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.

Successful in vitro fertilization and embryo transfer in cynomolgus monkeys.

We have started an in vitro fertilization program in cynomolgus monkeys in an effort to develop an appropriate animal model to improve our knowledge of early embryonic development. In 16 of 25 animals treated with menopausal gonadotropins, preovulatory follicles developed. Follicular aspiration was performed at laparotomy after human chorionic gonadotropin injection. A total of 299 follicles were aspirated, and 251 oocytes were recovered. Oocytes were cultured in 1 ml of growth medium or 100 microliter droplets of medium under mineral oil. Semen samples were obtained by electroejaculation, and the oocytes were inseminated 4 to 24 hours after aspiration. Culture under mineral oil significantly increased the fertilization and cleavage rates. Of 68 embryos produced, 24 have been used in 10 embryo transfers, resulting in two pregnancies.