The Cannabinoid receptor type 2 is the full name for CB2. CB2 is a protein. It is the main receptor of the Endocannabinoid System (ECS), along with CB1, and is responsible for maintaining the homeostasis of our body. CB2 assures the normal functioning of various systems such as metabolism, sleep, digestion, motor control, bone, and cardiovascular function.
In order for CB2 to carry out these functions, the two main natural cannabinoids that are produced by our body (Anandamide (AEA) and 2-arachidonoglycerol (2-AG)) must bind to it. External cannabinoids like Cannabidiol (CBD) from the hemp plant can also bind to CB2 receptors.
These cannabinoids find CB2 in different parts of our body, but mainly in the peripheral nervous system, mostly on the immune cells which are continuously circulating our bloodstream. They are in our spleen, liver cells, and adipose tissue.
Cannabinoids stimulate different actions by binding to CB2 receptors at different times and locations: while the effect at a time could be signaling that a part of our body that is inflamed, it could also lead to insulin production if the receptor is located on a digestive organ such as the pancreas, spleen or liver.
Structure of CB2
The CB2 receptor is a G-protein coupled receptor (GPCR). Like other proteins in our body, CB2 receptors are coded in our DNA, and the gene responsible for the CB2 is the CNR2 gene.
CB2 receptors allow cannabinoids to bind in a similar way to the lock and key hypothesis of enzymes: the CB2 receptor acting as a lock and the cannabinoid as the key. Once the cannabinoid binds with the CB2, we can say it unlocks it, and the relevant signals are released.
However scientists, unlike with CBD, are yet to have an express explanation of the exact 3D structure of CB2 and how exactly molecules bind to its receptors.
It’s Roles in the ECS
The CB2 receptor is less understood than the CB1, and this has resulted in insufficient knowledge about its role in the Endocannabinoid System, however, research in this area is growing. There are have been reports of the contributions of CB2 with many diseases affecting our organs and systems including body pains, lung cancer, kidney, liver, brain, bone and skin diseases. Let us see some of the roles of CB2 in the ECS in keeping us healthy.
CB2 and its role as a Pain and Inflammation Regulator
Pain is a part of our lives but the degree we experience it is what varies from one person to another. One person could be suffering from a burn while another is suffering rheumatoid arthritis.
When cannabinoids bind with CB2, it has been shown that it helps reduce pain alongside other receptors like the CB1, GPR55, etc. CB2 has been shown to have the potential in reducing pain caused by rheumatoid arthritis, neuropathic pain, inflammatory pain, etc. CB2 has been shown to inhibit pathways of inflammatory signals.
When CB2 receptors are activated, they may have effects in reducing stroke symptoms. Since we already know that CB2 has anti-inflammatory effects and the most significant symptom of a stroke is inflammation, CB2 may be of help.
CB2 and Oxidative stress
Oxidative stress is due to the presence of free radicals in the brain and bloodstream. These free radicals lead to degenerative diseases. Recent studies have shown that neurodegenerative diseases such as Parkinson’s disease affect CB2 receptors, hence the increased activation of CB2 receptors are believed to help treat these diseases.
To help reduce oxidative stress and help with neurodegenerative diseases, CB2 receptors have been shown to activate and prevent loss of TH-ir DA neurons, which are responsible for the protection of neurons. It helps to activate and augment antioxidants enzyme activities and reduce nitrite levels (free radicals).
By protecting the neurons, CB2 may prevent potential stroke victims from coming down with the disease.
CB2 and Bone Health
CB2 has been shown to improve our bone health, especially by maintaining bone mass. It does it in two ways;
- By making sure Osteoblasts, our cells responsible for making cells, keep reproducing
- By ensuring Osteoclasts, our cells responsible for breaking cells down, do not destroy more cells than the osteoblasts will produce
This is essential in women going through menopause who are susceptible to osteoporosis, a condition where there is an imbalance between the cells produced and the cells destroyed.
CB2 and addiction
CB2 helps reduce our tolerance to opioids like cocaine, hence reducing cases of overdose. It also helps reduce addiction. This is how it happens: CB1 is the receptor that opioids and other psychoactive substances bind to so we feel the high effect. This action is expressed in dopamine neurons in the Ventral Tegmental area (VTA) of our brain.
There is growing evidence that when CB2 receptors in the brain are activated, they may inhibit the activities of VTA, thereby stopping the effects of these psychoactive substances, and by extension reduce addiction to drugs like cocaine.
CB2, like its sister and more understood CB1 receptor, is a key part of the Endocannabinoid System. It can be activated by both Endocannabinoids (cannabinoids produced in our body) and Phytocannabinoids (produced outside the body, especially from plant sources such as hemp).
When the CB2 receptors are activated they may be of help in reducing pain and inflammation, reduce oxidative stress and symptoms of neurodegenerative diseases, improve our bone health, reduce addiction, etc.
Though CB2 has shown promise in helping with various diseases, there is still a lot of research underway. Its exact 3D structure and how cannabinoids bind to it are yet to be fully understood.