Regulation of hypothalamic luteinizing hormone-releasing hormone levels by testosterone and estradiol in male rhesus monkeys.
Castration of rhesus monkeys produces hypersecretion of pituitary luteinizing hormone (LH) and a marked reduction in hypothalamic luteinizing hormone-releasing hormone (LH-RH) content. We performed the present study to determine whether treatment with gonadal steroids would reverse the effect of castration by increasing LH-RH content. We found that, when administered in doses that suppressed serum LH, both testosterone (T) and estradiol (E) significantly increased LH-RH in the infundibular nucleus/median eminence. The LH-RH content of 8 other regions, some known to contain LH-RH neurons, was not significantly affected. Thus, gonadal steroids act within a discrete region of the basal hypothalamus to modify LH-RH content. The finding that both T and E were effective in male monkeys supports the hypothesis that aromatization is involved in the negative feedback mechanism.
Roselli
C E
CE
Department of Physiology, Oregon Health Sciences University, Portland 97201.
Resko
J A
JA
D000818:Animals; D004958:Estradiol / Q000494:pharmacology* / Q000502:physiology; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D008251:Macaca / Q000378:metabolism*; D008253:Macaca mulatta / Q000378:metabolism*; D008297:Male; D009919:Orchiectomy; D013739:Testosterone / Q000494:pharmacology* / Q000502:physiology
D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D004958:Estradiol