The Endocannabinoid System


The endocannabinoid system (ECS) refers to a collection of receptors and molecules. Cell receptors are like ‘locks’ on cell surfaces and the ‘keys’ are chemical molecules called agonists. Consequently, the ECS is composed of cell receptors, agonists and enzymes that break down those agonists.

The agonists in the ECS are termed ‘endocannabinoids’. ‘Endo’ means within and cannabinoid means that they act on the cannabinoid receptor. The two most widely studied endocannabinoids are anandamide (AEA) and 2-arachidadonoyl-glycerol (2-AG).

Using the lock and key mechanism analogy, only endocannabinoids are capable of binding to the cannabinoid receptors: the binding of the endocannabinoid to its receptor stimulates changes to occur within the cell.

Adapted from Emerald Bioceuticals

The ECS is a communications system that is located in the brain and body, and it affects many important functions, including how a person reacts to their environment, moves or even feels; the ECS helps to maintain optimal balance in the body – so-called homeostasis – and affects everything from sleep, appetite, pain, inflammation, memory, mood and even reproduction. Disruption of the ECS can cause imbalances in any one of these functions, resulting in several conditions such as anorexia, chronic motion sickness, schizophrenia, migraine, fibromyalgia, irritable bowel syndrome, multiple sclerosis and Huntington’s and Parkinson’s disease.

ECS receptors

Two primary receptors make up the ECS: cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2). CB1 receptor is the most abundant receptor of its kind expressed in the CNS, but it is  found mostly in the brain. CB2 receptors are predominantly found in the immune system. The CB2 receptors are also present in many other areas of our bodies such as nerves, heart and blood vessels, lung, intestines, liver, pancreas, muscle, bone, fat tissue, skin, spleen, and reproductive organs.

Chemicals capable of cannabinoid receptor interaction

Endocannabinoids are not the only chemicals that can interact with our ECS. Medical cannabis interacts with the ECS and has attracted much interest in recent years.

Endocannabinoids Produced in the body E.g. 2-AG, anandamide

Phytocannabinoids Produced by plants E.g. THC, CBD

Synthetic cannabinoids Chemicals synthesized to mimic endocannabinoids or phytocannabinoids

The phytocannabinoids THC and CBD, which are produced by the cannabis plant, are of particular medical interest owing to their interactions with our ECS and have, therefore, been the subject of many recent clinical trials.