Hormonal Regulation of Testicular LH/hCG Receptors in Rat

Summary

A single injection of 60 IU of hCG to 25-day-old rats led to a loss of LH/hCG receptors in the testis. The content of [¹²⁵I] hCG binding sites reached a nadir 2 days after hCG injection. At this time the effect of daily treatment of hormones and other agents on the formation of LH/hCG receptors was studied. Gonadotropin receptors were estimated 2, 4, 6, 8 and 10 days after injection of hCG. Daily treatment of rats with PMSG (30 IU/day) increased testicular content of hCG binding sites. The presence of the pituitary in these animals was necessary during the formation of receptors after hCG-induced loss of binding sites. LH/hCG receptor content remained low in rats treated with testosterone (250 μg/day), hCG (100 IU/day) or inhibitors of the synthesis and the secretion of prolactininhibitors-bromocryptine (250 μg/day), ergocryptine (200 μg/day) and deprenon (50 and 600 μg/day). Administration of cortisol (1 mg/day) had no effect on restoration of LH/hCG receptors. These data suggest an important role for FSH and prolactin in the formation of LH/hCG receptors in rat testis.