Autoradiographic localization of 3H-dihydrotestosterone in the preoptic area, hypothalamus, and amygdala of a male rhesus monkey.

In a preliminary study, autoradiography was used to localize target cells for 3H-dihydrotestosterone (DHT), a non-aromatizable androgen, in the brain of the rhesus monkey. One castrated male was injected intravenously with 2 mCi of 3H-DHT (0.42 microgram/kg), and was killed one hour later. Neurons that concentrated radioactivity in their nuclei were located in widespread areas of the brain, which included the medial and suprachiasmatic preoptic nuclei, bed nucleus of the stria terminalis, lateral septal nucleus, anterior hypothalamic area, ventromedial, arcuate, dorsomedial, and paraventricular hypothalamic nuclei, ventral premammillary nucleus, and medial, cortical, basal accessory, and lateral amygdaloid nuclei. These results indicate that the topographic distribution of androgen target neurons is considerably wider than that observed in a study using 3H-testosterone (T) in the male rhesus monkey (1). However, further work is needed to elucidate these differences before attempting correlations between behavioral activity and androgen receptors in the brain.