Why it matters
CB1 is one of the most abundant GPCRs in the brain, with high density in cortex, hippocampus, basal ganglia, cerebellum, and brainstem. Activation reduces neurotransmitter release at the presynaptic terminal, which produces the diverse cognitive, motor, and perceptual effects associated with cannabis use.
In practice
THC binds CB1 as a partial agonist; CBD does not bind the orthosteric site significantly but acts as a negative allosteric modulator. CB1 antagonists (rimonabant) have been studied for obesity and addiction but were withdrawn due to depressive side effects.
Common confusion
CB1 is sometimes called “the THC receptor” — accurate as a shorthand but it understates the receptor’s primary endogenous role.
This glossary entry is editorial content reviewed against primary sources. It is not medical advice. See our Editorial Policy.