[The long-term depression of the function of the hypothalamo-hypophyseal-adrenocortical system in rats].

Hypothalamo-pituitary-adrenocortical axis reactivity was studied in vivo and in vitro in 7 days after single administration of 30 mg/100 g body weight of hydrocortisone in rats. There were a blockade of stress-induced decrease of CRF-41 content in median eminence, and failure of increase of ACTH and corticosterone levels in the blood to stress in 7 days after hydrocortisone administration. A decrease of reactivity to ACTH was shown during incubation of adrenals from rats treated with hydrocortisone. 300 and 400 mg/100 g body weight of corticosterone s. c. imitates a stress-induced increase of corticosterone in the blood and can be used as replacement therapy. We conclude that high supraphysiological doses of glucocorticoids results in a decrease of reaction of hypothalamus, pituitary and adrenals to stress.