Acupuncture uses body's endorphin system to treat heart disease

Findings part of effort to merge ancient Chinese techniques, Western medicine.

provided by University of California, Irvine


team of researchers at UC Irvine and a university in China has found that acupuncture activates a group of nerve cells called the endorphin system to lower blood pressure and treat some types of heart disease.

The research is part of a growing number of scientific studies that are revealing exactly how acupuncture works. A 3,000-year-old technique that originated in China, acupuncture has been used to treat a variety of health problems, including heart disease.

Dr. John Longhurst, chair of the Department of Medicine at UCI's College of Medicine, and Peng Li of Shanghai Medical University in China found that injections of naloxone - a known inhibitor of the brain's endorphin system - in cats blocked acupuncture's ability to reduce blood pressure. The findings appear in the June 1999 American Journal of Physiology.

The endorphin system is a group of nerve cells in the brain, named after the chemicals these cells transmit to relax muscles, dull pain and reduce panic and anxiety. This system also has been shown to lower blood pressure and reduce cardiovascular workloads. The system is often called the body's "natural opiate system," because morphine and other opiate drugs affect the same nerve cells.

"By finding how acupuncture uses this system to regulate cardiovascular functions, we will gain a better understanding of how the technique eventually can be used on some patients to treat high blood pressure and heart disease," Longhurst said.

In order to uncover the nervous system pathways that are stimulated by acupuncture, the researchers increased levels of a chemical called bradykinin in cats. Bradykinin is produced when the body reacts to infections and, in general, works against the relaxing effects of the endorphin system. The chemical triggers inflammation, raises blood pressure and makes the heart pump harder and faster. Tiny electric probes that simulate acupuncture needles in the lab reduced bradykinin levels when the researchers applied the probes to nerve endings determined by Chinese acupuncture maps to work on heart disease. The reduced bradykinin levels quickly resulted in lower blood pressure and allowed the heart to pump less strenuously.

The effects of these acupuncture probes were negated when researchers introduced naloxone into the bloodstream; blood pressure rose and heart pumping action increased. Since naloxone blocks nerve cells in the endorphin system, the scientists concluded that acupuncture was doing its work by stimulating the body's natural endorphins.

"Endorphins have been known to help the body prevent heart disease, but we've never seen how they can be affected by acupuncture," Longhurst said. "Although the technique has been used for thousands of years, these findings help us merge what western medicine has taught us with the tradition of Chinese techniques."

Acupuncture treatments have lowered blood pressure in some patients and in certain instances have effectively treated a disorder called cardiac ischemia, which is caused by an inadequate supply of blood to the heart muscle cells. The disorder can be very painful and lead to more serious cardiovascular disorders.

The researchers will next try to determine which nerve cells are used by acupuncture in the endorphin pathways to treat heart disorders, and examine whether other parts of the nervous system help contribute to acupuncture's effects on the cardiovascular system. Stephanie Tjen-a-Looi of UCI's College of Medicine, Dong Chao and Lin Shen of Shanghai Medical University and Koullis F. Pitsillides of UC Davis' Division of Cardiovascular Medicine assisted the team in its research.

  Contact: Andrew Porterfield (949) 824-3969