Pituitary-Adrenal Function in the Absence of Vasopressin

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Abstract
Plasma corticosterone concentrations were compared in rats with hereditary hypothalamic diabetes insipidus (DI), which lack vasopressin, and in normal rats of the same strain andage. The stress of etherization raised plasma corticosterone in both groups of rats, but the elevation was significantly less in the rats with DI. Plasma corticosterone was also significantly lowerinthe group with DI after exposure to a mild stress of bleeding and restraint. Similar results were obtained even after dehydration had been corrected in DI animals by giving vasopressin in oil for several weeks. Initial values for adrenal ascorbic acid concentration were higher in DI than in normal rats, and adrenal ascorbic acid depletion from the stimulus of unilateral adrenalectomy was subnormal in rats with DI. Anterior pituitary, adrenal and testicular weights were less than those of normal rats of the same body weight. The corticotrophin-releasing activity in the stalk-median eminence and the pituitary ACTH concentration were not significantly different in DI and normal rats. Although not conclusive, these data are consistent with the thesis that, although vasopressin is not the corticotrophin-releasing factor, it may play a small role in adrenal cortical response to stress.