cannabinoids, principally delta-9-tetrahydrocannabinol
and synthetic analogs, are psychoactive ingredients of
marijuana. The cannabinoid receptors are members of the
family of guanine-nucleotide-binding protein (G-protein)
coupled receptors which inhibit adenylate cyclase activity
in a dose-dependent, stereoselective and pertussis toxin-sensitive
manner. The two receptors have been found to be involved
in the cannabinoid-induced CNS effects (including alterations
in mood and cognition) experienced by users of marijuana.
Two transcript variants encoding different isoforms have
been described for this gene.
Cannabinoids exert their well known physiological effects
through two G protein coupled receptors, cannabinoid receptor
1 (CB1) and CB2. Both cannabinoid receptors have been shown
to inhibit adenylyl cyclase as well as stimulate the mitogen-activated
protein kinase, MAPK. CB1 receptors also modulate ion channels
through direct G-protein interactions. Delta 9-tetrahydrocannibinol
and related ligands likely exert their psychoactive effects
by inhibiting presynaptic N- and P / Q type calcium channels.
CB2 is thought to function primarily in the immune system
although it has been suggested to be present in the central
nervous system, including the retina.