Oregon Health Sciences University researchers have discovered that a common molecule acts as a pain messenger in the nervous system. Their work appears in the May 29, 1997 issue of the British journal Nature and may pave the way for the design of new pain-relieving drugs.
"This molecule adenosine triphosphate or ATP has long been known to govern energy production in the cell," explains Sean Cook, Ph.D., lead author of the article and postdoctoral fellow at OHSU's Vollum Institute. "Our team has now discovered that it also signals the nervous system to register sensations of pain."
Together with researchers at the University of Minnesota, the Oregon team found that pain-sensing nerves are stimulated when ATP attaches to a receptor called P2X3 on the nerve cell membrane in a lock and key fashion. ATP does not generate a pain signal, however, when it attaches to other receptors on the nerve cell membrane.
Long known as the prime energy broker for cells, ATP has only recently gained acceptance by scientists as a transmitter of messages in the nervous system. The molecule is found in every cell and is leaked when cells are damaged.
"ATP had been suspected of being a pain signal off and on for 15 to 20years," says Ed McCleskey, OHSU scientist who heads the laboratory in which this work was done. "But no one had specific proof."
McCleskey further explains that when cells are damaged, they leak ATP which then binds to the P2X3 receptors on near by nerve cells. "The binding of ATP to the P2X3 receptor is an important player in the body's ability to sense pain," says McCleskey. "A therapeutic drug that would prevent ATP from attaching to the P2X3 receptors on nerve cells could eventually prove very useful clinically."
Besides ATP, only a few pain messengers and their nerve membrane receptors are presently known. They include protons (acid) and capsaicin, the notorious component of hot chili peppers.