Chapter 28. Role of polymodal receptors in the acupuncture-mediated endogenous pain inhibitory systems

Abstract

Publisher Summary This chapter focuses on the role of polymodal receptors in the acupuncture-mediated endogenous pain inhibitory systems. It was an epoch-making finding that intracranial electrical stimulation of the periaqueductal gray matter (PAG) in midbrain can produce a potent analgesic effect that enabled a surgical operation in rats. The electrical stimulation of certain brain sites can produce analgesia—a phenomenon later termed as “stimulation produced analgesia” (SPA)—and triggered numerous studies in this field. When an acupuncture needle is inserted into the sensitized tissues, the polymodal receptors can provoke stronger responses than those applied to normal tissues. Consequently activation of polymodal receptors by acupuncture and moxibustion can induce analgesic effects through activation of opiate or non-opiate mediated endogenous pain inhibitory systems. Thus, the existence of sensitized polymodal receptors in the tender/trigger points may provide the major functional basis for understanding the clinical significance of acupuncture points in both acupuncture and moxibustion treatments.