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Tetrahydrocannabinol (tet-rə-HY-drə-kə-NAB-i-nawl or THC) is the principal psychoactive constituent of the Cannabis plant.
Image courtesy of http://en.wikipedia.org/wiki/File:Tetrahydrocannabinol.svg
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Like most pharmacologically-active secondary metabolites (organic compounds that do not participate in the normal activities of homeostasis) of plants, THC in cannabis is assumed to be involved in self-defense, perhaps against herbivores. THC also possesses high UV-B absorption properties which may protect the plant from harmful UV radiation exposure.
(Wikipedia, Cannabis October 22, 2013, 1:30 PM)
Image: Creative Commons/DarkEvil
There are many possible names for this drug, and the plant it is derived from, including: cannabis, hemp, marijuana, weed, pot, ganja, grass, reefer, dope, maryjane, hash, herb, salad, bud, skunk, green, the list goes on and on...
Marijuana was legal in Canada until 1923 when it was added to the Confidential Restricted List which began with the Opium Act in 1908. Since 2001 it has been legal to use under medical prescription and, in point of fact, its consumption is not held to be a crime by the majority of Canadians (http://bccla.org/news/2004/11/opinion-poll-confirms-canadians-want-legal-marijuana/ ).
*Note that since the writing of this blog post in 2013, Canada has legalized the use of marijuana both medically and recreationally.
The diagram below summarizes the current state of law which governs the use of marijuana - without a prescription- and their enforcement around the world.
THC, or (−)-trans-Δ9-tetrahydrocannabinol, or (6aR,10aR) - delta - 9 -tetrahydrocannabinol, the chemical agent within marijuana that is responsible for its effects, was first isolated in a laboratory in Israel in 1963 by Mechoulam and Gaoni. The compound is classified by where the double bonds occur. The double bonds in the naturally occurring molecule lock the atoms in place creating cis and trans isomers. The "trans" form of THC is more potent and the main psychoactive ingredient in marijuana and its derivatives. The orientation of the side chain, as well as the length of the side chain, also determine how "high" a person will get from smoking or ingesting the molecule.
The pharmacological effects of THC result from the fact that it acts as a partial agonist. An agonist is a chemical that binds to some receptor of a cell and triggers a response by that cell. THC mimics the action of a naturally occurring substance - a cannabinoid - which is a class of diverse chemical compounds that repress neurotransmitter release in the brain.
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 appear to be responsible for the euphoric and anti-convulsive effects of cannabis.
CB2 receptors are usually 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.
- euphoria
- relaxation
- alteration of visual, auditory, and olfactory senses
- fatigue
- appetite stimulation.
Side effects on the PLUS side:
THC:
- has mild to moderate analgesic effects - it can be used to treat pain especially for conditions like multiple sclerosis.
- has anti nausea and vomiting properties and is therefore helpful in the treatment of anorexia, AIDS and cancer.
- has been shown to assist some glaucoma patients by reducing pressure within the eye
- has been shown to decrease spasticity
- may reduce aggression in certain people.
- has mild antioxidant properties which may be sufficient to protect neurons against oxidative stress. In humans, oxidative stress is thought to be involved in Parkinson's disease, Alzheimer's, atherosclerosis, heart failure, myocardial infarction, fragile X syndrome,Sickle Cell Disease, lichen planus, vitiligo, autism, and chronic fatigue syndrome.(http://en.wikipedia.org/wiki/Oxidative_stress).
- may also be an effective cancer treatment
Side effects on the NEGATIVE side:
THC:
- may cause short term memory loss with long term chronic use
- reduces mouse male fertility in vivo by inhibiting ATP production in sperm so it may impact human male fertility. This effect can also be seen in women;sperm entering the vagina are subject to the effects of THC ingested by the woman in exactly the same way as if the male ingested it.
- causes testicular atrophy and uterine and ovarian hypoplasia in mice that are force fed it for long periods
- Some studies have suggested that cannabis users have a greater risk of developing psychosis than non-users. This risk is most pronounced in cases with an existing risk of psychotic disorder.(This has recently been disputed as though cannabis use has increased dramatically in several countries over the past few decades, the rates of psychosis and schizophrenia have not generally increased, casting some doubt over whether the drug can cause cases that would not otherwise have occurred
- heavy marijuana users (consuming at least 5 marijuana cigarettes daily for on average 20 years)have a smaller hippocampus (12 percent smaller) and the amygdala (7 percent smaller). It has been suggested that such effects can be reversed with long term abstinence.
- A study of around 1000 people in New Zealand found that starting cannabis below the age of 18, when the brain is undergoing major development, induces a 8 point IQ drop on average. This effect was not fully reverted after stopping cannabis use. However, starting cannabis older seems to be safer.
Food for Thought:
Does legalizing a drug help our society to manage its use? Does it open up a path for educative conversations? Or does it just give people permission to abuse it?
Bibliography:
The Role of Chemistry in History http://itech.dickinson.edu/chemistry/?cat=85
Narconon International http://www.narconon.org/drug-information/marijuana-history.html
http://en.wikipedia.org/wiki/Tetrahydrocannabinol