Modulation of transmitter release via presynaptic cannabinoid receptors

Cannabis (marijuana) is not only a frequently abused drug but also has the potential for the development of useful agents for the treatment of emesis, anorexia. and multiple sclerosis. In this article, the effects of modulati on of transmitter release by cannabinoids. in both the CNS and the PNS of v arious species, including humans, will be discussed. Cannabinoids inhibit n eurotransmitter release via specific presynaptic cannabinoid CB1 receptors. Studies using either the CB1 receptor antagonist and inverse agonist SR141 716 or CB1-receptor-deficient mice suggest that numerous presynaptic cannab inoid receptors are tonically activated by endogenous cannabinoids and/or a re constitutively active. CB1-receptor-mediated inhibition of transmitter r elease might explain, for example, reinforcing properties and memory impair ment caused by cannabinoids.