Opposite effects of cannabinoid CB1 and CB2 receptors on antipsychotic clozapine‐induced cardiotoxicity

Article date: April 2019

By: Liliang Li, Xiaoru Dong, Chunyan Tu, Xiaoqing Li, Zhao Peng, Yiling Zhou, Dingang Zhang, Jieqing Jiang, Allen Burke, Ziqin Zhao, Li Jin, Yan Jiang in Volume 176, Issue 7, pages 890-905

Background and Purpose

Clozapine is an atypical antipsychotic drug that is very efficacious in treating psychosis, but the risk of severe cardiotoxicity limits its clinical use. The present study investigated the harmful effects of clozapine on myocardium and assessed the involvement of cannabinoid receptors in its cardiotoxicity.

Experimental Approach

Clozapine alone or in combination with selective cannabinoid receptor antagonists or agonists were used to treat mice and cardiomyocytes.

Key Results

Clozapine induced myocardial inflammation and infiltration 7 days after i.p. injection. Mice survival rate and myocardial infiltration, and fibrotic lesions were dose‐dependently worsened by clozapine. Clozapine decreased major endocannabinoid levels in sera and cultured cardiomyocytes. Cannabinoid CB1 receptors decreased in clozapine‐treated hearts and were translocated from cytomembranes to cytoplasm and nuclei, whereas CB2 receptors increased in clozapine‐treated hearts and inversely translocated from nuclei to the cytomembrane. Selective antagonists of CB1 receptors, rimonabant and AM281, but not its selective agonist arachidonyl‐2′‐chloroethylamide, ameliorated clozapine‐induced myocardial inflammatory infiltration and fibrotic lesions. In contrast, selective agonists of CB2 receptors, AM1241 and JWH‐133, but not its selective antagonist AM630, blunted clozapine‐mediated cardiotoxicity in mice. In cultured cardiomyocytes, clozapine increased the pro‐inflammatory factor IL‐1β and the concentrations of myocardial injury markers (LDH and aspartate aminotransferase); these effects were reversed by either a CB1 antagonist or CB2 agonist and further prevented by combined pretreatments.

Conclusions and Implications

Our data provide evidence that cannabinoid CB1 and CB2 receptors have opposite effects and selective antagonists of CB1 or agonists of CB2 receptors might confer protective effects against clozapine in myocardium.

DOI: 10.1111/bph.14591

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