SELECTIVE ACTIVATION OF ANDROGEN RECEPTORS IN THE SUBCORTICAL BRAIN OF MALE CYNOMOLGUS MACAQUES BY PHYSIOLOGICAL HORMONE LEVELS AND ITS RELATIONSHIP TO ANDROGEN-DEPENDENT AROMATASE-ACTIVITY

Aromatase activity (AA) is androgen dependent and independent in subco rtical regions of the nonhuman primate brain, but the correlation of a ndrogen receptor (AR) content with AA has not been demonstrated. Thus, we castrated 10 adult male cynomolgus monkeys (Macaca fasicularis) an d divided them into 2 groups. One group (n = 6) received empty Silasti c capsules, whereas the second group (n = 4) received Silastic capsule s filled with testosterone (T). Animals were killed after 3 weeks. Mic rosomal AA and cytosolic and nuclear AR were determined in specific br ain regions dissected from frozen sections. Sera from T-treated subjec ts contained T, dihydrotestosterone, and LH levels that were not signi ficantly different from the precastration amounts (P < 0.05). Cytosoli c AR concentrations declined after T treatment in 12 of 20 brain areas studied (P < 0.05). Nuclear AR levels, on the other hand, were signif icantly elevated after T treatment (activated) only in the ventral med ial nucleus (VMN) and infundibular nucleus/median eminence (P < 0.05). AA distribution was significantly different (P < 0.05) among 20 brain nuclei and subregions. The highest activities were found in the bed n ucleus of the stria terminalis, the medial preoptic area, the medial a nd cortical amygdala, and the VMN. Lesser activities were found in oth er brain regions. Physiological concentrations of T increased AA only in the VMN and infundibular nucleus-median eminence (P < 0.05). These data suggest that physiological levels of androgens are effective in r egulating AA only in those brain areas in which AR are activated.