Androgen receptor immunoreactivity in specific neural regions in normal and hypogonadal male mice: effect of androgens

This study examined the distribution and regulation of androgen receptor im munoreactivity (IR) in the brain of the hypogonadal (hpg) male mouse, genet ically deficient in GnRH. Five groups of animals were studied: intact, cast rated, or castrated and testosterone propionate (TP)-treated normal adult m ale mice, and intact or TP-treated hpg adult male mice. All groups were stu died 1 week after treatment. Five regions of the brain with high concentrat ions of androgen receptors in normal animals were examined, including the m edial preoptic area, the lateral ventral septum, the ventromedial hypothala mus, the bed nucleus of the stria terminalis and the medial amygdala. The r esults showed that the congenital absence of GnRH results in minimal expres sion of androgen receptor-IR in mice in all regions examined. However, trea tment with exogenous testosterone for 1 week was sufficient to induce the n umbers of neurons containing androgen receptors, as detected by immunocytoc hemistry, into the range seen in normal male mice in all the areas studied except the VMH. Similar plasticity was also observed in normal males after 1 week of castration and TP replacement. (C) 1999 Elsevier Science B.V. All rights reserved.