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Joan Stephenson, PhD

JAMA. 2006;296:1345.

	Since this article does not have an abstract, we have provided the first 150 words of the full text and any section headings.

Although the beneficial effects of cooling on pain have been known at least since the time of Hippocrates and Galen, the biological mechanism for this form of pain relief was a mystery. Now, in studies of chronic pain in rats, researchers from the University of Edinburgh have discovered that cooling analgesia's effects occur through activation of a recently identified protein called TRPM8, one of a group of protein receptors that mediate specific stimuli, such as hot, cold, taste, or touch (Proudfoot CJ et al. Curr Biol. 2006;16:1591-1605).

TRPM8 is expressed in nerve cells in the skin and is activated when the skin is cooled or when menthol or other cooling chemicals are applied. In the study, rats with injured paws were treated with a topical solution of icilin or menthol or with cool water (16°C-20°C). These interventions activated TRPM8 receptors and reduced the animals' sensitivity to pain; . . . [Full Text of this Article]