Region-specific regulation of cytochrome P450 aromatase messenger ribonucleic acid by androgen in brains of male rhesus monkeys

We demonstrated previously that testosterone regulates aromatase activity i n the anterior/dorsolateral hypothalamus of male rhesus macaques. To determ ine the level of the androgen effect, we developed a ribonuclease protectio n assay to study the effects of testosterone or dihydrotestosterone (DHT) o n aromatase (P450(AROM)) mRNA in selected brain areas. Adult male rhesus mo nkeys were treated with testosterone or DHT. Steroids in serum were quantif ied by RIA. Fourteen brain regions were analyzed for P450(AROM) mRNA. Signi ficant elevations of its message over controls (P < 0.05) were found in the medial preoptic area/anterior hypothalamus of both androgen treatment grou ps and the medial basal hypothalamus of the testosterone-treated males. Oth er brain areas were not affected by androgen treatment. We conclude that te stosterone and DHT regulate P450(AROM) mRNA in brain regions that mediate r eproductive behaviors and gonadotropin release. The P450(AROM) mRNA of othe r brain areas is not androgen dependent. Brain-derived estrogens may also b e important for maintaining neural circuitry in brain areas not related to reproduction. The control of P450(AROM) mRNA in these areas may differ from what we report here, but it is equally important to understand the functio n of in situ estrogen formation in these areas.