Effects of hCG on prostaglandin synthesis and function of corpus luteum

The effect of intramuscular injections of human chorionic gonadotropin (hCG) on subsequent in vitro prostaglandin (PG) production by the corpus luteum was studied in the rhesus monkey. Four monkeys received increasing doses of hCG from days 6 to 10 after ovulation. On day 11, laparotomy and luteectomy were performed. Five untreated animals served as controls. The production of prostaglandins F (PGF) and E (PGE) by the corpus luteum of the animals treated wit hCG was significantly lower than that of the controls (P less than .01). After hCG treatment, the decrease in PGF production was greater than that of PGE, resulting in a lower ratio of PGF:PGE production than in the controls (P less than .01). Histologic evaluation of the corpora lutea revealed regressive changes in the control group, whereas signs of active secretion were observed in the hCG-treated group. Progesterone concentrations in peripheral blood of the hCG-treated group were approximately fourfold higher than in the controls, and the hCG-treated group did not have a postmidluteal phase decrease. These results suggest that the ratio of production of PGF to PGE by the corpus luteum of the rhesus monkey may play a role in the control of its lifespan and steroidogenic capacity.