Cannabinoid receptor

Oct 7, 2020

The currently recognized cannabinoid receptors are: CB1 and CB2 receptors. In the early 1990s, the cannabinoid CB1 and CB2 receptors that bind to them were cloned. The cb1 receptor is composed of 473 amino acids and 7 transmembrane domains, and the CB2 receptor is composed of 360 amino acids and 7 transmembrane domains, all of which are G protein coupled receptors. Gene cloning studies found that these two receptors have 44% amino acid sequence homology. The amino acid sequence of human cannabinoid receptors and rat cannabinoid receptors have high homology. Therefore, adult rats can be used as ideal experimental animals to study the distribution and function of cannabinoid receptors.

CB1 receptors are mainly located in the brain, spinal cord and peripheral nervous system, and are also known as central cannabinoid receptors. CB1 receptors in the brain are mainly distributed in the basal ganglia (substantia nigra, globus pallidus, lateral striatum), hippocampal CA pyramidal cell layer, cerebellum and cerebral cortex. Its activation can reduce the release of neurotransmitters, such as dopamine and GABA, to participate in the regulation of memory, cognition, and motor control.

CB2 receptors are mainly distributed in the periphery, such as the marginal area of the spleen, immune cells, tonsils, thymus, etc., also known as peripheral cannabinoid receptors. Studies have shown that CB2 receptors are also distributed in the hair epidermis and hair follicle tissues of rats, and may be involved in certain physiological and pathological processes of the skin. It is composed of 360 amino acids, although much shorter than CB1, it is still a typical G protein coupled receptor. Its role mainly includes regulating the release of cytokines inside and outside the central nervous system and the migration of immune cells. Studies have found that CB2 cannabinoid receptors also have a protective effect on heat-stimulated nociception.

It can be seen that the common role of CB1 receptor and CB2 receptor is to regulate the release of chemical transmitters, but the CB1 receptor is mainly derived from nerve cells, and the CB2 receptor is mainly derived from immune cells.

In addition to CB1 and CB2 receptors, researchers have also observed some other types of cannabinoid receptors, but they have not yet been cloned, and their activity is not very clear.

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