Hypothermia induced by centrally administered vasopressin in rats: A structure-activity study

Vasopressin and related peptides cause short-lasting hypothermia when injected into the lateral ventricle of the rat. In the present study, the structure-activity relationships for the induction of this effect were examined. For the agonist peptides studied, the structural requirements were found to be similar to those required to cause peripheral vasoconstriction and to induce behavioral excitation in mice. However, an antagonist of the presser and behavioral effects of vasopressin was ineffective in antagonizing the hypothermie response. Moreover, this analog and another pressor antagonist themselves caused hypothermia. Comparison with the structure-activity relationships for other effects on the central nervous system strongly suggests that the hypothermie response is unrelated to the effects of vasopressin on consolidation of memory, development of tolerance to drugs, and mechanisms of reinforcement.