STEROID-SECRETION BY FOLLICLES AND CYSTS FROM THE HYPOTHYROID, HCG-TREATED RAT

Hypothyroid rats develop cystic follicles after daily administration o f human chorionic gonadotropin (hCG). This study was undertaken to com pare progesterone, testosterone, and estradiol secretion by antral fol licles (0.9-1.0 mm) and cysts (small: 1.2-2.0 mm; large: >2.0 mm) from hypothyroid, hCG-treated rats with that of antral follicles from euth yroid, saline-treated animals. After 3, 5, or 10 days of hCG injection s, follicles and cysts were dissected from the ovaries, diameter deter mined, and incubated in minimum essential medium (MEM) for 2 hr at 37 degrees C. Media were assayed for progesterone, testosterone, and estr adiol by RIA. Progesterone secretion by antral follicles removed after 3, 5, or 10 days was similar but small cysts secreted significantly m ore of this steroid than did antral follicles. Large cysts secreted si gnificantly more progesterone than all other follicles and cysts. Afte r 10 days of treatment with hCG, antral follicles from hypothyroid, hC G-treated rats secreted two to three times more testosterone than simi lar follicles from euthyroid, saline-treated animals. Changes in estra diol secretion were not apparent until after 10 days of hCG treatment. Both small and large cysts from those animals secreted significantly more estradiol than all other follicle and cyst groups. These results suggest that steroid secretion by follicles and cysts could be contrib uting to elevated serum levels of progesterone and testosterone during the first 10 days of cyst induction. However, cysts may be contributi ng estradiol only during the later stages of cyst induction.