Neurohypophyseal peptides maintain tolerance to the incoordinating effects of ethanol

Arginine vasopressin (AVP), lysine vasopressin (LVP) and [des-9-glycinamide]LVP (DGLVP), administered systemically, delayed the disappearance of functional tolerance to the motor-incoordinating effect of ethanol in mice. This result is consistent with previous findings that AVP and related neuropeptides maintain tolerance to the sedative-hypnotic and hypothermic effects of ethanol, and suggests that the peptides modulate the rate of disappearance of tolerance per se, rather than simply influencing the tests used to evaluate tolerance. However, both the duration of tolerance to the incoordinating effect of ethanol, and the duration of peptide maintenance of this tolerance, were less than those observed for tolerance to the hypnotic and hypothermic effects of ethanol. Tolerance to various effects of ethanol clearly can develop and dissipate at different rates, and our results suggest that the characteristics of the maintenance of ethanol tolerance by neurohypophyseal peptides are influenced, to some extent, by the neural systems which mediate the expression of the functional tolerance which is being investigated.