ABSTRACT
Although cannabis-based preparations have been used for centuries to treat pain, the biological basis for such pain-ameliorative effects of cannabinoids was unknown until recently. In animal studies, cannabinoids suppress pain behavior, noxious stimulus-evoked immediate early gene c-fos expression in the spinal cord, and noxious stimulus-evoked neuronal response. The effects on tactile sensitivity are selective for pain since cannabinoids were without effect on non-nociceptive neurons in the spinal cord and thalamus. The suppression of noxious stimulus-evoked responses are mediated by cannabinoid receptors through multiple sites of action in the brain, the spinal cord, and the periphery. Cannabinoids appear to be effective in both physiological (or acute) pain and clinical (or chronic) pain. Furthermore, studies in endocannabinoids have revealed that they serve a role in pain modulation. Advances such as these offer hope for new pharmacotherapies for pain, particularly in conditions that remain unresolved through current treatments.
