Endocannabinoids

What are endocannabinoids?

Endocannabinoids are naturally occurring lipid signalling molecules that are found in body, and that mediate normal physiological functions. The endocannabinoids appear to have evolved in the brain to maintain biological harmony and to reduce excessive and damaging excitability of neurons. They also play a role in neuronal plasticity, that is, how the brain adapts to change.

The two major endocannabinoids that have been discovered are:

• anandamide (ananda is the Sanskrit word for bliss), and
• 2-arachidonoyl glycerol (2-AG).

Various biological proteins also exist that regulate the formation, transport and degradation of the endocannabinoids. These provide another drug target to help boost endocannabinoid levels, as there is an emerging viewpoint that many diseases involve a deficiency in endocannabinoids.

Cannabinoid receptors

Endocannabinoids interact with cannabinoid (CB) receptors to influence biological function. The two types that have been discovered thus far are CB1 and CB2, which are found in tissues throughout the body.

In the brain, CB1 is found on neurons, and this is the receptor with which tetrahydrocannabinol (THC) binds to produce its psychoactive effects. It is noteworthy that many phytocannabinoids do not bind to CB1, and are therefore unlikely to be intoxicating.

CB2 is found largely in immune tissues, including the brain’s immune cells, the microglia. Triggering CB2 on these cells reduces inflammation of the brain. Targeting CB2 may then offer hope in treating various conditions that involve brain inflammation such as epilepsy, multiple sclerosis, Alzheimer’s disease and various psychiatric conditions.