Cannabinoids are various chemical compounds that bind to special receptors in the human body, together they make up the so-called endocannabinoid system. The "key and lock" metaphor is often used to describe this process. The human body has specific binding sites ("locks") on the surface of many cell types, and our body produces different endocannabinoids ("keys") that bind to these cannabinoid receptors (CB) to activate them or "unlock"them.
In 1992, researchers discovered for the first time a natural occuring (endogenous) substance that binds to cannabinoid receptors. This substance, called anandamide, comes from the Sanskrit "Ananda" for bliss and "amide" because of its chemical structure. In 1995 a second endocannabinoid, 2-arachidonoylglycerol (2-AG) was discovered. These two endocannabinoids are the best studied so far. Today it is thought that there are about 200+ related substances, similar to the endocannabinoids, which complement their function in what is called the so-called "entourage effect". Several endocannabinoids not only bind to cannabinoid receptors, but also to a possible CB3 receptor (the GPR55 receptor), vanilloid receptors and other receptors.
In addition to endocannabinoids, scientists have now also identified cannabinoids found in the cannabis plant (phytocannabinoids) that mimic or counteract the effects of some endocannabinoids. Phytocannabinoids and terpenes are produced in resin glands (trichomes) which are present on the flowers and upper leaves of cannabis plants in the flowering phase. The amount of resin produced and cannabinoid content varies according to plant, genus, growing conditions and harvest time. The chemical stability of cannabinoids in harvested plant material is affected by moisture, temperature, light and storage, but will degrade over time in all storage conditions.
When a cannabinoid causes a receptor to act in the same way as a natural hormone or neurotransmitter, it is referred to as "agonist". If, on the other hand, the cannabinoid prevents the receptor from bonding to the naturally occurring compound, thereby altering or reducing the resulting event (e. g. pain, appetite, alertness), it is referred to as "antagonist". Research is being done to better understand how specific cannabinoids can unlock (or in some cases lock) specific receptors.
More than 100 phytocannabinoids have been identified in the cannabis plant, many of which have medicinal value. Most of them are very closely related or differ with only one chemical component. The most commonly discussed and studied cannabinoids in the cannabis plant are tetrahydrocannabinol (THC) because of its psychoactive properties ("high sensation") and cannabidiol (CBD) because of its purported medicinal properties.
Cannabinoids can be administered by smoking, evaporation, oral ingestion, transdermal patches, intravenous injection, sublingual absorption or with a rectal suppositorium.