Neurobiology of Acupuncture: Toward CAM

Neurobiology of Acupuncture: Toward CAM
Received December 23, 2003; Accepted February 27, 2004
Sheng-Xing Ma
Evidence-based Complementary and Alternative Medicine (eCAM)
PubMed Central

Copyright © Oxford University Press, 2004.

Departments of Obstetrics and Gynecology, HarborÒUCLA Medical Center, David Geffen School of Medicine at University of California at Los Angeles, Torrance, CA, USA

For reprints and all correspondence: Department of Obstetrics and Gynecology, Harbor-UCLA Medical Center, David Geffen School of Medicine at University of California at Los Angeles, 1124 W. Carson Street, RB-1, Torrance, CA 90502, USA. E-mail: ma@humc.edu

AbstractIt has long been accepted that acupuncture, puncturing and scraping needles at certain points on the body, can have analgesic and anesthetic effects, as well as therapeutic effects in the treatment of various diseases. This therapy, including acupuncture anesthesia, has drawn the attention of many investigators and become a research subject of international interest around the world. Numerous studies have demonstrated that the nervous system, neurotransmitters, endogenous substances and Jingluo (meridians) may respond to needling stimulation and electrical acupuncture. An abundance of information has now accumulated concerning the neurobiological mechanisms of acupuncture, in relation to both neural pathways and neurotransmitters/hormonal factors that mediate autonomic regulation, pain relief and other therapeutics. Early studies demonstrated that the analgesic effects of electroacupuncture (EA) are mediated by opioid peptides in the periaqueductal gray. Recent evidence shows that nitric oxide plays an important role in mediating the cardiovascular responses to EA stimulation through the gracile nucleus-thalamic pathway. Other substances, including serotonin, catecholamines, inorganic chemicals and amino acids such as glutamate and α-aminobutyric acid (GABA), are proposed to mediate certain cardiovascular and analgesic effects of acupuncture, but at present their role is poorly understood. The increased interest in acupuncture health care has led to an ever-growing number of investigators pursuing research in the processes of the sense of needling touch, transduction of needling stimulation signals, stimulation parameters and placebos. In this Review, the evidence and understanding of the neurobiological processes of acupuncture research have been summarized with an emphasis on recent developments of nitric oxide mediating acupuncture signals through the dorsal medulla-thalamic pathways.

Keywords: acupuncture, neurobiology, neurotransmitter, nitric oxide, opiate, pain

Abstract

CAM Approaches to Acupuncture
Opioidergic Mechanism in the Periaqueductal Central Gray
Nitric Oxide in the Dorsal MedullaÒThalamic Pathways
The Descending Pain Modulatory System
EA Stimulation Parameters and Placebos
Placebo Effects and Sham Acupuncture
Conclusion
References CAM Approaches to AcupunctureOver the last few decades there has been a widespread and increasing interest in acupuncture around the world. Investigators have demonstrated that the nervous system, neurotransmitters and endogenous substances respond to needling stimulation and electroacupuncture (EA) (1Ò3). The EA afferent pathways and central sites have been identified in the anterolateral tract in the spinal cord, the reticulogigantocellular nucleus, the raphe magnus, the dorsal part of the periaqueductal central gray (D-PAG), the posterior and anterior hypothalamus and the medial part of the centromedian nucleus of the thalamus (4Ò7). It has been established that acupuncture analgesia is mediated by opioid peptides. Recent studies have demonstrated that EA stimulation of hindlimb acupoints induces an up-regulation of neuronal nitric oxide synthase (nNOS)/NADPH diaphorase (NADPHd) expression in the gracile nucleus. Nitric oxide (NO) in the gracile nucleus mediates acupuncture signals through dorsal medullaÒthalamic pathways.

Please visit the website to view the article in its entirety.