Cannabinoids

Cannabinoids are a group of terpenophenolic compounds present in Cannabis (Cannabis sativa L). The broader definition of cannabinoids refer to a group of substances that are structurally related to tetrahydrocannabinol (THC) or that bind to cannabinoid receptors. The chemical definition encompasses a variety of distinct chemical classes: the classical cannabinoids structurally related to THC, the nonclassical cannabinoids, the aminoalkylindoles, the eicosanoids related to the endocannabinoids, 1,5-diarylpyrazoles, quinolines and arylsulphonamides and additional compounds that do not fall into these standard classes but bind to cannabinoid receptors.[1] The term cannabinoids also refers to a unique group of secondary metabolites found in the cannabis plant, which are responsible for the plant's peculiar pharmacological effects.

Currently, there are three general types of cannabinoids: herbal cannabinoids occur uniquely in the cannabis plant; endogenous cannabinoids are produced in the bodies of humans and other animals; and synthetic cannabinoids are similar compounds produced in a laboratory.


CB1 receptors are found primarily in the brain, specifically in the basal ganglia and in the limbic system, including the hippocampus. They are also found in the cerebellum and in both male and female reproductive systems. CB1 receptors are essentially absent in the medulla oblongata, the part of the brain stem that is responsible for respiratory and cardiovascular functions. Thus, there is not a risk of respiratory or cardiovascular failure as there is with many other drugs. CB1 receptors appear to be responsible for the euphoric and anticonvulsive effects of cannabis.

CB2 receptors are almost exclusively found in the immune system, with the greatest density in the spleen. CB2 receptors appear to be responsible for the anti-inflammatory and possibly other therapeutic effects of cannabis.

THC is the primary psychoactive component of the plant. Medically, it appears to ease moderate pain and to be neuroprotective. THC has approximately equal affinity for the CB1 and CB2 receptors. Its effects are perceived to be more cerebral



Endocannabinoids serve as intercellular 'lipid messengers', signaling molecules that are released from one cell and activate the cannabinoid receptors present on other nearby cells. Although in this intercellular signaling role they are similar to the well-known monoamine neurotransmitters, such as acetylcholine, GABA or dopamine, endocannabinoids differ in numerous ways from them. Neurotransmitters are commonly small, water-soluble molecules that are contained within, and released from, tiny membrane-bound vesicles inside cells. Vesicles are often found in the tips, ‘terminals’, of long cellular branches called axons, and complex morphological and biochemical specializations mark the location from which vesicular release occurs. Endocannabinoids are lipophilic molecules that are not very soluble in water. They are not stored in vesicles, and exist as integral constituents of the membrane bilayers that make up cells. They are believed to be synthesized 'on-demand' rather than made and stored for later use. The mechanisms and enzymes underlying the biosynthesis of endocannabinoids remain elusive and continue to be an area of active research.

Endocannabinoids are described as ‘retrograde’ transmitters because they most commonly travel ‘backwards’ against the usual synaptic transmitter flow. They are in effect released from the postsynaptic cell and act on the presynaptic cell, where the target receptors are densely concentrated on axonal terminals in the zones from which conventional neurotransmitters are released. Activation of cannabinoid receptors temporarily reduces the amount of conventional neurotransmitter released. This endocannabinoid mediated system permits the postsynaptic cell to control its own incoming synaptic traffic. The ultimate effect on the endocannabinoid releasing cell depends on the nature of the conventional transmitter that is being controlled. When the release of the inhibitory transmitter, GABA, is reduced, the net effect is an increase in the excitability of the endocannabinoid-releasing cell. Conversely, when release of the excitatory neurotransmitter, glutamate, is reduced, the net effect is a decrease in the excitability of the endocannabinoid-releasing cell.

Endocannabinoids are hydrophobic molecules. They cannot travel unaided for long distances in the aqueous medium surrounding the cells from which they are released, and therefore act locally on nearby target cells. Hence, although emanating diffusely from their source cells, they have much more restricted spheres of influence than do hormones, which can affect cells throughout the body.

Endocannabinoids constitute a versatile system for affecting neuronal network properties in the nervous system.

The current understanding recognizes the role that endocannabinoids play in almost every major life function in the human body. Cannabinoids act as a bioregulatory mechanism for most life processes, which reveals why medical cannabis has been cited as treatments for many diseases and ailments in anecdotal reports and scientific literature. Some of these ailments include: pain, arthritic conditions, migraine headaches, anxiety, epileptic seizures, insomnia, loss of appetite, GERD (chronic heartburn), nausea, glaucoma, AIDS wasting syndrome, depression, bipolar disorder (particularly depression-manic-normal), multiple sclerosis, menstrual cramps, Parkinson's, trigeminal neuralgia (tic douloureux), high blood pressure, irritable bowel syndrome, and bladder incontinence