Glucocorticoids affect gonadotropin-releasing hormone immunoreactivity in musk shrew brain

Multiple interactions between the hypothalamic-pituitary-adrenal and the hy pothalamic-pituitary-gonadal systems exist. In this study, we asked if gluc ocorticoid administration affected gonadotropin-releasing hormone (GnRH) im munoreactivity. We found that musk shrews treated with dexamethasone (DEX), a synthetic glucocorticoid, had more GnRH-immunoreactive (ir) cells in the forebrain than did cortisol- or control-treated animals. The effects of DE X were noted rapidly, within 15 min, after administration. These effects we re observed in the forebrain as a whole and also in specific subpopulations of GnRH-ir cells located in the medial septum/diagonal band and the hypoth alamus. (C) 2001 Academic Press.