Diurnal and stimulated astrocyte morphology dynamics in the rodent central nervous system

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.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Molecular & Integrative Physi

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Rosenberg, Harry

Contributors dc:contributor

• Gillette, Martha U.
• Gillette, H R
• Raetzman, Lori T.
• Rhodes, Justin S.
• Sweedler, Jonathan V.

• suprachiasmatic nucleus (SCN)
• dentate gyrus
• glial fibrillary acidic protein (GFAP)
• circadian rhythms
• astrocytes

Statement dc:rights

• Copyright 2015 Harry Rosenberg

Handle dc:identifier

http://hdl.handle.net/2142/78704

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/78704