Abstract
Tissue levels of rat adrenal estrogens during the estrous cycle were determined by radioimmunoassay, and effect of ACTH on the adrenal estrogen levels was examined. The levels of estrone and estradiol in proestrus were 2.75±0.61 pg/mg tissue and 1.0± 0.19 pg/mg tissue (mean±SE), respectively. The higher level of estrone but not of estradiol was inclined to appear in proestrus rather than in other phases. Injection of 250 IU/kg of α1-24-ACTH significantly increased the estrone level at 15 and 30 min, and estradiol at 15 min. Administration of reserpine, which was used as the ACTH releaser, produced an increase in the estrone level but did not change the estradiol level. While dexamethasone injection decreased the estrone level significantly at 8 hours after the treatment, the level of estradiol remained unchanged. Hypophysectomy produced a considerable decrease in both steroid levels, particularly estrone. These results indicate that the major estrogen in the rat adrenal gland is estrone and that the level is regulated by hypophyseal ACTH.
