Summary: The endocannabinoid system (ECS) is a network of cell receptors and molecules found all through the human body. Receptors are like locks on a cell that only certain keys can open. The ECS was found in the 1990s. It came out of research on THC, the compound in cannabis that makes you high. The ECS has two main parts, the CB1 and CB2 receptors. The body’s own endocannabinoids switch them on. The ECS helps control pain, inflammation, appetite and mood. When the ECS fails, it has been linked to chronic pain, anxiety, depression and epilepsy. Finding the ECS changed how we understand the body. It has led to new therapies for many conditions.
Marijuana, also called cannabis, has been used for thousands of years. People used it in daily life and as medicine. It was often used for fun and in spiritual and cultural rites. It also has a long history as medicine. Old texts from China, India and Egypt record its use for pain, inflammation and other ills. In recent decades, interest in marijuana as medicine has grown. Much of it centers on chronic pain, nausea and other symptoms of disease. More US states and other countries have made medical marijuana legal. More recently, there has been a push to make it legal for fun as well. As of April 2023, recreational marijuana is legal in 19 US states, plus Washington DC and Guam. Several countries have done the same, including Canada, Uruguay and the Netherlands. Legal marijuana has given a big push to research on its health benefits. Researchers are studying how it helps in different conditions. They are also looking harder at how it works. Marijuana, THC and CBD seem to act mainly on the body’s endocannabinoid system. It also turns out the body makes many substances of its own that act on the same receptors. These body chemicals are quite similar to cannabinoids, including THC. Researchers now call them bliss molecules. Raising their levels in the body may help beat pain, inflammation and other health problems.
What is the endocannabinoid system?
The endocannabinoid system (ECS) is a network of cell receptors and molecules found all through the human body. It is a fairly new find in biology. Scientists first proposed it in the early 1990s. The story began in the 1960s, when THC was first isolated. THC is the compound in cannabis that makes you high. Researchers then asked how THC works in the body. That led to the discovery of the CB1 and CB2 receptors in the human brain and nervous system in the early 1990s. The CB1 and CB2 receptors are two main parts of the ECS. CB1 receptors sit mostly in the brain and spinal cord. CB2 receptors sit in the nerves of the body, in immune cells and in other body parts. THC and other cannabinoids from cannabis bind to these receptors. That can change mood, raise appetite and relieve pain. Scientists then found that the body makes its own cannabinoids. They are built much like the compounds in cannabis. These home-made cannabinoids are called endocannabinoids. They help control pain, inflammation, appetite, mood and much more. There are two main types: anandamide and 2-arachidonoylglycerol (2-AG). Anandamide is made mostly in the brain. 2-AG is made all through the body. The body makes both on demand, when certain signals call for them. Other parts of the ECS matter too, beyond the CB1 and CB2 receptors. Enzymes build and break down endocannabinoids. Other receptors, such as the TRPV1 receptor, also respond to them. The ECS does many jobs in the body. It helps control pain, inflammation, immune function, metabolism and mood. When it fails, it has been tied to many conditions. These include chronic pain, anxiety, depression and epilepsy. In short, finding the endocannabinoid system changed how we understand the body. It has led to new therapies for many conditions.
Is low endocannabinoid activity linked to chronic pain?
Pain is one of the most common symptoms. But chronic pain is different. It can last even after the problem that caused it is gone. New studies show that a weak endocannabinoid system, or low levels of the body’s own endocannabinoids, is one cause of chronic stress, chronic pain, irritable bowel syndrome, PTSD, bipolar disorder, and other chronic health issues. 
A new study published in 2022 looked at genes that help run the endocannabinoid system. Changes in them seem to raise the risk of early-onset Parkinson’s disease. Another study published in 2022 suggests a weak endocannabinoid system raises the risk of neurological disorders, including muscle weakness and vision problems. Other studies suggest that people with chronic pain also make fewer endocannabinoids. Researchers say this may explain why some people with chronic pain get real relief from marijuana. THC, one of the main cannabinoids in marijuana, seems especially good for managing chronic pain.
Frequently asked questions
Does the human body produce its own cannabinoids?
Yes. The body makes its own cannabinoids, called endocannabinoids. They are built much like the compounds in cannabis. The two main ones are anandamide and 2-arachidonoylglycerol (2-AG). The body makes them on demand, when certain signals call for them. They help control pain, inflammation, appetite and mood.
Is THC naturally in the body?
No. THC is the compound in cannabis that makes you high, so it comes from the plant. What the body does make are endocannabinoids. These molecules are quite similar to cannabinoids such as THC. They act on the same CB1 and CB2 receptors. Researchers call them bliss molecules. Raising their levels may help with pain and inflammation. That overlap is why marijuana, THC and CBD work mainly through the endocannabinoid system.
Where are endocannabinoids produced?
Anandamide is made mainly in the brain. 2-AG is made all through the body. The body makes both on demand, when it needs them. The endocannabinoid system also has enzymes that build and break down these molecules. It has receptors such as CB1, CB2 and TRPV1 that respond to them.
Where are cannabinoid receptors found in the body?
CB1 receptors sit mostly in the brain and spinal cord. CB2 receptors sit in the nerves of the body, in immune cells and in other body parts. Scientists found both in the early 1990s while studying how THC works. When cannabinoids bind to them, they can change mood, raise appetite and relieve pain.
What does the endocannabinoid system do?
It is a network of receptors and molecules. It helps control pain, inflammation, immune function, metabolism, appetite and mood. When it does not work right, it has been linked to chronic pain, anxiety, depression, epilepsy, irritable bowel syndrome and PTSD. People with chronic pain also seem to make fewer endocannabinoids.
Dr. Gurpreet Singh Padda, MD, MBA, MHP
