Effects of peptides related to neurohypophyseal hormones on ethanol tolerance.

Mice were rendered tolerant to the hypothermic effect of ethanol by forcing them to inhale ethanol vapor for 3 days. One day after withdrawal, tolerance was assessed by determining the response of the mice to an acute 3 g/kg IP challenge dose of ethanol. Thirty minutes before the injection of ethanol, saline or peptide solution was SC injected. The peptides studied were des-Gly9-Arg8-vasopressin (a peptide with reduced peripheral endocrine activities), oxytocin, and analogs and fragments of these peptides. None of the peptides, with the possible exception of oxytocin, affected body temperature in naive animals or the acute hypothermic response to ethanol in non-tolerant mice. Des-Gly9-Arg8-vasopressin enhanced the expression of tolerance to ethanol hypothermia; shorter fragments of vasopressin did not share this effect. Oxytocin attenuated the expression of tolerance but this may been due to an interaction with the acute effects of ethanol.