Inhibition of endogenous cannabinoid breakdown in the presence of verapamil on learning and memory in a rat

Endocannabinoids are one of the endogenous systems that modulate the learning and memory. There is currently debate over the interaction between L-type Ca2+ channels and endocannabinoid system on the learning and memory. The aim of this study was to examine the effects of acute administration of URB597, as endocannabinoid breakdown inhibitor, following chronic administration of verapamil, as Ca2+ channels blocker, on passive avoidance (PA) test. This behavioral study was carried out on 70 male Wistar rats. Animals were divided into seven groups (n=10 in each group). Rats were treated with verapamil hydrochloride (10, 25, 50 mg/kg, i.p.) or saline as the solvent of verapamil for 13 days (once daily). Before PA test, a single injection of saline, verapamil or URB597 (0.3 mg/kg, i.p.) was done. Then PA training was started. Retrieval test was done 24 h after training. Results showed that both URB597 and verapamil decreased the acquisition and retrieval of PA task. Moreover, URB597 can augment the inhibitory effect of verapamil on acquisition and retrieval of PA test. It can be concluded that L-type calcium channels may have a role in learning and memory. Also, there is an interaction between Ca2+ channels and endocannabinoid system. This may be due to changes made by endocannabinoids in neural structures involved in learning and memory processing.