Endocannabinoid Receptors

Updated: May 7

The following Higher Learning LV homework sample teaches students about the basic types of microscopic cellular receptors that perform the heavy lifting of binding with phytocannabinoids, including CBC, CBD, CBG, CBN, and THC.

In 1990, scientists discovered the first ECS receptor, which they dubbed CB1. Three years later, a second major ECS receptor was identified that was labeled CB2. Further investigation has revealed that both types of receptors appear throughout all areas of the body. However, CB1 receptors are found in their greatest densities in the brain and CNS. Although they are located in all areas of the body, CB1 receptors appear in lower densities outside of the brain and CNS.


CB2 receptors appear in their greatest densities in the organs, glands, and tissues involved in the immune system. However, they also appear in the brain and CNS.

CB2 receptors appear in their greatest densities in the organs, glands, and tissues involved in the immune system. However, they also appear in the brain and CNS, although in considerably lower densities than their CB1 siblings. ECS receptors are located in nearly every part of the body. This includes the heart, liver, pancreas, spleen (where CB2 receptors are most dense), and epidermis (skin). These receptors also appear on the surface of white blood cells, in reproductive organs, and within the gastrointestinal and urinary tracts.


CB2 receptors have even been discovered in the nasal passages of humans, indicating the potential effectiveness of molecules that bind with these special receptors when inhaled (such as via a nasal spray or inhaler).


Some researchers and medical professionals believe there are many undiscovered ECS receptors, well beyond the world of merely CB1 and CB2. Cellular receptors that may eventually officially qualify as ECS neurotransmitters include what are currently called "orphan receptors." These ECS orphan receptors include GPR17, GRP18, GPR55 (involved in immune function), and GPR119.

Boston physician Benjamin Caplan, MD


Dr. Benjamin Caplan is a clinical practitioner from Boston, Massachusetts who sometimes recommends cannabinoids and terpenes in the treatment of his patients. Caplan believes that the variety of ECS receptor types far exceeds CB1 and CB2. “What we know is that CB1 and CB2 are a very small part of the full picture. Many more receptors, throughout the human body, bind—either directly or indirectly—with cannabinoid molecules,” said Caplan during a 2019 interview.


A 2019 study entitled "Use of Cannabidiol in the Treatment of Epilepsy: Efficacy and Security in Clinical Trials" revealed that some cannabinoids interact more indirectly with the ECS and the CB1 and CB2 receptors that populate it. One example is CBD.


"CBD shows a low affinity for endocannabinoid receptors. It carries out its mechanisms of action by interacting with other molecular targets. One of the most important [of these] is the Transient Receptor Potential Vanilloid (TRPV)."


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