Subsensitive pituitary cyclic AMP response to stress following adrenalectomy is not caused by loss of adrenal epinephrine

Abstract

We have previously reported that various stressors acutely elevated levels of pituitary cyclic AMP in vivo and that this stress response is not seen in animals tested 7 or 30 days post-adrenalectomy. In this report we present data that demonstrate that the loss of the pituitary cyclic AMP stress response following adrenalectomy is not the result of the loss of stress-induced adrenal epinephrine release. These data show that (1) although administration of epinephrine to intact rats does elevate levels of pituitary cyclic AMP, administration of epinephrine to adrenalectomized animals does not elevate pituitary cyclic AMP levels in vivo ; (2) splanchnic denervation prevents stress-induced adrenal epinephrine release but does not abolish stress-induced increases in pituitary cyclic AMP ; and (3) the time course of the developing subsensitive pituitary cyclic AMP response to stress following adrenalectomy is much slower (2 to 3 days) than the loss of circulating epinephrine.