Secretion of corticosterone in rats with anterior hypothalamic lesions

¹ Department of Physiology, University of Texas, Southwestern Medical School, Dallas, Texas

Secretory rates of corticosterone were determined in rats with intact hypothalami, in animals with anterior hypothalamic lesions, and in hypophysectomized rats with anterior hypothalamic lesions. Animals with intact hypothalami secreted 10.7, 13.2, 14.2, 14.7, 16.6, 17.5, 17.8, and 17.7 µg corticosterone in the first through the eighth 15-min interval, respectively, of a 2-hr collection period. Rats with hypothalamic lesions secreted 1.8, 2.7, 3.6, 6.1, 9.0, 10.7, 11.1, and 10.6 µg corticosterone in the first through the eighth 15-min interval, respectively. Intravenous injection of 100 mU arginine vasopressin every 30 min did not affect the rate of production of steroid in animals with lesions. Removal of the pituitary from rats with hypothalamic lesions reduced the secretion to 0.3 µg corticosterone in 15 min. Administration of 5 mU ACTH at half-hour intervals to animals with lesions greatly increased the rate of production of corticosterone, suggesting that the low rate during the first 15-min collection period was not due to an unresponsive adrenal. The magnitude of the response of the acutely hypophysectomized rats to ACTH was slightly less than that of animals with lesions.