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Evidence-Based Complementary and Alternative Medicine
Volume 2012 (2012), Article ID 715024, 10 pages
Research Article

Kappa-Opioid Receptors in the Caudal Nucleus Tractus Solitarius Mediate 100 Hz Electroacupuncture-Induced Sleep Activities in Rats

1Department of Veterinary Medicine, School of Veterinary Medicine, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan
2Department of Sports, Health & Leisure, College of Sports Knowledge, Aletheia University, Matou Campus, No. 70-11, Beishiliao, Madou Dist., Tainan City 72147, Taiwan
3Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, No. 1, Sec. 1, Ren-Ai Road, Taipei 10051, Taiwan
4Graduate Institute of Acupuncture Science, College of Chinese Medicine, China Medical University, No. 91 Hsueh-Shih Road, Taichung 40402, Taiwan

Received 15 August 2011; Revised 12 October 2011; Accepted 16 October 2011

Academic Editor: Andreas Sandner-Kiesling

Copyright Š 2012 Chiung-Hsiang Cheng 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.


Previous results demonstrated that 10 Hz electroacupuncture (EA) of Anmian acupoints in rats during the dark period enhances slow wave sleep (SWS), which involves the induction of cholinergic activity in the caudal nucleus tractus solitarius (NTS) and subsequent activation of opioidergic neurons and 𝜇 -receptors. Studies have shown that different kinds of endogenous opiate peptides and receptors may mediate the consequences of EA with different frequencies. Herein, we further elucidated that high-frequency (100 Hz)-EA of Anmian enhanced SWS during the dark period but exhibited no direct effect on rapid eye movement (REM) sleep. High-frequency EA-induced SWS enhancement was dose-dependently blocked by microinjection of naloxone or 𝜅 -receptor antagonist (nor-binaltorphimine) into the caudal NTS, but was affected neither by 𝜇 - (naloxonazine) nor 𝛿 -receptor antagonists (natatrindole), suggesting the role of NTS 𝜅 -receptors in the high-frequency EA-induced SWS enhancement. Current and previous results depict the opioid mechanisms of EA-induced sleep.