Every animal, have an Endocannabinoid System. Cannabinoid receptors are found throughout the body. But where has CB3 been hiding? Well, turns out it hasn’t exactly been hiding. It’s more like researchers didn’t connect it to endocannbinoid activity before now.
Firstly, the two most researched receptors are CB1 and CB2. While CB1 receptors are prominent in the central nervous system, and CB2 receptors typically reside in the immune system. CB3 receptors were incognito, previously identified as GPR55. At first, science didn’t know that this receptor even accepted cannabinoids.
The CB3 receptor stayed hidden from scientists because it’s so unlike the other cannabinoid receptors. It only shares 13% of amino acid identity with them. It simply doesn’t look like it would react with cannabis, so scientists on the hunt for new cannabinoid receptors passed over it for years. This designation means that while the receptor had been found, science doesn’t yet know what activated that receptor.
When CB3 was first discovered in 1999, many doubted it was a cannabis receptor. It wasn’t until real proof came along years later that medical researchers accepted that GPR55 was indeed the 3rd Cannabinoid Receptor.