Study Is Latest Step to Understanding How Ancient Technique Works on Nerve Cells, May Help Design Specific Treatments for Heart Disease

Irvine, Calif. -- A common acupuncture technique can ease blood pressure by stimulating specific receptors in the central nervous system, a UC Irvine College of Medicine study has found.

The study on cats, which appears in the June 1 issue of Autonomic Neuroscience, provides greater insight into how the 3,000-year-old practice of acupuncture works. The research also may eventually result in more effective therapies for heart disease, currently the No. 1 cause of death in the United States.

Dr. John Longhurst, professor of medicine, and Dr. Peng Li, visiting professor of medicine, found that electrical stimulation of certain nerves (which mimicked a traditional Chinese medical technique called electroacupuncture) eased blood pressure of cats by stimulating two receptors in the brain. The receptors are known to be part of the body's natural opiate, or endorphin and enkephalin system, which can regulate neuronal activity in the brain.

The finding is a continuation of Longhurst's and Li's work on identifying the nerve-cell pathways in the cardiovascular system that are affected by electroacupuncture.

"Electroacupuncture has been used in traditional Chinese medicine to treat abnormal heart rhythms, high blood pressure and insufficient blood flow to the heart, called myocardial ischemia," Longhurst said. "But it has never been shown why or how this technique works. Uncovering the pathways in the nervous system and their influence on the cardiovascular organs may help us not only understand acupuncture from a Western perspective, but also help us find other ways by which acupuncture may help treat heart disease and other disorders."

Previously, the researchers had found that when they increased blood pressure by stimulating the gallbladder with a chemical called bradykinin, electroacupuncture reversed bradykinin's action, reducing the body's normal response of raising blood pressure. By reducing this response, electroacupuncture in turn decreased cardiac ischemia.

In this study, the researchers found that electroacupuncture stimulated two types of receptors in this area of the brain, known as opioid receptors, best known for their ability to control pain.

The electrified needles reduced the cardiovascular stress when placed in a traditional acupuncture site called the Neiguan acupoint, which lies just above the median nerve. This nerve provides input to the central nervous system where it connects to an area in the brainstem called the rostral ventrolateral medulla. This part of the brain regulates outflow to the sympathetic nervous system, which causes constriction of blood vessels and increased blood pressure. Acupuncture helps control elevations in blood pressure through its effect on the opioid system, reducing the body's need for more oxygen under stressful conditions.

"This study supports findings from other researchers, which indicate that other opioid receptors in the brain control blood pressure and can be stimulated using a number of methods, including acupuncture," Li said. "It's possible that many acupoint locations may ultimately stimulate these opioid receptors in this part of the brain to help regulate the actions of the cardiovascular system."
The researchers are now working on identifying specific neurons in regions of the brain that are regulated by the actions of these receptors. These neurotransmitters themselves could be used to create better treatments for heart disease.

Li is a visiting professor of physiology from Shanghai Medical University, China. Longhurst and Li's colleagues in the study include Stephanie Tjen-A-Looi of UCI.

The National Institutes of Health and the Samueli Center for Complementary and Alternative Medicine fund the researchers' work. The center was established in 2000 with a grant from Henry and Susan Samueli to support research to bridge the gap between traditional and alternative medicine. Researchers funded by the center conduct scientific studies of alternative and complementary medicine therapies--including herbs and homeopathic medicine--as they relate to such areas as cardiovascular, autoimmune and neuromuscular diseases, cancer treatment and prevention, menopause and aging.

The center also helps medical students better understand alternative therapies such as acupuncture, evaluates the value of these therapies and serves as a source of science-based information for physicians, alternative medicine practitioners and the community.

---University of California, Irvine

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