Hormone secretion by euthyroid and hypothyroid rat ovaries during the early stages of hCG-induced ovarian cyst development.

This study was undertaken to examine ovarian steroid production during the early stages of hCG-induced ovarian cyst formation in the hypothyroid rat. Rats were placed into two groups with one group made hypothyroid by adding thiouracil to their diet. After 10 days, each group was divided into two subgroups with one subgroup receiving daily injections of hCG for 2 days and the other subgroup receiving saline. On the morning of Day 13, ovaries were removed and incubated for 2 hr. No significant difference in progesterone secretion was observed. However, ovaries from hypothyroid, hCG-treated rats secreted significantly more testosterone and estradiol than ovaries from vehicle-treated, hypothyroid rats and euthyroid, hCG-treated rats. In a second experiment, ovaries from euthyroid and hypothyroid rats treated with hCG were incubated in medium supplemented with 100 nM androstenedione and 0 or 100 ng FSH/ml. FSH failed to affect progesterone, testosterone, and estradiol secretions by ovaries from euthyroid, hCG-treated rats. In contrast, FSH significantly enhanced testosterone and estradiol secretion by ovaries from hypothyroid, hCG-treated rats. These results support the hypothesis that increased levels of testosterone and estradiol secretion have a central role in the induction of polycystic ovaries by hCG in the hypothyroid rat.