Enhanced glial fibrillary acidic protein RNA response to fornix transection in aged mice.
The effects of age on basal and lesion-induced changes in astrocyte RNA messages reported to respond to neurodegeneration were examined in the mouse brain. The first study found an age-related increase in glial fibrillary acidic protein RNA throughout the brain. Other astrocyte RNAs remained generally stable with age. We hypothesize this increase is due to astrocytes undergoing a mild reaction to the small amount of synaptic degeneration occurring with usual aging. To test this theory, we used an experimental model of modest synaptic loss in the hippocampus by transecting the fimbria/fornix bundle in mice and examined the same series of messages. In situ hybridization revealed the expected increase in glial fibrillary acidic protein RNA after the lesion; however, we unexpectedly found that aged mice showed a greater magnitude of this response, which appeared to develop more slowly. There was no significant change in the hippocampus for any of the other messages, although responses were observed at the site of transection. This study supports the idea that the age-related increase in glial fibrillary acidic protein may be secondary to modest synaptic degeneration. We also demonstrated an exaggerated reactive astrocytic response in aged mice, which may be associated with age-related deficits in reactive synaptogenesis and behavioral recovery in normal aging.
Goss
J R
JR
Division of Neurogerontology, Andrus Gerontology Center, University of Southern California, Los Angeles.
Morgan
D G
DG
D000375:Aging; D000682:Amyloid / Q000235:genetics; D000818:Animals; D001057:Apolipoproteins E / Q000235:genetics; D001253:Astrocytes / Q000378:metabolism*; D001921:Brain / Q000378:metabolism*; D001931:Brain Mapping; D051152:Clusterin; D015870:Gene Expression; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics*; D005974:Glutamate-Ammonia Ligase / Q000235:genetics; D006023:Glycoproteins / Q000235:genetics; D006624:Hippocampus / Q000293:injuries*; D017403:In Situ Hybridization; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018832:Molecular Chaperones; D009410:Nerve Degeneration; D000072002:Prion Proteins; D011328:Prions; D011498:Protein Precursors / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D009418:S100 Proteins / Q000235:genetics
D000682:Amyloid; D001057:Apolipoproteins E; C495243:Clu protein, mouse; D051152:Clusterin; D005904:Glial Fibrillary Acidic Protein; D006023:Glycoproteins; D018832:Molecular Chaperones; D000072002:Prion Proteins; D011328:Prions; C512657:Prnp protein, mouse; D011498:Protein Precursors; D012333:RNA, Messenger; D009418:S100 Proteins; D005974:Glutamate-Ammonia Ligase