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Title:Diurnal and stimulated astrocyte morphology dynamics in the rodent central nervous system
Author(s):Rosenberg, Harry
Director of Research:Gillette, Martha U.
Doctoral Committee Chair(s):Gillette, Martha U.
Doctoral Committee Member(s):Gillette, H R; Raetzman, Lori T.; Rhodes, Justin S.; Sweedler, Jonathan V.
Department / Program:Molecular & Integrative Physl
Discipline:Molecular & Integrative Physi
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):suprachiasmatic nucleus (SCN)
dentate gyrus
glial fibrillary acidic protein (GFAP)
circadian rhythms
Abstract:Cellular heterogeneity between brain regions has been attributed to differences in neurons, although differences between astrocytic glia of distinct brain regions are emerging. Relatively little is understood concerning heterogeneity in astrocyte structural dynamics between brain regions. The following studies report differences in structural complexities and diurnal morphological dynamics between astrocytes of the hippocampal dentate gyrus (DG) and suprachiasmatic nucleus (SCN). Glial fibrillary acidic protein (GFAP) branch terminal-points are significantly less numerous in the DG than the SCN. Terminal-points increase and decrease in complexity throughout the day-night cycle. Branching peaks at early night in the DG, but at early day in the SCN. Daily changes in cytoskeleton architecture in the DG and SCN are mediated by protein reorganization and not turnover. Light is necessary for astrocyte rhythms, as both brain regions do not exhibit morphology changes in constant darkness. Light exposure at early night rapidly alters astrocyte branch complexity in both the DG and SCN, but in opposite ways. The effect of light on astrocyte complexity in the SCN, but not DG, is mediated by glutamatergic signaling. Astrocyte remodeling in the SCN upon dehydration is similar to effects in the supraoptic nucleus (SON), but no dehydration changes are seen in the DG. These findings extend recent observations of astrocyte heterogeneity with evidence for daily, region-specific structural remodeling. They also provide evidence for a role of light signaling in modulating astrocyte structure. The relative timing of high-low astrocyte complexity suggests that daily changes in astrocyte morphology in the DG and SCN may promote functional changes in neuronal activity and solute diffusion.
Issue Date:2015-01-13
Rights Information:Copyright 2015 Harry Rosenberg
Date Available in IDEALS:2015-07-22
Date Deposited:May 2015

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