Adrenal cortical secretory responses to histamine and cyanide in dogs with hypothalamic lesions

Experiments were performed on dogs with hypothalamic lesions as well as on intact and hypophysectomized dogs. Adrenal venous blood samples were collected and analyzed for 17-hydroxycorticosteroids (17-OHCS). In intact dogs, a marked increase in adrenal 17-OHCS secretion was observed after an i.v. injection of histamine and following an i.v. infusion of cyanide. Adrenal 17-OHCS secretion in response to histamine was markedly reduced but not completely abolished by hypophysectomy and was partially impaired by anterior median eminence lesions and by posterior median eminence lesions, but was not significantly impaired by supramammillary lesions. Adrenal 17-OHCS secretion in response to cyanide was completely abolished by hypophysectomy, markedly reduced by posterior median eminence lesions and partially impaired by anterior median eminence lesions and by supramammillary lesions. Thus, a partial dissociation of the adrenocortical secretory responses to histamine and cyanide was observed in dogs with hypothalamic lesions, suggesting that the mechanism and the pathway to the anterior pituitary involved in the adrenocortical secretory response to histamine and cyanide are somewhat different.