Autoradiographic localization of estrogen and androgen receptors in the sexually dimorphic area and other regions of the gerbil brain.

Autoradiography was used to localize sex hormone-accumulating cells in the gerbil brain. Some areas had a high density of both androgen and estrogen receptors. These areas included the lateral septum, the bed nucleus of the stria terminalis, the medial and cortical amygdaloid nuclei, the medial preoptic area (MPOA), the arcuate nucleus, the ventromedial hypothalamus, and the periventricular central gray. This distribution of hormone receptors agrees closely with that seen in other mammals. In contrast to what has been reported for other species, the distribution of estradiol-accumulating cells in the gerbil MPOA is different in males and females. Estradiol uptake in the posterior MPOA followed the morphology of a sexually dimorphic area (SDA) and was therefore sexually dimorphic. Moreover, the percentage of SDA cells that accumulated estradiol appeared to be higher in males than in females. The pattern of androgen accumulation also followed the morphology of the SDA but differed from the pattern of estrogen accumulation in one way. The uptake of 5 alpha-dihydrotestosterone in the SDA pars compacta (pc), a component of the SDA, was much greater than in the rest of the SDA. This was not true for estradiol. Since most females lack the SDApc, androgen uptake in the gerbil SDA may also be sexually dimorphic. Androgen uptake was more widespread than estrogen uptake in the brainstem. Brainstem nuclei that accumulated 5 alpha-dihydrotestosterone included the locus ceruleus, the dorsal raphe, the hypoglossal nucleus, the area postrema, the nucleus of the solitary tract, and the dorsal nucleus of the vagus.