The mechanism of action of cannabis
The active ingredient of cannabis is ∆9-tetrahydrocannabinol (∆9-THC) and it is thought to exert its effect by binding to cannabinoid CB1 receptors on pre-synaptic nerve terminals in the brain. ∆9-THC binding to CB1 receptors activates G-proteins that activate/inhibit a number of signal transduction pathways. The G-proteins directly inhibit N and P/Q-type voltage dependant calcium channels and sodium channels and indirectly inhibit A-type calcium channels via inhibition of adenylate cyclase. ∆9-THC binding and G-protein activation also activates inwardly rectifying potassium channels and the MAP kinase signalling pathway. The cumulative effect of these pathways is the euphoric feelings associated with cannabis use.
