CB1 and CB2 receptors had opposite effects on clozapine heart damage in mice
Blocking CB1 receptors or activating CB2 receptors protected mouse hearts from clozapine-induced inflammation and fibrosis, revealing opposing cannabinoid receptor roles in drug-induced cardiotoxicity.
Quick Facts
What This Study Found
Clozapine decreased endocannabinoid levels and caused myocardial inflammation and fibrosis in mice. CB1 receptor antagonists (rimonabant, AM281) reduced heart damage, while CB2 receptor agonists (AM1241, JWH-133) also protected the heart. Combined treatment with both provided even greater protection.
Key Numbers
Clozapine decreased endocannabinoid levels in serum and cardiomyocytes. CB1 receptors decreased and relocated intracellularly; CB2 receptors increased and moved to cell surface. Combined CB1 antagonist + CB2 agonist provided additive cardioprotection.
How They Did This
Mice received clozapine alone or with selective CB1 antagonists or CB2 agonists. Heart tissue was examined for inflammation, fibrosis, and receptor expression. Cultured cardiomyocytes were used to confirm direct cellular effects.
Why This Research Matters
Clozapine is the most effective antipsychotic for treatment-resistant schizophrenia, but cardiotoxicity limits its use. Understanding how the endocannabinoid system mediates this damage could lead to cardioprotective co-treatments.
The Bigger Picture
This finding has implications beyond clozapine. The opposing roles of CB1 and CB2 receptors in cardiac inflammation could be relevant to understanding how cannabis use affects heart health more broadly.
What This Study Doesn't Tell Us
Mouse study with clozapine doses that may not directly translate to human therapeutic levels. The study did not test whether cardioprotection interfered with clozapine's antipsychotic efficacy. No human data.
Questions This Raises
- ?Could CB2 agonists be co-prescribed with clozapine to prevent cardiotoxicity without affecting its psychiatric benefits?
- ?Does cannabis use by schizophrenia patients on clozapine affect cardiac risk?
Trust & Context
- Key Stat:
- Opposite CB1/CB2 effects
- Evidence Grade:
- Preliminary: mouse study with in vitro confirmation but no human data.
- Study Age:
- Published in 2019.
- Original Title:
- Opposite effects of cannabinoid CB1 and CB2 receptors on antipsychotic clozapine-induced cardiotoxicity.
- Published In:
- British journal of pharmacology, 176(7), 890-905 (2019)
- Authors:
- Li, Liliang, Dong, Xiaoru, Tu, Chunyan, Li, Xiaoqing, Peng, Zhao, Zhou, Yiling, Zhang, Dingang, Jiang, Jieqing, Burke, Allen, Zhao, Ziqin, Jin, Li, Jiang, Yan
- Database ID:
- RTHC-02137
Evidence Hierarchy
Tests effects in animals (usually mice or rats), not humans.
What do these levels mean? →Frequently Asked Questions
Why is clozapine cardiotoxicity a concern?
Clozapine is the most effective antipsychotic for treatment-resistant schizophrenia, but it can cause myocardial inflammation and fibrosis that limits its clinical use.
Could cannabinoids protect the heart during clozapine treatment?
In mice, blocking CB1 receptors or activating CB2 receptors reduced clozapine-induced heart damage. Whether this translates to human patients has not been tested.
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Cite This Study
https://rethinkthc.com/research/RTHC-02137APA
Li, Liliang; Dong, Xiaoru; Tu, Chunyan; Li, Xiaoqing; Peng, Zhao; Zhou, Yiling; Zhang, Dingang; Jiang, Jieqing; Burke, Allen; Zhao, Ziqin; Jin, Li; Jiang, Yan. (2019). Opposite effects of cannabinoid CB1 and CB2 receptors on antipsychotic clozapine-induced cardiotoxicity.. British journal of pharmacology, 176(7), 890-905. https://doi.org/10.1111/bph.14591
MLA
Li, Liliang, et al. "Opposite effects of cannabinoid CB1 and CB2 receptors on antipsychotic clozapine-induced cardiotoxicity.." British journal of pharmacology, 2019. https://doi.org/10.1111/bph.14591
RethinkTHC
RethinkTHC Research Database. "Opposite effects of cannabinoid CB1 and CB2 receptors on ant..." RTHC-02137. Retrieved from https://rethinkthc.com/research/li-2019-opposite-effects-of-cannabinoid
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.