The endocannabinoid system: structure and function

Author: Dipl.-Chem. Mohammad Reza Talebnasab
Editorially updated: 12 October 2026

The endocannabinoid system, or ECS, is a signalling network within the body. It comprises particular signalling molecules, receptors and enzymes that produce and break down these molecules. The system is active even without contact with cannabis. Its name arose because research into the cannabis plant contributed to the discovery of these biological relationships. Scientific review of signalling in the nervous system

How was the endocannabinoid system discovered?

The discovery took place in stages through the work of several research groups. In 1988, William A. Devane, Allyn C. Howlett and other researchers described a specific cannabinoid binding site in rat brain. In 1992, anandamide was identified as a substance produced by the body that binds to a cannabinoid receptor. The molecular description of another receptor, later called CB2, followed in 1993. In 1995, 2-arachidonoylglycerol, or 2-AG, was also described as an endogenous cannabinoid receptor ligand. Devane et al., 1988 · Devane et al., 1992 · Munro et al., 1993 · Mechoulam et al., 1995

These studies established important foundations. However, today's understanding of the ECS extends far beyond its earliest discoveries and continues to develop through new research.

The three central components of the ECS

The classical endocannabinoid system comprises three closely connected components:

• Endocannabinoids: signalling molecules produced by the body, particularly anandamide and 2-AG.

• Cannabinoid receptors: principally CB1 and CB2, through which signals are transmitted in cells.

• Enzymes: proteins involved in producing and breaking down the signalling molecules.

Their interaction is crucial. The effect of a signal depends not only on whether a receptor is present, but also on when and where signalling molecules form and how quickly they are broken down again. Scientific review

Anandamide and 2-AG: the body's own cannabinoids

Anandamide is also called AEA; 2-AG stands for 2-arachidonoylglycerol. Both are lipid-like signalling molecules produced by the body, not substances taken in from the cannabis plant. Their original identification already demonstrated that the body has its own molecules that interact with cannabinoid receptors. Original anandamide study · Original 2-AG study

Fatty acid amide hydrolase, FAAH, is one of the enzymes important for anandamide breakdown. Monoacylglycerol lipase, MAGL, plays a central role in breaking down 2-AG. This regulates signalling and limits its duration. Cravatt et al., 1996 · Dinh et al., 2002

CB1 and CB2: where are the receptors located?

CB1 receptors are particularly important in the nervous system. CB2 receptors are often investigated in connection with immune cells and immune processes. This description identifies areas of emphasis, not a rigid division into ‘brain only’ and ‘immune system only’. Distribution and function depend on the tissue, cell type and biological state. Understanding the receptors

In simple terms, a receptor can be understood as a molecular docking site. However, this picture does not explain every interaction: different cannabinoids may affect different targets and do not automatically act in the same way.

What functions does the endocannabinoid system have?

The ECS helps regulate various bodily processes. Research areas include neuronal signalling, pain processing, memory processes and the response to stress. In the nervous system, endocannabinoids can also act as feedback signals: they influence how much of other signalling molecules a preceding nerve cell releases. Endocannabinoid signalling in the nervous system

Connections with food intake, energy metabolism and processes in the digestive tract are also being investigated. The endocannabinoid system is part of a larger biological network, not a single switch controlling every bodily function. Scientific review of appetite regulation · Scientific review of the digestive system

How are CBD, CBG and CBN related to the ECS?

CBD, CBG and CBN are plant cannabinoids or cannabinoid compounds associated with the plant. They are distinct from the body's own endocannabinoids. Belonging to this group of substances does not imply a shared or guaranteed effect.

For example, CBD cannot accurately be described as a simple ‘activator’ of all cannabinoid receptors. Cell-based investigations show more complex interactions, including a modifying effect on CB1 receptor signalling. Such mechanisms are important for basic research, but do not alone establish a health benefit of a particular product. Experimental study of CBD and CB1

What can be inferred for everyday life?

The ECS being involved in many processes does not mean that everyone needs additional cannabinoids. General symptoms cannot be used here to diagnose a personal ‘endocannabinoid deficiency’. Nor can a single receptor finding establish a suitable treatment. Medical questions require individual assessment by a doctor.

For a closer look at the differences between the plant-derived substances, further information is available on CBD, CBG and CBN. Other information pages explain cannabichromene (CBC) and delta-9-tetrahydrocannabinol (THC). The history of cannabis explains the historical context.

Note: this article explains biological principles and research. It does not replace diagnosis, medical advice or treatment and contains no dosage or use recommendations.

​

​​Further reading: Cannabinoids and medicines: mechanisms and risks of interactions.