In vitro inhibition of vasopressin release in brain by behaviorally relevant ethanol concentrations

We have investigated the effect of ethanol upon vasopressin (AVP) content in brain and upon in-vitro release of AVP from the rat median eminence. In-vitro ethanol concentrations (5-25 mM), comparable to behaviorally relevant blood ethanol levels, induce a substantial inhibition of AVP release from the median eminence, whereas higher ethanol concentrations (greater than 50 mM) potentiate release. In vivo, ethanol, at a behaviorally relevant blood ethanol concentration (126 mg%), does not produce a significant difference in AVP content in brain although there is a consistent trend towards an increase in the hypothalamus and neurohypophysis. The results are considered in relation to the effects of ethanol on biogenic amine release and to memory impairments induced by low doses of acute ethanol exposure.