The effect of intraluteal infusion of deglycosylated human chorionic gonadotropin on the corpus luteum in rhesus monkeys.

Abstract

Removal of the carbohydrates from hCG results in an antagonist (degly-hCG) that competitively inhibits hCG/LH-stimulated adenylate cyclase in macaque luteal tissue in vitro, but its effect in vivo is controversial. To examine the effect of degly-hCG on the lifespan and steroidogenic activity of the primate corpus luteum, the antagonist was administered to female rhesus monkeys (n = 7) beginning at the midluteal phase of the menstrual cycle. In a control cycle the saline vehicle was infused via an osmotic minipump directly into the corpus luteum. In a subsequent cycle, one of three dose rates of degly-hCG (0.001, 0.009, and 0.09 nmol/h) was infused into the corpus luteum. Pump implantation and infusion began 5-9 days after the midcycle LH surge and continued for 7 days. Peripheral venous blood was collected daily from day 8 of the cycle until menses, and serum progesterone levels were determined by RIA. Progesterone levels and patterns were similar in animals that received either the saline vehicle or degly-hCG, and the length of the luteal phase in monkeys receiving any dose of degly-hCG (16.4 +/- 0.5 days) was not different from that in animals receiving a control infusion (16.1 +/- 0.9 days). In a corollary study, an intraluteal infusion of degly-hCG (0.009 nmol/h) in the midluteal phase did not prevent stimulation of progesterone levels after im injection of hCG (15 IU/day for 5 days). We conclude that whereas degly-hCG is a useful tool to examine gonadotropin action in vitro, it is not a potent gonadotropin antagonist in vivo.