Lack of effect of suprachiasmatic infusion of a vasopressin antagonist on the circadian rhythm of wheel-running activity in rats.

Abstract

Circadian patterns of wheel-running activity were studied in male Wistar rats before, during, and after continuous infusion of (Pmp1, Tyr(Me)2)-Arg8-vasopressin, a V1 receptor antagonist, in the suprachiasmatic region by means of Alzet mini-osmotic pumps. The lack of any significant effect on the pattern of wheel-running activity argues against a role for vasopressin in the generation of circadian rhythms by the suprachiasmatic nuclei.