THC and cannabinoid receptor. Computer-generated molecular model of cannabinoid receptor 1 (CB1) complex (multicoloured) with THC, tetrahydrocannabinol (centre), the principle psychoactive constituent of cannabis. CB1 is a cell membrane receptor found mainly in the nervous system. The natural neurotransmitter anandamide (red, blue and white, left) and THC both bind to the CB1 receptor, inducing cellular responses and playing a role in memory, regulation of feeding behaviour and motivation.