Androgen and estrogen receptors coexist within individual neurons in the brain of the Syrian hamster.

Many aspects of reproductive neuroendocrine function and sexual behavior are responsive to both androgens and estrogens, suggesting that receptors for these steroid hormones may reside within single cells in brain regions that control reproductive function. We determined the distribution of estrogen receptor-containing neurons in 40-microns coronal brain sections in gonadectomized, DHT-treated male Syrian hamsters using immunocytochemistry with the H222 antibody (10 micrograms/ml; Abbott Laboratories). Subsequently, we colocalized estrogen receptors with androgen receptors using the PG-21 antibody (0.5 microgram/ml; G.S. Prins). In males, the distribution of estrogen receptor-containing neurons was similar to that reported previously for the female hamster. Colocalization of androgen and estrogen receptor immunoreactivity was observed in brain regions that contain numerous androgen and estrogen receptor-positive neurons, including subdivisions of the medial preoptic area, bed nucleus of the stria terminals, ventromedial nucleus of the hypothalamus, and the amygdalohippocampal area. Single-labelled estrogen receptor-containing neurons were most numerous in the amygdalohippocampal area and the rostral medial preoptic nucleus; androgen receptor-immunoreactive cells were most abundant in the ventral premammillary nucleus and the lateral septum. These data suggest the potential of androgens and estrogens to influence neuronal function within individual steroid receptor-containing neurons of the hamster limbic system.