Prolactin and gonadotrophin dynamics in response to antagonists of LHRH and dopamine in ovariectomized rhesus monkeys: a dissection of their common secretion.
This experiment was designed to study the prolactin (PRL) and gonadotrophin response to an inhibitory analogue of luteinizing hormone releasing hormone (LHRH-A; ORG 30276) and a dopamine antagonist, metoclopramide (MCP), in castrated female rhesus monkeys. The LHRH-A given as an i.v. bolus followed by an infusion 2 h later induced a significant decline in circulating PRL levels reaching a maximum suppression 1 h after initiation of the LHRH-A infusion. Intravenous administration of MCP, performed 1 h after beginning the LHRH-A infusion, resulted in a prompt and abrupt rise in PRL levels in the LHRH-A group as well as in the controls. Luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels showed a progressive decline during LHRH-A treatment. Injection of MCP did not affect the levels of LH and FSH in either of the groups. The data obtained demonstrate in primates that the prolactin inhibitory effect of LHRH-A is easily overcome by the dopamine antagonist, MCP, whereas the LHRH-A-induced gonadotrophin suppression remains unaffected by MCP.
D000818:Animals; D018492:Dopamine Antagonists; D005260:Female; D005640:Follicle Stimulating Hormone / Q000097:blood; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D006065:Gonadotropins, Pituitary / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000097:blood; D008253:Macaca mulatta; D008787:Metoclopramide / Q000494:pharmacology*; D010052:Ovariectomy; D011388:Prolactin / Q000097:blood*
D018492:Dopamine Antagonists; D006065:Gonadotropins, Pituitary; D007987:Gonadotropin-Releasing Hormone; C042691:LHRH, N-acetyl-(4-chlorophenylalanyl)(1)-(4-chlorophenylalanyl)(2)-tryptophyl(3)-arginyl(6)-alanine(10)-; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D008787:Metoclopramide