Effects of Marijuana

Effects of Marijuana

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The dominant fear about marijuana in the 20th century has been that its effects were somehow similar to the dangerously addictive effects of opiates such as morphine and heroin. Scientists feared that , like opiates, it had an extremely high potential for abuse and addiction. Despite widespread decriminalization of marijuana in the United States in the 1970's, this concern has remained the basis for federal law and policies regarding the use and study of marijuana. But the discovery of THC receptor sites in the brain refutes that thinking and may force scientists to re-evaluate their positions.

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The next century will veiw the 1988 discovery of the THC receptor site in the brain as the pivotal event which led to the legalization of marijuana. The receptor breakthrough occurred in 1988 at the St. Louis University Medical School where Allyn Howlett, William Devane, and their associates identified and characterized a cannabinoid receptor in a rat brain. Receptors are binding sites for chemicals in the brain, chemicals that instruct brain cells to start, stop, or otherwise regulate various brain and body functions. Before this discovery, no one knew for sure just how the psychoactive chemical in marijuana workes on the brain. Throughout the 1970's and 1980's, researchers made tremendous strides in understanding how the brain works by using receptor sites as switches which respond to various chemicals by regulating brain and body functions. The chemicals which trigger receptors are known as neurotransmitters. The brain's neurotransmitters are known as endogenous ligands. In many instances, drugs mimic these natural chemicals working in the brain. Scientists are just now confirming their determinations as to which endogenous ligands work on the cannabinoid receptors. It is likely that the neurotransmitter which naturally triggers cannabinoid receptors is one known as anandamide.

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Many important brain functions which affect human behavior involve the neurotransmitter dopamine. Serious drugs of abuse such as heroin and cocaine, interfere

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with the brain's use of dopamine in manners that can seriously alter an individual's behavior. A drug's ability to affect the neural systems related to dopamine production has now become the defining characteristic of drugs with serious abuse potential.

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The discovery of a previously unknown system of cannabinoid neural transmitters is profound. While century-old questions such as why marijuana is nontoxic are finally being answered, new fascinating questions are emerging. In the words of Israeli researcher Raphael Mechoulam, the man who first isolated the structure of THC, "Why do we have cannabinoid receptors?"

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Medical research into the health effects of cannabis have also matured. In a comprehensive 1986 article in the Pharmacological Review, Leo Hollister of the Stanford University School of Medicine concluded that "compared with other licit social drugs, such as alcohol, tobacco and caffeine, marijuana does not pose greater risks." He also wondered if these currently licit drugs would have seen such popular acceptance based on our current knowledge of them.

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The primary question was how do cannabinoids work on the brain? The triennial reports from the National Institute on Drug Abuse summarizing research on marijuana had begun to omit references to research on marijuana related brain damage and instead focus on brain receptor research. A comprehensive article by Renee Wert and Michael Raoulin was published in the International Journal of the Addictions in 1986 detailing the flaws in all previous studies that claimed to show brain damage resulting from marijuana use. As Hollister independently concluded, "Brain damage has not been proved." The reason, obviously, is that the brain was prepared in some respects to process THC.

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Dopamine is a neurotransmitter which is associated with extremely pleasurable sensations so that the neural systems which trigger dopamine release are known as the "brain reward system." The rewarding properties of dopamine are what accounts for animal studies in which animals will forgo food and drink or willingly experience electric shocks in order to stimulate the brain reward system. It is now widely held that the drugs of abuse directly or indirectly affect the brain reward system. The key clinical test of whether a substance is a drug of abuse potential