Humans have used drugs derived from plants, such as the opium poppy, for thousands of years to lessen pain and produce euphoria. In 1973, scientists discovered the brain receptors that interact with these opiates, which include opium, morphine, and heroin. In 1975, the first of the brain's natural chemicals that bind with these receptors was identified. The similarity of this chemical, enkephalin, to morphine suggests opiate drugs work primarily by mimicking natural opiate-like molecules. The discovery of this endorphin (a term meaning endogenous morphine) system helped explain the effects of opiate drugs and opened the door to the development of powerful new therapeutic drugs that revolutionized pain management.
Similarly, humans have used the cannabis plant for thousands of years to reduce pain, control nausea, stimulate appetite, control anxiety, and produce feelings of euphoria. The first cannabinoid was isolated in 1899, but it wasn't until 1964 that THC was isolated. Since the discovery of THC, researchers have made new discoveries that help us better understand not just why and how cannabis works so well for so many people but its full therapeutic potential.
The therapeutic benefits of cannabis are derived from the interactions of cannabinoids and the human body's endocannabinoid system (ECS), identified in 1984. The ECS is a sophisticated group of ligands (such as the natural cannabinoid anandamide), their receptors, and signaling pathways involved in regulating a variety of physiological processes, including movement, mood, memory, appetite, and pain.
More than 20 years since researchers began developing an understanding of the ECS, two types of cannabinoid receptors, CB1 and CB2, have been identified, setting the stage for discoveries that have dramatically increased our understanding of how cannabis and its many constituent cannabinoids affect the human body.
CB1 receptors are found in the central nervous system, particularly the brain, and in other organs and tissues such as the eyes, lungs, kidneys, liver, and digestive tract. In fact, the brain's receptors for cannabinoids far outnumber the presence of all other neurotransmitter receptors combined, yet they are highly localized. The relative safety of cannabis is in part explained by the fact that cannabinoid receptors are virtually absent from those regions at the base of the brain (i.e., brain stem) that are responsible for such vital functions as breathing and heart control. CB2 receptors are primarily located in tissues associated with immune function, such as the spleen, thymus, tonsils, bone marrow, and white blood cells.
