Concurrent treatment with verapamil suppresses immune and behavioural response to endogenous cannabinoid anandamide

Abstract

The cellular effects of anandamide, endogenous cannabinoid receptor agonist, include changes in cellular immunity and calcium currents. The present study investigated the effects of anandamide, the calcium channel antagonist verapamil and the combined treatment with verapamil+anandamide on leukocyte phagocytosis and the social behaviour in aggressive singly-housed mice on dyadic interactions with non-aggressive group-housed partners. Verapamil was used at the dose (1 mg/kg) which did not markedly affect either phagocytosis or the behaviour of the mice. Anandamide given alone elicited a biphasic effect on phagocytosis: stimulation after the low dose (0·01 mg/kg) and inhibition after the high dose (10 mg/kg). Both doses of anandamide caused dose-related inhibition of aggressiveness in singly-housed mice. Anandamide combined with verapamil prevented both the stimulatory and inhibitory effect of anandamide on phagocytosis and on inhibition of aggression elicited by the low dose of anandamide. The dose of verapamil used did not influence behavioural changes caused by the high dose of anandamide. © 1997 John Wiley & Sons, Ltd.