Central action of mepiprazole.

Mepiprazole, a phenylpiperazine derivative, strongly antagonizes the behavioral syndromes evolved by 5-hydroxytrypotophan. The drug did not affect the serotonin neurons in the preparation of flexor reflex of the hind paw of the spinal rat: in higher doses it depressed the reflex showing noradrenolytic properties. Mepiprazole antagonized the fenfluramine-induced hyperthermia, depressed spontaneous locomotor activity, produce hypothermia and was inactive in the despair test. The results suggest that mepiprazol may have noradenolytic properties; its possible influence on the serotonergic system is masked by noradrenolytic properties and hence difficult to demonstrate.