Resveratrol reduces morphine tolerance

Resveratrol, a substance in red wine, preserves the pain-relieving effect of morphine in rats that developed morphine tolerance, researchers in Taiwan say. Dr. Chih-Shung Wong and colleagues of Cathay General Hospital, Taipei, Taiwan, said if the findings were confirmed in humans, resveratrol might become a useful addition to clinical pain management approaches, especially in patients with chronic, severe pain who have become tolerant to morphine. Wong and colleagues designed experiments to evaluate whether and how resveratrol affects behavioral pain responses to morphine in morphine-tolerant rats. Morphine and related opioid drugs play an important role in the treatment of severe pain, including cancer pain and other chronic pain conditions, but the development of tolerance requiring higher doses is an important limiting factor on their use, Wong said. Resveratrol is a polyphenol compound found in many plant-based foods and its presence in the skins of grapes may contribute to the health benefits of red wine. After inducing morphine tolerance in rats, the researchers tested the animals' spinal cord responses to morphine, with or without resveratrol. The study, scheduled to be published in the October issue of Anesthesia & Analgesia, found significant enhancement of morphine's effects in animals receiving resveratrol. In morphine-tolerant rats, the pain-relieving response to morphine was about 20 percent of normal. In rats receiving resveratrol, morphine responses were restored to about 60 percent of normal, the study said.