CB1 Receptor

Definition: The CB1 receptor is a cannabinoid receptor found mainly in the brain and nervous system. It’s the receptor THC activates to produce a high. CB1 receptors help regulate memory, mood, appetite, pain, movement, and coordination, and they’re among the most abundant receptors of their kind in the mammalian brain.

Where Are CB1 Receptors Found?

CB1 receptors are densest in brain regions that handle memory (hippocampus), decision-making (cortex), movement (basal ganglia and cerebellum), and reward. They also appear outside the brain, in the liver, fat tissue, digestive tract, and peripheral nerves. That spread helps explain why THC affects so many things at once, from short-term memory to appetite.

What Does the CB1 Receptor Do?

CB1 sits on nerve endings and acts as a brake on signaling. When the body’s own endocannabinoids, like anandamide and 2-AG, activate CB1, the nerve releases less of its chemical messenger. This feedback helps fine-tune pain signals, stress responses, hunger, and how memories form.

How Do THC and CBD Interact With CB1?

THC is a partial agonist at CB1, meaning it binds and activates the receptor. That’s what produces euphoria, altered perception, the munchies, and impaired short-term memory. CBD binds CB1 only weakly. Some lab research suggests it may subtly change how the receptor responds to THC, but that hasn’t been settled in human studies.

Has CB1 Been a Drug Target?

Yes. Rimonabant, a drug that blocks CB1, was approved in Europe in 2006 to treat obesity by reducing appetite. It was withdrawn in 2008 because of serious psychiatric side effects, including depression, which showed how central CB1 is to mood.

Related terms: Cannabinoid Receptors, CB2 Receptors, THC, Cannabinoids

Sources: Lu HC, Mackie K, “An Introduction to the Endogenous Cannabinoid System,” Biological Psychiatry, 2016; National Institute on Drug Abuse: Cannabis (Marijuana).