Testosterone regulates aromatase activity in discrete brain areas of male rhesus macaques.
The nonhuman primate brain contains two divergent pathways for testosterone (T) metabolism. Estradiol is biosynthesized from T by aromatization through the first pathway, whereas dihydrotestosterone is produced by the action of 5 alpha-reductase through the second pathway. Previously, we mapped the distribution of these enzyme activities within specific microdissected brain area and determined that aromatase activity (AA), but not 5 alpha-reductase activity (5 alpha RA), was reduced in certain brain areas after castration. In the present study, we measured AA and 5 alpha RA in thirteen brain nuclei and subregions from five castrated and five T-treated castrated male rhesus monkeys to determine whether exogenous androgen treatment could reverse the effects of castration on brain AA. We found that T, administered in a dose that maintained serum levels at 14.2 +/- 1.6 (SEM) ng/ml, suppressed circulating luteinizing hormone (Castrates = 491.9 +/- 86 ng/ml vs. T-treated castrates = 1.8 +/- 0.2 ng/ml), and stimulated AA in specific nuclei including the suprachiasmatic nucleus (n.), periventricular area, ventromedial n., and lateral hypothalamus. T treatment had no significant effect on AA in nine other nuclei or on 5 alpha RA in any brain areas that we studied. These data indicate that AA in diencephalic and limbic structures of the nonhuman primate brain is distributed heterogeneously into androgen-dependent and androgen-independent regions. This distribution is similar to that found in rodents. 5 alpha RA, on the other hand, is more homogeneously distributed than AA in these same brain regions and is not controlled by androgens.
Roselli
C E
CE
Department of Physiology, Oregon Health Sciences University, Portland 97201.
Resko
J A
JA
D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000378:metabolism; D000818:Animals; D001141:Aromatase / Q000378:metabolism*; D001921:Brain / Q000201:enzymology*; D013196:Dihydrotestosterone / Q000097:blood; D007986:Luteinizing Hormone / Q000097:blood; D008253:Macaca mulatta; D008297:Male; D009919:Orchiectomy; D013739:Testosterone / Q000097:blood / Q000378:metabolism / Q000494:pharmacology*
D013196:Dihydrotestosterone; D013739:Testosterone; D007986:Luteinizing Hormone; D001141:Aromatase; D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase