Luteolytic effect of D-Trp6-luteinizing hormone-releasing hormone in the rhesus monkey (Macaca mulatta).

A potent agonist of luteinizing hormone, D-Trp6-LRH, was administered at different stages during the luteal phase of rhesus monkeys (Macaca mulatta). Luteolysis, evidenced by short luteal phases and decreased serum progesterone concentrations, was consistently induced when the analog was injected on days 3 or 5 post ovulation; however, no effect was observed when it was given on day 7 post ovulation. Increasing doses of hCG administered from days 6-10 post ovulation prevented the luteolytic effect of D-Trp6-LRH. The possible mechanisms of action and the potential uses of LRH analogs as contraceptive agents are discussed.