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.
Woller
M J
MJ
Wisconsin Regional Primate Research Center, University of Wisconsin-Madison 53715, USA.
Terasawa
E
E
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