Rats with naturally higher anandamide levels and lower FAAH activity in a specific brainstem region had higher resting heart rates, and injecting anandamide into this region increased heart rate.
Researchers interested in how the endocannabinoid system affects cardiovascular function.
Higher brain anandamide levels correlated with higher resting heart rate
What the researchers found
Researchers examined whether natural animal-to-animal variation in endocannabinoid signaling in the dorsal periaqueductal gray (dPAG), a brainstem region involved in autonomic control, correlated with baseline heart rate.
Higher resting heart rate was associated with increased anandamide content and decreased FAAH enzyme activity in this brain region. FAAH and MAGL gene expression levels were negatively correlated with heart rate. When anandamide was directly injected into the dPAG of anesthetized rats, heart rate increased.
Autonomic tone and heart rate (but not blood pressure) correlated with FAAH gene expression levels, suggesting that the endocannabinoid system in this specific brain region helps regulate baseline cardiovascular function.
Why it matters
This study identifies a specific brain region where endocannabinoid signaling influences cardiovascular function. Understanding how the endocannabinoid system regulates heart rate has implications for understanding both the cardiovascular effects of cannabis and potential therapeutic targets.
The numbers in context
Higher anandamide content in dPAG correlated with higher heart rate. Lower FAAH activity correlated with higher heart rate. FAAH and MAGL transcript levels negatively correlated with heart rate. Exogenous anandamide in dPAG increased heart rate.
How the study worked
Blood pressure was recorded telemetrically in rats. Heart rate variability was analyzed. Endocannabinoid content, enzyme activities, and gene transcript levels were measured in the dPAG. Exogenous anandamide was injected into the dPAG of anesthetized rats to test causality.
What this study cannot tell us
This was an animal study using rats, and the findings may not directly translate to human cardiovascular regulation. Only the dPAG was examined; other brain regions also regulate heart rate. The correlational design (except for the injection experiment) cannot establish that endocannabinoids cause heart rate differences.
How to read the evidence
This is an animal study combining correlational analysis with a causal intervention (anandamide injection), providing preliminary mechanistic evidence.
When this study was published
Published in 2016. Research on endocannabinoid regulation of cardiovascular function continues.
The bigger picture
Cannabis use is known to increase heart rate, and this study identifies one brain mechanism through which endocannabinoids regulate cardiovascular function. The dPAG is part of the brain's autonomic control circuitry, connecting endocannabinoid signaling to the broader cardiovascular regulation system.
Questions still open
- Does cannabis-induced tachycardia involve this brainstem endocannabinoid mechanism? Could targeting endocannabinoid signaling in this region help manage heart rate disorders?
Common questions
Does cannabis increase heart rate?
Is this why some people feel their heart racing after using cannabis?
Read the original research
Components of the cannabinoid system in the dorsal periaqueductal gray are related to resting heart rate.
American journal of physiology. Regulatory, integrative and comparative physiology, 311(2), R254-62
Citation
Dean, Caron; Hillard, Cecilia J; Seagard, Jeanne L; Hopp, Francis A; Hogan, Quinn H. (2016). Components of the cannabinoid system in the dorsal periaqueductal gray are related to resting heart rate.. American journal of physiology. Regulatory, integrative and comparative physiology, 311(2), R254-62. https://doi.org/10.1152/ajpregu.00154.2016
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