Electroacupuncture Attenuates Inflammation in a Rat Model

Center for Integrative Medicine, School of Medicine, University of Maryland, Baltimore, MD, USA.
The Journal of Alternative and Complementary Medicine (Impact Factor: 1.59). 03/2005; 11(1):135-42. DOI: 10.1089/acm.2005.11.135
Source: PubMed


Acupuncture has traditionally been used in China and is being increasingly applied in Western countries to treat a variety of conditions, including inflammatory disease. However, clinical trials investigating the effectiveness of the anti-inflammatory effects of acupuncture have yielded inconsistent results, and the underlying mechanisms of acupuncture-produced anti-inflammation are unclear.
To evaluate the effectiveness of electroacupuncture (EA) on inflammation in a rat model.
Four experiments were conducted on male Sprague-Dawley rats (n = 8-9 per group). Inflammation was induced by injecting complete Freund's adjuvant (CFA) subcutaneously into the plantar surface of one hind paw of the rat. Experiment 1: To determine the effect of EA (10 and 100 Hz) versus sham treatment on inflammation. Experiment 2: To investigate the involvement of the adrenal glands on the effect of EA treatment using adrenalectomized (ADX) rats. Experiment 3: To determine the effects of EA on plasma levels of corticosterone. Experiment 4: To determine the effects of EA treatment versus immobilization on such stress indicators as heart rate and blood pressure.
At 10 Hz EA significantly reduced CFA-induced hind paw edema. The effect was partially blocked in the ADX rats. EA significantly increased plasma levels of corticosterone but produced no noticeable signs of stress.
At 10 Hz but not 100 Hz, EA suppresses inflammation by activating the hypothalamus-pituitary-adrenal axis (HPA) and the nervous system.

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Available from: Arthur Yin Fan, Sep 07, 2015
    • "According to TCM theory, the fundamental of acupuncture treatment is regarded as regulating and balancing Yin and Yang (Cheng, 1999), whereas research within the last couple of years revealed diverse molecular signalling pathways involved in AA (Zhao, 2008; Goldman et al., 2010; Zhang et al., 2010; Su et al., 2011). In addition, anti-inflammatory effects of EA were also seen in some previous studies (Li et al., 2005; Zhang et al., 2005b; Shiue et al., 2008; Kuai et al., 2009; Gondim et al., 2012; Su et al., 2012). Endogenous opioid-mediated central analgesia was found to be one of the important mechanisms of AA (Ha et al., 1981; Mayer et al., 1977; Pomeranz and Cheng, 1979; Shen et al., 1973). "
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    ABSTRACT: Background: 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. Methods: 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. Results: 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. Conclusions: 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.
    No preview · Article · May 2013 · European journal of pain (London, England)
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    • "The same treatment was given to nonacupoint (the upper lateral gluteal muscle but not GB30 acupoint) to be set as the sham control group entitled S-GM [13]. Another sham control group, entitled S-Acu, was induced by needling into ST36 acupoint without manipulation [14, 15]. "
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    ABSTRACT: Several voltage-gated sodium channels (Navs) from nociceptive nerve fibers have been identified as important effectors in pain signaling. The objective of this study is to investigate the electroacupuncture (EA) analgesia mechanism by changing the expression of Navs in mice dorsal root ganglia (DRG). We injected carrageenan and complete Freund's adjuvant (CFA) into the mice plantar surface of the hind paw to induce inflammation and examined the antinociception effect of EA at the Zusanli (ST36) acupoint at 2 Hz low frequency. Mechanical hyperalgesia was evaluated by using electronic von Frey filaments, and thermal hyperalgesia was assessed using Hargreaves' test. Furthermore, we observed the expression and quality of Navs in DRG neurons. Our results showed that EA reduced mechanical and thermal pain in inflammatory animal model. The expression of Nav1.7 and Nav1.8 was increased after 4 days of carrageenan- and CFA-elicited inflammatory pain and further attenuated by 2 Hz EA stimulation. The attenuation cannot be observed in Nav1.9 sodium channels. We demonstrated that EA at Zusanli (ST36) acupoint at 2 Hz low-frequency stimulation attenuated inflammatory pain accompanied by decreasing the expression of Nav1.7 and 1.8, rather than Nav1.9, sodium channels in peripheral DRG neurons.
    Full-text · Article · Mar 2013 · Evidence-based Complementary and Alternative Medicine
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    • "Moreover, intrathecal administration of a p38 MAPK inhibitor into spinal cord has been shown to effectively reduce pain behavior associated with the peripheral inflammation [3, 8–10]. Electroacupuncture (EA), as a traditional complementary and alternative medicine approach, has been used for several decades in the treatment of many acute and chronic inflammatory diseases [11]. Accumulative evidence demonstrates that EA significantly inhibits paw inflammation and hyperalgesia in a rat model [12] [13] [14]. "
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    ABSTRACT: Activation of mitogen-activated protein kinases (MAPKs), especially p38 MAPK, plays an important role in the development of central sensitization related to persistent inflammatory pain. Electroacupuncture (EA) is well known to relieve persistent inflammatory pain. However, little is known about relationship between EA and p38 MAPK. Inflammatory pain rat model was induced by intraplantar injection of complete Freund's adjuvant (CFA). Male adult SD rats were randomly divided into the saline group, CFA group, and CFA + EA group. EA (constant saquare wave, 2 Hz and 100 Hz alternating frequencies, intensities ranging from 1 to 2 mA) was applied to bilateral "Zusanli" (ST 36) and "Kunlun" acupoints (BL 60) for 30 min, once per day. The paw edema and paw withdrawal threshold (PWT) were measured at preinjection and days postinjection 1, 3, and 14. Spinal p-p38MAPK- immunoreactivty (p-p38MAPK-IR) cells were detected by immunohistochemistry at postinjection day 3 and 14. EA significantly inhibited paw edema at postinjection days 14 and increased PWT at postinjection days 3 and 14. Moreover, the increasing number of spinal p-p38MAPK-IR cells which was induced by CFA injection was suppressed by EA stimulation. These results indicate that anti-inflammatory and analgesic effect of EA might be associated with its inhibition of spinal p38 MAPK activation and thereby provide a potential mechanism for the treatment of inflammatory pain by EA.
    Full-text · Article · Jan 2012 · Evidence-based Complementary and Alternative Medicine
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