Estradiol enhances the action of neuropeptide Y on in vivo luteinizing hormone-releasing hormone release in the ovariectomized rhesus monkey.
The effect of estrogen on the responsiveness of the luteinizing hormone-releasing hormone (LHRH) neurosecretory system to neuropeptide Y (NPY) stimulation was examined using a push-pull perfusion method in conscious monkeys. NPY, at doses of 10(-6) to 10(-12) M, was infused into the stalk-median eminence (S-ME) of ovariectomized monkeys with or without estrogen, while perfusates were continuously collected. LHRH in perfusates was measured by RIA. The results indicate that in both estrogen-primed and unprimed monkeys, NPY infusion into the S-ME elicited LHRH release in a dose-dependent manner (p < 0.01). Moreover, estrogen priming enhanced the responsiveness of LHRH release to NPY infusion: (1) the minimum NPY dose necessary to elicit a significant LHRH response was reduced, (2) the peak LHRH response to NPY at a dose of 10(-6) to 10(-10) M was increased, and (3) the total release of LHRH in response to NPY at doses of 10(-6) to 10(-12) M was increased. These results suggest that NPY stimulates LHRH release in the S-ME in the presence or absence of estrogen and that estrogen enhances the responsiveness of the LHRH neurosecretory system to NPY stimulation in the rhesus monkey.
Wisconsin Regional Primate Research Center, University of Wisconsin-Madison 53715, USA.
M J
MJ
Woller
E
E
Terasawa
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology* / Q000502:physiology; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism*; D008253:Macaca mulatta; D008473:Median Eminence / Q000187:drug effects* / Q000378:metabolism; D009478:Neuropeptide Y / Q000494:pharmacology*; D010052:Ovariectomy; D013997:Time Factors
D009478:Neuropeptide Y; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol