Cannabinoid receptor

Cannabinoid receptors are a type of protein that are part of the endocannabinoid system. They are involved in a variety of physiological processes including appetite, pain-sensation, mood, and memory. Cannabinoid receptors are of a class of cell membrane receptors in the G protein-coupled receptor superfamily. As is typical of G protein-coupled receptors, the cannabinoid receptors contain seven transmembrane spanning domains.

Types of Cannabinoid Receptors

There are currently two known subtypes of cannabinoid receptors, termed CB1 and CB2. The CB1 receptor is expressed mainly in the brain, but also in the lungs, liver and kidneys. The CB2 receptor is expressed mainly in the immune system and in hematopoietic cells.

CB1

The CB1 receptor is one of the most abundant G protein-coupled receptors in the brain and is particularly abundant in the cerebellum, basal ganglia, and hippocampus. It is also present in other areas, including the peripheral nervous system. Activation of CB1 receptors produces a characteristic set of responses including inhibition of adenylate cyclase, decreased formation of cyclic AMP, and increased activation of potassium channels.

CB2

The CB2 receptor is primarily associated with cells in the immune system and appears to be less frequently expressed in the brain than CB1. Activation of CB2 receptors does not appear to result in the psychoactive effects associated with activation of CB1 receptors. Instead, it is thought to play roles in immune function and inflammation.

Function

Cannabinoid receptors are activated by cannabinoids, which are a group of ligands that are produced by the body (endocannabinoids), synthesized in the lab (synthetic cannabinoids), or occur naturally in the cannabis plant (phytocannabinoids). The most notable of the phytocannabinoids is THC, the primary psychoactive compound in cannabis.

Clinical significance

Cannabinoid receptors are a promising target for the development of novel therapeutics for a variety of conditions, including pain, obesity, and multiple sclerosis.

See also

• Endocannabinoid system
• Cannabinoids
• Medical cannabis

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