Increased ACTH Release Without Increased Synthesis

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Abstract
Male white rats were treated with saline (controls) or puromycin or dexamethasone and morphine and subjected to laparotomy. Corticosterone secretion rates were measured at intervals for 30 to 120 min following incision. Incorporation of 14C-valine into pituitary and adrenal protein and polypeptides served as an index of the effect of experimental agents on ACTH synthesis. In control animals corticosterone secretion averaged 0.6-0.7 μg/min following laparotomy and incorporation of 14C-valine increased roughly linearly with time. Corticosterone secretions (0.2-0.3 μg/min) of dexamethasone- morphine blocked rats were inhibited, but incorporation of 14C-valine was similar to that of control rats. In the puromycin-treated group, both corticosterone secretion (0.2 μg/min) and incorporation of labeled valine were inhibited, but plasma ACTH levels (3.8 mU/100ml) and plasma ACTH half-time (3.0 min) were similar to those of the control animals. Pituitary ACTH content of puromycin-treated animals 2 hr after laparotomy was significantly reduced, whereas pituitary ACTH content of dexamethasone-morphine blocked rats was not significantly different from that of controls. The results indicate that, under conditions of stress, ACTH may be released for extended periods of time independently of synthesis of new hormone. (Endocrinology 80: 719, 1967)