The cannabis plant has been used for centuries; however, the psychotropic compound responsible for the reported “high”, tetrahydrocannabinol (THC), was isolated in 1964. It is now believed that this hydrophobic compound works on a distinct family of receptors in the brain and other tissues. The first of these receptors were discovered in 1988 using synthetic cannabinoids.
G Protein Receptors
The cannabinoid receptors are part of the G protein-coupled receptor family. In general, they are activated by endocannabinoids that are synthesized on demand by the body during times of stress to restore homeostasis, phytocannabinoids that occur naturally in the cannabis plant, and synthetic cannabinoids that are artificially manufactured. Cannabinoid receptors are involved in a variety of physiological processes including appetite, pain modulation, mood, and memory. The discovery of these receptors has renewed interest and enhanced the understanding of the therapeutic potential of cannabinoids, as the receptors provide pathways and targets for formulations and drugs.
The CB1 receptor is thought to be widely expressed in the brain at the synapsis of the central nervous system. It has subsequently been found in peripheral nerves and tissues such as muscle, lungs, liver, kidney, and fat. They are abundant in areas of the brain that affect emotion, pain, memory, sensory perception, cognition, movement, certain autonomous functions, and the endocrine functions. They are also implicated with appetite, energy metabolism, and reward centers.
CB2 receptors are mainly found in the immune system on T cells, B cells, macrophages, and in hematopoietic cells. These receptors, are implicated in the relief of certain kinds of pain and may be responsible for the anti-inflammatory effects of cannabis among other functions. While these two receptors are the better-studied targets of cannabis, recent and mounting evidence suggests that additional cannabinoid receptor types exist that produce cannabinoid-like effects without activating the CB1 and CB2 receptors.
US Federal Laws
Though this has been known, research into this area has been curtailed in the U.S. because of the federal laws that schedule marijuana.