Non-opioid-dependent anti-inflammatory effects of low frequency electroacupuncture

The preemptive analgesia of pre-electroacupuncture in rats with formalin-induced acute inflammatory pain

Background

Electroacupuncture has been elicited to effectively alleviate the pain sensation. Preemptive analgesic effect of pre-electroacupuncture has also been suggested in recent studies, while the underlying analgesic mechanism of pre-electroacupuncture requires further investigation. This study aimed to explore the preemptive analgesia of pre-electroacupuncture in formalin-induced acute inflammatory pain model.

Methods

Forty rats were randomly divided into control, model, pre-electroacupuncture, and post-electroacupuncture group. Inflammatory pain model was induced via injecting 50 µl 5% formalin into the plantar surface of right hind paw, while the equal volume of saline injection in the control group. Rats in the pre-electroacupuncture group were treated with electroacupuncture at ipsilateral Zusanli (ST36) and Weizhong (BL40) acupoints (2 Hz, 1 mA) for 30 min before formalin injection, while received the same electroacupuncture treatment immediately after formalin injection in the post-electroacupuncture group. Flinching number and licking time were recorded during 60 min after formalin injection. Immunofluorescence and Western blot were used to detect the expression of ionized calcium binding adapter molecule 1 (Iba1) and c-fos in spinal cord. Moreover, enzyme-linked immunosorbent assay was applied to measure the secretion of IL-6, IFN-γ, IL-4, substance P, and calcitonin gene-related peptide in spinal cord.

Results

Paw flinching and licking were obviously induced by formalin injection. Iba1, c-fos, proinflammatory cytokines (IL-6 and IFN-γ), and pain neurotransmitters (substance P and calcitonin gene-related peptide) were dramatically increased in the L4-5 spinal cord after formalin injection, while anti-inflammatory cytokine IL-4 was decreased. Pre-electroacupuncture and post-electroacupuncture administration significantly attenuated formalin-induced nociceptive effects, spinal microglia and neurons activation, proinflammatory cytokines and pain neurotransmitters upregulation, and upregulated the anti-inflammatory cytokine. Furthermore, these effects of pre-electroacupuncture were more significant than that of post-electroacupuncture.

Conclusions

This study illustrates the potential therapeutic effect of pre-electroacupuncture against acute inflammatory pain and reveals the mechanism underlying pre-electroacupuncture mediated analgesia, thus providing a novel preemptive analgesic treatment.

Imidazole alkaloids inhibit the pro-inflammatory mechanisms of human neutrophil and exhibit anti-inflammatory properties in vivo

OBJECTIVES

Epiisopiloturine (EPI) and epiisopilosine (EPIIS) are side products in the pharmaceutical industry. The present study aimed to investigate the anti-inflammatory potential of the alkaloids EPI and EPIIS in human neutrophils and mechanical hyperalgesia in mice.

METHODS

Neutrophils (5 × 10⁶  cells/ml) incubated with EPI and EPIIS and stimulated by the addition of N-formyl-methionyl-leucyl-phenylalanine or phorbol 12-myristate-13-acetate. The release of myeloperoxidase (MPO), reactive oxygen species (ROS) production, calcium influx, gene expression of NF-κB and pro-inflammatory cytokines production were evaluated. It was also investigated the effect these alkaloids on carrageenan-induced mechanical hyperalgesia model in mice.

KEY FINDINGS

We demonstrated that both EPI and EPIIS inhibited the degranulation of activated neutrophils. This effect was accompanied by the reduction in ROS, the prevention of the increase in intracellular Ca²⁺ and decrease in the density of cytosolic NF-κB, and inhibition of TNF-α and IL-6 production. Evaluating hypernociception in mice, EPI and EPIIS inhibited carrageenan-induced inflammatory hypernociception and reduced MPO levels.

CONCLUSIONS

The results obtained suggest EPI and EPIIS not only inhibit neutrophils functions in vitro, but also exhibits anti-inflammatory properties in vivo, acting through the modulation of the activation and/or accumulation of neutrophils in the inflammatory focus. Thus, EPI and EPIIS possess promising anti-inflammatory therapeutic potential.

How effective is acupuncture for reducing pain due to plantar fasciitis?

INTRODUCTION

Plantar fasciitis is a commonly seen outpatient condition that has numerous treatment modalities of varying degrees of efficacy. This systematic review aimed to determine the effectiveness of acupuncture in reducing pain caused by plantar fasciitis.

METHODS

Online literature searches were performed on the PubMed and Cochrane Library databases for studies on the use of acupuncture for pain caused by plantar fasciitis. Studies designed as randomised controlled trials and that compared acupuncture with standard treatments or had real versus sham acupuncture arms were selected. The Delphi list was used to assess the methodological quality of the studies retrieved.

RESULTS

Three studies that compared acupuncture with standard treatment and one study on real versus sham acupuncture were found. These showed that acupuncture significantly reduced pain levels in patients with plantar fasciitis, as measured on the visual analogue scale and the Plantar Fasciitis Pain/Disability Scale. These benefits were noted between four and eight weeks of treatment, with no further significant reduction in pain beyond this duration. Side effects were found to be minimal.

CONCLUSION

Although acupuncture may reduce plantar fasciitis pain in the short term, there is insufficient evidence for a definitive conclusion regarding its effectiveness in the longer term. Further research is required to strengthen the acceptance of acupuncture among healthcare providers.

100-Hz Electroacupuncture but not 2-Hz Electroacupuncture is Preemptive Against Postincision Pain in Rats

Preemptive analgesia involves introducing an analgesic before noxious stimulation. Electroacupuncture (EA) activates descending mechanisms that modulate nociceptive inputs into the spinal dorsal horn. This study evaluated whether preoperative EA is more effective than postoperative EA in reducing incision pain in rats. The nociceptive threshold to mechanical stimulation was utilized to examine the effects of an intraperitoneal injection of saline (0.1 mL/kg) or naloxone (1 mg/kg) on antinociception induced by a 20-minute period of 2-Hz or 100-Hz EA applied to the Zusanli (ST36) and Sanyinjiao (SP6) acupoints before surgical incision, or 10 minutes after or 100 minutes after surgical incision of the hind paw. The extent of mechanical hyperalgesia after the incision was significantly attenuated by the application of 100-Hz EA preoperatively, but not by its application at 10 minutes or 100 minutes postoperatively. By contrast, 2-Hz EA was effective against postoperative hyperalgesia when applied 10 minutes or 100 minutes after surgery but not when it was applied preoperatively. Only the effect of 2-Hz EA applied 10 minutes after surgery was sensitive to naloxone. The present study showed for the first time that 100-Hz EA, but not 2-Hz EA, exerts a nonopioidergic preemptive effect against postincision pain in rats.

The Clinical Effect of Acupuncture in the Treatment of Obstructive Sleep Apnea: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Purpose. This study aims to determine the clinical efficacy of acupuncture therapy in the treatment of obstructive sleep apnea. Methods. A systematic literature search was conducted in five databases including PubMed, EMBASE, CENTRAL, Wanfang, and CNKI to identify randomized controlled trials (RCTs) on the effect of acupuncture therapy for obstructive sleep apnea. Meta-analysis was conducted using the RevMan version 5.3 software. Results. Six RCTs involving 362 subjects were included in our study. Compared with control groups, manual acupuncture (MA) was more effective in the improvement of apnea/hypopnea index (AHI), apnea index, hypopnea index, and mean SaO₂. Electroacupuncture (EA) was better in improving the AHI and apnea index when compared with control treatment, but no statistically significant differences in hypopnea index and mean SaO₂ were found. In the comparison of MA and nasal continuous positive airway pressure, the results favored MA in the improvement of AHI; there was no statistical difference in the improvement in mean SaO₂. No adverse events associated with acupuncture therapy were documented. Conclusion. Compared to control groups, both MA and EA were more effective in improving AHI and mean SaO₂. In addition, MA could further improve apnea index and hypopnea index compared to control.

Mediators, Receptors, and Signalling Pathways in the Anti-Inflammatory and Antihyperalgesic Effects of Acupuncture

Acupuncture has been used for millennia to treat allergic diseases including both intermittent rhinitis and persistent rhinitis. Besides the research on the efficacy and safety of acupuncture treatment for allergic rhinitis, research has also investigated how acupuncture might modulate immune function to exert anti-inflammatory effects. A proposed model has previously hypothesized that acupuncture might downregulate proinflammatory neuropeptides, proinflammatory cytokines, and neurotrophins, modulating transient receptor potential vallinoid (TRPV1), a G-protein coupled receptor which plays a central role in allergic rhinitis. Recent research has been largely supportive of this model. New advances in research include the discovery of a novel cholinergic anti-inflammatory pathway activated by acupuncture. A chemokine-mediated proliferation of opioid-containing macrophages in inflamed tissues, in response to acupuncture, has also been demonstrated for the first time. Further research on the complex cross talk between receptors during inflammation is also helping to elucidate the mediators and signalling pathways activated by acupuncture.

Acupuncture for seasonal allergic rhinitis: a randomized controlled trial

BACKGROUND

Seasonal allergic rhinitis (SAR) is a common condition with relatively high prevalence in Australia. It causes a significant impact on sufferers' quality of life (QoL). Meta-analysis has shown that the efficacy of acupuncture for SAR is uncertain.

OBJECTIVE

To evaluate the efficacy and safety of 12 sessions of acupuncture treatment during 4 weeks for SAR in a randomized, subject- and assessor-blinded, sham-controlled trial conducted during the pollen seasons in 2009 through 2011 in Melbourne.

METHODS

Patients diagnosed with SAR and confirmed allergic to rye grass pollen were randomly allocated to receive real acupuncture (RA) or sham acupuncture (SA) treatment. RA was delivered manually, whereas SA involved superficial needling at non-acupoints without additional stimulation. Severity of SAR symptoms was the primary outcome measurement. Secondary outcomes were QoL, global change, SAR-related medication usage, and adverse events. Analysis of covariance using pollen count as a covariate was used to analyze outcome data.

RESULTS

A total of 175 participants were included in this trial. RA was significantly better than SA for decreasing SAR symptom severity (sneezing, mean difference -0.28, 95% confidence interval -0.51 to -0.05; itchiness of ears and palate, mean difference -0.40, 95% confidence interval -0.69 to -0.11) at the end of treatment and improving participants' QoL at the end of the treatment and follow-up phases. Furthermore, the acupuncture treatment was safe and well tolerated.

CONCLUSION

Four weeks of acupuncture treatment is a safe and effective option for clinical management of SAR in the Melbourne area for patients' symptom relief and QoL improvement.

Miniscalpel-Needle versus Steroid Injection for Plantar Fasciitis: A Randomized Controlled Trial with a 12-Month Follow-Up

Plantar fasciitis is the most common cause of heel pain in adults. A novel alternative medical instrument, the miniscalpel-needle (MSN), which is based on an acupuncture needle, has been recently developed in China. The objective of this study was to evaluate the effectiveness of the MSN release treatment versus that of traditional steroid injection for plantar fasciitis. Patients with plantar fasciitis were randomly assigned to 2 groups and followed up for 12 months, with 29 receiving MSN treatment and 25 receiving steroid injection treatment. The results showed that visual analog scale scores for morning pain, active pain, and overall heel pain all were decreased significantly in the MSN group from 1 to 12 months after treatment. In contrast, treatment with steroid injection showed a significant effect only at the 1-month follow-up but not at 6 or 12 months after treatment. Moreover, the MSN group achieved more rapid and sustained improvements than the steroid group throughout the duration of this study. No severe side effects were observed with MSN treatment. Our data suggest that the MSN release treatment is safe and has a significant benefit for plantar fasciitis compared to steroid injection.

Effects of electroacupuncture on oxaliplatin-induced neuropathic cold hypersensitivity in rats

This study investigated whether and how electroacupuncture (EA) attenuates cold hypersensitivity (allodynia) in a rat model of oxaliplatin-induced neuropathic pain. Cold allodynia [evaluated by immersing the tail into cold water (4 °C) and measuring the withdrawal latency] was induced 3 days after an oxaliplatin administration (6 mg/kg, i.p.). EA stimulation (2/100 Hz, 0.3-ms pulse duration, 0.2-0.3 mA) was delivered to ST36 acupoint or non-acupoint for 20 min. Low-frequency (2 Hz) EA at ST36 relieved cold allodynia more effectively than high-frequency EA at ST36 or low-frequency EA at non-acupoint. Naloxone (opioid antagonist, 2 mg/kg, i.p.) completely blocked such EA-induced anti-allodynia, whereas phentolamine (α-adrenergic antagonist, 2 mg/kg, i.p.) did not. Moreover, plasma β-endorphin levels significantly increased right after the end of EA and subsequently decreased. These results indicate that low-frequency EA at ST36 in rats has a marked relieving effect on oxaliplatin-induced cold allodynia that is mediated by the endogenous opioid, but not noradrenergic, system.

Effect of bee venom acupuncture on oxaliplatin-induced cold allodynia in rats

Oxaliplatin, a chemotherapy drug, often leads to neuropathic cold allodynia after a single administration. Bee venom acupuncture (BVA) has been used in Korea to relieve various pain symptoms and is shown to have a potent antiallodynic effect in nerve-injured rats. We examined whether BVA relieves oxaliplatin-induced cold allodynia and which endogenous analgesic system is implicated. The cold allodynia induced by an oxaliplatin injection (6 mg/kg, i.p.) was evaluated by immersing the rat's tail into cold water (4°C) and measuring the withdrawal latency. BVA (1.0 mg/kg, s.c.) at Yaoyangguan (GV3), Quchi (LI11), or Zusanli (ST36) acupoints significantly reduced cold allodynia with the longest effect being shown in the GV3 group. Conversely, a high dose of BVA (2.5 mg/kg) at GV3 did not show a significant antiallodynic effect. Phentolamine (α-adrenergic antagonist, 2 mg/kg, i.p.) partially blocked the relieving effect of BVA on allodynia, whereas naloxone (opioid antagonist, 2 mg/kg, i.p.) did not. We further confirmed that an intrathecal administration of idazoxan (α₂-adrenergic antagonist, 50 μg) blocked the BVA-induced anti-allodynic effect. These results indicate that BVA alleviates oxaliplatin-induced cold allodynia in rats, at least partly, through activation of the noradrenergic system. Thus, BVA might be a potential therapeutic option in oxaliplatin-induced neuropathy.

The anti-inflammatory effects of acupuncture and their relevance to allergic rhinitis: a narrative review and proposed model

Classical literature indicates that acupuncture has been used for millennia to treat numerous inflammatory conditions, including allergic rhinitis. Recent research has examined some of the mechanisms underpinning acupuncture's anti-inflammatory effects which include mediation by sympathetic and parasympathetic pathways. The hypothalamus-pituitary-adrenal (HPA) axis has been reported to mediate the antioedema effects of acupuncture, but not antihyperalgesic actions during inflammation. Other reported anti-inflammatory effects of acupuncture include an antihistamine action and downregulation of proinflammatory cytokines (such as TNF-α, IL-1β, IL-6, and IL-10), proinflammatory neuropeptides (such as SP, CGRP, and VIP), and neurotrophins (such as NGF and BDNF) which can enhance and prolong inflammatory response. Acupuncture has been reported to suppress the expression of COX-1, COX-2, and iNOS during experimentally induced inflammation. Downregulation of the expression and sensitivity of the transient receptor potential vallinoid 1 (TRPV1) after acupuncture has been reported. In summary, acupuncture may exert anti-inflammatory effects through a complex neuro-endocrino-immunological network of actions. Many of these generic anti-inflammatory effects of acupuncture are of direct relevance to allergic rhinitis; however, more research is needed to elucidate specifically how immune mechanisms might be modulated by acupuncture in allergic rhinitis, and to this end a proposed model is offered to guide further research.

Acupuncture stimulation and neuroendocrine regulation

Acupuncture has been used to treat different conditions for at least 3000 years in China and has gained increasing acceptance worldwide. The acupuncture needle inserted into the muscle layer at the acupoint produces the so-called obtaining qi sensation that causes the excitation of A-δ and C-fibers of the muscle tissue, resulting in afferent signals. The afferent signals pass through the dorsal horn cells of the spinal cord ascending to the brain, such as the hypothalamus, enhancing the release of neuropeptides and hormones, and these afferent signals in the spinal segment may innervate the visceral organ, inducing effect on visceral function. Here, we reviewed the effect of acupuncture stimulation on neuropeptides and hormones, including β-endorphin, serotonin, oxytocin, adrenocorticotropic hormone, gonadotropin-releasing hormone, corticotrophin-releasing hormone, cholecystokinin, and acetylcholine, as well as insulin sensitivity, immunomodulation (anti-inflammation), and autonomic nerve activity.

Systems biology of meridians, acupoints, and chinese herbs in disease

Meridians, acupoints, and Chinese herbs are important components of traditional Chinese medicine (TCM). They have been used for disease treatment and prevention and as alternative and complementary therapies. Systems biology integrates omics data, such as transcriptional, proteomic, and metabolomics data, in order to obtain a more global and complete picture of biological activity. To further understand the existence and functions of the three components above, we reviewed relevant research in the systems biology literature and found many recent studies that indicate the value of acupuncture and Chinese herbs. Acupuncture is useful in pain moderation and relieves various symptoms arising from acute spinal cord injury and acute ischemic stroke. Moreover, Chinese herbal extracts have been linked to wound repair, the alleviation of postmenopausal osteoporosis severity, and anti-tumor effects, among others. Different acupoints, variations in treatment duration, and herbal extracts can be used to alleviate various symptoms and conditions and to regulate biological pathways by altering gene and protein expression. Our paper demonstrates how systems biology has helped to establish a platform for investigating the efficacy of TCM in treating different diseases and improving treatment strategies.

Electroacupuncture increases the concentration and organization of collagen in a tendon healing model in rats

The aim of this study was to investigate the effect of electroacupuncture (EA) on the composition and organization of the extracellular matrix of the rat Achilles tendon after a partial transection during the proliferative phase of healing. Wistar rats were divided into three groups: rats that were not tenotomized (G1), tenotomized rats (G2), and rats that were tenotomized and submitted to EA (G3). EA was applied 15 days after injury at the ST36 and BL57 acupoints for 20 min, three times per week on alternate days for a total of six sessions. Biochemical analyses were performed using non-collagenous proteins, glycosaminoglycans, and hydroxyproline quantifications. An analysis of metalloproteinase-2 was carried out by zymography. The general organization of the extracellular matrix and the metachromasy of the tendons were analyzed under light microscopy. The organization of the bundles of collagen fibers was analyzed by birefringence analysis. The results showed that EA did not alter the concentration of non-collagenous proteins or glycosaminoglycans or the enzymatic activity of metalloproteinase-2 in the transected tendons. However, the concentration of hydroxyproline was significantly increased when these tendons were treated by EA. The analysis of birefringence showed a higher organization of collagen fibers in the group treated by EA. These results indicate, for the first time, that EA may offer therapeutic benefits for the treatment of tendon injuries by increasing the concentration of collagen and by inducing a better molecular organization of the collagen fibers, which may improve the mechanical strength of the tendon after injury.

A review of Omics research in acupuncture: the relevance and future prospects for understanding the nature of meridians and acupoints

RELEVANCE

Acupuncture is an intrinsic part of traditional Chinese medicine. The current understanding of the acupuncture meridian system, acupoints and the potential utilizing Omics technologies are summarized in this review.

MATERIAL AND METHODS

A systematic search for acupuncture involving Omics technologies was carried out using multiple online literature databases. The records retrieved were from the full collections of each database dated to September 2011. Data produced from functional genomic technologies were extracted from the collected acupuncture/moxibustion studies and subjected to evaluation. Analyses and comments were summarized on the advances in experimental research in acupuncture/moxibustion-related studies, and the future for strategies and approaches in the era of functional genomics highlighted.

RESULTS

An overview of articles indicated that several diseases or symptoms with evidence of effectiveness had been piloted for using functional genomic technologies, such as Parkinson's disease, allergic disorders, pain, and spinal cord injury, most of which are chronic "difficult diseases". High-throughput genomic and proteomic profiling of gene expression in tissues has been able to identify potential candidates for the effects of acupuncture and provide valuable information toward understanding the possible mechanisms of the therapy. However, without further holistic and sophisticated analyses in the context of metabolomics and systems biology, the current attempts and the foreseeable developments appear to be insufficient to produce firm conclusions. Noticeably, the recent rapid advances in functional molecular imaging targeting specific metabolites have shown great promise and if combined with other post-genomic technologies, could be extremely helpful for the acupuncture studies in human subjects.

CONCLUSION

This review suggest that disease-oriented studies using the approach of multi-indexed high-throughput technologies and systems biology analyses will be a preferred strategy for future acupuncture/moxibustion research.

The effects of electroacupuncture at the ST36 (Zusanli) acupoint on cancer pain and transient receptor potential vanilloid subfamily 1 expression in Walker 256 tumor-bearing rats

BACKGROUND

Several studies have addressed the expression of transient receptor potential vanilloid subfamily 1(TRPV1) playing an important role in the generation of cancer pain. Electroacupuncture (EA) is an effective method of acupuncture shown to attenuate different kinds of pain such as inflammatory, neuropathic, and cancer. In this study, we investigated the effect of EA on cancer pain caused by intraplantar injection of Walker 256 carcinoma cells and cancer-driven TRPV1 expression in the dorsal root ganglions (DRGs).

METHODS

Rats were randomly divided into 4 groups: the nontumor cell inoculation group (normal control, n = 8); Walker 256 carcinoma cell inoculation group (tumor control, n = 8); sham point electrical stimulation treatment with Walker 256 carcinoma cell inoculation group (SES, n = 8); EA treatment with Walker 256 carcinoma cell inoculation group (EA, n = 8). The time courses of thermal, mechanical sensitivity, and spontaneous nocifensive behavior were determined. In addition, TRPV1 expression in DRGs was observed by quantitative real-time polymerase chain reaction and Western blotting.

RESULTS

Injection of cancer cells decreased the paw withdrawal threshold, increased spontaneous nocifensive behavior, and induced significant thermal hyperalgesia that was attenuated by EA at the ST36 acupoint (2 Hz, 0.3 ms, ≤1 mA). TRPV1 mRNA and protein in DRGs were upregulated in the cancer pain model, and EA at ST36 acupoint counteracted the cancer-driven upregulation of TRPV1 expression in the corresponding DRGs.

CONCLUSIONS

EA at ST36 could attenuate cancer-induced pain, at least in part, through suppressing TRPV1 mRNA and protein upregulation in the DRGs.

The mechanistic studies of acupuncture and moxibustion in Taiwan

Traditional Chinese acupuncture has a history of over 2500 years. It is effective in the treatment of many conditions with few side effects. The best known mechanism is via endogenous opiates and their receptors. In addition to opioids, researchers have focused on the role of central monoamimergic systems. Acupuncture therapy is used not only to relieve pain but also to treat various medical conditions in traditional Chinese medicine (TCM). Some experiments have revealed a relationship between acupuncture and the autonomic nervous system (ANS). Besides, electroacupuncture (EA) can modulate the imbalance between innate and acquired immune systems. This review is focusing on the mechanistic studies of acupuncture that my colleagues and I have performed in Taiwan in recent years. We found that EA analgesia was closely related to not only the serotonergic neurons but also the adrenergic neurons in the central nervous system. The electrophysiological recordings suggested the involvement of the cerebral cortex in acupuncture. Local somatothermal stimulation inhibited the motility of sphincter of Oddi and internal anal sphincter through nitrergic neural release of nitric oxide. Mild local heat stress upregulated hepatic gene expression of heat shock protein 70 and protected the liver from subsequent ischemia-reperfusion injury. These studies supplement the knowledge of the mechanism of acupuncture.

Electroacupuncture reduces the evoked responses of the spinal dorsal horn neurons in ankle-sprained rats

Acupuncture is shown to be effective in producing analgesia in ankle sprain pain in humans and animals. To examine the underlying mechanisms of the acupuncture-induced analgesia, the effects of electroacupuncture (EA) on weight-bearing forces (WBR) of the affected foot and dorsal horn neuron activities were examined in a rat model of ankle sprain. Ankle sprain was induced manually by overextending ligaments of the left ankle in the rat. Dorsal horn neuron responses to ankle movements or compression were recorded from the lumbar spinal cord using an in vivo extracellular single unit recording setup 1 day after ankle sprain. EA was applied to the SI-6 acupoint on the right forelimb (contralateral to the sprained ankle) by trains of electrical pulses (10 Hz, 1-ms pulse width, 2-mA intensity) for 30 min. After EA, WBR of the sprained foot significantly recovered and dorsal horn neuron activities were significantly suppressed in ankle-sprained rats. However, EA produced no effect in normal rats. The inhibitory effect of EA on hyperactivities of dorsal horn neurons of ankle-sprained rats was blocked by the α-adrenoceptor antagonist phentolamine (5 mg/kg ip) but not by the opioid receptor antagonist naltrexone (10 mg/kg ip). These data suggest that EA-induced analgesia in ankle sprain pain is mediated mainly by suppressing dorsal horn neuron activities through α-adrenergic descending inhibitory systems at the spinal level.

Acupuncture treatment for plantar fasciitis: a randomized controlled trial with six months follow-up

Plantar fasciitis is a common cause of heel pain. It has been suggested that some acupoints have a specific effect on heel pain. The aim of this study was to determine the efficacy and specificity of acupuncture treatment for plantar fasciitis. Subjects were randomly assigned to the treatment group (n = 28) or control group (n = 25). The treatment group received needling at the acupoint PC 7, which is purported to have a specific effect for heel pain. The control group received needling at the acupoint Hegu (LI 4), which has analgesic properties. Treatment was administered five times a week for 2 weeks, with an identical method of manual needling applied to the two acupoints. The primary outcome measure was morning pain on a 100-point visual analog scale (VAS) at one month post-treatment. Secondary outcome measures included a VAS for activity pain, overall pain rating as well as pressure pain threshold using algometry. Significant differences in reduction in pain scores, favoring the treatment group, were seen at one month for morning pain (22.6 ± 4.0 versus 12.0 ± 3.0, mean ± SEM), overall pain (20.3 ± 3.7 versus 9.5 ± 3.6) and pressure pain threshold (145.5 ± 32.9 versus −15.5 ± 39.4). No serious adverse event was observed in either group. The results indicate that acupuncture can provide pain relief to patient with plantar fasciitis, and that PC 7 is a relatively specific acupoint for heel pain.

Peripheral muscarinic receptors mediate the anti-inflammatory effects of auricular acupuncture

BACKGROUND

The cholinergic and opioid systems play important roles in modulating inflammation. This study tests whether auricular acupuncture (AA) produces anti-inflammatory effects via opioid and peripheral cholinergic receptors in a rat model.

METHODS

Rats were anesthetized with chloral hydrate and inflammation was induced by intraplantar injection of carrageenan. Electroacupuncture was performed at auricular points bilaterally. The severity of inflammation was assessed using changes in paw volume and thermal and mechanical pain thresholds of the rats during recovery from anesthesia.

RESULTS

Electroacupuncture at selected auricular acupoints significantly reduced paw edema and mechanical hyperalgesia, with no significant effect on thermal hyperalgesia. The anti-edematous and analgesic effects of AA were abolished by blockade of peripheral cholinergic muscarinic receptors with methyl atropine. Blockade of local muscarinic receptors at the inflamed site with a small dose of atropine also antagonized the anti-edematous effect of AA. By contrast, systemic opioid receptor blockade with naloxone did not antagonize the anti-inflammatory effects of AA.

CONCLUSION

This study discovers a role of peripheral muscarinic receptors in mediating the anti-inflammatory effects of AA. The cholinergic muscarinic mechanism appears to be more important than the opioid mechanism in the anti-inflammatory action of AA.

Immediate effect of acupuncture on the sleep pattern of patients with obstructive sleep apnoea

BACKGROUND

Most patients with obstructive sleep apnoea (OSA) do not tolerate treatment with nasal continuous positive airway pressure, the 'gold standard' treatment for this condition. It was shown in a pilot study that acupuncture was more effective than placebo treatment (sham acupuncture) in producing significant changes in the respiratory events assessed by polysomnography (PSG).

OBJECTIVES

To investigate the immediate effect of manual acupuncture (MA) and electroacupuncture (EA) on the sleep pattern of patients presenting with moderate OSA.

METHODS

40 patients with an Apnoea-Hypopnoea Index (AHI) of 15-30/h were randomly allocated to MA treatment (n=10), EA 10 Hz treatment (n=10), EA 2 Hz treatment (n=10) and a no-treatment control group (n=10). The patients received MA or EA (2 or 10 Hz) just before the PSG study at 20:00.

RESULTS

The AHI (p=0.005; p=0.005), the Apnoea Index (p=0.038; p=0.009) and the respiratory events (p=0.039; p=0.014) decreased significantly in the MA and EA 10 Hz groups, respectively (AHI (21.9, 11.2), Apnoea Index (5.15, 0.7), respiratory events (120.5, 61.0) in the MA group before and after. AHI (20.6, 9.9), Apnoea Index (8.2, 0.3), respiratory events (117.0, 56.0) in the EA 10 Hz group before and after). The micro-arousals decreased only in the MA group (146.0 vs 88.5, p=0.0002). There were no significant changes in the EA 2 Hz group or in the control group.

CONCLUSION

A single session of either MA or EA 10 Hz had an acute effect in reducing the AHI as well as the number of nocturnal respiratory events of patients presenting with moderate OSA.

Contralateral electroacupuncture pretreatment suppresses carrageenan-induced inflammatory pain via the opioid-mu receptor

Acupuncture has been used to treat various clinical diseases in Eastern medicine. To investigate the analgesic effect of electroacupuncture (EA) pretreatment on carrageenan-induced inflammatory pain, we studied on the effect of EA parameters on an animal model of acute arthritic pain. Pretreatment with 1 mA, 10 Hz EA prior to carrageenan injection under halothane anesthesia suppressed carrageenan-induced pain. Interestingly, EA stimulation of the 'Zu-San-Li' (ST36) acupuncture point (1 mA, 10 Hz) contralateral to the site of the carrageenan injection in the rat synovial cavity produced significantly greater improvement of the weight-bearing force compared with EA stimulation of the 'San-Yin-Jiao' acupuncture point. To determine how ST36 EA treatment suppresses carrageenan-induced inflammatory pain, we examined the effect of a mu opioid receptor antagonist on ST36 EA-induced analgesia. The selective antagonist of the mu opioid receptor (OR) significantly suppressed contralateral ST36 EA-induced analgesia against carrageenan-induced inflammation. These results suggested that the analgesic effect mediated by the mu OR during low-frequency contralateral EA pretreatment has an anti-nociceptive action against inflammatory pain and that it may provide a potential strategy to treat inflammatory arthritic pain.

Pre-emptive anti-hyperalgesic effect of electroacupuncture in carrageenan-induced inflammation: role of nitric oxide

Central sensitization theory has been defined as pivotal for understanding the excitability changes in central neurons following peripheral inflammation or neuropathic injury. Considerable evidence has demonstrated that activation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors and subsequent nitric oxide (NO) production are the key in these changes. Consequently, neuromodulator drugs have been developed during the last decades. The electroacupuncture (EA) that acts as biochemical modulator in the spinal horn cord would prevent these changes. The aim of this study was to determine the thermal anti-hyperalgesic effect of EA (10 Hz, 3 mA) and its combination with L-NAME as nitric oxide synthase (NOS) inhibitor in carrageenan-induced hyperalgesia in rats. Also, it investigated the changes in the plasmatic concentrations of NO metabolites. Moreover, the EA combination with sub-effective dose of ketamine as a NMDA antagonist was tested. The EA pre-treatment conducted in unsedated, unrestrained and conscious animals showed a thermal anti-hyperalgesic effect in correspondence with plasmatic increase of NO metabolites. The L-NAME (30 mg/kg) pre-administration decreased significantly the plasmatic concentrations of NO(2)(-)/NO(3)(-) and suppressed the anti-hyperalgesic effect of EA. The combination of EA with ketamine enhanced the anti-hyperalgesic effect. These data constitute the first report that suggested the participation, at least in part, of the L-arginine-NOS-NO-GMPc pathway activation in anti-hyperalgesic effect of EA in carrageenan-induced inflammation model.

Shoulder tip pain after laparoscopic surgery analgesia by collateral meridian acupressure (shiatsu) therapy: a report of 2 cases

OBJECTIVES

This article describes 2 cases of collateral meridian acupressure (shiatsu) therapy (CMAT) for treatment of shoulder tip pain after laparoscopic cholecystectomy (LC). Both cases showed marked pain relief with reduction of skin temperature (1 degrees C) of the affected shoulder after CMAT.

CLINICAL FEATURES

A 32- and a 53-year-old female presented with right shoulder tip pain after LC surgery. The repeated dose of intravenous ketorolac 30 mg and meperidine 50 mg did not improve the pain. Because of persistent pain and episodes of nausea and vomiting after intravenous nonsteroidal anti-inflammatory drugs and opioid medications, patients refused to take more analgesics, and we were consulted for pain management.

INTERVENTION AND OUTCOME

After informed written consent obtained, CMAT was performed using acupoints located on the contralateral (left) kidney meridian to treat affected (right) shoulder pain. Postoperatively, patients' pain intensity was measured using a numeric pain scale. The infrared thermography of shoulder tip was obtained before and after the CMAT. Both patients reported immediate pain relief after the CMAT, with pain scores decreased from 5 to 1 of 10 and 5 to 0 of 10, respectively. Moreover, the local skin temperature of affected shoulders were significantly decreased in both patients after the CMAT. Similarly, the temperature difference between patients' affected and nonpainful shoulders were also significant after the CMAT.

CONCLUSION

The results of these 2 cases suggest that the CMAT may be effective in reducing patients' post-LC shoulder tip pain without medication. An associated reduction of skin temperature of the painful shoulder with CMAT warrants further investigation.

Acupuncture analgesia: a review of its mechanisms of actions

The mechanism of acupuncture analgesia (AA) has been widely explored since the 1970s. Early studies investigated the relationship between acupuncture and endogenous opiates (beta-endorphin, enkephalin, endomorphin and dynorphin). Before the 1990s, most experts agreed on the concept that in normal animal models, lower frequency electroacupuncture (EA) stimulates the release of beta-endorphin, enkephalin and endomorphin, which in turn activates the mu- and delta-opioid receptors, and that higher frequency EA stimulates dynorphin which activates the kappa-opioid receptor. Besides endogenous opiates, our studies have focused on serotonin. The serotoninergic descending inhibitory pathway is suggested to be an important mechanism of acupuncture analgesic, collaborating with endogenous opiates. Many efforts have been made to clarify these mechanisms, but to date no satisfactory consensus has been reached. In the late 1990s, researchers began to focus on the different analgesic effects of EA between normal and hyperalgesic animal models. Published data from these studies imply that normal and hyperalgesic animals respond differently to EA. Results from experiments on the anti-hyperalgesia effect of EA have raised a new issue about the influences of EA on receptors to excitatory amino acid in the spinal cord level. Results from various studies have shown that these receptors play a role in the mechanism of AA. Recently, research on the autonomic nervous system (ANS) seem to indicate its connection with acupuncture. The inflammatory reflex (via the ANS) might be a crucial part of anti-hyperalgesia elicited by acupuncture, and this reflex, which regulates the immune system in the organism, can elucidate not only the mechanism of AA but also the mechanism of acupuncture applied to other inflammatory conditions. Innovation of functional image study enables us to analyze the responses of cortex on living human body to acupuncture. However, results of these experiments are still controversial. After 30 years of acupuncture research, there are still many puzzles left to be solved regarding the mechanism of AA.

Peripheral therapeutic ultrasound stimulation alters the distribution of spinal C-fos immunoreactivity induced by early or late phase of inflammation

The purpose of this investigation was to examine the central modulated effects of therapeutic ultrasound (US) on neuronal activity in the spinal cord on early and late phases of inflammation. In this study, induction of c-Fos protein, which reflects neuronal activation (particularly inflammatory nociception), was investigated in the lumbar spinal cord with immunohistochemistry. Inflammatory monoarthritis was induced in 20 male Wistar rats (weighing 250-300 g) via intra-articular injection of complete Freund's adjuvant (CFA) into the tibiotarsal joint. Two phases of arthritis, early phase (18 h after adjuvant injection) and late phase (7 d after adjuvant injection), were studied in the rats. Pulsed-mode US (1 MHz, the spatial average temporal average intensity [I(SATA)] = 0.5 W/cm(2), 50% duty cycle) was applied for 5 min. The effects of US and sham treatments against these phases of arthritis were demonstrated by spinal c-Fos-like immunoreactivity (c-Fos-LI). All data were evaluated statistically with the paired t-test or analysis of variance with Bonferroni corrections. c-Fos-LI neurons were abundant (average 264.2 +/- 11.9) in the L3 and L4 neurons of the spinal cord in areas ipsilateral to the CFA-induced arthritic leg in the early phase, but few were present (average 40.4 +/- 4.5) in the late phase in sham-treated animals. Bonferroni corrections to the alpha level were used to check the group differences in spinal c-Fos expression, and significance was reached when p < 0.025. In the early inflammatory phase, US treatment significantly suppressed the increased number of c-Fos-LI neurons associated with CFA-induced arthritis in superficial laminae, nucleus proprius, deep laminae and ventral horn of the spinal cord. However, during the late inflammatory phase, US significantly triggered c-Fos expression in most laminae, particularly in the nucleus proprius, deep laminae and ventral horn of the spinal cord. The results of our study suggest that administration of US causes a reduction of early nociceptive inflammatory processing, as shown by a decrease in CFA-induced c-Fos-LI neurons at the level of the spinal cord. In contrast, the US did not suppress, but rather enhanced, the number of c-Fos-LI neurons during the late inflammatory phase. The peripheral influences of US on the central modulation of the spinal nociceptive processing system is suggested and may reflect the work being done through the neuroplasticity of spinal cord in response to peripheral stimulation of US. Therefore, we propose a difference in spinal expression of c-Fos-LI neurons between effects of peripheral US stimulation in arthritic models that underlie early and late inflammatory pain. (E-mail: sherrie@sunrise.hk.edu.tw).

Evidence for suppression of electroacupuncture on spinal glial activation and behavioral hypersensitivity in a rat model of monoarthritis

Our previous study demonstrated that single intrathecal (i.t.) application of fluorocitrate, a glial metabolic inhibitor, synergized electroacupuncture (EA) antagonizing behavioral hypersensitivity in complete Freund's adjuvant (CFA)-induced monoarthritic rat. To further investigate the relationship between spinal glial activation and EA analgesia, the present study examined the effects of multiple EA on spinal glial activation evoked by monoarthritis (MA). The results showed that (1) unilateral intra-articular injection of CFA produced a robust glial activation on the spinal cord, which was associated with the development and maintenance of behavioral hypersensitivity; (2) multiple EA stimulation of ipsilateral "Huantiao" (GB30) and "Yanglingquan" (GB34) acupoints or i.t. injection of fluorocitrate (1 nmol) significantly suppressed spinal glial activation; (3) inhibitory effects of EA on spinal glial activation and behavioral hypersensitivity were significantly enhanced when EA combined with fluorocitrate, indicating that disruption of glial function may potentiate EA analgesia in inflammatory pain states. These data suggested that analgesic effects of EA might be associated with its counter-regulation to spinal glial activation, and thereby provide a potential strategy for the treatment of arthritis.

Protein array analysis of cytokine levels on the action of acupuncture in carrageenan-induced inflammation

BACKGROUND

The aim of this study was to investigate the anti-inflammatory effect of acupuncture on acute paw edema induced by carrageenan (CR) injection and to detect differential cytokine responses in response to acupuncture stimulation using protein array technology.

METHODS

Control group was injected with CR (1%, 50 mul) into the plantar surface of the male Sprague-Dawley rats. Acupuncture group was stimulated with acupuncture at Zusanli (ST36) 30 minutes after CR injection. Rat cytokine antibody array coated with 19 specific cytokine antibodies were probed with protein samples and the relative cytokine levels were investigated.

RESULTS

Acupuncture stimulation significantly inhibited the inflammatory response to CR injection. Compared to control group, three cytokines, interleukin-6 (IL-6), beta-nerve growth factor (beta-NGF) and tissue inhibitors of metalloproteinase-1 (TIMP-1), showed significantly decreased expression levels in the acupuncture group. The other 16 cytokines did not exhibit significant changes between two groups.

CONCLUSION

These results indicate that acupuncture markedly inhibited CR-induced edema and modulated the expressions of certain cytokines in response to CR-induced inflammation. These findings might give us a clue in elucidating the underlying mechanism of anti-inflammatory effect of acupuncture.

The effect of 2 Hz and 100 Hz electrical stimulation of acupoint on ankle sprain in rats

The electrical stimulation of acupoint (ESA) releases several endogenous neuropeptides, which play important roles in management of pain and inflammation. ESA with low and high frequencies has been shown to release different neuropepides, suggesting its various therapeutic effects. Pain and edema are major problems for ankle sprain. However, there have been few reports on the effects of ESA for ankle sprain. We aimed to investigate that ESA can reduce pain and edema resulting from ankle sprain, and whether there is a difference in therapeutic effects between low and high frequency ESA. To induce ankle sprain in Sprague-Dawley rats, the ankle of right hindpaw was overextended in direction of simultaneous inversion and plantar flexion. Stepping force and edema in the paw of the sprained ankle were measured by electronic balance and plethysmometer, respectively. In both 2 and 100 Hz ESA groups, stepping force was increased significantly in similar degrees (p<0.05). Only 2 Hz ESA produced the significant rapid decrease in ankle edema. This study demonstrates that ESA of 2 Hz and 100 Hz shows comparable analgesic effects, but only 2 Hz ESA can facilitate the reduction of edema caused by ankle sprain.

Effects of intensity of electroacupuncture upon experimental pain in healthy human volunteers: a randomized, double-blind, placebo-controlled study

Electroacupuncture is commonly used for pain relief. Despite an extensive evidence-base guiding the selection of stimulation parameters, little methodologically robust research exists regarding the level of intensity required to provide effective doses. This study investigated the hypoalgesic effects of two stimulation intensities compared to placebo on pressure pain thresholds (PPTs) in pain-free humans. Forty-eight acupuncture-naïve volunteers (mean age 23), stratified by gender, were screened for relevant contraindications and randomly allocated to four groups: control, placebo, high-intensity ("to tolerance but sub-noxious") or low-intensity ("strong but comfortable"). True or placebo electroacupuncture, using the Streitberger placebo needle, was administered to acupoints on dominant forearm (LI10, TH5) and ipsilateral leg (GB34, ST38). True needles (30 mm long, 0.3 mm diameter) were inserted 20-25 mm and "de-qi" was elicited from active groups, prior to administering 30 min of 4 Hz, 200 micros electroacupuncture. No electrical stimulation was performed on control and placebo groups, and placebo needles were used. After the intervention period, all needles were removed. Volunteers were monitored for 30 further minutes. Two PPT measurements were taken bilaterally from muscle bellies of first dorsal interosseous by an independent rater, at baseline and at six subsequent 10-min intervals. Square-root transformed data were analysed using repeated-measures ANOVA, with baseline data as covariate. The high-intensity group was significantly different from the placebo group for both measurement sites (p=.020, p=.033). The control group displayed stable PPT readings over time. No significant differences were observed between the placebo and control groups. These findings suggest that high-intensity levels may be important in optimal dose selection.

Disruption of glial function enhances electroacupuncture analgesia in arthritic rats

Activated glia play a major role in mediating behavioral hypersensitive state following peripheral inflammation. Electroacupuncture is well known to relieve persistent inflammatory pain. The present study was undertaken to examine whether fluorocitrate, a glial metabolic inhibitor, could synergize electroacupuncture antagonizing thermal hyperalgesia and mechanical allodynia evoked by ankle joint inflammation. Monoarthritis of rat ankle joint was induced by an intra-articular injection of Complete Freund's Adjuvant (CFA). The paw withdrawal latency (PWL) from a thermal stimulus and paw withdrawal threshold (PWT) from von Frey hairs were measured in awake rats. Intrathecal (i.t.) injection of 1 nmol fluorocitrate markedly suppressed monoarthritis-induced thermal hyperalgesia and mechanical allodynia. Unilateral electroacupuncture stimulation of "Huantiao" (GB30) and "Yanglingquan" (GB34) acupuncture points (100/2 Hz alternation, 1-2-3 mA) significantly elevated the PWLs and PWTs for 45 min after cessation of electroacupuncture in monoarthritic rats. Co-application of 0.1 or 1 nmol fluorocitrate with electroacupuncture significantly potentiated electroacupuncture analgesia, although 0.1 nmol fluorocitrate alone had no effect on PWLs and PWTs in monoarthritic rats. These results suggested that electroacupuncture and disrupting glial function could synergistically antagonize inflammatory pain, which might provide a potential strategy for the treatment of arthritic pain.

The Anti-Inflammatory Effects of Low- and High-Frequency Electroacupuncture Are Mediated by Peripheral Opioids in a Mouse Air Pouch Inflammation Model

BACKGROUND

Although acupuncture has been widely used for complementary therapeutic approaches to treat inflammatory diseases and inflammation-induced pain, the potential anti-inflammatory effects of acupuncture treatment remain controversial in clinical trials, and the underlying mechanisms are still unclear.

OBJECTIVE

The objective was to determine whether electroacupuncture (EA) is able to suppress the peripheral inflammatory response (e.g., zymosan-induced leukocyte migration into air pouch). As part of a mechanistic approach, it was further evaluated whether endogenous opioid systems are involved in the "EA-induced anti-inflammatory effect" (EA-AI).

METHODS

EA (1 or 120 Hz) was performed bilaterally in the Zusanli acupoint (ST36) or in a nonacupoint (gluteal muscle) for 30 min in ICR mice under anesthetic condition. The number of leukocytes that migrated into the air pouch was counted 4 hours after zymosan injection. EA was performed at 0, 0.5, 1, or 2 hours prior to zymosan injection, respectively. To evaluate opioid involvement in EA-AI, intrathecal naloxone (36 microg/mouse) and intraperitoneal naloxone methiodide (30 mg/kg) were administered 10 min before EA stimulation.

RESULTS

Both the 1 and 120 Hz frequencies of EA into Zusanli acupoint at the same time with zymosan injection significantly reduced leukocyte migration into the air pouch as compared with those of control groups (i.e., anesthetic control and needling control into Zusanli acupoint without electrical stimulation). The EA stimulation into nonacupoint did not produce any significant anti-inflammatory effect. EA treatment at 0.5 hours prior to zymosan injection also produced an anti-inflammatory effect but 1 and 2 hours prior to zymosan injection did not elicit any effect. Peripheral opioid blockage significantly reversed EA-AI, whereas spinal opioid blockage did not alter EA-AI.

CONCLUSION

EA can suppress peripheral inflammation through a peripheral opioid mechanism. To achieve the full effectiveness of EA, repeated application is recommended for the treatment of a variety of inflammatory diseases.

Analgesic effect of electroacupuncture on complete Freund's adjuvant-induced inflammatory pain in mice: a model of antipain treatment by acupuncture in mice

Electroacupuncture (EA) was applied bilaterally to the acupoints of Zu-san-li (ST-36) and Kun-lun (BL-60) in the hindlimbs of mice. The therapeutic effect of EA on inflammatory pain induced by an ipsilateral injection of complete Freund's adjuvant (CFA) into the right paw of the mouse was investigated in this study. The time of paw-withdrawal latency (PWL) was used as an indicator for judging the intensity of the pain induced by the CFA injection. The EA effects were divided into immediate (PWL tests within 2 h after EA treatment) and cumulative (PWL tests during and after repetitive EA treatments for 3 weeks) effects. As immediate effects, PWL was significantly shortened in the CFA-injected paw, but was again prolonged 20 min after an EA treatment and lasted until 30 min after. As cumulative effects, PWL was significantly shortened in the CFA-injected paw, but recovered from the 2nd to the 8th day during repetitive EA treatments. No such effects could be observed after sham EA treatment, which resulted in behavior similar to that in untreated animals. These results demonstrate that the CFA-induced inflammatory pain in mice is an ideal model system for the investigation of EA effects and may serve as a valuable reference for the clinical treatment of inflammatory pain in human beings. Furthermore, the mouse pain model opens the possibility to apply the investigation also to transgenic mice.

Endogenous opiates and behavior: 2004

This paper is the 27th consecutive installment of the annual review of research concerning the endogenous opioid system, now spanning over 30 years of research. It summarizes papers published during 2004 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors, opioid agonists and opioid antagonists. The particular topics that continue to be covered include the molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors related to behavior, and the roles of these opioid peptides and receptors in pain and analgesia; stress and social status; tolerance and dependence; learning and memory; eating and drinking; alcohol and drugs of abuse; sexual activity and hormones, pregnancy, development and endocrinology; mental illness and mood; seizures and neurologic disorders; electrical-related activity and neurophysiology; general activity and locomotion; gastrointestinal, renal and hepatic functions; cardiovascular responses; respiration and thermoregulation; and immunological responses.

Electro-acupuncture stimulation protects dopaminergic neurons from inflammation-mediated damage in medial forebrain bundle-transected rats

Through producing a variety of cytotoxic factors upon activation, microglia are believed to participate in the mediation of neurodegeneration. Intervention against microglial activation may therefore exert a neuroprotective effect. Our previous study has shown that the electro-acupuncture (EA) stimulation at 100 Hz can protect axotomized dopaminergic neurons from degeneration. To explore the underlying mechanism, the effects of 100 Hz EA stimulation on medial forebrain bundle (MFB) axotomy-induced microglial activation were investigated. Complement receptor 3 (CR3) immunohistochemical staining revealed that 24 sessions of 100 Hz EA stimulation (28 days after MFB transection) significantly inhibited the activation of microglia in the substantia nigra pars compacta (SNpc) induced by MFB transection. Moreover, 100 Hz EA stimulation obviously inhibited the upregulation of the levels of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta mRNA in the ventral midbrains in MFB-transected rats, as revealed by reverse transcriptase polymerase chain reaction (RT-PCR). ED1 immunohistochemical staining showed that a large number of macrophages appeared in the substantia nigra (SN) 14 days after MFB transection. The number of macrophages decreased by 47% in the rats that received 12 sessions of EA simulation after MFB transection. These data indicate that the neuroprotective role of 100 Hz EA stimulation on dopaminergic neurons in MFB-transected rats is likely to be mediated by suppressing axotomy-induced inflammatory responses. Taken together with our previous results, this study suggests that the neuroprotective effect of EA on the dopaminergic neurons may stem from the collaboration of its anti-inflammatory and neurotrophic actions.

Electroacupuncture combined with indomethacin enhances antihyperalgesia in inflammatory rats

Our previous study showed that electroacupuncture (EA), an adjuvant to conventional medicine, significantly attenuated hyperalgesia and inflammation. The present study is an evaluation of the potential synergism of EA and a subeffective dosage of indomethacin (INDO) in a rat model. Inflammation and hyperalgesia, manifesting as edema and decreased paw withdrawal latency (PWL) to a noxious stimulus, were induced by injecting complete Freund's adjuvant (CFA) subcutaneously into the plantar surface of one hind paw of the rat. EA treatments were given at acupoint GB30 immediately and 2 h post-CFA. INDO at 2 mg/kg was given (intraperitoneally) 40 min before the second EA. PWL and edema were measured prior to CFA and 2.5 and 5 h post-CFA. Ten and 100 Hz EA significantly inhibited CFA-induced hind paw hyperalgesia. Both low- and high-frequency EA combined with INDO enhanced antihyperalgesia compared to each component alone, and 10 Hz but not 100 Hz EA significantly reduced CFA-induced hind paw edema. A combination of low-frequency EA and INDO did not show synergistic inhibitory effects on edema. The results demonstrate that EA combined with INDO synergistically inhibits hyperalgesia and suggest an improved treatment strategy for inflammatory pain.