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----------------------------------------------------------------------- Chili peppers and pain ----------------------------------------------------------------------- LONDON (October 22, 1997 1:46 p.m. EDT http://www.nando.net) - American scientists have discovered a molecular key to what makes chili peppers so hot. The discovery could provide clues about how humans experience pain. David Julius and Michael Caterina of the University of California in San Francisco found the protein ion receptor for capsaicin, the pungent ingredient in hot chili peppers that causes painful heat sensation. The protein, known as vanilloid receptor subtype 1 (VR1), is activated by binding to capsaicin. High, painful temperatures work in a similar way and cause the same sensation. "In the same way that the study of morphine led to the discovery of nerve pathways in the brain that suppress pain, we believe that our having found the target of capsaicin activity will illuminate fundamental mechanisms of pain production," Julius said. In a report in the scientific journal Nature, he explained that with prolonged exposure to capsaicin, people build up a tolerance to the hot taste because the sensory nerves lose their responsiveness. "This phenomenon ... underlies the seemingly paradoxical use of capsaicin as a painkiller for treating disorders ranging from diabetic neuropathies (which harm the nerve cells) to rheumatoid arthritis," he added. Julius explained how the VR1 channel opens up when it is activated by hot peppers and allows an influx of calcium and sodium ions to react to sensory nerve cells called nociceptors. They send impulses about tissue damage to the pain processing centers in the spinal cord and brain, which cause the hot sensation in the mouth. Hot temperatures that produce pain in humans produce the same response. The finding could lead to new and better drugs that would kill pain signals transmitted through the vanilloid receptor without harming neighboring cells. VR1 may also play a role in registering pain from inflammation, blows, burning heat and caustic chemicals. David Clapham of Harvard Medical School in Massachusetts said a better name for VR1 would be the hot channel because it is possible that the real purpose of the receptor may be to sense high temperatures. In an accompanying report in Nature, he praised Julius and Caterina's work and said it could be used to develop new strategies to manage chronic pain caused by arthritis and spinal-cord injury. Copyright 1997 Nando.net Copyright 1997 Reuters <http://www.nando.net/newsroom/ntn/health/102297/health25_28140_noframes.html> ----------------------------------------------------------------------- janet paterson - 50/9 - sinemet/selegiline/prozac - [log in to unmask]