Long-term antinociception by electroacupuncture is mediated via peripheral opioid receptors in free-moving rats with inflammatory hyperalgesia.
Wang Y, Hackel D, Peng F, Rittner HL.
Department of Anesthesiology, University Hospital of Würzburg, Germany.
Electroacupuncture (EA) has been widely accepted and applied as an important acupuncture-related technique for acupuncture analgesia (AA) research. The involvement of opioid peptides and receptors in acute AA has been shown via pre-EA application of opioid receptor/peptide antagonists. In this study, we intended to reproducibly institute acupoint position and needling excluding influences from anaesthesia or restrainers on rats with complete Freund's adjuvant (CFA) hind paw inflammatory pain, as well as to explore opioid-dependency and anti-inflammatory effects in sustained acupuncture analgesia.
Accurate position and needling approach on acupoint GB30 was modelled by computer-based three-dimensional (3D) images and followed by an optimal EA treatment protocol (100 Hz, 2-3 mA, 20 min) at 0 and 24 h post-CFA in conscious free-moving rats. Opioid receptor antagonists, naloxone (NLX) and naltrindole (NTI) were applied intraplantarly post-EA at late phase (96 h) of CFA. Nociceptive thresholds were assessed by paw pressure threshold (Randall-Sellito) or paw withdrawal latency (Hargreaves), and anti-inflammatory effects were evaluated by measurement of plantar temperature and paw volume.
EA elicited significant sustained mechanical and thermal antinociception up to 144 h. Mechanical antinociception of EA was suppressed by peripheral intraplantar application of NLX and NTI. EA also reduced paw temperature and volume during the same time frame indicating anti-inflammatory effects.
By employing a reproducible EA treatment model on GB30 in free-moving rats, we demonstrated the involvement of peripheral opioid receptors mediated EA-induced long-term antinociception. Future studies should examine the specific neuroimmunological connection of EA-induced sustained antinociception in inflammation.
© 2013 European Federation of International Association for the Study of Pain Chapters.
J Acupunct Meridian Stud. 2014 Feb;7(1):15-24. doi: 10.1016/j.jams.2013.05.004. Epub 2013 Jun 19.
Electroacupuncture analgesia in a rabbit ovariohysterectomy.
Parmen V.
Author information

This study investigated the effectiveness of electroacupuncture analgesia (EAA) at local and paravertebral acupoints for a rabbit undergoing an ovariohysterectomy. Twelve clinically healthy New Zealand white rabbits were chosen and divided into two groups: the control group (5 rabbits) and the experimental group (7 rabbits). A neuroleptanalgesic (ketamine + xylazine) was administered to the control group (NLA group); the experimental group received EAA treatment (EAA group). The EAA treatment includes one acupuncture formula for local stimulation at the incision site and systemic stimulation. Results of clinical research have shown postoperative analgesia using EAA treatment to be superior to that using NLA. The average postoperative recovery time was 5.2 times longer in the NLA group than in the EAA group. Because consciousness was maintained, EAA presented an advantage in thermoregulation. Animals administered NLA had prolonged thermal homeostasis because of neurovegetative disconnection. For the EAA group, the operative times were characterized as excellent (28%, p = 0.28) or good (72%, p = 0.72). Local stimulation at the incision site provided excellent analgesia of the abdominal wall (100%). In conclusion, EA can provide general analgesia with a considerable analgesic effect for a rabbit undergoing an ovariohysterectomy, resulting in a short postoperative recovery time.
Copyright © 2014. Published by Elsevier B.V.
electroacupuncture, electroacupuncture analgesia, neuroleptanalgesia, ovariohysterectomy, rabbit

Eur J Pain. 2015 Feb 17. doi: 10.1002/ejp.671. [Epub ahead of print]
Local and distant acupuncture points stimulation for chronic musculoskeletal pain: A systematic review on the comparative effects.
Wong Lit Wan D1, Wang Y, Xue CC, Wang LP, Liang FR, Zheng Z.
Author information
Eur J Pain. 2013 May 6. doi: 10.1002/j.1532-2149.2013.00325.x. [Epub ahead of print]

PMID: 23649949 [PubMed - as supplied by publisher]

School of Health Sciences, and Health Innovations Research Institute, RMIT University, Bundoora, Vic., Australia.
One in four people suffers from chronic musculoskeletal pain (CMP). Acupuncture points stimulation is increasingly used for pain relief for CMP. Commonly, a combination of local and distant points is used. However, the difference between the effects of local and distant point stimulation is unknown. This systematic review aimed to determine if there was a difference in effects between stimulating local and distant points, and the combination of both when compared with either alone. English and Chinese electronic databases were searched to identify randomized controlled trials, where local or distant points were stimulated in adults with CMP. Pain intensity was the primary outcome measure. Nineteen were included in the qualitative analysis and 15 in the meta-analysis. Local and distant point stimulation was more effective than their respective controls in pain reduction immediately after treatment. Three studies directly compared the stimulation of local and distant points and found no significant difference between the two. No studies compared combined local and distant point stimulation with either alone. Subgroup analyses showed that, local tender point stimulation was more effective than local acupuncture points. Local and distant point stimulation induces similar degree of acupuncture analgesia. The benefit of combining local and distant point stimulation is unknown. However, subgroup analyses suggested that local tender points could be important in the treatment of CMP for short-term pain relief.

Front Med. 2016 Nov 28. [Epub ahead of print]
Distinct roles of ASIC3 and TRPV1 receptors in electroacupuncture-induced segmental and systemic analgesia.
Xin J1, Su Y1, Yang Z1, He W1, Shi H1, Wang X1, Hu L1, Yu X1, Jing X2, Zhu B3.
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Previous studies have demonstrated the effects of different afferent fibers on electroacupuncture (EA)-induced analgesia. However, contributions of functional receptors expressed on afferent fibers to the EA analgesia remain unclear. This study investigates the roles of acid-sensing ion channel 3 (ASIC3) and transient receptor potential vanilloid 1 (TRPV1) receptors in EA-induced segmental and systemic analgesia. Effects of EA at acupoint ST36 with different intensities on the C-fiber reflex and mechanical and thermal pain thresholds were measured among the ASIC3-/-, TRPV1-/-, and C57BL/6 mice. Compared with C57BL/6 mice, the ipsilateral inhibition of EA with 0.8 C-fiber threshold (0.8Tc) intensity on C-fiber reflex was markedly reduced in ASIC3-/- mice, whereas the bilateral inhibition of 1.0 and 2.0Tc EA was significantly decreased in TRPV1-/- mice. The segmental increase in pain thresholds induced by 0.3 mA EA was significantly reduced in ASIC3-/- mice, whereas the systemic enhancement of 1.0 mA EA was markedly decreased in TRPV1-/- mice. Thus, segmental analgesia of EA with lower intensity is partially mediated by ASIC3 receptor on Aβ-fiber, whereas systemic analgesia induced by EA with higher intensity is more likely induced by TRPV1 receptor on Aδ- and C-fibers.