Cannabinoid receptors are 7-transmembrane receptors that mediate the central and peripheral actions of extracts from the cannabis plant (Cannabis sativa), known under a variety of pseudonyms from hashish and marijuana to ganja and bhang. Although many endogenous agonists of cannabinoid receptors have been described, a categorical role of these (lipid-derived) molecules as the endogenous ligand for cannabinoid receptors is currently lacking. Cannabinoid receptors have been implicated in diverse physiological and pathophysiological roles in the body, including regulation of mood, appetite, pain sensation, vascular and nonvascular smooth muscle tone, and immune function. The wide distribution of cannabinoid receptors in the central and peripheral nervous systems, as well as non-nervous tissue, supports these putative roles. Currently, there appear to be only two subtypes of cannabinoid receptor, CB1 and CB2, which appear to be located predominantly on cells of the nervous and immune systems, respectively. Both receptor subtypes couple principally through the Gi/o family of G proteins.
