The Endocannabinoid System

Endogenous cannabinoids (a.k.a. endocannabinoids) are lipid-based retrograde neurotransmitters produced by the body. Endocannabinoids bind to CB1 and CB2 receptors located in the endocannabinoid system (ECS) throughout the entire body. These functions affect internal environment stability, which can help the body achieve homeostasis. Homeostasis is a stable equilibrium for physiological processes, an overall balance within the body between all of its components. If factors, such as illness or pain, throw off homeostasis within the body, the ECS kicks in and helps the body return to a more ideal status.

Endocannabinoid System of Animals

Excluding the Phyla Protozoa and Insecta, all animals have been found to have an endocannabinoid system. This includes vertebrates (birds, fish, reptiles, and animals) and invertebrates (nematodes, mussels, leeches, and sea urchins). Biological importance is strongly represented by ECS identification in invertebrates, showing how far back this system’s history goes.  As multicellular animals developed with increasing complexity, the ECS surfaced in the phylogeny concurrently with the development of the nervous system. ¹


The two most well studied endocannabinoids identified within the body are anandamide (AEA) and 2-arachidonoylglyerol (2-AG). Anandamide, found also in chocolate, has also been called the “bliss molecule” due to its activation of cannabinoid receptors in the brain, heightening motivation and happiness. ² There are many other isolated cannabinoids found throughout nature, like that of AEA, each performing different functions in the human body. Endocannabinoids have been shown to regulate many functions within the body like sleep, inflammation, mood regulation, cardiac function, muscle fiber formation, energy metabolism, appetite, immune function, pain, and neuroprotection. ³

CB1 & CB2 Receptors

Endocannabinoid receptors are found on cell surfaces; both CB1 & CB2 receptors serve multiple functions. The structure of the CB1 receptor is similar amongst all mammalian species. CB2 receptor functions are dependent on its level of expression on cell membranes and the type of signaling pathways involved. ¹ CB1 receptors are concentrated in the brain and central nervous system but are also sparsely located in other parts of the body. CB2 receptors are mostly located in peripheral organs, especially cells associated with the immune system.