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As the controversy over medical marijuana rages, new research is adding to evidence that marijuana's active constituents have medical potential.
A National Institute of Mental Health (NIMH) research team including Nobel Laureate Julius Axelrod, Ph.D., and colleague Aidan Hampson, Ph.D., reported in the July 6 issue of the Proceedings of the National Academy of Sciences that cannabidiol and delta-9 tetrahydrocannabinol (THC) exert neuroprotective effects. The cannabinoids exerted a protective, antioxidant effect on rat cortical neuron cultures exposed to toxic levels of the neurotransmitter glutamate. Both cannabidiol, which is not psychoactive, and THC, which is highly psychoactive, were found to be more protective against glutamate neurotoxicity than either vitamin C or vitamin E. Because cannabidiol is not psychoactive, it could be administered in higher doses than would be feasible for THC, the authors comment. Studies on the efficacy of cannabidiol as a treatment for experimentally induced stroke in rats are in progress.
In ischemic disorders such as stroke, neurotoxic amounts of glutamate are released, overstimulating glutamate receptors and thus permitting a massive influx of calcium and formation of toxic, oxidative groups of atoms known as free radicals. Antioxidants counter this toxicity.
In another study published in the July 16 issue of Nature, Danielle Piomelli, Ph.D., of the Neurosciences Institute in San Diego and colleagues described how endogenous cannabinoids act locally at the site of tissue damage, controlling the initiation of pain signals.
Piomelli and colleagues found that anandamide and palmitylethanolamide, two endogenous cannabinoids, are released at injury sites, synergistically triggering local cannabinoid receptors in peripheral tissues. In laboratory rats, the endogenous cannabinoids reduced inflammation and, when administered together, exerted a pain-reducing effect 100 times more potent than either alone. The work provides a rationale for investigating the creation of cannabis-based drugs that may be able to provide analgesia through local action, thus minimizing psychotropic effects that accompany central nervous system-induced analgesia.
The Web site for the Proceedings of the National Academy of Sciences is: www.pnas.org. The Web site for Nature is www.nature.com.