Pharmacology of cannabinoid CB1 and CB2 receptors.

There are at least two types of cannabinoid receptors, CB1 and CB2, both coupled to G-proteins. CB1 receptors are present in the central nervous system and CB1 and CB2 receptors in certain peripheral tissues. The existence of endogenous cannabinoid receptor agonists has also been demonstrated. These discoveries have led to the development of selective cannabinoid CB1 and CB2 receptor ligands. This review focuses on the classification, binding properties, effector systems and distribution of cannabinoid receptors. It also describes the various cannabinoid receptor agonists and antagonists now available and considers the main in vivo and in vitro bioassay methods that are generally used.