Cannabinoid receptor 1 (CB1), is a G protein-coupled cannabinoid receptor that in humans is encoded by the CNR1 gene. It was discovered by determination and characterization in 1988, and cloned in 1990 for the first time. The human CB1 receptor is expressed in the peripheral nervous system and central nervous system. It is activated by endogenous cannabinoids called endocannabinoids, a group of retrograde neurotransmitters that include lipids, such as anandamide and 2-arachidonoylglycerol; plant phytocannabinoids, such as docosatetraenoylethanolamide found in wild dagga, the compound tetrahydrocannabinol which is an active constituent of the psychoactive drug cannabis; and synthetic analogs of tetrahydrocannabinol. CB1 is antagonized by the phytocannabinoid tetrahydrocannabivarin at low doses and at higher doses, it activates the CB1 receptor as an agonist, but with less potency than tetrahydrocannabinol.
The primary endogenous agonist of the human CB1 receptor is anandamide.
