Neuro-glial underpinning mechanisms in myelin plasticity for memory enhancement

Background and aim: Learning continually shapes our neuronal circuits to form new memories. Neural plasticity was considered as the principal mechanism for learning many decades ago. Although myelin was considered for a long time as static inert insulator, recent studies showed that myelination is dynamically changed to enhance neuronal activity under neural plasticity umbrella in terms of myelin plasticity, so our study aims to figure out the underlying mechanisms of myelin plasticity associated with learning and memory. Hypothesis: We hypothesized that many mechanisms promote memory consolidation by enhancing myelination and that glial cells have a crucial role in this myelin plasticity effect. Methods: The study was conducted on 24 rats, divided into 3 groups, with 8 rats in each; Group I (control); rats remained in their home cage, Group II (control untrained); rats were allowed to move and explore the maze for equal time but there was no active platform location learning, and Group III (trained); rats were trained using Barnez maze behavior test including three days of acquisition trials (AT), followed by two probe trials (PT). The gene expression analysis for SOX10, MYRF, NRG, EDGF, SERPINE2 and MBP was evaluated by qRT-PCR in hippocampus tissues, in addition, histopathological assessment was done with immunohistochemistry for Myelin Basic Protein (MBP), Glial Fibrillary Acidic Protein (GFAP), and Gallyas-Braak Silver staining. Furthermore, Pearson correlation was done comparing all genes with MBP expression. Results and data: The present study showed improved spatial memory with increased myelination in the trained group compared to all other groups (P<0.001), in addition to increase of SOX10, and MYRF expression in the trained group indicating more OPC differentiation into mature oligodendrocytes (P<0.001). NRG and EDGF were highly expressed in the trained group compared to other groups, in addition to the marked increase of number of the neuronal cells with more dendrites formation. SERPINE 2 and GFAP as markers of astrocytes showed high expression in the trained group in comparison with other groups (P<0.001) with strong positive correlation between SEPRINE 2 and MBP (r= 0.76, P=0.02). Conclusion: Myelin plasticity as one of the crucial learning mechanisms, was influenced by different neural and environmental signals. Although role of glial cells was almost apparent in oligodendrocytes differentiation and proliferation, there was a significant role of astrocytes in promoting such myelination effect. There were no external funding sources for this study, it is self-funding This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.