In a recent study, researchers find that chronic, frequent tobacco smokers have a decreased number of cannabinoid CB1 receptors, the “pot receptor”, when compared with non-smokers.
The finding supports that CB1 receptors play a role in smoking and suggests that reduction of CB1 receptors is a common feature of addiction.
In the study, the team enrolled 46 men who were considered healthy.
Among them, 18 of the participants were frequent cigarette smokers and 28 did not smoke.
The researchers measured the number of receptors in their brains using a brain imaging technique to detect a drug that binds to CB1 receptors.
The team found a nearly 20% reduction in CB1 receptors in the brains of smokers compared to non-smokers.
The reduced receptor number was present throughout the brain (in all 18 regions examined in the study), with some regions more affected than others.
The reduction in receptors was not exacerbated by more cigarettes smoked per day, or by starting before the age of 18.
The team suggests that reduction of CB1 receptors may be unhealthy because these receptors are involved in many normal brain functions, such as memory and coping with stress.
This finding is related to a new drug that blocks CB1 receptors, called rimonabant.
The drug has been tested in clinical trials for smoking quitting Although the drug seemed to help people quit smoking, it caused problematic psychiatric side effects.
The drug was associated with unacceptable risk for mood symptoms and suicidal ideation.
The researchers suggest that other addiction treatments targeting cannabinoid signaling should be explored.
Jussi Hirvonen, MD, Ph.D., of NIH and University of Turku, Finland, is a co-author of the study.
The study is published in Biological Psychiatry.
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