Vasoactive intestinal polypeptide in the pituitary pars nervosa.

Vasoactive intestinal polypeptide (VIP) is a widely distributed neuropeptide which has recently been found in the hypothalamus and in hypothalamo-hypophyseal portal blood. We have examined the pituitary of several mammalian species for the presence of VIP by immunocytochemistry and radioimmunoassay and report here that the pars nervosa contains a considerable quantity of VIP (100-250 fmol/mg) which, in the dog, can be shown to be present in nerve fibres. It is possible that neurohypophyseal VIP may be a local releasing agent for vasopressin.