Humans have a unique relationship with the cannabis plant for completely biological reasons – simply put, the plant’s active ingredients affect many systems within the human body. However, this relationship was not always as clear as it is today. Compared to other common medical substances that were isolated and thoroughly researched as early as the late 19th century, cannabis and its derivatives only began to be isolated and researched in 1963, with the work of Raphael Mechoulam, an Israeli professor. Prof. Mechoulam’s research led to the discovery of the endocannabinoid system – a general nervous system that regulates a wide range of bodily functions through the enzymatic breakdown of cannabinoids from both the cannabis plant and the human body.
THC was the first cannabinoid to be isolated under laboratory conditions, and this was the first step toward the discovery of the endocannabinoid system. Research into THC led to a theory about the existence of a receptor in the brain that enables cannabis to affect humans. This theory was confirmed in the 1980s when a group of scientists discovered brain receptors that were activated by a cannabinoid compound of THC. These receptors were named CB1. Prof. Mechoulam immediately began searching for endocannabinoids (in other words, internal cannabinoids within the human body that correspond to the cannabinoids found in the cannabis plant), as receptors do not exist solely for external stimulus.
The search did not take long. Within a few years, the first molecule was found: Anandamide, named after the Sanskrit word for joy, "ananda." Another molecule, 2-Arachidonoylglycerol (2-AG) was discovered soon after. Prof. Mechoulam’s research had revealed and shed light on the endocannabinoid system for the very first time: it is a signal transduction system involving brain activity that affects a variety of functions and systems in the human body in ways that had not been recognized previously. Shortly afterwards, another receptor was identified at the University of Cambridge: CB2, which also responds to cannabinoids, but with effects that tend to be more related to physical functions rather than mood or psychoactive effects.
As CB1 receptors are mainly located in the brain and nervous system, their impact is also focused there. When a cannabinoid (internal: endocannabinoid, or external: exogenous) interacts with the receptor, we can expect activity in the hippocampus related to certain emotional functions, as well as responses in areas of the brain responsible for movement, motion, and motor control, and there also appears to be an effect on nerve centers in the spine. Although the role of the CB1 receptor is primarily focused on the nervous system, this is only the beginning. CB1 receptors are also found within fat cells in the digestive tract, liver cells, muscle cells, various areas of the lungs and kidneys, and even in sperm cells and throughout the female reproductive system. The correct development and functioning of CB1 receptors is vital to healthy embryonic development.
In contrast, CB2 receptors are mainly located within local tissues of the immune system, such as the thymus gland, spleen, tonsils, blood cells, and the B and T cells responsible for immune response. A small amount of CB2 receptors are also found in microglia cells throughout the brain and spinal cord, as well as in the central and peripheral nervous systems. Although CB2 receptors are present in the brain, they appear in much lower numbers than CB1 receptors and took many years to detect. As CB2 receptors are primarily found along the gastrointestinal tract, these receptors have become a focus for researchers investigating digestive problems.
The endocannabinoid system is therefore made up of three key interacting parts. The first part consists of the CB1 and CB2 receptors, which include neural synapses throughout the body. A synapse is a tiny structure within the nervous system, with one end firing an electric nerve impulse and the other end receiving it. You can imagine a river of neural signals flowing between two points. The second part is made up of the endocannabinoids produced within the human body and the cannabinoids from the cannabis plant. These serve as a "dam" in the river, preventing the water from overflowing or, alternatively, from drying up. The third and final part of the system consists of the enzymes that are tasked with ensuring that these various cannabinoids are broken down.
The cannabis plant contains cannabinoids which, when absorbed, create a reaction that regulates many systemic activities within the human body thanks to the endocannabinoid system. Thanks to this system, as well as the special biological key that allows the cannabis plant to "unlock" this system, a close relationship has been created between human and plant.