Analgesic effect of electroacupuncture on paclitaxel-induced neuropathic pain via spinal opioidergic and adrenergic mechanisms in mice

Electroacupuncture alleviates paclitaxel-induced peripheral neuropathy by reducing CCL2-mediated macrophage infiltration in sensory ganglia and sciatic nerve

BACKGROUND

Paclitaxel-induced peripheral neuropathy (PIPN) is prevalent among patients receiving paclitaxel chemotherapy, which results in sensory abnormality as well as neuropathic pain. Conventional medications lack effectiveness on PIPN. Clinical trials identified beneficial effects of acupuncture on PIPN among patients receiving chemotherapy. Here we explored the mechanisms underlying how acupuncture might alleviate PIPN.

METHODS

A mouse model of PIPN was established by repeated paclitaxel application. Electroacupuncture (EA) was applied at ST36 and BL60 acupoints of model mice. Immunostaining, flow cytometry, behavioral assay, in vivo imaging were utilized for effects determination and mechanism exploration.

RESULTS

EA ameliorated mechanical and cold pain hypersensitivities, reduced sensory neuron damage and improved loss in intra-epidermal nerve fibers (IENFs) in model mice. Macrophages infiltration were detected in DRG and sciatic nerve of model mice, which was reduced by EA. EA affected M1-like pro-inflammatory macrophage infiltration in DRG, whereas it did not affect M2-like macrophages. DRG neurons released chemoattractant CCL2 that recruited macrophages via CCR2 to DRG. EA reduced CCL2 overproduction by DRG neurons and reduced macrophage infiltration. Blocking CCR2 mimicked EA's anti-allodynic effect, whereas exogenously applying recombinant CCL2 reversed the ameliorative effect of EA on macrophage infiltration and abolished EA's anti-allodynia on model mice. EA ameliorated other signs of PIPN, including sensory neuron damage, sciatic nerve morphology impairment and IENFs loss. In mice inoculated with breast cancer cells, EA didn't affect paclitaxel-induced antitumor effect.

CONCLUSIONS

These findings suggest EA alleviates PIPN by reducing CCL2/CCR2 mediated-pro-inflammatory macrophage infiltration into sensory ganglia as well as the sciatic nerve. Our study supports EA could be used as a potential non-pharmacological therapy for PIPN.

Electroacupuncture Relieves Neuropathic Pain via Adenosine 3 Receptor Activation in the Spinal Cord Dorsal Horn of Mice

Neuropathic pain (NPP) is a devastating and unbearable painful condition. As prevailing treatment strategies have failed to mitigate its complications, there remains a demand for effective therapies. Electroacupuncture (EA) has proved a potent remedial strategy in NPP management in humans and mammals. However, past studies have investigated the underlying mechanism of the analgesic effects of EA on NPP, focusing primarily on adenosine receptors in peripheral tissues. Herein, we elucidate the role of the adenosine (Adora-3) signaling pathway in mediating pain relief through EA in the central nervous system, which is obscure in the literature and needs exploration. Specific pathogen-free (SPF) male adult mice (C57BL/6 J) were utilized to investigate the effect of EA on adenosine metabolism (CD73, ADA) and its receptor activation (Adora-3), as potential mechanisms to mitigate NPP in the central nervous system. NPP was induced via spared nerve injury (SNI). EA treatment was administered seven times post-SNI surgery, and lumber (L4-L6) spinal cord was collected to determine the molecular expression of mRNA and protein levels. In the spinal cord of mice, following EA application, the expression results revealed that EA upregulated (p < 0.05) Adora-3 and CD73 by inhibiting ADA expression. In addition, EA triggered the release of adenosine (ADO), which modulated the nociceptive responses and enhanced neuronal activation. Meanwhile, the interplay between ADO levels and EA-induced antinociception, using an Adora-3 agonist and antagonist, showed that the Adora-3 agonist IB-MECA significantly increased (p < 0.05) nociceptive thresholds and expression levels. In contrast, the antagonist MRS1523 exacerbated neuropathic pain. Furthermore, an upregulated effect of EA on Adora-3 expression was inferred when the Adora-3 antagonist was administered, and the EA treatment increased the fluorescent intensity of Adora-3 in the spinal cord. Taken together, EA effectively modulates NPP by regulating the Adora-3 signaling pathway under induced pain conditions. These findings enhance our understanding of NPP management and offer potential avenues for innovative therapeutic interventions.

Unlocking the potential: How acupuncture reshapes the liver-centered lipid metabolism pattern to fight obesity

Obesity, a widespread global health issue, is frequently linked to disrupted lipid metabolism, resulting in excessive accumulation of adipose tissue and associated health complications. Acupuncture, a traditional Chinese medical modality, has exhibited potential as a viable intervention for addressing obesity. The underlying mechanism proposed involves the stimulation of specific acupoints to exert a regulatory influence on hepatic function. The liver has a central role in lipid metabolism, including processes such as lipid synthesis, storage and distribution. Acupuncture is believed to enhance the liver's efficiency in processing lipids, thereby reducing lipid accumulation and improving metabolic functions. Research indicates that acupuncture can influence the expression of certain genes and proteins involved in lipid metabolism in the liver. This includes upregulating genes that promote lipid breakdown and oxidation, and downregulating those involved in lipid synthesis. Additionally, acupuncture has been shown to improve insulin sensitivity, which is crucial for the regulation of lipid metabolism. Furthermore, the potential anti-inflammatory effects of acupuncture may play a significant role in its efficacy for the treatment of obesity. The presence of chronic inflammation has been strongly associated with metabolic disorders such as obesity. Through its ability to mitigate inflammation, acupuncture can potentially aid in the restoration of lipid metabolism and the reduction of body weight. Moreover, the amelioration of hepatic oxidative stress represents another mechanism by which acupuncture may contribute to the reduction of lipid deposition. Notably, the liver, being the primary site of lipid metabolism, maintains communication with various organs including the brain, adipose tissue, skeletal muscle and intestines. This perspective opens new avenues for the treatment of obesity, emphasizing the importance of holistic approaches in managing complex metabolic disorders. Please cite this article as: Yang SR, Chen L, Luo D, Wang YY, Liang FX. Unlocking the potential: How acupuncture reshapes the liver-centered lipid metabolism pattern to fight obesity. J Integr Med. 2024; 22(5): 523-532.

The cumulative analgesic effect of repeated electroacupuncture is modulated by Adora3 in the SCDH of mice with neuropathic pain

BACKGROUND

Existing remedial approaches for relieving neuropathic pain (NPP) are challenging and open the way for alternative therapeutic measures such as electroacupuncture (EA). The mechanism underlying the antinociceptive effects of repeated EA sessions, particularly concerning the regulation of the Adora3 receptor and its associated enzymes, has remained elusive.

METHODS

This study used a mouse model of spared nerve injury (SNI) to explore the cumulative analgesic effects of repeated EA at ST36 (Zusanli) and its impact on Adora3 regulation in the spinal cord dorsal horn (SCDH). Forty-eight male mice underwent SNI surgery for induction of neuropathic pain and were randomly assigned to the SNI, SNI + 2EA, SNI + 4EA, and SNI + 7EA groups. Spinal cord (L4-L6) was sampled for immunofluorescence, adenosine (ADO) detection and for molecular investigations following repeated EA treatment.

RESULTS

Following spared nerve injury (SNI), there was a significant decrease in mechanical withdrawal thresholds (PWTs) and thermal nociceptive withdrawal latency (TWL) in the ipsilateral hind paw on the third day post-surgery, while the contralateral hind paw PWTs showed no significant changes. On subsequent EA treatments, the SNI + EA groups led to a significant increase in pain thresholds (p < 0.05). Repeated EA sessions in SNI mice upregulated Adenosine A3 (Adora3) and cluster of differentiation-73 (CD73) expression while downregulating adenosine deaminase (ADA) and enhancing neuronal instigation in the SCDH. Colocalization analysis of Neun-treated cells revealed increased Adora3 expression, particularly in the SNI + 7EA group.

CONCLUSIONS

In conclusion, cumulative electroacupuncture treatment reduced neuropathic pain by regulating Adora3 and CD73 expression, inhibiting ADA and most likely increasing neuronal activation in the SCDH. This study offers a promising therapeutic option for managing neuropathic pain, paving the way for further research.

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.

Global research trends of acupuncture therapy on cancer pain: A bibliometric and visualized study

Background

The number of publications on acupuncture for cancer pain is increasing rapidly with an upward tendency. Considering that no bibliometric articles related to this topic have been published yet. It is necessary to evaluate the global scientific output of research in this field, and shed light on the direction of clinical cancer pain management in the future.

Methods

Research publications regarding acupuncture on cancer pain from inception to 2022 were downloaded from the Web of Science Core Collection. Bibliometric analyses were performed using CiteSpace software, the bibliometrix R package, and VOSviewer software. Network maps were generated to assess the collaborations between different countries, institutions, authors, and keywords. And clusters map was generated to evaluate reference.

Results

A total of 790 articles related to acupuncture therapy for cancer pain were identified. We observe that the number of publications is gradually increasing over time. China and the United States were the main contributors. Mem Sloan Kettering Canc Ctr (38 papers) and Beijing Univ Chinese Med (28 papers) contributed the most publications, becoming the leading contributors in this field. Although J Clin Oncol (28 articles) ranked ninth in terms of publication volume, it was the journal with the most citations and the highest number of IF (50.717) and H-index (494) at the same time. MAO J from Mem Sloan Kettering Canc Ctr was the most prolific author (23 articles). The main hot topics included matters related to acupuncture (239 times), pain (199 times), management (139 times), quality of life (107 times), electroacupuncture (100 times), and breast cancer (82 times).

Conclusion

Our bibliometric analysis provides a comprehensive overview of the development of acupuncture for cancer pain, enabling relevant authors and research teams to identify the current research status in this field. At the same time, acupuncture for breast cancer (BC) pain, aromatase inhibitor-induced arthralgia (AIA), and chemotherapy-induced peripheral neuropathy (CIPN) may soon become prospective focus.

The effectiveness and safety of acupuncture for chemotherapy-induced peripheral neuropathy: A systematic review and meta-analysis

Objectives

This systematic review and meta-analysis aimed to evaluate the effectiveness and safety of acupuncture on chemotherapy-induced peripheral neuropathy (CIPN).

Methods

We searched for relevant randomized controlled trials (RCTs) in PubMed, Cochrane Library, and Embase databases from their inception to 1 April 2022. The Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity (FACT/GOG-Ntx), Brief Pain Inventory-Short Form (BPI-SF), the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire-Core30 (EORTC QLQ-C30), Numerical Rating Scale (NRS), and adverse events were the outcome measures. All studies had at least one of these outcome measures. Mean differences (MDs) with 95% confidence intervals (CIs) were assessed in the meta-analysis using the RevMan 5.3 software.

Results

Five studies were included in the analysis. The results showed that acupuncture and placebo acupuncture were not significantly different in reducing chemotherapy-induced neurotoxicity and functional disability (random-effects estimates; MD: 4.30; 95% CI: −0.85~9.45; P = 0.10; I² = 74%). Acupuncture was better than placebo acupuncture in reducing pain severity and pain interference with patients' daily function (fixed-effect estimates; MD: −1.14; 95% CI: 1.87 to −0.42; P = 0.002; I² = 13%). Acupuncture was not significantly different from placebo acupuncture in relieving CIPN symptoms (MD: −0.81; 95% CI: −2.02 to 0.40, P = 0.19). Acupuncture improved quality of life better than placebo acupuncture (MD: 10.10; 95% CI: 12.34 to 17.86, P = 0.01). No severe adverse events were recorded in all five studies.

Conclusion

This meta-analysis suggests that acupuncture may be more effective and safer in reducing pain severity and pain interference with patients' daily function than placebo acupuncture. Additionally, acupuncture may improve the quality of life of patients with CIPN. However, large sample size studies are needed to confirm this conclusion.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=324930, identifier: CRD42022324930.

Mechanisms underlying paclitaxel-induced neuropathic pain: Channels, inflammation and immune regulations

Paclitaxel is a chemotherapeutic agent widely used for many types of malignancies. However, when paclitaxel is used to treat tumors, patients commonly experience severe neuropathic pain that is difficult to manage. The mechanism underlying paclitaxel-induced neuropathic pain remains unclear. Evidence demonstrates correlations between mechanisms of paclitaxel-mediated pain and associated actions of ion channels, neuroinflammation, mitochondrial damage, and other factors. This review provides a comprehensive analysis of paclitaxel-induced neuropathic pain mechanisms and suggestions for effective interventions.

Bibliometric and visualized analysis of electroacupuncture in the past 10 years

BACKGROUND

There are many studies that have interrogated the evolution and use of electroacupuncture (EA). We aimed to evaluate the research status, cooperation and development of EA in the past 10 years.

METHODS

We obtained data on the EA from the Web of Science core collection database. CiteSpace 5.7. R1 software was used to assess research cooperation through analysis of authors, institutions and countries. In addition, keyword cluster analysis, references and burst detection were analyzed to explore research hotspots and trends in the field of EA.

RESULTS

We included a total of 3019 citing literature and 78,235 cited literature for analysis. The data showed that there has been a rise in the global number of EA studies in the past decade. Besides, the data demonstrated that China has made outstanding contribution in the development of EA. Whereas there is inter-agency cooperation in China, there is less cooperation with other countries. In addition, we showed frequent use of keywords such as "expression", "stimulation", or "pain". Besides, neuroscience was the main research area, followed by general medicine and oncology. Furthermore, with the improved research methods and technologies, there is enhanced overall quality of the studies.

CONCLUSION

Taken together, our findings demonstrate a steady increase in the studies involving EA. However, the studies are unevenly distributed among countries and thus there is need for closer international cooperation.

Inhibition of Spinal TRPV1 Reduces NMDA Receptor 2B Phosphorylation and Produces Anti-Nociceptive Effects in Mice with Inflammatory Pain

Transient receptor potential vanilloid 1 (TRPV1) has been implicated in peripheral inflammation and is a mediator of the inflammatory response to various noxious stimuli. However, the interaction between TRPV1 and N-methyl-D-aspartate (NMDA) receptors in the regulation of inflammatory pain remains poorly understood. This study aimed to investigate the analgesic effects of intrathecal administration of capsazepine, a TRPV1 antagonist, on carrageenan-induced inflammatory pain in mice and to identify its interactions with NMDA receptors. Inflammatory pain was induced by intraplantar injection of 2% carrageenan in male ICR mice. To investigate the analgesic effects of capsazepine, pain-related behaviors were evaluated using von Frey filaments and a thermal stimulator placed on the hind paw. TRPV1 expression and NMDA receptor phosphorylation in the spinal cord and glutamate concentration in the spinal cord and serum were measured. Intrathecal treatment with capsazepine significantly attenuated carrageenan-induced mechanical allodynia and thermal hyperalgesia. Moreover, carrageenan-enhanced glutamate and phosphorylation of NMDA receptor subunit 2B in the spinal cord were suppressed by capsazepine administration. These results indicate that TRPV1 and NMDA receptors in the spinal cord are associated with inflammatory pain transmission, and inhibition of TRPV1 may reduce inflammatory pain via NMDA receptors.

Acupuncture Relieved Chemotherapy-Induced Peripheral Neuropathy in Patients with Breast Cancer: A Pilot Randomized Sham-Controlled Trial

Chemotherapy-induced peripheral neuropathy (CIPN) is a disabling side effect caused by neurotoxic chemotherapy. This randomized controlled trial aimed to evaluate the effect of manual acupuncture on CIPN. Twenty eligible breast cancer patients receiving taxane chemotherapy treatment were recruited and randomly divided into verum acupuncture and sham acupuncture groups. Each group received 15 treatments over 9 weeks. Quantitative tactile detection thresholds were measured using Semmes–Weinstein monofilament testing (SWM). The World Health Organization Quality of Life scale (WHOQOL-BREF), the Functional Assessment of Cancer Therapy/Gynecologic Oncology Group-Neurotoxicity (FACT/GOG-Ntx), and the Brief Pain Inventory-Short Form (BPI-SF) were measured before and after treatment. The between-group comparison of SWM revealed that the verum acupuncture group had more improvement of touch perception thresholds compared to the sham acupuncture group. The average pain severity in the BPI-SF of the verum acupuncture group was significantly lower than that of the sham acupuncture group. There were no significant differences in the FACT/GOG-Ntx trial outcome index and WHOQOL-BREF scores between the acupuncture and sham groups. The results suggest that acupuncture can alleviate the neuropathic pain of CIPN and improve touch perception thresholds.

Acupuncture for Paclitaxel-Induced Peripheral Neuropathy: A Review of Clinical and Basic Studies

Paclitaxel-induced peripheral neuropathy (PIPN) is a common and intractable side effect of the conventional chemotherapeutic agent paclitaxel. Acupuncture has been reported as an effective alternative therapy in treatment of PIPN in both basic studies and clinical trials. However, there is a lack of comprehensive surveys to summarize the action of acupuncture in management of PIPN. In this review, we briefly demonstrate the basic pathology of PIPN, which includes the activation of ion channels, mitochondrial dysfunction, disruption of axonal transport and also neuro-inflammatory involvement. Meanwhile, we review both the clinical and basic studies as an emphasis to give a general overview of the therapeutic effect of acupuncture against PIPN. Finally, we summarize the current known mechanisms underlying the action of acupuncture against PIPN mainly at peripheral and spinal levels, which include various neurotransmitters, multiple receptors, different types of enzymes and molecules. In conclusion, acupuncture could be considered as a potential alternative therapy in treatment of PIPN, and further clinical and experimental studies are called for in the future.

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.

Compounds of traditional Chinese medicine and neuropathic pain

Neuropathic pain (NP) has become a serious global health issue and a huge clinical challenge without available effective treatment. P2 receptors family is involved in pain transmission and represents a promising target for pharmacological intervention. Traditional Chinese medicine (TCM) contains multiple components which are effective in targeting different pathological mechanisms involved in NP. Different from traditional analgesics, which target a single pathway, TCMs take the advantage of multiple components and multiple targets, and can significantly improve the efficacy of treatment and contribute to the prediction of the risks of NP. Compounds of TCM acting at nucleotide P2 receptors in neurons and glial cells could be considered as a potential research direction for moderating neuropathic pain. This review summarized the recently published data and highlighted several TCMs that relieved NP by acting at P2 receptors.

Electroacupuncture Treatment Attenuates Paclitaxel-Induced Neuropathic Pain in Rats via Inhibiting Spinal Glia and the TLR4/NF-κB Pathway

Background and Purpose

Neuropathic pain is a major side-effect of paclitaxel (PTX) chemotherapy. Although the precise mechanisms responsible for this pain are unclear, the activation of neuroglia and upregulation of the TLR4/NF-κB pathway are known to be involved. In this study, we determined whether electroacupuncture (EA) could limit mechanical hypersensitivity resulting from the chemotherapeutic drug PTX in rats, and investigated the potential mechanisms involved.

Methods

Rats intraperitoneally received a cumulative dose of 8 mg/kg PTX (2 mg/kg per day) or vehicle control on alternate days (day 0, 2, 4 and 6). EA treatment (10 Hz, 1 mA) was applied at bilateral ST36 acupoints in rats once every other day on days 0–14. For sham EA, needles were inserted at ST36 acupoints without electrical stimulation. Mechanical allodynia was measured by mechanical withdrawal latency (MWL) of paws to a mechanical stimulus every 2 days. Protein expression of TLR4 and NF-κB p65, as well as TMEM119 and GFAP (indicators of microglia and astrocytes, respectively) in spinal cord was quantified by Western blot analysis. Levels of inflammatory cytokines IL-1β and TNF-α in spinal cord and serum were detected by ELISA.

Results

Mechanical allodynia induced by PTX in both paws (right and left) of rats was significantly attenuated by EA but not sham EA treatment. In addition, EA, but not sham EA, inhibited the activation of both microglia (TMEM119) and astrocytes (GFAP) in lumbar spinal cord. Moreover, Western blot analysis revealed that protein expression of TLR4 and NF-κB in spinal cord was suppressed by EA but not sham EA treatment. PTX significantly increased inflammatory cytokines in spinal cord and serum, which were ameliorated by EA treatment but not by sham EA.

Conclusion

These results indicate that EA treatment attenuates PTX-induced mechanical allodynia. The putative mechanism corroborating this finding could be related to the suppression of activated microglia and astrocytes in spinal cord, as well as the inhibition of the activated TLR4/NF-κB signaling pathway by EA treatment.

Molecular mechanism of electroacupuncture treatment on oxaliplatin-induced peripheral neurotoxicity in rats

Oxaliplatin (L-OHP) has been widely used in the treatment of various tumors, especially in colorectal cancer. The mechanism of peripheral neurotoxicity induced by L-OHP (OIPN) is unclear and current therapeutic options only serve to alleviate the symptoms rather than prevent OIPN. To observe the effects of electroacupuncture (EA) stimulation on OIPN in rats, rats were randomly divided into the control group, OIPN model group, and OIPN + EA group. To establish OIPN rat models, a single intraperitoneal injection with 10 mg/kg L-OHP in the OIPN model rats. Rats in the control group received a single intraperitoneal injection with 0.9% lactose. From the third day after establishing OIPN models, the rats were treated with EA. Cold allodynia and heat sensitivity were assessed using the acetone drop and the Hargreaves method, respectively. Pathological changes in nerves were detected using hematoxylin and eosin (H&E) staining and transmission electron microscopy. Related mRNA and protein expression levels were measured by real-time polymerase chain reaction (PCR) and western blotting from 14 days after establishing OIPN models. Our results showed that L-OHP significantly increased the sensitivity to cold allodynia and nervous injury, which were ameliorated after EA treatment. The expression of glucocorticoid receptor alpha (GR-α) and B-cell lymphoma 2 (Bcl-2) was significantly decreased and that of Bax was significantly increased in sciatic nerve of OIPN model rats compared with control rats. However, EA treatment significantly inhibited L-OHP-induced protein expressions in rats. Moreover, compared with the control rats, the nucleus NF-κBp65 levels were significantly increased, while the cytoplasm NF-κBp65 levels were significantly decreased, which were reversed by EA treatment. In conclusion, EA treatment may reduce peripheral neurotoxicity induced by L-OHP through regulating related protein expression.

The Involvement of Descending Pain Inhibitory System in Electroacupuncture-Induced Analgesia

Chronic pain is a major health problem, which can impair quality of life and reduce productivity. Electroacupuncture (EA), a modality of medicine based on the theories of Traditional Chinese Medicine (TCM), presents great therapeutic effects on chronic pain. Its clinical application has gained increasing popularity, and in parallel, more research has been performed on the mechanisms of EA-induced analgesia. The past decades have seen enormous advances both in neuronal circuitry of needle-insertion and in its molecular mechanism. EA may block pain by activating the descending pain inhibitory system, which originates in the brainstem and terminates at the spinal cord. This review article synthesizes corresponding studies to elucidate how EA alleviate pain via the mediation of this descending system. Much emphasis has been put on the implication of descending serotonergic and noradrenergic pathways in the process of pain modulation. Also, other important transmitters and supraspinal regions related to analgesic effects of EA have been demonstrated. Finally, it should be noticed that there exist some shortcomings involved in the animal experimental designed for EA, which account for conflicting results obtained by different studies.

Acupuncture-Analgesia-Mediated Alleviation of Central Sensitization

Pain can trigger central amplification called central sensitization, which ultimately results in hyperalgesia and/or allodynia. Many reports have showed acupuncture has an analgesic effect. We searched the related article on PubMed database and Cochrane database to discover central sensitization pathway in acupuncture analgesia. We summarized that acupuncture enhances the descending inhibitory effect and modulates the feeling of pain, thus modifying central sensitization. The possible mechanisms underlying the analgesic effects of acupuncture include segmental inhibition and the activation of the endogenous opioid, adrenergic, 5-hydroxytryptamine, and N-methyl-D-aspartic acid, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid/kainate pathways. Moreover, acupuncture can locally reduce the levels of inflammatory mediators. In clinical settings, acupuncture can be used to treat headache, neuropathic pain, low back pain, osteoarthritis, and irritable bowel syndrome. These mechanisms of acupuncture analgesia may be involved in the alleviation of central sensitization.

Neonatal Maternal Deprivation Followed by Adult Stress Enhances Adrenergic Signaling to Advance Visceral Hypersensitivity

The pathophysiology of visceral pain in patients with irritable bowel syndrome remains largely unknown. Our previous study showed that neonatal maternal deprivation (NMD) does not induce visceral hypersensitivity at the age of 6 weeks in rats. The aim of this study was to determine whether NMD followed by adult stress at the age of 6 weeks induces visceral pain in rats and to investigate the roles of adrenergic signaling in visceral pain. Here we showed that NMD rats exhibited visceral hypersensitivity 6 h and 24 h after the termination of adult multiple stressors (AMSs). The plasma level of norepinephrine was significantly increased in NMD rats after AMSs. Whole-cell patch-clamp recording showed that the excitability of dorsal root ganglion (DRG) neurons from NMD rats with AMSs was remarkably increased. The expression of β₂ adrenergic receptors at the protein and mRNA levels was markedly higher in NMD rats with AMSs than in rats with NMD alone. Inhibition of β₂ adrenergic receptors with propranolol or butoxamine enhanced the colorectal distention threshold and application of butoxamine also reversed the enhanced hypersensitivity of DRG neurons. Overall, our data demonstrate that AMS induces visceral hypersensitivity in NMD rats, in part due to enhanced NE-β₂ adrenergic signaling in DRGs.

The evaluation of changes in peripheral neuropathy and quality-of-life using low-frequency electrostimulation in patients treated with chemotherapy for breast cancer: a study protocol

BACKGROUND

Chemotherapy-induced peripheral neuropathy (CIPN) is a progressive, enduring, and sometimes irreversible neurotoxic symptom that occurs in 30-40% of chemotherapy-treated cancer patients. CIPN negatively affects both the patient's abilities to perform daily activities and their health-related quality of life (HRQOL) after chemotherapy treatment. Although this neuropathy has been treated with duloxetine and/or gabapentin, limited therapeutic benefits have been reported, thereby necessitating the development of an integrated approach that combines pharmacological management and complementary methods such as acupuncture and electric nerve stimulation. Therefore, this study is designed to examine the effect of a portable, low-frequency electrostimulation (ES) device on CIPN symptoms and HRQOL of female patients diagnosed with CIPN immediately after chemotherapy for breast cancer.

METHODS

This study is a single-center, randomized, placebo-controlled trial with two parallel groups and a 2-week follow-up. We will enroll 80 breast cancer patients who are newly diagnosed with CIPN after chemotherapy. Duloxetine or pregabalin will be prescribed to all participants from the initial assessment. Half of the patients will be assigned into the experimental group and the other half to the control group. The CarebandR (Piomed Inc., Seoul, Korea), a wearable wristband that generates low-frequency electrostimulation, will be administered only to the experimental group. Electrostimulation will be administered on the unilateral PC6 acupoint. A numerical rating scale will be used to assess the overall intensity of CIPN symptoms. The key secondary outcome variables include patient-reported CIPN symptom distress tested by a self-rated questionnaire, physician-rated symptom severity assessed by the Total Neuropathy Score, and HRQOL.

DISCUSSION

It is expected that the combination of a low-frequency electrostimulation device and pharmacological intervention (duloxetine or pregabalin) will produce synergistic effects in breast cancer patients with CIPN after treatment. To our knowledge, this is the first study to investigate the beneficial effect of a new integrated approach for CIPN management after breast cancer treatment. The study findings can expand our knowledge and understanding of the occurrence of CIPN and the efficacy of integrated intervention efforts to ameliorate CIPN symptoms.

TRIAL REGISTRATION

Clinical Research Information Service (CRIS), Republic of Korea, ID: KCT0002357 . Registered retrospectively on 13 June 2017.

The efficacy of combination treatment of gabapentin and electro-acupuncture on paclitaxel-induced neuropathic pain

Paclitaxel, a chemotherapeutic drug, induces severe peripheral neuropathy. Gabapentin (GBT) is a first line agent used to treat neuropathic pain, and its effect is mediated by spinal noradrenergic and muscarinic cholinergic receptors. Electro-acupuncture (EA) is used for treating various types of pain via its action through spinal opioidergic and noradrenergic receptors. Here, we investigated whether combined treatment of these two agents could exert a synergistic effect on paclitaxel-induced cold and mechanical allodynia, which were assessed by the acetone drop test and von Frey filament assay, respectively. Significant signs of allodynia were observed after four paclitaxel injections (a cumulative dose of 8 mg/kg, i.p.). GBT (3, 30, and 100 mg/kg, i.p.) or EA (ST36, Zusanli) alone produced dose-dependent anti-allodynic effects. The medium and highest doses of GBT (30 and 100 mg/kg) provided a strong analgesic effect, but they induced motor dysfunction in Rota-rod tests. On the contrary, the lowest dose of GBT (3 mg/kg) did not induce motor weakness, but it provided a brief analgesic effect. The combination of the lowest dose of GBT and EA resulted in a greater and longer effect, without inducing motor dysfunction. This effect on mechanical allodynia was blocked by spinal opioidergic (naloxone, 20 μg), or noradrenergic (idazoxan, 10 μg) receptor antagonist, whereas on cold allodynia, only opioidergic receptor antagonist blocked the effect. In conclusion, the combination of the lowest dose of GBT and EA has a robust and enduring analgesic action against paclitaxel-induced neuropathic pain, and it should be considered as an alternative treatment method.

Electro-Acupuncture is Beneficial for Knee Osteoarthritis: The Evidence from Meta-Analysis of Randomized Controlled Trials

Knee osteoarthritis (KOA) is a common chronic degenerative disease of the elderly. Electro-acupuncture (EA) is considered as a beneficial treatment for KOA, but the conclusion is controversial. This systematic review compiled the evidence from 11 randomized controlled trials to objectively assess the effectiveness and safety of EA for KOA. Eight databases including PubMed, Cochrane Library, Clinic trials, Foreign Medical Literature Retrial Service (FMRS), Science Direct, China National Knowledge Infrastructure (CNKI), Chinese Scientific Journal Database (VIP), and Wanfang Data were extensively searched up to 5 July 2016. The outcomes included the evaluation of effectiveness, pain and physical function. Risk of bias was evaluated according to the Cochrane risk of bias tool. Eleven RCTs with 695 participants were included. Meta-analysis indicated that EA was more effective than pharmacological treatment (RR [Formula: see text] 1.14; 95% CI [Formula: see text] 1.01,1.28; [Formula: see text]) and manual acupuncture (RR [Formula: see text] 1.12; 95% CI [Formula: see text] 1.02,1.22; [Formula: see text]). Also, EA had a more significant effect in reducing the pain intensity (SMD [Formula: see text]; 95% CI [Formula: see text]; [Formula: see text]) and improving the physical function in the perspective of WOMAC (MD [Formula: see text]; 95% CI [Formula: see text], 5.56; [Formula: see text]) and LKSS (pharmacological treatment: MD [Formula: see text]; 95% CI [Formula: see text], 6.64; [Formula: see text]). Furthermore, these studies implied that EA should be performed for at least 4 weeks. Conclusively, the results indicate that EA is a great opportunity to remarkably alleviate the pain and improve the physical function of KOA patients with a low risk of adverse reaction. Therefore, more high quality RCTs with rigorous methods of design, measurement and evaluation are needed to confirm the long-term effects of EA for KOA.

Electroacupuncture Promotes Central Nervous System-Dependent Release of Mesenchymal Stem Cells

Electroacupuncture (EA) performed in rats and humans using limb acupuncture sites, LI-4 and LI-11, and GV-14 and GV-20 (humans) and Bai-hui (rats) increased functional connectivity between the anterior hypothalamus and the amygdala and mobilized mesenchymal stem cells (MSCs) into the systemic circulation. In human subjects, the source of the MSC was found to be primarily adipose tissue, whereas in rodents the tissue sources were considered more heterogeneous. Pharmacological disinhibition of rat hypothalamus enhanced sympathetic nervous system (SNS) activation and similarly resulted in a release of MSC into the circulation. EA-mediated SNS activation was further supported by browning of white adipose tissue in rats. EA treatment of rats undergoing partial rupture of the Achilles tendon resulted in reduced mechanical hyperalgesia, increased serum interleukin-10 levels and tendon remodeling, effects blocked in propranolol-treated rodents. To distinguish the afferent role of the peripheral nervous system, phosphoinositide-interacting regulator of transient receptor potential channels (Pirt)-GCaMP3 (genetically encoded calcium sensor) mice were treated with EA acupuncture points, ST-36 and LIV-3, and GV-14 and Bai-hui and resulted in a rapid activation of primary sensory neurons. EA activated sensory ganglia and SNS centers to mediate the release of MSC that can enhance tissue repair, increase anti-inflammatory cytokine production and provide pronounced analgesic relief. Stem Cells 2017;35:1303-1315.

Acupuncture and Lifestyle Modification Treatment for Obesity: A Meta-Analysis

Obesity is an epidemic health hazard associated with many medical conditions. Lifestyle interventions are foundational to the successful management of obesity. However, the body's adaptive biological responses counteract patients' desire to restrict food and energy intake, leading to weight regain. As a complementary and alternative medical approach, acupuncture therapy is widely used for weight control. The objective of this study was to assess the efficacy of acupuncture treatment alone and in combination with lifestyle modification. We searched the MEDLINE, EMBASE, CENTRAL and Chinese Biomedical Literature Databases for relevant publications available as of 24 October 2015 without language restriction. Eligible studies consisted of randomized controlled trials for acupuncture with comparative controls. A total of 23 studies were included with 1808 individuals. We performed meta-analyses of weighted mean differences based on a random effect model. Acupuncture exhibited a mean difference of body mass index reduction of 1.742[Formula: see text]kg/m2 (95% confidence interval [Formula: see text]) and 1.904[Formula: see text]kg/m2 (95% confidence interval [Formula: see text]) when compared with untreated or placebo control groups and when lifestyle interventions including basic therapy of both treatment and control groups. Adverse events reported were mild, and no patients withdrew because of adverse effects. Overall, our results indicate that acupuncture is an effective treatment for obesity both alone and together with lifestyle modification.

Immediate Effects of Acupuncture Treatment on Intra- and Inter-Limb Contributions to Body Support During Gait in Patients with Bilateral Medial Knee Osteoarthritis

Knee osteoarthritis (OA) often leads to altered balance control, joint motion and loading patterns during gait. Acupuncture has been proven to be effective in pain relief but its effects on inter-joint load-sharing for body balance have not been reported. The current study bridged the gap by quantifying the immediate effects of acupuncture on the inter-joint and inter-limb load-sharing in patients with knee OA during level walking in terms of the total support moment (Ms) and the contribution of individual joints to the total support moment. Gait analysis was performed on fifteen healthy controls and on fifteen patients with mild to moderate bilateral medial knee OA. After acupuncture treatment the patients with bilateral knee OA walked with significantly increased speed ([Formula: see text]), and were able to resist greater and closer-to-normal knee flexion moments ([Formula: see text]). They also changed the inter-joint sharing of the support moments with increased knee ([Formula: see text]) contributions, but reduced hip contributions ([Formula: see text]) to the sagittal Ms during single-limb support. They showed an asymmetric inter-limb load-sharing similar to the normal controls, with increased sharing of the time integral of both the sagittal and frontal whole body support moment by the leading limb during double-limb support ([Formula: see text]). The altered intra- and inter-limb contributions to the demand of supporting the body during gait suggests that acupuncture treatment led to immediate changes in the control strategy toward a normal pattern. However, the effects of these changes on the progression of the disease in the long term would require further investigation.

Endogenous Opiates and Behavior: 2015

This paper is the thirty-eighth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2015 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, drug abuse and alcohol, 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.

Antinociceptive Profile of Levo-tetrahydropalmatine in Acute and Chronic Pain Mice Models: Role of spinal sigma-1 receptor

We have recently reported that repeated systemic treatments of extract from Corydalis yanhusuo alleviate neuropathic pain and levo-tetrahydropalmatine (l-THP) is one of active components from Corydalis. We designed this study to investigate antinociceptive effect of l-THP in acute and chronic pain models and related mechanism within the spinal cord. We found that intraperitoneal pretreatment with l-THP significantly inhibited the second phase of formalin-induced pain behavior. In addition, intrathecal as well as intraperitoneal pretreatment with l-THP reduced the mechanical allodynia (MA) induced by direct activation of sigma-1 receptor (Sig-1). In chronic constriction injury mice, these treatments remarkably suppressed the increase in MA and spinal phosphorylation of the NMDA receptor NR1 subunit expression on day 7 after surgery. Intrathecal treatment with l-THP combined with the Sig-1R antagonist, BD1047 synergistically blocked MA suggesting that l-THP modulates spinal Sig-1R activation. CatWalk gait analysis also supported that antinociceptive effect of l-THP as demonstrated by restoration of percentages of print area and single stance. Meanwhile, intrathecal pretreatment with naloxone, non-selective opioid receptor antagonist, did not affect the effect of l-THP. In conclusion, these results demonstrate that l-THP possesses antinociceptive effects through spinal Sig-1R mechanism and may be a useful analgesic in the management of neuropathic pain.

Effects of Electroacupuncture Treatment on Bone Cancer Pain Model with Morphine Tolerance

Objective. To explore the efficacy of electroacupuncture treatment in cancer induced bone pain (CIBP) rat model with morphine tolerance and explore changes of calcitonin-gene related peptide (CGRP) expression in dorsal root ganglion (DRG). Methods. Forty SD rats were divided into five groups: sham, CIBP (B), CIBP + morphine (BM), CIBP + electroacupuncture (BE), and CIBP + morphine + electroacupuncture (BME). B, BM, BE, and BME groups were prepared CIBP model. The latter three groups then accepted morphine, electroacupuncture, and morphine combined electroacupuncture, separately, nine days consecutively (M1 to M9). Mechanical withdraw threshold (MWT) was evaluated. Results. BE group only had differences in M1, M2, and M3 compared to B group (P < 0.01). From M5, BM group showed significantly decreased MWT. Electroacupuncture could obtain analgesic effects only at early stage (M1 to M5). From M5 to M9, BME had the differences with BM group (P < 0.01). IOD value of CGRP in BM and BME was substantially less than in B group. CGRP in BME was significantly lower than that in BM group (P < 0.01). Conclusion. When used in combination with electroacupuncture, morphine could result in improving analgesic effects and reducing tolerance. CGRP may be associated with pain behaviors.

Electroacupuncture Attenuates Cerebral Ischemia and Reperfusion Injury in Middle Cerebral Artery Occlusion of Rat via Modulation of Apoptosis, Inflammation, Oxidative Stress, and Excitotoxicity

Electroacupuncture (EA) has several properties such as antioxidant, antiapoptosis, and anti-inflammatory properties. The current study was to investigate the effects of EA on the prevention and treatment of cerebral ischemia-reperfusion (I/R) injury and to elucidate possible molecular mechanisms. Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) for 2 h followed by reperfusion for 24 h. EA stimulation was applied to both Baihui and Dazhui acupoints for 30 min in each rat per day for 5 successive days before MCAO (pretreatment) or when the reperfusion was initiated (treatment). Neurologic deficit scores, infarction volumes, brain water content, and neuronal apoptosis were evaluated. The expressions of related inflammatory cytokines, apoptotic molecules, antioxidant systems, and excitotoxic receptors in the brain were also investigated. Results showed that both EA pretreatment and treatment significantly reduced infarct volumes, decreased brain water content, and alleviated neuronal injury in MCAO rats. Notably, EA exerts neuroprotection against I/R injury through improving neurological function, attenuating the inflammation cytokines, upregulating antioxidant systems, and reducing the excitotoxicity. This study provides a better understanding of the molecular mechanism underlying the traditional use of EA.

Adrenergic stimulation sensitizes TRPV1 through upregulation of cystathionine β-synthetase in a rat model of visceral hypersensitivity

The pathogenesis of pain in irritable bowel syndrome (IBS) is poorly understood and treatment remains difficult. The present study was designed to investigate roles of adrenergic signaling and the endogenous hydrogen sulfide producing enzyme cystathionine β-synthetase (CBS) in a previously validated rat model of IBS induced by neonatal colonic inflammation (NCI). Here we showed that NCI-induced visceral hypersensitivity (VH) was significantly attenuated by β₂ subunit inhibitor but not by β₁ or β₃ or α subunit inhibitor. NCI markedly elevated plasma norepinephrine (NE) concentration without alteration in expression of β₂ subunit receptors in dorsal root ganglion (DRGs) innervating the colon. In addition, NCI markedly enhanced TRPV1 and CBS expression in the colon DRGs. CBS inhibitor AOAA reversed the upregulation of TRPV1 in NCI rats. In vitro experiments showed that incubation of DRG cells with NE markedly enhanced expression of TRPV1, which was reversed by application of AOAA. Incubation of DRG cells with the H₂S donor NaHS greatly enhanced TRPV1 expression. Collectively, these data suggest that activation of adrenergic signaling by NCI sensitizes TRPV1 channel activity, which is likely mediated by upregulation of CBS expression in peripheral sensory neurons, thus contributing to chronic visceral hypersensitivity.