There are over 200 different names for Marijuana such as pot, weed, herb, Mary Jane, Gangster, Chronic, etc… Medicinal use of the Cannabis plant dates back thousands of years. We know now that ancient cultures such as Roman, Greek, Assyrian, Indian and Chinese societies consumed it for the more varied reasons. The plant, Cannabis sativa, was known for its remarkable capacity of inducing euphoria, relaxation and many other symptoms at psychopharmacological level. Nowadays, its intake is mainly for recreational purposes although spiritual and medicinal reasons continue to be stated (the United Nations estimated that in 2004 about 0.6% of the world’s adult population consumed it on a daily basis).
The way Marijuana (the herbal form of Cannabis) interacts with your brain was better understood by the discovery that Δ9 – tetrahydrocannabinol (THC) is the active component of this plant. This discovery aloud the development of synthetic derivatives like rimonabant, used to study the action of THC. Receptors for this kind of components (called cannabinoids) are present in your brain and distribute themselves with strong regional variation. They are particularly enriched in areas known to be linked to drug addiction such as the caudate putamen and the substantia nigra. If the brain exhibits the receptors, naturally the researchers assumed it would also exhibit endogenous cannabinoid signals, which led to the discovery of endocannabinoids like anandamide and 2 – arachidonylglycerol (2-AG). These compounds are unsaturated fatty acids with polar head groups that are produced by enzymatic degradation of membrane lipids.
It is due to the THC interaction with the endocannabinoid receptors present in your brain, especially with the ones named CB1 (the most abundant G-protein coupled receptors), that people experience the physiological and behavioral symptoms of marijuana. For instance, effects on perception are probably due to CB1 receptors in the neocortex and alterations in psychomotor control are probably related to the presence of these receptors in the cerebellum and basal ganglia. Another typical symptom (e.g. used in benefit of immune-depressed patients) is the stimulated appetite, which is thought to be connected to hypothalamic actions.
Research continues in order to fully understand the synaptic mechanisms behind the behavioral effects of one of the most popular drugs in the world.
Purves, Dale et al (2008), Neuroscience 4th ed, pp 146 – 149