Sonam Akther: "Regional characterization of mouse cerebellar glycogen"

PhD student, Hirase Lab

Abstract
Glycogen, a branched polymer of glucose, is an intermediate form of energy reserve for mammalian body that is readily mobilized upon demand. While most glycogen is stored in the liver and muscles, a small fraction is stored in the brain. Astrocytes, a major glial cell type, have been identified to store glycogen in brain, and recent studies have demonstrated glycogen consumption in the forebrain is linked to learning and memory consolidation in experimental animals. Despite the importance of glycogen in memory formation, the brain-wide distribution of glycogen has not been described in detail until recently. In 2016, Oe et al. characterized the distribution of glycogen by immunohistochemistry with detailed descriptions in forebrain in mice. However, the glycogen distribution of the cerebellar cortex has remained poorly characterized despite the known abundance of glycogen. Here, I took a similar approach to characterize glycogen distribution in the mouse cerebellum. Similar to the forebrain, Bergmann glia, a radial glial cell type, considered to be analogous to forebrain astrocytes, were found to contain high glycogen immunohistochemical signals in their processes. We also observed large glycogen puncta surrounding Purkinje neuron somata. Co-localization of these large puncta with Bergmann glia somata was not very obvious, which indicates another different cellular structure might contain glycogen. Moreover, molecular layer has the highest glycogen, which is conceivably correlated to the high synapse density formed by parallel fibers. We are currently investigating the detailed distribution of cerebellar glycogen at the subcellular level.