Neurochemical basis of cannabis addiction.

Cannabis derivatives have become the most widely used illicit substances in developed countries, and constitute a major health concern. The psychoactive compounds contained in cannabis induce their pharmacological effects by the activation of at least two different receptors, CB1 and CB2 cannabinoid receptors. Multiple studies have demonstrated the specific involvement of CB1 cannabinoid receptors in the addictive properties of cannabinoids. Several neurotransmitter systems involved in the addictive effects of other prototypical drugs of abuse, such as the dopaminergic and the opioid system are also involved in cannabis addiction. The participation of other neurochemical systems in behavioural responses of cannabinoids related to their addictive effects has also been reported. This review describes the experimental methods now available to study the pharmacological responses of cannabinoids related to their addictive effects and how these methods have contributed to advance the knowledge of the specific contribution of different neurochemical systems in cannabis addiction.