The cannabinoid receptor type 1, often abbreviated as CB₁, is a G protein-coupled cannabinoid receptor located primarily in the central and peripheral nervous system. It is activated by the endocannabinoid neurotransmitters anandamide and 2-arachidonoylglycerol (2-AG); by plant cannabinoids, such as the compound THC, an active ingredient of the psychoactive drug cannabis; and by synthetic analogues of THC.