Regulation of LH/hCG receptor by gonadotropins in rat ovary

To investigate the regulation of the LH/hCG receptor gene by gonadotropins, we examined the effect of PMSG and hCG on the expression of LH/hCG receptor in immature rat ovary. Northern blot analysis of ovarian RNA revealed a major mRNA of 5400 nucleotides and minor species of 7500, 3600, 2300, and 1200 nucleotides, and PMSG treatment slightly increased the intensity of all LH/hCG receptor messengers. Subsequently, hCG treatment decreased the number of LH/hCG receptor by day 2 and mRNA levels by 12h after injection. The level of mRNA recovered and increased 5-fold of control by day 6, then returned to control levels by day 10, followed by slower decline in LH/hCG receptor in plasma membrane. These studies demonstrate that the effects of PMSG and hCG on the number of LH/hCG receptor are closely related to the actions of these hormones on LH/hCG receptor messenger levels.