction, and red arrows indicate the typical DS alterations. Created with Biorender.com.</p>
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<p>Schematic representation of the effects of astrocytic alterations on synaptogenesis in Down syndrome (DS) brain development. Reduced dendritic branching and impaired dendritic spine maturation in DS are associated with several astrocytic factors. DS astrocytes produce lower levels of the synaptogenic factor thrombospondin-1 (TSP-1) (1), partially attributable to increased interferon (IFN) hypersensitivity (2). In addition, elevated astrocytic expression of metabotropic glutamate receptor-5 (mGluR5) (3), which is involved in astrocyte–synapse signaling, further contributes to synaptogenesis abnormalities; similar effects are caused by increased astrocytic secretion of insulin-like growth factor binding protein (IGFBP2) (4), which interacts with insulin-like growth factor (IGF) and interferes with synaptogenesis regulation. Moreover, reduced expression of adhesion molecules, such as astrocytic protocadherins (5), impairs cell adhesion/recognition processes during synapse formation. Finally, DS neurons exhibit higher Akt/mammalian target of rapamycin (Akt/mTOR) signaling (6), a pathway involved in synapses regulation, partially mediated by astrocytic secreted paracrine signals (7). Plain arrows indicate the signaling direction, dotted arrows indicate signaling reduction, and red arrows indicate the typical DS alterations. Created with Biorender.com.</p>
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<p>Schematic representation of the effects of astrocytic alterations on neuronal connectivity and neuronal circuits in Down syndrome (DS) brain development. DS exhibit increased calcium fluctuations (1), which can reduce neuronal excitability (2). Moreover, astrocytes play a role in the excitatory/inhibitory (E/I) imbalance typical of DS; overexpression of sodium potassium chloride cotransporter1 (NKCC1) (3) fosters DS GABAergic over-inhibition, further amplified by increased expression of glutamate–aspartate transporter (GLAST) (4) on astrocytic membranes, which, in turn, increases glutamate uptake (5). Plain arrows indicate the signaling direction; red arrows indicate the typical DS alterations. Created with Biorender.com.</p>
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15 pages, 5394 KiB  
Article
Intrauterine Growth Restriction Alters Postnatal Hippocampal Dentate Gyrus Neuron and Microglia Morphology and Cytokine/Chemokine Milieu in Mice
by Frank A. Strnad, Ashley S. Brown, Matthew Wieben, Emilio Cortes-Sanchez, Megan E. Williams and Camille M. Fung
Life 2024, 14(12), 1627; https://doi.org/10.3390/life14121627 - 9 Dec 2024
Viewed by 536
Abstract
Infants born with intrauterine growth restriction (IUGR) have up to a five-fold higher risk of learning and memory impairment than those with normal growth. Using a mouse model of hypertensive diseases of pregnancy (HDP) to replicate uteroplacental insufficiency (UPI), we have previously shown [...] Read more.
Infants born with intrauterine growth restriction (IUGR) have up to a five-fold higher risk of learning and memory impairment than those with normal growth. Using a mouse model of hypertensive diseases of pregnancy (HDP) to replicate uteroplacental insufficiency (UPI), we have previously shown that UPI causes premature embryonic hippocampal dentate gyrus (DG) neurogenesis in IUGR offspring. The DG is a brain region that receives the first cortical information for memory formation. In the current study, we examined the postnatal DG neuron morphology one month after delivery (P28) using recombinant adeno-associated viral labeling of neurons. We also examined DG microglia’s morphology using immunofluorescent histochemistry and defined the hippocampal cytokine/chemokine milieu using Luminex xMAP technology. We found that IUGR preserved the principal dendrite lengths but decreased the dendritic branching and volume of DG neurons. IUGR augmented DG microglial number and cell size. Lastly, IUGR altered the hippocampal cytokine/chemokine profile in a sex-specific manner. We conclude that the prematurely-generated neuronal progenitors develop abnormal morphologies postnatally in a cell-autonomous manner. Microglia appear to modulate neuronal morphology by interacting with dendrites amidst a complex cytokine/chemokine environment that could ultimately lead to adult learning and memory deficits in our mouse model. Full article
(This article belongs to the Special Issue Feature Paper in Physiology and Pathology: 2nd Edition)
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<p>(<b>a</b>) Schematic diagram of the experimental timeline and (<b>b</b>) a cartoon of the recombinant adeno-associated vector (rAAV) construct that labels CaMKII<sup>+</sup> glutamatergic neurons with an enhanced green fluorescent protein (EGFP). Mating mouse pairs were placed into the same cage the night before. A copulated plug the next morning denoted embryonic day (E) 0.5 of pregnancy. We performed sham surgery or IUGR induction via micro-osmotic pump implantation of either a vehicle (0.05% ethanol) or a thromboxane A<sub>2</sub> (TXA<sub>2</sub>)-analog infusion at E12.5. All pups were delivered naturally and cross-fostered to unmanipulated mouse dams. On postnatal day (P) 21, we sedated and injected rAAV-EGFP vectors into the retro-orbital veins. Brains were harvested at P28 for immunohistochemistry.</p>
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<p>The average principal dendrite lengths per DG neuron (μm). Representative immunofluorescent photomicrograph images of the P28 sham and IUGR hippocampal DG are shown (n = 15–20 neurons per section from eight brains in both treatment groups separated by sex). The yellow dotted line denotes the anatomical border between entorhinal cortical neuron axons interfacing with DG neuron dendrites. DG neuron soma are seen at the base of dendrite projections. The box and whisker plots below the photomicrographs show that IUGR did not alter the average principal dendrite lengths per group and sex. NS = not statistically significant with the Kruskal Wallis test.</p>
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<p>The average dendritic volumes per identical brain region (mm<sup>3</sup>). Representative three-dimensional dendritic volume plots of P28 sham and IUGR hippocampal DG are shown (n = 15–20 neurons per section from eight brains in both treatment groups separated by sex). The box and whisker plots show that IUGR decreased the average dendritic volumes in both females and males compared to sex-matched shams. <span class="html-italic">p</span> &lt; 0.05 in IUGR vs. sex-matched shams with the Kruskal Wallis test.</p>
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<p>Representative photomicrographs of Iba1<sup>+</sup> microglia staining in P28 sham and IUGR hippocampal DG (n = 8 brains per group and sex). Red staining has been rendered black and white for ease of viewing of microglial morphology.</p>
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<p>Quantification of Iba1<sup>+</sup> immunofluorescence (IF) per unit area (arbitrary units, n = 8 brains per group and sex). (<b>a</b>) The box and whisker plots show that IUGR females and males had increased Iba1<sup>+</sup> microglial IF per unit of hippocampal DG area, and (<b>b</b>) the Iba1<sup>+</sup> cell sizes were larger compared to sex-matched shams. <span class="html-italic">p</span> &lt; 0.0001 vs. sex-matched shams with Kruskal Wallis test.</p>
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<p>Representative immunofluorescent images of P28 sham and IUGR hippocampal DG green GFP-labeled DG neurons and their dendrites co-staining with red Iba1<sup>+</sup> microglia. The higher magnification images (60x) below each lower magnification image (40x) show the yellow co-staining to highlight that red microglial processes are in direct contact with green DG dendrites/synapses.</p>
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<p>Quantification of P28 hippocampal chemokine levels in sham and IUGR (pg/mL, n = 4 hippocampi/group/sex). Black and dark gray bar graphs denote sham and IUGR males (SM, IM), respectively. Light gray and white bar graphs denote sham and IUGR females (SF, IF), respectively. Sham males and females exhibited sex-specific differences at baseline (** <span class="html-italic">p</span> &lt; 0.05 SM vs. SF). All IUGR offspring decreased hippocampal IL-17A expression (<sup>&amp;</sup> <span class="html-italic">p</span> &lt; 0.005 IM vs. SM and * <span class="html-italic">p</span> &lt; 0.05 IF vs. SF). IUGR males additionally decreased IL-27 (<sup><span>$</span></sup> <span class="html-italic">p</span> &lt; 0.05 IM vs. SM), whereas IUGR females decreased GM-CSF (* <span class="html-italic">p</span> &lt; 0.05 IF vs. SF) but increased IL-2 (<sup>#</sup> <span class="html-italic">p</span> &lt; 0.01 IF vs. SF). Statistical significance was determined by ANOVA with PLSD post hoc test.</p>
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<p>Quantification of P28 hippocampal chemokine levels in sham and IUGR (pg/mL, n = 4 hippocampi/group/sex). Black and dark gray bar graphs denote sham and IUGR males (SM, IM), respectively. Light gray and white bar graphs denote sham and IUGR females (SF, IF), respectively. IUGR males increased CCL4 compared to sham males (* <span class="html-italic">p</span> &lt; 0.05). Statistical significance was determined by ANOVA with PLSD post hoc test.</p>
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9 pages, 3029 KiB  
Case Report
Two Different Brain Injury Patterns Associated with Compound Heterozygosis of the PIGO Gene in a Term Newborn: A Case Report
by Francesco Dellepiane, Giulia Moltoni, Sara Ronci, Alessia Guarnera, Maria Camilla Rossi-Espagnet, Maria Cristina Digilio, Diego Martinelli, Francesca Campi and Daniela Longo
Biomedicines 2024, 12(12), 2779; https://doi.org/10.3390/biomedicines12122779 - 6 Dec 2024
Viewed by 446
Abstract
The glycosylphosphatidylinositol (GPI) is a glycol–lipid that anchors several proteins to the cell surface. The GPI-anchor pathway is crucial for the correct function of proteins involved in cell function, and it is fundamental in early neurogenesis and neural development. The PIG gene family [...] Read more.
The glycosylphosphatidylinositol (GPI) is a glycol–lipid that anchors several proteins to the cell surface. The GPI-anchor pathway is crucial for the correct function of proteins involved in cell function, and it is fundamental in early neurogenesis and neural development. The PIG gene family is a group of genes involved in this pathway with six genes identified so far, and defects in these genes are associated with a rare inborn metabolic disorder manifesting with a spectrum of clinical phenotypes in newborns and children. Among them, the PIGO gene encodes for phosphatidylinositol glycan anchor biosynthesis class O protein (PIGO), an enzyme participating in this cascade, and the loss of its function often leads to a severe clinical picture characterized by global developmental delay, seizures, Hirschsprung disease, and other congenital malformations. To date, 19 patients with confirmed PIGO deficiency have been described in the literature with a host of clinical and radiological manifestations. We report a case of a male term newborn with two compound heterozygous variants of the PIGO genes, presenting with encephalopathy, drug-resistant epilepsy, and gastrointestinal abnormalities. Brain MRI first showed diffusion restriction in the ponto-medullary tegmentum, ventral mesencephalon, superior cerebellar peduncles, cerebral peduncles, and globi pallidi. This pattern of lesion distribution has been described as part of the neuroradiological spectrum of PIG genes-related disorders. However, after one month of life, he also showed a previously undescribed MRI pattern characterized by extensive cortical and subcortical involvement of the brain hemispheres. The presence of two different mutations in both the PIGO genes may have been responsible for the particularly severe clinical picture and worse outcome, leading to the death of the newborn in the sixth month of life despite therapeutic attempts. This case expands the neuroradiological spectrum and may bring new insights on glycosylation-related disorders brain manifestations. Full article
(This article belongs to the Special Issue Understanding Diseases Affecting the Central Nervous System)
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<p>The first MRI at 15 days of life shows a “mild” pattern with no evident abnormalities of the brain cortex and WM (<b>a</b>,<b>b</b>) but diffusion restriction of the midbrain tegmentum (<b>c</b>) and cerebral peduncles (<b>d</b>) on DWI (arrows).</p>
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<p>The MRI performed at 35 days shows a “severe” pattern with diffuse T2 hyperintensity of the brain cortex and WM, which is prevalent in the parieto-temporo-occipital lobes ((<b>a</b>–<b>c</b>), red arrowheads), pairing with a significant diffusion restriction in the same regions ((<b>d</b>–<b>f</b>), yellow arrowheads). There is also diffusion restriction of the corpus callosum, consistent with pre-Wallerian degeneration ((<b>e</b>), red arrow), and persistent diffusion restriction in the midbrain ((<b>d</b>), yellow arrow).</p>
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<p>The last MRI, performed after an additional 2 months, shows overall brain tissue shrinkage and ventricle/subarachnoid space dilatation, cystic and gliotic degeneration of the WM, particularly in the previously involved parieto-temporo-occipital lobes characterized by T2 hyperintensity ((<b>a</b>–<b>c</b>), arrowheads) with resolution of diffusion restriction on DWI (<b>f</b>). There is persistent diffusion restriction of the midbrain tegmentum (<b>d</b>) and basal ganglia (<b>e</b>) (arrows).</p>
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20 pages, 3365 KiB  
Article
A Morphological and Behavioral Study of Demyelination and Remyelination in the Cuprizone Model: Insights into APLNR and NG2+ Cell Dynamics
by Boycho Landzhov, Lyubomir Gaydarski, Stancho Stanchev, Ivanka Kostadinova, Alexandar Iliev, Georgi Kotov, Pavel Rashev, Milena Mourdjeva, Despina Pupaki and Nikola Stamenov
Int. J. Mol. Sci. 2024, 25(23), 13011; https://doi.org/10.3390/ijms252313011 - 3 Dec 2024
Viewed by 534
Abstract
Multiple sclerosis (MS) is a chronic neurodegenerative disorder involving demyelination. The cuprizone model is commonly used to study MS by inducing oligodendrocyte stress and demyelination. The subventricular zone (SVZ) plays a key role in neurogenesis, while the neuronal/glial antigen 2 (NG2) is a [...] Read more.
Multiple sclerosis (MS) is a chronic neurodegenerative disorder involving demyelination. The cuprizone model is commonly used to study MS by inducing oligodendrocyte stress and demyelination. The subventricular zone (SVZ) plays a key role in neurogenesis, while the neuronal/glial antigen 2 (NG2) is a marker for immature glial cells, involved in oligodendrocyte differentiation. The apelin receptor (APLNR) is linked to neurogenesis and behavior modulation. This study explores the role of APLNR in NG2-positive cells during de- and remyelination phases in the experimental cuprizone mouse model. Thirty male C57BL/6 mice were divided into control (not treated), demyelination (5 weeks cuprizone administration), and remyelination (5 weeks cuprizone administration + 5 weeks recovery) groups. Histological examinations, immunohistochemistry, and immunofluorescence on serial coronal sections were conducted to evaluate corpus callosum (CC) morphology and APLNR and NG2 expression in the SVZ, in addition to behavioral assessments. The histological analysis showed a significant reduction in the CC’s thickness and area after five weeks of cuprizone exposure, followed by recovery five weeks post-exposure. During the demyelination phase, APLNR-expressing cells peaked while NG2-positive cells decreased. In the remyelination phase, APLNR-expressing cells declined, and NG2-positive cells increased. Confocal microscopy confirmed the co-localization of NG2 and APLNR markers. Statistically significant differences were observed across experimental groups. Correlation analyses highlighted associations between APLNR/NG2 cell counts and CC changes. Behavioral tests revealed impaired motor coordination and memory during demyelination, with gradual recovery during remyelination. Significant changes in the CC structure and the number of APLNR and NG2-positive cells were observed during de- and remyelination, suggesting that NG2-positive cells expressing APLNR may play a key role in remyelination. Full article
(This article belongs to the Section Molecular Neurobiology)
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<p>(<b>A</b>)—Luxol fast blue/Cresyl violet staining for visualization of the corpus callosum. Control group (CO); (<b>B</b>)—demyelination group (DE); (<b>C</b>)—remyelination group (RE). Scale bar—250 μm; (<b>D</b>)—graphical representation of the parameters area (μm<sup>2</sup>) and thickness (μm) of corpus callosum (<b>E</b>) in the control group (CO); demyelination group (DE); remyelination group (RE) presented with box and whisker plot showing the mean (x), surrounded by a ‘box’, the vertical edge of which is the interval between the lower and upper quartile [25–75%]. ‘Whiskers’ originating from this ‘box’ represent the non-outlier range. *—<span class="html-italic">p</span> &lt; 0.001.</p>
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<p>Immunohistochemical staining for apelin receptor (APLNR) in the control group (<b>A</b>); demyelination group (<b>C</b>); remyelination group (<b>E</b>). Immunohistochemical staining for neuronal/glial antigen 2 (NG2) in the control group (<b>B</b>); demyelination group (<b>D</b>); remyelination group (<b>F</b>). Scale bar—25 μm. Black arrow heads pointing positive cells.</p>
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<p>Immunofluorescence confocal microscopy. Green marks the apelin receptor (APLNR), red—neuro/glial antigen (NG2), blue—Hoechst for nuclear visualization; negative control—((<b>A</b>–<b>C</b>) Scale bar 20 μm); control group—((<b>D</b>–<b>F</b>) Scale bar 20 μm); demyelination group—((<b>G</b>–<b>I</b>) Scale bar 30 μm); remyelination group—((<b>J</b>–<b>L</b>) Scale bar 20 μm.). Graphical representation of the number of cells expressing APLNR (<b>M</b>); NG2 (<b>N</b>) and cells with co-localization of APLNR/NG2 (<b>O</b>), presented with box and whisker plot showing the mean (x), surrounded by a ‘box’, the vertical edge of which is the interval between the lower and upper quartile [25–75%]. ‘Whiskers’ originating from this ‘box’ represent the non-outlier range. CO—control group; DE—demyelination group; RE—remyelination group. *—<span class="html-italic">p</span> &lt; 0.001.</p>
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<p>Graphical representation of correlations between the area of corpus callosum and the number of cells expressing apelin receptor (APLNR) in the control group (<b>A</b>), r = −0.21, <span class="html-italic">p</span> = 0.1; demyelination group (<b>C</b>), r = −0.52, <span class="html-italic">p</span> &lt; 0.001; remyelination group (<b>E</b>) r = 0.31, <span class="html-italic">p</span> = 0.02. Graphical representation of correlations between the area of corpus callosum and the number of cells expressing neuronal/glial antigen 2 (NG2) in the control group (<b>B</b>) r = 0.22, <span class="html-italic">p</span> = 0.09; demyelination group (<b>D</b>) r = 0.46, <span class="html-italic">p</span> &lt; 0.001; remyelination group (<b>F</b>) r = 0.39, <span class="html-italic">p</span> = 0.003.</p>
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<p>Graphical representation of correlations between the thickness of corpus callosum and the number of cells expressing apelin receptor (APLNR) in the control group (<b>A</b>) r = −0.20, <span class="html-italic">p</span> = 0.1; demyelination group (<b>C</b>) r = −0.50, <span class="html-italic">p</span> &lt; 0.001; remyelination group (<b>E</b>) r = 0.34, <span class="html-italic">p</span> = 0.007. Graphical representation of correlations between the thickness of corpus callosum and the number of cells expressing neuronal/glial antigen 2 (NG2) in the control group (<b>B</b>) r = 0.25, <span class="html-italic">p</span> = 0.09; demyelination group (<b>D</b>) r = 0.48, <span class="html-italic">p</span> &lt; 0.001; remyelination group (<b>F</b>) r = 0.41, <span class="html-italic">p</span> = 0.003.</p>
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<p>Graphical representation of the results of the performed behavior test. (<b>A</b>)—The rotarod test performed once weekly during the demyelination and remyelination period. The results are presented as mean ± SEM. * <span class="html-italic">p</span> &lt; 0.05—Statistically significant improvement in motor coordination between weeks 2 and 9, ** <span class="html-italic">p</span> &lt; 0.01—between weeks 3 and 10 in the demyelination and remyelination group; (<b>B</b>)—the passive avoidance test performed once weekly during the demyelination and remyelination period. The results are presented as mean ± SEM. ** <span class="html-italic">p</span> &lt; 0.01—statistically significant increase in latency time was observed between weeks 3 and 9, 3 and 10 when comparing periods of demyelination and remyelination.</p>
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<p>Graphical representation of changes in mean values for (<b>A</b>) corpus callosum area (μm<sup>2</sup>), (<b>B</b>) corpus callosum length (μm), (<b>C</b>) latency time in the rotarod test (s), (<b>D</b>) latency time in the passive avoidance test (s), and number of (<b>E</b>) APLNR-positive cells and (<b>F</b>) NG2-positive cells in the subventricular zone across control (CO), demyelination (DE), and remyelination (RE) groups.</p>
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21 pages, 2794 KiB  
Review
The BDNF-Interactive Model for Sustainable Hippocampal Neurogenesis in Humans: Synergistic Effects of Environmentally-Mediated Physical Activity, Cognitive Stimulation, and Mindfulness
by Mohamed Hesham Khalil
Int. J. Mol. Sci. 2024, 25(23), 12924; https://doi.org/10.3390/ijms252312924 - 1 Dec 2024
Viewed by 755
Abstract
This paper bridges critical gaps through proposing a novel, environmentally mediated brain-derived neurotrophic factor (BDNF)-interactive model that promises to sustain adult hippocampal neurogenesis in humans. It explains how three environmental enrichment mechanisms (physical activity, cognitive stimulation, and mindfulness) can integratively regulate BDNF and [...] Read more.
This paper bridges critical gaps through proposing a novel, environmentally mediated brain-derived neurotrophic factor (BDNF)-interactive model that promises to sustain adult hippocampal neurogenesis in humans. It explains how three environmental enrichment mechanisms (physical activity, cognitive stimulation, and mindfulness) can integratively regulate BDNF and other growth factors and neurotransmitters to support neurogenesis at various stages, and how those mechanisms can be promoted by the physical environment. The approach enables the isolation of specific environmental factors and their molecular effects to promote sustainable BDNF regulation by testing the environment’s ability to increase BDNF immediately or shortly before it is consumed for muscle repair or brain update. This model offers a novel, feasible method to research environment enrichment and neurogenesis dynamics in real-world human contexts at the immediate molecular level, overcoming the confounds of complex environment settings and challenges of long-term exposure and structural plasticity changes. The model promises to advance understanding of environmental influences on the hippocampus to enhance brain health and cognition. This work bridges fundamental gaps in methodology and knowledge to facilitate more research on the enrichment–neuroplasticity interplay for humans without methodological limitations. Full article
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<p>A conceptual molecularly mediated model for hippocampal neurosustainability.</p>
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<p>The path between environmental enrichment and hippocampal neurosustainability in humans, where solid lines represent linear and dotted lines inverse relationships.</p>
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<p>The role of BDNF with neurotransmitters in mediating depression, hippocampal neurogenesis and neurosustainability, and cerebral neuroplasticity.</p>
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<p>BDNF dynamics with cognitive stimulation, physical activity, and mindfulness.</p>
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<p>Environmental enrichment framework for hippocampal neurosustainability in humans.</p>
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<p>Mechanisms of BDNF increase for neurosustainability.</p>
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25 pages, 436 KiB  
Review
Exploring the Complex Relationship Between Antidepressants, Depression and Neurocognitive Disorders
by Monica Neațu, Iulia Ioniță, Ana Jugurt, Eugenia Irene Davidescu and Bogdan Ovidiu Popescu
Biomedicines 2024, 12(12), 2747; https://doi.org/10.3390/biomedicines12122747 - 30 Nov 2024
Viewed by 614
Abstract
The coexistence of dementia and depression in older populations presents a complex clinical challenge, with each condition often exacerbating the other. Cognitive decline can intensify mood disturbances, and untreated or recurring depression accelerates neurodegenerative processes. As depression is a recognized risk factor for [...] Read more.
The coexistence of dementia and depression in older populations presents a complex clinical challenge, with each condition often exacerbating the other. Cognitive decline can intensify mood disturbances, and untreated or recurring depression accelerates neurodegenerative processes. As depression is a recognized risk factor for dementia, it is crucial to address both conditions concurrently to prevent further deterioration. Antidepressants are frequently used to manage depression in dementia patients, with some studies suggesting they offer neuroprotective benefits. These benefits include promoting neurogenesis, enhancing synaptic plasticity, and reducing neuroinflammation, potentially slowing cognitive decline. Additionally, antidepressants have shown promise in addressing Alzheimer’s-related pathologies by reducing amyloid-beta accumulation and tau hyperphosphorylation. However, treatment-resistant depression remains a significant challenge, particularly in older adults with cognitive impairment. Many do not respond well to standard antidepressant therapies due to advanced neurodegenerative changes. Conflicting findings from studies add to the uncertainty, with some research suggesting that antidepressants may increase dementia risk, especially when used in patients with undiagnosed early-stage dementia. This article aims to explore the intricate relationship between depression and dementia, examining the benefits and risks of antidepressant use. We highlight the urgent need for personalized, comprehensive treatment strategies that balance mental health improvement with cognitive protection. Full article
(This article belongs to the Special Issue Antidepressants: 70 Years)
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