Evidence that vasopressin is involved in the isoprenaline-induced beta-endorphin release

We investigated in conscious rats, whether vasopressin, whose release was stimulated by isoprenaline (i.m.), caused the simultaneous increase in plasma beta-endorphin-like immunoreactivity (beta-EI). The increase in plasma beta-EI following isoprenaline administration was diminished by about 50% in rats pretreated with a vasopressin antagonist and also in rats with a hereditary absolute lack of vasopressin. We conclude that the isoprenaline-induced release of beta-EI is mediated in part by vasopressin.