title: Gonadal steroids regulate number of astrocytes immunostained for glial fibrillary acidic protein in mouse hippocampus.
abstract: The aim of this study was to determine the effect of sex and sex steroids on the distribution of glial fibrillary acidic protein (GFAP) -containing astrocytes in the hippocampal CA1 region of normal, testicular feminized (Tfm/Y) and hypogonadal (hpg) mice. The number of GFAP-immunoreactive (GFAP-IR) cells, assessed by immunohistochemistry, was significantly higher in Tfm/Y and hpg mice than in normal mice. There was no significant sex difference in numbers of GFAP-IR cells in either strain, and no effect of gonadectomy on GFAP-IR cell number in normal mouse hippocampus. In adult male hpg mice, the higher GFAP expression was reduced to normal following treatment with either testosterone or estradiol-17beta, but not 5alpha-dihydrotestosterone. Administration of testosterone from birth significantly reduced the number of hippocampal GFAP-IR cells in both normal and hpg adult mice. These data strongly suggest that the increased number of GFAP-IR astrocytes in the hippocampus is due to the congenital absence of gonadal steroids in hpg mice and androgen insensitivity in Tfm/Y mice. Our findings have important implications for our understanding of the sex steroid modulation of astrocyte reactivity and show that a remarkable degree of plasticity is retained throughout life.
authors.affiliation: MRC Brain Metabolism Unit, Department of Pharmacology, University of Edinburgh, 1 George Square, Edinburgh EH8 9JZ, Scotland.
authors.forename: J K
authors.initials: JK
authors.lastname: McQueen
authors.forename: R C
authors.initials: RC
authors.lastname: Dow
authors.forename: G
authors.initials: G
authors.lastname: Fink