The stimulatory effect of cholecystokinin implanted in the medial preoptic area on luteinizing hormone secretion in the ovariectomized estrogen-primed rat.
The effect of implantation of cholecystokinin(CCK)-8 into the medial preoptic area (MPO) through the chronically implanted guide cannula on the release of LH was examined in the ovariectomized estradiol-primed rat. An inner cannula with CCK-8 at the tip, as well as an empty inner cannula as the control, was implanted into the MPO at 12.00 h. Blood samples were obtained at 11.00, 12.00, 16.00, 18.00 and 20.00 h, and serum concentration of LH was measured by RIA. There was no significant fluctuation over time in the mean serum LH values for each sampling time in the group of animals implanted with empty cannulae in the MPO. In the group of animals implanted with CCK-8 into the MPO, the fluctuation of the mean LH values over time was significant, with a marked and significant elevation of LH values peaking at 16.00 h. It was strongly suggested that CCK-8 was capable of stimulating LH-RH release, acting at the MPO.
D000818:Animals; D002369:Castration; D002940:Circadian Rhythm; D004343:Drug Implants; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D007986:Luteinizing Hormone / Q000378:metabolism*; D011301:Preoptic Area / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012844:Sincalide / Q000494:pharmacology*
D004343:Drug Implants; D004958:Estradiol; D007986:Luteinizing Hormone; D012844:Sincalide