Electroacupuncture exerts an anti-migraine effect via modulation of the 5-HT7 receptor in the conscious rat

The Mechanism of Acupuncture Therapy for Migraine: A Systematic Review of Animal Studies on Rats

Background

Acupuncture has long been used for migraine treatment as it is convenient for use and has remarkable efficacy. The acupuncture-based comprehensive treatment plan has been widely recognized for migraine prevention and treatment. However, the mechanism underlying acupuncture efficacy in migraine treatment is not yet completely understood. Our goal is to systematically analyze and evaluate this efficacy mechanism in migraine treatment-related basic research.

Methods

To retrieve animal experiments investigating the action mechanism of acupuncture in migraine treatment, We conducted a literature search in major databases, the search period was the inception of each database to April 1, 2024. Literature was screened and data were extracted independently based on predefined inclusion and exclusion criteria. The animal models, acupuncture points, and acupuncture methods specified in the included studies were statistically analyzed and summarized. Furthermore, the potential action mechanisms of acupuncture were discussed.

Results

In total, 20 animal experimental studies were included in the present analysis, and all of these studies used rats. In the order of frequency of use, the migraine animal models employed in the searched studies were the dural stimulation model, the nitroglycerin model, and the cortical spreading depression model. The primary acupuncture points selected were Fengchi (GB20) and Yanglingquan (GB34), and electroacupuncture was the most frequently used acupuncture method. The action mechanism of acupuncture underlying migraine treatment primarily involves regulating the descending pain modulatory system and inhibiting neurotransmitters such as CGRP, SP, and 5-HT, as well as microglial cell activation. It also reduces the levels of inflammatory cytokines, thereby mitigating neurogenic inflammation and improving central sensitization.

Conclusion

Acupuncture exerts its therapeutic effect on migraine by regulating neurotransmitter release, inhibiting inflammatory responses, modulating central analgesic mechanisms, and suppressing glial cell activation. However, further in-depth exploration is needed in the study of the mechanisms underlying acupuncture treatment for migraine.

Animal Models of Chronic Migraine: From the Bench to Therapy

PURPOSE OF REVIEW

Chronic migraine is a disabling progressive disorder without effective management approaches. Animal models have been developed and used in chronic migraine research. However, there are several problems with existing models. Therefore, we aimed to summarize and analyze existing animal models to facilitate translation from basic to clinical.

RECENT FINDINGS

The most commonly used models are the inflammatory soup induction model and the nitric oxide donor induction model. In addition, KATP openers have also been used in model induction. Based on the above models, some molecular targets have been identified, such as glutamate receptors. However, each model has its shortcomings and characteristics, and there are still some common problems that need to be solved, such as spontaneous headache, evaluation criteria after model establishment, and identification methods. In this review, we summarized and highlighted the advantages and limitations of the currently commonly used animal models of chronic migraine with a special focus on drug discovery and current therapeutic strategies, and discussed the directions that can be worked on in the future.

Restoring brain health: Electroacupuncture at GB20 and LR3 for migraine mitigation through mitochondrial restoration

BACKGROUND

Electroacupuncture (EA) is a promising alternative therapy for migraine, with mitochondrial dysfunction hypothesized as a pivotal mechanism in migraine pathophysiology. This research endeavors to investigate the therapeutic potential of EA in addressing migraines and shed light on the associated mechanisms linked to mitochondrial anomalies.

MATERIALS AND METHODS

Migraine in rats was induced by 10 mg/kg nitroglycerin, followed by 2/15 Hz EA treatment at GB20 and LR3. Nociceptive behavior was recorded via a camera and analyzed using EthoVision XT 12.0 software. The hind-paw withdrawal threshold was assessed using the von Frey test. We assessed the levels of calcitonin gene-related peptide (CGRP), nitric oxide (NO), and endothelin (ET) - key parameters in migraine pathophysiology using immunohistochemistry and enzyme-linked immunosorbent assay. Mitochondrial morphology in brain tissues was observed through transmission electron microscopy. Reactive oxygen species (ROS) level in mitochondria was measured by flow cytometry. The levels of PINK1 and Parkin were assessed using Western blot analysis.

RESULTS

EA at GB20 and LR3 decreased nociceptive behaviors (resting and grooming) and increased exploratory and locomotor behaviors in migraine rats. The hind-paw withdrawal threshold in migraine rats was significantly elevated following EA treatment. Post-EA treatment, levels of CGRP and NO decreased, while ET level increased, suggesting an alteration in pain and vascular physiology. Notably, EA treatment mitigated the mitochondrial damage and reduced ROS level in the brain tissues of migraine rats. EA treatment upregulated the expression of PINK1 and Parkin in migraine rats.

CONCLUSION

EA at GB20 and LR3 may treat migraine by alleviating PINK1/Parkin-mediated mitochondrial dysfunction.

Electroacupuncture at GB20 improves cognitive ability and synaptic plasticity via the CaM-CaMKII-CREB signaling pathway following cerebral ischemia-reperfusion injury in rats

BACKGROUND

This study aimed to investigate the effects of electroacupuncture (EA) on cognitive recovery and synaptic remodeling in a rat model of middle cerebral artery occlusion (MCAO) followed by reperfusion and explore the possible mechanism.

METHOD

Focal cerebral ischemia was modeled in healthy adult Sprague-Dawley rats by MCAO. The MCAO rats were classified into four groups: sham, MCAO, MCAO + GB20 (receiving EA at GB20) and MCAO + NA (receiving EA at a "non-acupoint" location not corresponding to any traditional acupuncture point location about 10 mm above the iliac crest). Neurological deficit scores and behavior were assessed before and during the treatment. After intervention for 7 days, the hippocampus was dissected to analyze growth-associated protein (GAP)-43, synaptophysin (SYN) and postsynaptic density protein (PSD)-95 expression levels by Western blotting. Bioinformatic analysis and primary hippocampal neurons with calcium-voltage gated channel subunit alpha 1B (CACNA1B) gene overexpression were used to screen the target genes for EA against MCAO.

RESULTS

Significant amelioration of neurological deficits and learning/memory were found in MCAO + GB20 rats compared with MCAO or MCAO + NA rats. Protein levels of GAP-43, SYN and PSD-95 were significantly improved in MCAO + GB20-treated rats together with an increase in the number of synapses in the hippocampal CA1 region. CACNA1B appeared to be a target gene of EA in MCAO. There were increased mRNA levels of CACNA1B, calmodulin (CaM), Ca2+/calmodulin-dependent protein kinase type II (CaMKII) and cyclic adenosine monophosphate response element binding (CREB) and increased phosphorylation of CaM, CaMKII and CREB in the hippocampal region in MCAO + GB20 versus MCAO and MCAO + NA groups. CACNA1B overexpression modulated expression of the CaM-CaMKII-CREB axis.

CONCLUSION

EA treatment at GB20 may ameliorate the negative effects of MCAO on cognitive function in rats by enhancing synaptic plasticity. EA treatment at GB20 may exert this neuroprotective effect by regulating the CACNA1B-CaM-CaMKII-CREB axis.

Effectiveness of Complementary and Alternative Medicine in Fibromyalgia Syndrome: A Network Meta-Analysis

Objective

Fibromyalgia (FM) is a prevalent chronic disorder characterized by widespread skeletal muscle pain. In recent years, complementary and alternative medicine (CAM) has increasingly been recognized for its potential in treating FM symptoms. This study aims to assess the efficacy of CAM therapies in mitigating the symptoms of FM.

Methods

This systematic review was registered with INPLASY. A thorough search of both English and Chinese databases was undertaken from their inception until April 15, 2023. The search criteria focused on prospective controlled trials examining CAM therapies in FM patients. The statistical analysis employed mean values and standard deviations. Additionally, an evaluation of the literature's quality and potential biases was conducted.

Results

The search yielded 41 articles, encompassing 2877 FM patients and involving 20 different interventions. All studies were randomized controlled trials (RCTs). The results of the network meta-analysis (NMA) indicated that a combination of Acupuncture and Massage therapy, as well as Navel Needling therapy, effectively alleviated pain symptoms in FM patients. Furthermore, Abdominal Acupuncture and Electroacupuncture were found to be beneficial in improving patients' mood and sleep quality.

Conclusion

Acupuncture + Massage and Umbilical Acupuncture emerged as the most efficacious therapies in relieving pain symptoms in FM patients. Abdominal Acupuncture and Electroacupuncture demonstrated their effectiveness in enhancing mood and sleep quality. Overall, CAM therapies exhibited a high safety profile for patients with fibromyalgia.

Electroacupuncture improves allodynia and central sensitization via modulation of microglial activation associated P2X4R and inflammation in a rat model of migraine

Background: Recent studies have demonstrated that activated microglia were involved in the pathogenesis of central sensitization characterized by cutaneous allodynia in migraine. Activation of microglia is accompanied by increased expression of its receptors and release of inflammatory mediators. Acupuncture and its developed electroacupuncture (EA) have been recommended as an alternative therapy for migraine and are widely used for relieving migraine-associated pain. However, it remains rare studies that show whether EA exerts anti-migraine effects via inhibiting microglial activation related to a release of microglial receptors and the inflammatory pathway. Therefore, this study aimed to investigate EA' ability to ameliorate central sensitization via modulation of microglial activation, microglial receptor, and inflammatory response using a rat model of migraine induced by repeated epidural chemical stimulation. Methods: In the present study, a rat model of migraine was established by epidural repeated inflammatory soup (IS) stimulation and treated with EA at Fengchi (GB20) and Yanglingquan (GB34) and acupuncture at sham-acupoints. Pain hypersensitivity was further determined by measuring the mechanical withdrawal threshold using the von-Frey filament. The changes in c-Fos and ionized calcium binding adaptor molecule 1 (Ibal-1) labeled microglia in the trigeminal nucleus caudalis (TNC) were examined by immunflurescence to assess the central sensitization and whether accompanied with microglia activation. In addition, the expression of Ibal-1, microglial purinoceptor P2X4, and its associated inflammatory signaling pathway mediators, including interleukin (IL)-1β, NOD-like receptor protein 3 (NLRP3), and Caspase-1 in the TNC were investigated by western blot and real-time polymerase chain reaction analysis. Results: Allodynia increased of c-Fos, and activated microglia were observed after repeated IS stimulation. EA alleviated the decrease in mechanical withdrawal thresholds, reduced the activation of c-Fos and microglia labeled with Ibal-1, downregulated the level of microglial purinoceptor P2X4, and limited the inflammatory response (NLRP3/Caspase-1/IL-1β signaling pathway) in the TNC of migraine rat model. Conclusions: Our results indicate that the anti-hyperalgesia effects of EA ameliorate central sensitization in IS-induced migraine by regulating microglial activation related to P2X4R and NLRP3/IL-1β inflammatory pathway.

The Analgesic Effect and Potential Mechanisms of Acupuncture for Migraine Rats: A Systematic Review and Meta-Analysis

Purpose

To assess the inhibitory effect of acupuncture on pain symptoms in migraine models, and to further summarize the potential mechanisms of acupuncture in regulating hyperalgesia in the treatment of migraine.

Materials and Methods

Literature search in databases such as China National Knowledge Infrastructure (CNKI), PubMed, and Web of Science (WOS) etc. The quality was evaluated by the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) bias risk assessment tool and Collaborative Approach to Meta-analysis and Review of Animal Data from Experimental Studies (CAMARADES) checklist. Meta-analyses were performed using Stata 17.0 software.

Results

Twenty-one studies involving 489 animals were identified. The qualitative score ranged from 3 to 9 points. Facial mechanical withdrawal threshold (FMWT) and paw mechanical withdrawal threshold (PMWT) measured by Von Frey filaments were selected as major outcomes, and serum calcitonin gene-related peptide (CGRP) levels measured by ELISA were selected as secondary outcome. Meta-analysis results revealed that true acupuncture (TA) group significantly increased FMWT, PMWT and CGRP compared to model group. TA group showed superior effect in FMWT, PMWT relative to sham acupuncture (SA) group. Subgroup analysis results showed that high risk of bias scores may be responsible for the high heterogeneity of FMWT; additionally, CGRP analysis suggests that acupoint selection and blood collection sites may be sources of heterogeneity. In the treatment of migraine pain symptoms, the underlying mechanism of acupuncture treatment is either the regulation of hyperalgesia and neurotransmitters, or the reduction of inflammatory factors.

Conclusion

The results indicate that TA treatment effectively increased the pain threshold and reduced hyperalgesia in migraine rats. In summary, our study highlights the potential of TA as an effective treatment for migraine, but further investigation is required to fully comprehend its mechanism of action and optimize its clinical application.

Electroacupuncture at Fengchi(GB20) and Yanglingquan(GB34) Ameliorates Paralgesia through Microglia-Mediated Neuroinflammation in a Rat Model of Migraine

Background: Multiple studies have suggested that paralgesia (hyperalgesia and cutaneous allodynia) in migraine reflects the activation and sensitisation of the trigeminovascular system (TGVS). In particular, it reflects the second-order and higher nerve centre sensitisation, which is caused and maintained by neuroinflammation. Microglia activation leads to the release of proinflammatory cytokines involved in inflammatory responses. Accumulating evidence indicates that electroacupuncture (EA) is effective in ameliorating paralgesia, but the underlying mechanisms of EA in migraine attacks caused by microglia and microglia-mediated inflammatory responses are still unclear. The purpose of this study was to explore whether EA could ameliorate the dysregulation of pain sensation by suppressing microglial activation and the resulting neuroinflammatory response, and to evaluate whether this response was regulated by Toll-like receptor 4 (TLR4)/nuclear factor-kappa B(NF-κB) in the trigeminal nucleus caudalis (TNC) in a rat model of migraine. Methods: Repeated Inflammatory Soup (IS) was infused into the dura for seven sessions to establish a recurrent migraine-like rat model, and EA treatment was administered at Fengchi (GB20) and Yanglingquan (GB34) after daily IS infusion. Facial mechanical withdrawal thresholds were measured to evaluate the change in pain perception, and plasma samples and the TNC tissues of rats were collected to examine the changes in calcitonin gene-related peptide (CGRP), the Ibal-1-labelled microglial activation, and the resulting inflammatory response, including interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6), and their regulatory molecules TLR4/NF-κB, via enzyme-linked immunosorbent assay (ELISA), real-time polymerase chain reaction (RT-PCR), immunohistochemistry (IHC) and Western blot analysis. Results: Repeated IS injections into the dura induced facial mechanical paralgesia, which is the manifestation of migraine attacks, and increased the expression of CGRP, Ibal-1, microglial mediated inflammatory cytokines (IL-1β, TNF-α, IL-6), and regulatory molecules TLR4/NF-κB. EA at GB20/34 significantly attenuated repetitive IS-induced pain hypersensitivity. This effect was consistent with decreased levels of CGRP and inflammatory cytokines in the plasma and the TNC via the inhibition of microglia activation, and this response may be regulated by TLR4/NF-κB. Conclusions: EA ameliorated paralgesia in repetitive IS-induced migraine-like rats, which was mainly mediated by a reduction in microglial activation and microglial-mediated inflammatory responses that could be regulated by TLR4/NF-κB.

A study on the correlation of the asymmetric regulation between the periaqueductal gray and the bilateral trigeminal nucleus caudalis in migraine male rats

BACKGROUND

The study was designed to explore the correlation of the asymmetric regulation between periaqueductal gray (PAG) and bilateral trigeminal nucleus caudalis (TNC) in migraine rats through studying the changes of metabolites in pain regulatory pathway of acute migraine attack.

METHODS

Thirty male Sprague-Dawley (SD) rats were randomly divided into three groups: blank, control, model groups. Then, blank group was intraperitoneally injected with ultrapure water, while control group injected with saline and model group injected with Glyceryl Trinitrate (GTN). Two hours later, PAG and bilateral TNC were removed respectively, and metabolite concentrations of PAG, Left-TNC, Right-TNC were obtained. Lastly, the differences of metabolite among three brain tissues were compared.

RESULTS

The relative concentrations of rNAA, rGlu, rGln, rTau, rMI in PAG or bilateral TNC had interaction effects between groups and sites. The concentration of rLac of three brain tissues increased in migraine rats, however, the rLac of LTNC and RTNC increased more than that of PAG. Besides, the concentrations of rNAA and rGln increased in RTNC, while rGABA decreased in RTNC.

CONCLUSIONS

There is correlation between PAG, LTNC and RTNC in regulation of pain during acute migraine attack, and the regulation of LTNC and RTNC on pain is asymmetric.

The mechanistic basis for the effects of electroacupuncture on neuropathic pain within the central nervous system

Nociceptive signaling responses to painful stimuli are transmitted to the central nervous system (CNS) from the afferent nerves of the periphery through a series of neurotransmitters and associated signaling mechanisms. Electroacupuncture (EA) is a pain management strategy that is widely used, with clinical evidence suggesting that a frequency of 2-10 Hz is better able to suppress neuropathic pain in comparison to higher frequencies such as 100 Hz. While EA is widely recognized as a viable approach to alleviating neuralgia, the mechanistic basis underlying such analgesic activity remains poorly understood. The present review offers an overview of current research pertaining to the mechanisms whereby EA can alleviate neuropathic pain in the CNS, with a particular focus on the serotonin/norepinephrine, endogenous opioid, endogenous cannabinoid, amino acid neurotransmitter, and purinergic pathways. Moreover, the corresponding neurotransmitters, neuromodulatory compounds, neuropeptides, and associated receptors that shape these responses are discussed. Together, this review seeks to provide a robust foundation for further studies of the EA-mediated alleviation of neuropathic pain.

Role of nerve signal transduction and neuroimmune crosstalk in mediating the analgesic effects of acupuncture for neuropathic pain

Neurogenic pain rises because of nervous system damage or dysfunction and is the most difficult to treat among other pathological pains. Acupuncture has been reported as a great treatment option for neurogenic pain owing to its unlimited advantages. However, previous studies on the analgesic effects of acupuncture for NP were scattered and did not form a whole. In this study, we first comprehensively review the relevant basic articles on acupuncture for NP published in the last 5 years and summarize the analgesic mechanisms of acupuncture in terms of nerve signaling, neuro-immune crosstalk, and metabolic and oxidative stress regulation. Acupuncture inhibits the upstream excitatory system and suppresses neuronal transmission efficiency by downregulating glutamate, NMDA receptors, P2XR, SP, CGRP, and other neurotransmitters and receptors in the spinal cord, as well as plasma channels such as TRPV1, HCN. It can also activate the downstream pain inhibitory pathway by upregulating opioid peptide (β-endorphin), MOR receptors, GABA and GABA receptors, bi-directional regulating 5-hydroxytryptamine (5-HT) and its receptors (upregulate 5-HT 1A and downregulate 5-HT7R) and stimulating hypothalamic appetite-modifying neurons. Moreover, neuroinflammation in pain can be inhibited by acupuncture through inhibiting JAK2/STAT3, PI3K/mTOR pathways, down regulating chemokine receptor CX3CR1 on microglia and up regulating adenosine receptor A1Rs on astrocytes, inhibiting the activation of glia and reducing TNF-α and other inflammatory substances. Acupuncture also inhibits neuronal glucose metabolism by downregulating mPFC's GLUT-3 and promotes metabolic alterations of the brain, thus exerting an analgesic effect. In conclusion, the regulation of nerve signal transduction and neuroimmune crosstalk at the peripheral and central levels mediates the analgesic effects of acupuncture for neuropathic pain in an integrated manner. These findings provide a reliable basis for better clinical application of acupuncture in the management of neuropathic pain.

Acupuncture for migraine prophylaxis: A protocol for systematic review and Bayesian network meta-analysis

BACKGROUND

Migraine causes health problems in 1 billion people worldwide and imposes a huge social burden. Acupuncture therapy has a good clinical effect in migraine prophylaxis and is recommended by authoritative journals. We plan to conduct a Bayesian network meta-analysis to compare the efficacies of different acupuncture therapies.

METHODS

We will search PubMed, Web of Science, Embase, Cochrane Library, China National Knowledge Infrastructure, VIP database for Chinese technical periodicals, Chinese biological medical database, WanFang Data, Cochrane register of controlled trials, Chinese Clinical Trial Register, and ClinicalTrials.gov from their inception to July 1, 2022, for randomized controlled trials that studied different acupuncture therapies and other therapies for the preventive treatment of migraine. Migraine episodes, migraine days, headache intensity, and adverse events will be counted as outcomes. Two reviewers will independently complete the study selection, data extraction, and risk of bias assessment of all filtered trials. Pairwise meta-analysis and Bayesian network meta-analysis will be performed (if applicable) through Review Manager 5.3 and the "gemtc" and "rjags" packages of the R software. Confidence in Network Meta-Analysis will be used to evaluate the quality and credibility of the evidence for each outcome.

RESULTS

The protocol will compare the efficacies of different acupuncture therapies for migraine prophylaxis.

CONCLUSION

This study aims to help clinicians develop an effective and safe treatment plan for migraine prophylaxis.

Comparative efficacy of acupuncture-related therapy for migraine: A systematic review and network meta-analysis

Background

Migraine is a worldwide disabling chronic brain disorder, some studies suggest acupuncture-related therapy plays an important role in raising efficiency rates and reducing migraine attacks. However, clinical trials comparing the efficacy of different interventions for migraine are limited and controversial. This network meta-analysis (NMA) was performed to review all randomized controlled trials (RCTs) comparing the effects of acupuncture-related therapy for migraine.

Methods

Randomized controlled trials (RCTs) of acupuncture-related therapy for migraine were searched in the following databases from the date of database inception to March 31, 2022, including PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), VIP Database, Wanfang Database, and Chinese Biomedical Database (CBM). The primary endpoint was visual analog scale (VAS) scores. The secondary endpoints were the number of migraine days, duration of migraine, and frequency of migraine attacks. We used Cochrane risk of bias to assess the quality of evidence for outcomes.

Results

Thirty-nine studies involving 4379 patients with 13 different acupuncture-related methods were evaluated. According to surface under the cumulative ranking curve value, acupoint injection was ranked the highest (98.0%) in VAS scores, followed by acupoint implantation (79.0%); electroacupuncture was the optimal intervention method (82.4%) in the number of migraine days, followed by embedding needle therapy (73.1%); embedding needle therapy ranked first (99.9%) in the duration of migraine, followed by acupoint injection (77.4%); acupoint injection was the best intervention (99.3%) in the frequency of migraine attacks, followed by conventional acupuncture plus massage (73.8%).

Conclusion

These results provide preliminary evidence that acupuncture-related therapy could be recommended as one of the effective treatments for migraine. Conventional acupuncture has significant effects on improving VAS scores, the number of migraine days, duration of migraine, and frequency of migraine attacks. However, more high-quality studies should be carried out to verify this finding.

Systematic review registration

https://inplasy.com/, identifier: INPLASY202110035.

Therapeutic applications and potential mechanisms of acupuncture in migraine: A literature review and perspectives

Acupuncture is commonly used as a treatment for migraines. Animal studies have suggested that acupuncture can decrease neuropeptides, immune cells, and proinflammatory and excitatory neurotransmitters, which are associated with the pathogenesis of neuroinflammation. In addition, acupuncture participates in the development of peripheral and central sensitization through modulation of the release of neuronal-sensitization-related mediators (brain-derived neurotrophic factor, glutamate), endocannabinoid system, and serotonin system activation. Clinical studies have demonstrated that acupuncture may be a beneficial migraine treatment, particularly in decreasing pain intensity, duration, emotional comorbidity, and days of acute medication intake. However, specific clinical effectiveness has not been substantiated, and the mechanisms underlying its efficacy remain obscure. With the development of biomedical and neuroimaging techniques, the neural mechanism of acupuncture in migraine has gained increasing attention. Neuroimaging studies have indicated that acupuncture may alter the abnormal functional activity and connectivity of the descending pain modulatory system, default mode network, thalamus, frontal-parietal network, occipital-temporal network, and cerebellum. Acupuncture may reduce neuroinflammation, regulate peripheral and central sensitization, and normalize abnormal brain activity, thereby preventing pain signal transmission. To summarize the effects and neural mechanisms of acupuncture in migraine, we performed a systematic review of literature about migraine and acupuncture. We summarized the characteristics of current clinical studies, including the types of participants, study designs, and clinical outcomes. The published findings from basic neuroimaging studies support the hypothesis that acupuncture alters abnormal neuroplasticity and brain activity. The benefits of acupuncture require further investigation through basic and clinical studies.

Effect of Electroacupuncture at Fengchi on Facial Allodynia, Microglial Activation, and Microglia-Neuron Interaction in a Rat Model of Migraine

The purpose of the work was to investigate whether electroacupuncture (EA) could ameliorate migraine central sensitization by modulating microglial activation and the subsequent release of inflammatory cytokines in the trigeminal nucleus caudalis (TNC) in a rat model. Establishment of a rat model of recurrent migraine was achieved through repeated dural electrical stimulation (DES). After nine sessions of acupuncture treatment at Fengchi (GB20), facial mechanical thresholds were measured by electronic von Frey measurements. Microglial activation and cytokine receptors of TNC were evaluated by immunofluorescence staining. The expression of microglial biological marker Ibal-1, proinflammatory cytokines, and cytokine receptors in the TNC were evaluated by Western blot and/or real-time polymerase chain reaction. In addition, the effects of inhibition of microglial activation on facial thresholds and neuronal activation (i.e., expression of c-Fos in the TNC) induced by DES were observed. After consecutive EA-GB20 treatments, the facial withdrawal threshold was significantly higher than in the model group at different time points (p < 0.05). The hyperreactivity of microglia induced by DES was significantly inhibited, and the expressions of Ibal-1, interleukin-1β, tumor necrosis factor-α, and their receptors in the TNC were also significantly decreased (p < 0.05). Inhibition of microglia by minocycline demonstrated an acupuncture-like role, which was manifested by ameliorated mechanical hyperalgesia and decreased neuronal expression of c-Fos, Iba-1, and inflammatory factors. EA at GB20 could ameliorate migraine facial allodynia by inhibiting microglial activation and the subsequent release of inflammatory cytokines and their receptors in the TNC.

Increasing Efficiency of Repetitive Electroacupuncture on Purine- and Acid-Induced Pain During a Three-Week Treatment Schedule

Acupuncture (AP) is an important constituent of the therapeutic repertoire of traditional Chinese medicine and has been widely used to alleviate chronic painful conditions all over the world. We studied in rats the efficiency of electroacupuncture (EAP) applied to the Zusanli acupoint (ST36) as an analgesic treatment over a 3-week period of time on purine (α,β-methylene ATP, dibenzoyl-ATP)- and acid (pH 6.0 medium)-induced pain in the rat paw. The two ATP derivatives stimulated P2X3 and P2X7 receptors, respectively, while the slightly acidic medium stimulated the “acid-sensitive ion channel 3” (ASIC3). It was found that the P2X7 receptor and ASIC-mediated pain was counteracted by EAP with greater efficiency at the end than at the beginning of the treatment schedule, while the P2X3 receptor–mediated pain was not. Our findings have important clinical and theoretical consequences, among others, because they are difficult to reconcile with the assumption that AP is primarily due to the release of peripheral and central opioid peptides causing the well-known tolerance to their effects. In consequence, AP is a convenient therapeutic instrument to treat subacute and chronic pain.

ST36 Acupuncture Alleviates the Inflammation of Adjuvant-Induced Arthritic Rats by Targeting Monocyte/Macrophage Modulation

Background

Rheumatoid arthritis (RA) is a chronic systemic chronic autoimmune disease characterized by the aggregation of immune cells and secretion of cytokines in the joint synovium, causing hyperblastosis and even bone destruction. Acupuncture has been proven effective in RA treatment. This study aimed to investigate the anti-inflammatory action of acupuncture, specifically, in relation to immune cell interactions and key mediators.

Methods

Rats with adjuvant-induced arthritics (AIA) were treated with manual acupuncture (MA) at Zusanli (ST36). Joint edema and paw withdrawal latency were monitored to observe the effects on inflammation. The levels of 24 cytokines, chemokines, and growth factors in ankle joints during the treatment (on days 1, 7, 15, and 21) were detected by multiplex immunoassay. A bioinformatics analysis based on a directed weighted mathematical model was used to construct cell communication network diagrams and identify the key cells through calculation. The monocyte/macrophage polarization in inflamed joints was investigated by detecting M1- and M2-phenotypic populations and their related cytokines.

Results

ST36 MA alleviated paw edema and upregulated the nociceptive threshold of AIA rats. Several innate and adaptive immune cytokines were dynamically regulated by MA, and MA-treated rats showed a significant improvement in symptoms compared with AIA rats by day 21. The immune cell-cell communication networks were intensified with the development of RA but were significantly reduced after treatment with MA. MA was found to specifically regulate monocytes/macrophages in inflamed ankle joints ST36 MA also inhibited M1-phenotype macrophages accompanied by decreased levels of IL-1β.

Conclusions

ST36 MA showed anti-inflammatory and analgesic effects as well as inhibition of immune cell communication networks in inflamed joints of AIA rats. Inhibiting the polarization of macrophages to the M1-phenotype in inflamed joints may be one of the key mechanisms of MA anti-inflammatory action. This research highlighted a systematic research paradigm for investigating mechanisms of acupuncture action.

The Role of Neuroglial Crosstalk and Synaptic Plasticity-Mediated Central Sensitization in Acupuncture Analgesia

Although pain is regarded as a global public health priority, analgesic therapy remains a significant challenge. Pain is a hypersensitivity state caused by peripheral and central sensitization, with the latter considered the culprit for chronic pain. This study summarizes the pathogenesis of central sensitization from the perspective of neuroglial crosstalk and synaptic plasticity and underlines the related analgesic mechanisms of acupuncture. Central sensitization is modulated by the neurotransmitters and neuropeptides involved in the ascending excitatory pathway and the descending pain modulatory system. Acupuncture analgesia is associated with downregulating glutamate in the ascending excitatory pathway and upregulating opioids, 𝛾-aminobutyric acid, norepinephrine, and 5-hydroxytryptamine in the descending pain modulatory system. Furthermore, it is increasingly appreciated that neurotransmitters, cytokines, and chemokines are implicated in neuroglial crosstalk and associated plasticity, thus contributing to central sensitization. Acupuncture produces its analgesic action by inhibiting cytokines, such as interleukin-1β, interleukin-6, and tumor necrosis factor-α, and upregulating interleukin-10, as well as modulating chemokines and their receptors such as CX3CL1/CX3CR1, CXCL12/CXCR4, CCL2/CCR2, and CXCL1/CXCR2. These factors are regulated by acupuncture through the activation of multiple signaling pathways, including mitogen-activated protein kinase signaling (e.g., the p38, extracellular signal-regulated kinases, and c-Jun-N-terminal kinase pathways), which contribute to the activation of nociceptive neurons. However, the responses of chemokines to acupuncture vary among the types of pain models, acupuncture methods, and stimulation parameters. Thus, the exact mechanisms require future clarification. Taken together, inhibition of central sensitization modulated by neuroglial plasticity is central in acupuncture analgesia, providing a novel insight for the clinical application of acupuncture analgesia.

A Comprehensive Review of Alternative Therapies for the Management of Chronic Pain Patients: Acupuncture, Tai Chi, Osteopathic Manipulative Medicine, and Chiropractic Care

INTRODUCTION

Non-pharmacologic alternative therapies for pain have been around for a long time, some for hundreds of years. They have been used throughout history to treat many issues.

RECENT FINDINGS

Currently, alternative medicine is most frequently used to treat musculoskeletal pain, and between 59 and 90% of patients utilizing alternative therapies for chronic pain claimed they were helpful and can serve as an effective adjunctive for the treatment of chronic pain. Some examples of alternative therapies that will be discussed in this review include acupuncture, tai chi, osteopathic manipulation, and chiropractic care. Acupuncture, traditionally a Chinese practice, is becoming more popular across the world to attempt to relieve pain. It involves the placement of thin needles at various points in the body. The efficacy of acupuncture for pain is heavily debated. More research and discussion are necessary to determine the exact role it plays in the treatment of chronic pain. Tai chi is also a traditional Chinese practice that is often used as a form of meditation and for potential health benefits. Tai chi involves a series of complex movements such as squatting combined with deep breathing to achieve relaxation and pain reduction. Osteopathic manipulative treatment (OMT) is a technique used by both osteopathic physicians (DO) as well as other health professionals to manage a wide range of conditions in any given patient. The technique involves utilization and manipulation of the musculoskeletal system to achieve potential health benefits. OMT has been used as therapy for many issues but is commonly used for pain conditions. Alternative therapies may serve as an effective adjunctive treatment modality for the management of chronic pain conditions. There has been a tremendous amount of research dictating the effectiveness of alternative therapies for chronic pain management. The purpose of this review is to provide a comprehensive evidence-based update of alternative therapy used for the management of chronic pain conditions.

Acupuncture for Pain Management: Molecular Mechanisms of Action

Acupuncture reduces pain by activating specific areas called acupoints on the patient’s body. When these acupoints are fully activated, sensations of soreness, numbness, fullness, or heaviness called De qi or Te qi are felt by clinicians and patients. There are two kinds of acupuncture, manual acupuncture and electroacupuncture (EA). Compared with non-acupoints, acupoints are easily activated on the basis of their special composition of blood vessels, mast cells, and nerve fibers that mediate the acupuncture signals. In the spinal cord, EA can inhibit glial cell activation by down-regulating the chemokine CX3CL1 and increasing the anti-inflammatory cytokine interleukin-10. This inhibits P38 mitogen-activated protein kinase and extracellular signal-regulated kinase pathways, which are associated with microglial activation of the C-Jun N-terminal kinase signaling pathway and subsequent astrocyte activation. The inactivation of spinal microglia and astrocytes mediates the immediate and long-term analgesic effects of EA, respectively. A variety of pain-related substances released by glial cells such as the proinflammatory cytokines tumor necrosis factor [Formula: see text], interleukin-1[Formula: see text], interleukin-6, and prostaglandins such as prostaglandins E2 can also be reduced. The descending pain modulation system in the brain, including the anterior cingulated cortex, the periaqueductal gray, and the rostral ventromedial medulla, plays an important role in EA analgesia. Multiple transmitters and modulators, including endogenous opioids, cholecystokinin octapeptide, 5-hydroxytryptamine, glutamate, noradrenalin, dopamine, [Formula: see text]-aminobutyric acid, acetylcholine, and orexin A, are involved in acupuncture analgesia. Finally, the “Acupuncture [Formula: see text]” strategy is introduced to help clinicians achieve better analgesic effects, and a newly reported acupuncture method called acupoint catgut embedding, which injects sutures made of absorbable materials at acupoints to achieve long-term effects, is discussed.

Effect of Electroacupuncture on Hyperalgesia and Vasoactive Neurotransmitters in a Rat Model of Conscious Recurrent Migraine

Migraine onset is associated with the abnormal release of vasoactive neurotransmitters from perivascular nerves, and these neurotransmitters are involved in the pathophysiology of migraine. Hyperalgesia is a key feature of migraine, and accumulating evidence indicates that electroacupuncture (EA) at the single acupuncture point (Fengchi [GB20]) is effective in ameliorating hyperalgesia. In clinical practice, multiple acupuncture points are widely used, especially GB20 and Yanglingquan (GB34). However, the role played by vasoactive neurotransmitters in acupuncture antihyperalgesic effect at the single or multiple acupuncture points remains unknown. We aimed to determine whether EA would exert its antihyperalgesic effects by modulating vasoactive neurotransmitter release from the perivascular nerves. Furthermore, we examined whether targeting multiple acupuncture points would be more effective than targeting a single point in reducing hyperalgesia. The mechanical and thermal hyperalgesia were evaluated by measuring the facial and hind-paw mechanical withdrawal thresholds, tail-flick and hot-plate latencies. Plasma concentrations of vasoactive neurotransmitters were determined using rat-specific ELISA kits from jugular vein, including calcitonin gene-related peptide (CGRP), substance P (SP), vasoactive intestinal peptide (VIP), neuropeptide Y (NPY), pituitary adenylate cyclase-activating polypeptide (PACAP), nitric oxide (NO), and endothelin-1 (ET-1). The result suggested that EA significantly ameliorated the mechanical and thermal hyperalgesia, reduced c-Fos levels in the trigeminal ganglion, and attenuated plasma and dural levels of vasoactive neurotransmitters, especially in the multiple acupuncture points group (GB20+GB34). In conclusion, EA exerts antihyperalgesic effect in a rat model of conscious recurrent migraine, possibly via modulation of the vasoactive neurotransmitters. Furthermore, targeting multiple acupuncture points is more effective than targeting a single point in reducing hyperalgesia.