Fos expression in gonadotropin-releasing hormone neurons by naloxone or bicuculline in intact male rats.

Double immunocytochemistry for Fos and GnRH was performed after the intravenous infusion of naloxone or bicuculline. Either naloxone or bicuculline significantly increased serum LH concentrations. After the naloxone infusion, some Fos-positive GnRH neurons were found from the preoptic area to the basal hypothalamic area, whereas those were found from the diagonal band of Broca to the preoptic area after the bicuculline infusion. These results suggest the distribution of GnRH neurons activated by naloxone and bicuculline in intact male rats.