Mechanism of action of cannabis

 

The active compound of cannabis is delta 9 tetrahydrocannabinol (THC). When the drug is smoked, the THC enters the blood stream and is rapidly transported to the brain, where it binds to cannabinoid receptors.

 

It acts on CB1 receptors in the brain which are found in the hippocampus (memory), cerebellum (co-ordination), hypothalamus (appetite control and temperature regulation), substantia nigra and the mesolimbic DA pathways associated with reward.

 

CB1 receptor activation inhibits neurotransmitter release via inhibition of Ca2+ entry and hyperpolarisation due to activation of K channels. THC can also act on CB2 receptors in the periphery.

 

A “stoned” effect is caused by THC acting on the CNS to give psychotomimetic, depressant and autonomic effects. The effect after smoking takes an hour for the full effect and usually lasts between 2-3 hours.