What is the endocannabinoid system (ecs) and what is its role?

The plant Cannabis sativa contains more than 60 phytocannabinoids of which delta-9-tetrahydrocannabinol (THC) is the most abundant. Of the rest of the cannabinoids, the most studied are dronabinol (DBN) and nabilone (NB); followed by cannabinol (CBN), which is the product of the oxidation of THC and containing 10% of its psychoactive effect.

Additionally, cannabidiol (CBD) is the one that has no psychoactive effect but seems to potentially have certain positive health benefits, for example, it is known to have anti-inflammatory (1), analgesic (2), antipsychotic, anti-ischemic (3), anxiolytic/antiepileptic effects. It has also shown to provide additional health benefits in the areas of psychosis, epilepsy, anxiety, sleep disturbances and about some neurodegenerative diseases and immunity. (4,5)

These diverse physiological positive effects of cannabinoids explain the broad spectrum of health benefits without necessarily being medical or therapeutic. However, they have encouraged the interest of the scientific community for its study and research.

The endocannabinoid system constitutes a cellular communication and regulation system from which progressively different elements are known:

• The endocannabinoid signaling system is composed of the cannabinoid receptors; their endogenous ligands, the endocannabinoids; the enzymes that produce and inactivate the endocannabinoids; and the endocannabinoid transporters. (6)
• Unlike neurotransmitter molecules that are typically held in vesicles before synaptic release, endocannabinoids are synthesized on demand within the plasma membrane. (8)
• Endocannabinoids act as neuromodulators through a process called retrograde synapse.

Consequently, the activation of CB1 presynaptic receptors can inhibit the release of
neurotransmitters such as glutamate, GABA, noradrenaline, dopamine, serotonin and acetylcholine. 9 Regarding its functions, in general it can be said that the endocannabinoid system plays a modulating role in different physiological processes, mainly in the brain, but also in the immune and cardiovascular and less clear, at the level of energy metabolism and endocrine level. 10 In the brain, endocannabinoids participate in the regulation of motor activity, learning and memory. They also play a role remarkable during brain development. 11

THE THERAPEUTIC POTENTIAL OF CANNABINOIDS

Cannabis preparations provide many positive therapeutic effects. They have antispastic, analgesic, antiemetic, neuroprotective, and anti-inflammatory actions, and are effective against certain psychiatric diseases. Data about the therapeutic potential of cannabis has been greatly improved by many scientific documents and clinical trials. Some of the health benefits of cannabinoids are:

Pain Relief

Cannabinoids have a certain analgesic effect regarding chronic pain. This is a consequence of the presence of receivers CB1 in the regions that participate in the control of nociception, both at the spinal level and at the supraspinal. (12) Other scientific studies have shown that the cannabinoids might be used to reduce the dose of morphine in chronic pain treatments, without depletion of the analgesic effect, but with a reduction of the opiates addictive potential.

Motor Coordination

There is a high density of CB1 receptors in the basal ganglia and in the cerebellum. According to the role that the endocannabinoid system seems to play in the control of movement, it has been suggested that there may be a beneficial effect of direct or indirect agonists of CB1 receptors in diseases that are characterized by hyperkinesia as Korea's Huntington and the Gilles de la Tourette Syndrome; while the CB1 receptor antagonists could be useful as adjuvants in the Treatment of Hypokinetic Syndromes such as Parkinson's disease. (13)

Multiple Sclerosis

In this neurological disease of autoimmune origin, both are implicated CB1 receivers like CB2. A few clinical trials have taken place to support the numerous anecdotal or preclinical data regarding the beneficial effects of cannabinoids on some of the symptoms of multiple sclerosis. Most studies that exist are preclinical and they have reported that cannabinoids can reduce the symptoms of this condition. (13)

Glaucoma

Whereas CB1 receptors and CB2 are expressed in the retina, cannabinoids through the activation of these receptors, could be able to reduce the increase in intraocular pressure of glaucoma and avoid decreased visual capacity. (14) 

Cancer and AIDS

Because cannabinoids have a potential effect at increasing appetite, the cannabinoids have shown to reduce nausea and vomiting in cancer patients treated with antineoplastic, or to reduce cachexia in patients with AIDS. Both effects seem to have to do with the activation of CB1 receptors, present in certain brain regions, which participate in the control of emesis and appetite.