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Evidence-Based Complementary and Alternative Medicine
Volume 2012 (2012), Article ID 438460, 11 pages
http://dx.doi.org/10.1155/2012/438460
Research Article

NMDA Receptor-Dependent Synaptic Activity in Dorsal Motor Nucleus of Vagus Mediates the Enhancement of Gastric Motility by Stimulating ST36

1Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences, 16 Nanxiaojie Street, Dongzhimennei, Beijing 100700, China
2Qingdao Haici Medical Group, 4 Renmin Road, Qingdao 266033, China
3Guanganmen Hospital, China Academy of Chinese Medical Sciences, Beijing 100053, China
4The Affiliated Hospital, Shandong University of Traditional Chinese Medicine, Jinan 250014, China
5Department of Pharmacology, Southern Medical University, Guangzhou 510515, China
6Department of Biomedical Sciences, Florida State University College of Medicine, Tallahassee, FL 32306, USA

Received 12 July 2012; Revised 4 September 2012; Accepted 8 September 2012

Academic Editor: Ying Xia

Copyright © 2012 Xinyan Gao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Previous studies have demonstrated the efficacy of electroacupuncture at ST36 for patients with gastrointestinal motility disorders. While several lines of evidence suggest that the effect may involve vagal reflex, the precise molecular mechanism underlying this process still remains unclear. Here we report that the intragastric pressure increase induced by low frequency electric stimulation at ST36 was blocked by AP-5, an antagonist of N-methyl-D-aspartate receptors (NMDARs). Indeed, stimulating ST36 enhanced NMDAR-mediated, but not 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic-acid-(AMPA-) receptor-(AMPAR-) mediated synaptic transmission in gastric-projecting neurons of the dorsal motor nucleus of the vagus (DMV). We also identified that suppression of presynaptic μ-opioid receptors may contribute to upregulation of NMDAR-mediated synaptic transmission induced by electroacupuncture at ST36. Furthermore, we determined that the glutamate-receptor-2a-(NR2A-) containing NMDARs are essential for NMDAR-mediated enhancement of gastric motility caused by stimulating ST36. Taken together, our results reveal an important role of NMDA receptors in mediating enhancement of gastric motility induced by stimulating ST36.