Stereological analysis of astrocyte and microglia in aging mouse hippocampus

Recent evidence suggests neuroglia-mediated inflammatory mechanisms may sti mulate neurodegenerative processes in mammalian brain during aging. To test the hypothesis that the number of microglia and astrocytes increase in the hippocampus during normal aging, unbiased stereological techniques were us ed to estimate total cell number in hippocampal subregions (CAI, dentate gy rus and hilus) of male C57BL/6J mice of different ages: 4-5 months, 13-14 m onths and 27-28 months. Immunocytochemical visualization for microglia and astrocytes were via Mac-1 and GFAP antibody, respectively. Estimates of tot al microglia and astrocyte number were assessed using the optical fractiona tor. No statistically significant age differences were found in the numbers of microglia or astrocytes in the hippocampal regions sampled. These findi ngs suggest that age-related increases in the total numbers of hippocampal microglia and astrocytes is not causal for observed age-related increases i n cytokine response. (C) 1998 Elsevier Science Inc.