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

Acupoint massage: a comprehensive descriptive review of its forms, applications, and underlying mechanisms

Acupoint massage is a non-invasive traditional therapy that has demonstrated reliable clinical outcomes in pain management, mental health relief, sleep disorder regulation, gastrointestinal treatment, and as an adjunct therapy for cancer. Its convenience and cost-effectiveness further enhance its appeal. However, the existing English literature lacks a systematic review that encompasses the various forms of acupoint massage. The acupoint massage forms adaptability is particularly notable when considering the diverse conditions, it addresses, as well as its applicability across different age groups and gender differences. Providing a comprehensive understanding, it is crucial to outline common practices and explore specific applications in key areas. The comprehensive understanding can create opportunities for effective collaboration between preclinical and clinical studies. Defining and categorizing different forms of acupoint massage is essential, alongside investigating the neural circuits involved in touch sensation. Future efforts should enhance collaboration with modern biology, facilitating the transition from empirical to evidence-based practice. This review summarizes forms, applications, and mechanisms of mainstream acupoint massage and provides insights for future research and applications, promoting deeper integration into healthcare.

Capsaicin-induced Ca2+ overload and ablation of TRPV1-expressing axonal terminals for comfortable tumor immunotherapy

As a common malignancy symptom, cancer pain significantly affects patients' quality of life. Approximately 60%-90% of patients with advanced cancer experience debilitating pain. Therefore, a comprehensive treatment system that combines cancer pain suppression and tumor treatment could provide significant benefits for these patients. Here, we designed a manganese oxide (MnO2)/Bovine serum albumin (BSA)/polydopamine (PDA) composite nanoplatform internally loaded with capsaicin for cancer pain suppression and immunotherapy. MBD&C nanoparticles (NPs) can ablate tumor-innervated sensory nerve fibers via Transient receptor potential vanilloid 1 (TRPV1) channels, thereby reducing the pain caused by various inflammatory mediators. The ablation of TRPV1+ nerve terminals can also decrease the secretion of calcitonin gene-related peptide (CGRP) and substance P (SP) in sensory nerve fibers, thus reducing the tumor pain and inhibit tumor progression. MBD&C can promote calcium influx by activating overexpressed TRPV1 channels on the tumor membrane surface, thereby achieving cancer immunotherapy induced by endogenous Ca2+ overloading. In addition, MnO2 NPs can alleviate tumor hypoxia and mitigate the immunosuppressive tumor microenvironment (TME). Ultimately, this treatment system with dual capabilities of inhibiting tumor growth and relieving cancer pain makes comfortable tumor therapy feasible and paves the way for the development of patient-centered approaches to cancer treatment in the future.

Electroacupuncture alleviates paradoxical sleep deprivation-induced postoperative hyperalgesia via a7nAChR mediated BDNF/TrkB-KCC2 signaling pathway in the spinal cord

Perioperative Paradoxical sleep deprivation (PSD) is associated with postoperative hyperalgesia. However, the clinical therapeutic strategies for PSD-induced postoperative hyperalgesia are limited. Electroacupuncture (EA) has been used for attenuating many types of pain, including neuropathic pain and inflammatory pain, but its effect on PSD-induced postoperative hyperalgesia is still unclear, and its analgesia mechanism should be further explored. In this study, we designed to investigate the possible mechanism of PSD-induced postoperative hyperalgesia and the effect of EA on PSD-induced postoperative hyperalgesia, and whether the mechanism is related to the BDNF/TrkB signaling pathway mediated by α7nAChR in the spinal cord. The paw withdrawal thermal latency (PWTL) and paw withdrawal mechanical threshold (PWMT) of rats were used to detect PSD-induced hyperalgesia. The expression of α7nAChR, BDNF, TrkB and KCC2 in the spinal cord were evaluated by Western blot and immunofluorescence. The results showed that preoperative 24 h PSD significantly decreased the PWTL and PWMT. The expression of α7nAChR and KCC2 significantly downregulated in the spinal cord of PSD-induced postoperative hyperalgesia rats, the opposite was observed for BDNF and TrkB expression. Moreover, intrathecal injection of alpha-bungarotoxin (α-BGT), a selective antagonist for α7nAChR, not only aggravated the pain hypersensitivity, but also demonstrated a further decrease of α7nAChR and KCC2 expression and a further increase of BDNF and TrkB expression. EA stimulation increased the PWTL and PWMT values of PSD-induced postoperative hyperalgesia rats, significantly upregulated α7nAChR and KCC2 expression, and significantly downregulated BDNF and TrkB expression. Moreover, intrathecal injection of α-BGT suppressed the analgesic effect of EA, inhibited the enhancement of α7nAChR and KCC2 expression and the reduction of BDNF and TrkB expression induced by EA. In conclusion, our study indicated that 24 h PSD can cause postoperative hyperalgesia, and the mechanism may be related to the disorder of α7nAChR mediated BDNF/TrkB-KCC2 signaling pathway. EA can alleviate postoperative hyperalgesia induced by PSD, which may be related to its effect in activating α7nAChR, inhibiting the expression of BDNF/TrkB, and up-regulating the expression of KCC2 in the spinal cord.

The effect of cannabinoid type 2 receptor agonist on morphine tolerance

Pain highly impacts the quality of life of patients. Morphine is used for pain treatment; however, its side effects, especially morphine tolerance, limit its use in the clinic. The problem of morphine tolerance has plagued health workers and patients for years. Unfortunately, the exact mechanism of morphine tolerance has not been fully clarified. The mechanisms of morphine tolerance that are currently being studied may include μ-opioid receptor (MOR) desensitization and internalization, mitogen-activated protein kinase (MAPK) pathway activation and crosstalk, the effects of microglia and the increase in inflammatory factors. Morphine tolerance can be alleviated by improving the pathophysiological changes that lead to morphine tolerance. Previous studies have shown that a cannabinoid type 2 (CB2) receptor agonist could attenuate morphine tolerance in a variety of animal models. Many studies have shown an interaction between the cannabinoid system and the opioid system. The CB2 receptor may modulate the effect of morphine through a pathway that is common to the MOR, since both receptors are G protein-coupled receptors (GPCRs). This study introduces the potential mechanism of morphine tolerance and the effect of CB2 receptor agonists on reducing morphine tolerance, which can provide new ideas for researchers studying morphine and provide beneficial effects for patients suffering from morphine tolerance.

Calcium Carbonate/Polydopamine Composite Nanoplatform Based on TGF-β Blockade for Comfortable Cancer Immunotherapy

Cancer pain seriously reduces the quality of life of cancer patients. However, most research about cancer focuses solely on inhibiting tumor growth, neglecting the issue of cancer pain. Therefore, the development of therapeutic agents with both tumor suppression and cancer pain relief is crucial to achieve human-centered treatment. Here, the work reports curcumin (CUR) and ropivacaine (Ropi) coincorporating CaCO3/PDA nanoparticles (CaPNMCUR+Ropi) that realized efficient tumor immunotherapy and cancer pain suppression. The therapeutic efficiency and mechanism are revealed in vitro and in vivo. The results indicate that CaPNMCUR+Ropi underwent tumor microenvironment-responsive degradation and realized rapid release of calcium ions, Ropi, and CUR. The excessive intracellular calcium triggered the apoptosis of tumor cells, and the transient pain caused by the tumor injection was relieved by Ropi. Simultaneously, CUR reduced the levels of immunosuppressive factor (TGF-β) and inflammatory factor (IL-6, IL-1β, and TNF-α) in the tumor microenvironment, thereby continuously augmenting the immune response and alleviating inflammatory pain of cancer animals. Meanwhile, the decrease of TGF-β leads to the reduction of transient receptor potential vanilloid 1 (TRPV1) expression, thereby alleviating hyperalgesia and achieving long-lasting analgesic effects. The design of the nanosystem provides a novel idea for human-centered tumor treatment in the future.

Electroacupuncture attenuates nociceptive behaviors in a mouse model of cancer pain

Pain is a major symptom in cancer patients, and cancer-induced bone pain (CIBP) is the most common type of moderate and severe cancer-related pain. The current available analgesic treatments for CIBP have adverse effects as well as limited therapeutic effects. Acupuncture is proved effective in pain management as a safe alternative therapy. We evaluated the analgesic effect of acupuncture in treatment of cancer pain and try to explore the underlying analgesic mechanisms. Nude mice were inoculated with cancer cells into the left distal femur to establish cancer pain model. Electroacupuncture (EA) treatment was applied for the xenograft animals. Pain behaviors of mice were evaluated, followed by the detections of neuropeptide-related and inflammation-related indicators in peripheral and central levels. EA treatment alleviated cancer-induced pain behaviors covering mechanical allodynia, thermal hyperalgesia and spontaneous pain, and also down-regulated immunofluorescence expressions of neuropeptide CGRP and p75 in the skin of affected plantar area in xenograft mice, and inhibited expressions of overexpressed neuropeptide-related and inflammation-related protein in the lumbar spinal cord of xenograft mice. Overall, our findings suggest that EA treatment ameliorated cancer-induced pain behaviors in the mouse xenograft model of cancer pain, possibly through inhibiting the expressions of neuropeptide-related and inflammation-related protein in central level following tumor cell xenografts.

Relationship between acupuncture and transient receptor potential vanilloid: Current and future directions

Acupuncture is a common complementary and alternative therapy around the world, but its mechanism remains still unclear. In the past decade, some studies indicated that transient receptor potential vanilloid (TRPV) channels play a great role in the response of acupuncture stimulation. In this article, we discussed the relationship between acupuncture and TRPV channels. Different from inhibitors and agonists, the regulation of acupuncture on TRPV channels is multi-targeted and biphasic control. Acupuncture stimulation shows significant modulation on TRPV1 and TRPV4 at the autonomic nervous system (ANS) including central and peripheral nervous systems. On the contrary, the abundant expression and functional participation of TRPV1 and TRPV4 were specific to acupuncture stimulation at acupoints. The enhancement or inhibition of TRPV channels at different anatomical levels will affect the therapeutic effect of acupuncture. In conclusion, TRPV channels help to understand the principle of acupuncture stimulation, and acupuncture also provides a potential approach to TRPV-related trials.

Effects of Electroacupuncture on Gastrointestinal Motility Function, Pain, and Inflammation via Transient Receptor Potential Vanilloid 1 in a Rat Model after Colonic Anastomoses

Background. Complications after colon surgery are a major obstacle to postoperative recovery. The purpose of this study was to investigate the effect of electroacupuncture (EA) at Zusanli (ST36) on gastrointestinal motility in rats after colonic anastomosis and the mechanism of transient receptor potential vanillin 1 (TRPV1) channel in regulating gastrointestinal motility, pain, and inflammation. Methods. The rats were randomly divided into six groups, including the control, model, EA, sham-EA, capsaicin, and capsaicin+EA groups, with preoperative capsaicin pretreatment and EA treatment at ST36 acupoint after surgery. Rats were treated using EA at ST36 or sham acupoints after surgery for 5 days. Capsaicin was intraperitoneally injected into rats 3 hours before surgery. Gastrointestinal motility was assessed by measuring the gastric residue, small intestinal propulsion in vivo, contractile tension, and frequency of isolated muscle strips in vitro. The mechanical withdrawal threshold (MWT) of abdominal incision skin and spontaneous nociceptive scores were observed and recorded in rats after colon anastomosis. The expressions of TRPV1, substance P (SP), neurokinin 1 (NK1) receptor, nuclear factor kappa-B (NF-κB), interleukin- (IL-) 6, L-1β, and tumor necrosis factor- (TNF-) α were determined. Results. Compared with the model group, electroacupuncture at ST36 point could significantly reduce the residual rate of stomach in rats after operation and increase the propulsive force of the small intestine and the contraction tension of the isolated smooth muscle. Electroacupuncture also increased postoperative day 3 MWT values and decreased postoperative spontaneous nociception scores. In addition, electroacupuncture treatment downregulated the expressions of IL-6, IL-1β, TNF-α, TRPV1, NF-κB, SP, and NK1 receptors in the colon tissue of rats after colonic anastomosis. Conclusions. Our study showed that electroacupuncture at ST36 acupoint could improve gastrointestinal motility in rats after colonic anastomosis and relieve intestinal inflammation and pain. The mechanism may be to inhibit the activation of NF-κB and SP/NK1 receptor signaling pathways by inhibiting TRPV1.

Publication Trends in Rehabilitative Effects of Acupuncture: A Visual Analysis of the Literature

Objectives

To conduct a comprehensive analysis of scientific outputs in 2011–2021 regarding the rehabilitative effects of acupuncture on diseases.

Methods

The study was conducted in the form of knowledge graph and data visualization, with data being drawn from the Web of Science Core Collection database.

Results

Articles and reviews were the dominant types; China, Guangzhou University of Chinese Medicine and Medicine ranked was the active country, institution, and journal, respectively, in terms of issued articles. Systematic reviews and the meta-analyses of stroke and pain were extensively carried out in the past decade, whose principal interventions were manual acupuncture, electroacupuncture, scalp acupuncture, and dry needling correspondingly at Baihui (DU20) and Zusanli (ST36). And most frequently utilized rehabilitation assessment criteria were the Fugl-Meyer Assessment Scale and the Barthel Index. More recently, motor function and chronic obstructive pulmonary disease have captured researchers' attention, which might be the futuristic frontier.

Conclusions

This article provided a relatively panoramic picture of the scientific outputs in acupuncture for disease rehabilitation, which may help readers embrace the heated topic and grasp the recent research focus on this field.

Anti-Inflammatory Effects of Acupuncture at ST36 Point: A Literature Review in Animal Studies

So far, a number of acupuncture studies have shown anti-inflammatory effects of acupuncture treatment, mostly known at specific point ST36. However, there is no literature that oversaw the inflammation-regulatory effects of acupuncture in each tissue. Therefore, we investigated how acupuncture at specific acupoint ST36 regulates inflammation and its underlying mechanisms. We searched literatures on PubMed until July 2021 using the keywords “animal, acupuncture, ST36, inflammation, immune,” and 292 literatures were searched. We ultimately selected 69 studies to determine the anti-inflammatory actions of acupuncture at ST36 and classified the changes of inflammatory mediators according to target regions. Forty-three studies were included in body fluids, 27 studies in the digestive system, 17 studies in the nervous system, and 30 studies in other tissues or organs. In this review, we found that acupuncture at ST36 has clinical benefits in relieving inflammation through several mechanisms such as vagus nerve activation, toll-like receptor 4 (TLR4)/NF-κB signaling, macrophage polarization, mitogen-activated protein kinase (MAPK) signaling pathway, and cholinergic anti-inflammatory pathway. We expect that these data will inform further studies related to ST36 acupuncture on inflammation.

Effects of Acupuncture on Cancer Pain in Animal Intervention Studies: A Systematic Review and Quality Assessment

BACKGROUND

Preclinical studies often provide the evidence base for clinical studies. However, the design and reporting of preclinical trial results are inadequate, resulting in poor reproducibility and clinical translatability. We aimed to systematically evaluate the methodology and reporting quality of animal studies of acupuncture for cancer pain.

METHODS

About 7 databases were searched for animal research articles on acupuncture for cancer pain from the beginning of the database to January 31, 2022. ARRIVE guidelines, STRICTA, and SYRCLE risk of bias tools were used to assess the reporting quality and risk of bias of the selected studies.

RESULTS

A total of 18 studies were evaluated. Of the 22 items on the SYRCLE tool, only 6 items had a positive reporting rate of more than 50%. Of the 39 items in the ARRIVE guidelines, 14 were rated excellent, and the least frequently reported checklist items were 7. Out of the 17 STRICTA checklist items analyzed, 10 were considered appropriately reported in more than 80% of the studies, while 4 were correctly reported in less than 20%.

CONCLUSIONS

Some crucial points in the design, implementation, and reporting of the experiments included in the study were not well developed, which could significantly affect the clarity, reproducibility, and translatability of the experiments. There is a need to fully implement scientific tool guidelines for future experimental studies in order to improve the quality of preclinical studies and facilitate effective translation of their results to the clinic.

Effects of Transcutaneous Electrical Acupoint Stimulation on Systemic Inflammatory Response Syndrome of Patients after Percutaneous Nephrolithotomy: A Randomized Controlled Trial

Purpose

Transcutaneous electrical acupoint stimulation (TEAS) is widely used. However, no study evaluated TEAS on systemic inflammatory response syndrome (SIRS) of patients after percutaneous nephrolithotomy (PCNL). The study was to evaluate TEAS on SIRS of patients after PCNL.

Methods

67 patients were enrolled and divided into group TEAS and group sham TEAS. Data were collected from 60 participants finally. In the study, TEAS or sham TEAS on bilateral Shenshu (BL23), Yinlingquan (SP9), Hegu (LI4), and Neiguan (PC6) was performed continuously throughout the procedure. The primary outcome included the incidence of systemic inflammatory response syndrome (SIRS) within 48 h after surgery. The secondary outcomes included the serum levels of inflammatory cytokines, hemodynamics changes, complications, and hospital stay after surgery. The serum levels of tumor necrosis factor- (TNF-) α and interleukin- (IL-) 6, mean arterial pressure (MAP), and heart rate (HR) at 30 min before anesthesia (T₀), the time after surgery (T₁), 24 h postoperation (T₂), and 48 h postoperation (T₃) were recorded. The consumption of analgesic during surgery was also recorded, as well as the complications and duration of hospital stay after PCNL.

Results

The incidence of SIRS in group TEAS was lower than group sham TEAS (30% vs. 6.67%, p=0.023). Compared with the sham TEAS group, both levels of TNF-α and IL-6 at T₁, T₂, and T₃ were lower in the TEAS group (p < 0.05). The levels of MAP and HR in sham TEAS at T₁, T₂, and T₃ were markedly higher than that in the TEAS group (p < 0.05). The total consumption of propofol and remifentanil during surgery in group TEAS was lower than that in the sham TEAS group. The incidence of hypotension, hypertension, emergence agitation, and postoperative nausea and vomiting (PONV) was also lower in group TEAS after PCNL (p < 0.05).

Conclusions

TEAS could effectively reduce the incidence of SIRS and inflammatory cytokines for patients who underwent PCNL. In addition, TEAS helped to maintain the hemodynamic stability and cut down the consumption of analgesics during PCNL, reducing the complications after PCNL.

Phosphoproteomic Profiling of Rat's Dorsal Root Ganglia Reveals mTOR as a Potential Target in Bone Cancer Pain and Electro-Acupuncture's Analgesia

Bone cancer pain (BCP) is a clinical refractory mixed pain involving neuropathic and inflammatory pain, with the underlying mechanisms remaining largely unknown. Electro-acupuncture (EA) can partly alleviate BCP according to previous research. We aim to explore the proteins and major pathways involved in BCP and EA treatment through phosphoproteomic profiling. BCP rat model was built by tibial inoculation of MRMT-1 mammary gland carcinoma cells. Mechanical hyperalgesia determined by paw withdrawal thresholds (PWTs) and bone destruction manifested on the radiographs confirmed the success of modeling, which were attenuated by EA treatment. The differentially expressed phosphorylated proteins (DEPs) co-regulated by BCP modeling and EA treatment in rat dorsal root ganglions (DRGs) were analyzed through PEX100 Protein microarray. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that DEPs were significantly enriched in mammalian target of rapamycin (mTOR) signaling pathway. The phosphorylations of mTOR at Ser2448 and Thr2446 were increased in BCP and downregulated by EA. In addition, the phosphorylation of S6K and Akt, markers of the mTOR complex, were also increased in BCP and downregulated by EA. Inhibition of mTOR signaling alleviated the PWTs of BCP rats, while the mTOR agonist impaired the analgesic effect of EA. Thus, our study provided a landscape of protein phosphorylation changes in DRGs of EA-treated BCP rats and revealed that mTOR signaling can be potentially targeted to alleviate BCP by EA treatment.

Knowledge Mapping of Acupuncture for Cancer Pain: A Scientometric Analysis (2000-2019)

Objective

This study aimed to demonstrate the state of the present situation and trends concerning the global use of acupuncture for cancer pain in the past 20 years.

Methods

Searched the Web of Science database from 2000 to 2019 related to acupuncture for cancer pain, and then used CiteSpace to conduct scientometric analysis to acquire the knowledge mapping.

Results

Yearly output has increased year by year, and the growth rate has become faster after 2012. According to the cluster analysis of institutions, authors, cited references, and keywords, 4, 4, 15, and 14 categories were obtained, respectively. The most productive countries, institutions, and authors are the USA, Mem Sloan Kettering Cancer Center, and Mao JJ, whose frequencies are 196, 24, and 17, respectively. However, the most important of them are Australia, Univ. Maryland, and Bao T, owing to their highest centrality, they are 0.90, 0.21, and 0.09 separately. Moreover, cited references that contributed to the most co-citations are Crew KD (2010), however, the most key cited reference is Roscoe JA (2003). Keywords such as acupuncture, pain, breast cancer, palliative care, and quality of life are the most frequently used. But auricular acupuncture is the crucial keyword. In the cluster analysis of institutions, authors, cited references, and keywords, the more convincing research categories are multiple myeloma, placebo effect, neck malignancies, and early breast cancer, with S values of 0.990, 0.991, 0.990, and 0.923, respectively. Therefore, they can be regarded as research hotspots in this field.

Conclusion

Based on the scientometric analysis in the past 20 years, the knowledge mapping of the country, institution, author, cited reference, and the keyword is gained, which has an important guiding significance for quickly and accurately positioning the trend in this field.

Effects of low- and high-frequency electroacupuncture on protein expression and distribution of TRPV1 and P2X3 in rats with peripheral nerve injury

BACKGROUND

Whether electroacupuncture (EA) stimulation at different frequencies has a similar effect on spared nerve injury (SNI) as other neuropathic pain models, and how EA at different frequencies causes distinct analgesic effects on neuropathic pain is still not clear.

METHODS

Adult male Sprague-Dawley rats were randomly divided into sham SNI, SNI, 2 Hz, 100 Hz and sham EA groups. Paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were measured. EA was performed once a day on days 1 to 14 after SNI. The expressions of transient receptor potential cation subfamily V member 1 (TRPV1) and peripheral purinergic P2X receptor 3 (P2X3) were determined by western blotting and immunofluorescence. TRPV1 siRNA and P2X3 siRNA were administered by intrathecal injection. TRPV1 or P2X3 agonists were combined with EA.

RESULTS

There were significant decreases in PWT, but no changes in PWL in the 14 days after SNI. EA using 2- or 100-Hz stimulation similarly increased PWT at every time point. The cytosol protein expression of P2X3 in the L4-L6 dorsal root ganglia (DRG) increased, but the expression of TRPV1 decreased in the SNI model. Both these effects were ameliorated by EA, with 2-Hz stimulation having a stronger effect than 100-Hz stimulation. Blocking either TRPV1 or P2X3 specific siRNAs attenuated the decreased PWT induced by SNI. Administration of either a TRPV1 or P2X3 agonist inhibited EA analgesia.

CONCLUSION

2- and 100-Hz EA similarly induced analgesic effects in SNI. This effect was related to up-regulation and down-regulation, respectively, of cytosol protein expression of P2X3 and TRPV1 in L4-L6 DRG, with 2 Hz having a better effect than 100 Hz.

Acupuncture stimulation attenuates TNF-α production via vagal modulation in the concanavalin A model of hepatitis

Background:

A growing body of evidence shows that neuronal activity is involved in modulating the efficacy of acupuncture therapy. However, it has been seldom investigated whether neuronal activity following acupuncture stimulation is effective at regulating hepatic inflammation.

Objective:

Using the concanavalin A (ConA) model of hepatitis, we investigated the regulation of inflammatory cytokine tumor necrosis factor (TNF)-α in the liver tissue and the blood after acupuncture stimulation at ST36.

Methods:

Mice were subjected to ConA injection, acupuncture stimulation at ST36 by manual acupuncture (MA) or electroacupuncture (EA) procedures, and vagotomy (VNX). Liver tissue and blood were collected for TNF-α analysis. TNF-α mRNA was analyzed by real-time polymerase chain reaction (PCR), and TNF-α, CD11b, CD68, and Erk1/2 proteins were analyzed by Western blotting, immunofluorescence staining, and enzyme-linked immunosorbent assay.

Results:

TNF-α mRNA and protein were induced in CD11b-positive hepatic cells and the plasma at 6–24 h after ConA injection. The application of MA or EA was very effective at attenuating the production of TNF-α. Anti-inflammatory effects of acupuncture were greatly suppressed by VNX in ConA-injected animals, suggesting the requirement of vagus nerve activity in acupuncture-mediated anti-inflammatory responses. Electrical stimulation of the sciatic nerve (SNS) resulted in an anti-inflammatory effect similar to acupuncture stimulation. In parallel with TNF-α, production of phospho-Erk1/2, which was induced in the liver tissue, was downregulated by MA and EA in liver cells.

Conclusion:

The regulatory effects of acupuncture stimulation on inflammatory responses in the liver may be modulated through the activation of the vagus nerve pathway.

Wrist-ankle acupuncture attenuates cancer-induced bone pain by regulating descending pain-modulating system in a rat model

Background

Cancer-induced bone pain (CIBP) presents a multiple-mechanism of chronic pain involving both inflammatory and neuropathic pain, and its pathogenesis is closely related to endogenous descending system of pain control. However, the action mechanism underlying the effects of wrist–ankle acupuncture (WAA) versus electroacupuncture (EA) on CIBP remains unknown.

Methods

Thirty-two Wistar rats were divided into sham, CIBP, EA-treated and WAA-treated groups. CIBP was induced in rats of the latter three groups. Time courses of weight and mechanical hyperalgesia threshold (MHT) were evaluated. After 6 days of EA or WAA treatment, the expressions of 5-hydroxytryotamine type 3A receptor (5-HT_3AR) and μ-opioid receptor (MOR) in rostral ventromedial medulla (RVM) and/or spinal cord, as well as the levels of 5-HT, β-endorphin, endomorphin-1 and endomorphin-2 in RVM and spinal cord, were detected.

Results

Injection of cancer cells caused decreased MHT, which was attenuated by EA or WAA (P < 0.05). WAA had a quicker analgesic effect than EA (P < 0.05). No significant difference of MOR in RVM was found among the four groups. EA or WAA counteracted the cancer-driven upregulation of 5-HT_3AR and downregulation of MOR in spinal cord (P < 0.05), and upregulation of 5-HT and downregulation of endomorphin-1 in both RVM and spinal cord (P < 0.05). β-endorphin and endomorphin-2 in RVM and spinal cord decreased in CIBP group compared with sham group (P < 0.05), but EA or WAA showed no significant effect on them, although a tendency of increasing effect was observed.

Conclusion

WAA, similar to EA, alleviated mechanical hyperalgesia in CIBP rats by suppressing the expressions of 5-HT and 5-HT_3AR, and increasing the expressions of MOR and endomorphin-1 in RVM-spinal cord pathway of the descending pain-modulating system. However, WAA produced a quicker analgesic effect than EA, the mechanisms of which need further investigation.

Acupuncture/Electroacupuncture as an Alternative in Current Opioid Crisis

Opioid drugs are the first line of defense in severe pain but the adverse effects associated with opioids are considered as a serious issue worldwide. Acupuncture/electroacupuncture is a type of Chinese medicine therapy which is an effective analgesic therapy, well documented in animals and human studies. Electroacupuncture stimulation could release endogenous opioid peptides causing analgesia in a variety of pain models. It can be used as an alternative therapy to control the opioid crisis.

Electroacupuncture alleviates morphine‑induced hyperalgesia by regulating spinal CB1 receptors and ERK1/2 activity

Electroacupuncture (EA), a traditional Chinese therapeutic technique, is considered an effective method for treating certain painful neuropathies induced by various neuropathological damage. The current study investigated the effect of EA on intrathecal (IT) morphine-induced hyperalgesia (MIH) and examined the hypothesis that activation of cannabinoid receptor 1 (CB1) could enhance the antinociceptive effect of EA on MIH via regulation of the extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathway. Using a rat model of IT MIH, mechanical and thermal hyperalgesia were evaluated by an electronic von Frey filament and hotplate at baseline (1 day before IT administration) and at days 1, 3, 5 and 7 after IT administration. Rats received IT normal saline, IT morphine or IT morphine + EA at ST36-GB34. The protein levels of ERK1/2, phosphorylated (p)-ERK1/2 and CB1 in the spinal cord were assayed by western blotting. Furthermore, the effect of IT injection of the CB1 agonist WIN 55,212-2 and the CB1 antagonist SR141716 on the antinociceptive effect of EA in rats with MIH was investigated. Nociceptive behavior and ERK1/2, phosphorylated (p)-ERK1/2 and CB1 protein levels were evaluated as mentioned above. The results revealed that chronic IT injections of morphine induced a significant decrease in mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) accompanied with remarkable upregulation of p-ERK1/2 in the spinal cord, which could be attenuated by EA at the ST36-GB34 acupoints. In the rat model of MIH, IT injection of WIN 55,212-2 combined with EA induced a significant increase in MWT and TWL accompanied with a significant decrease in p-ERK1/2 and a significant increase in CB1 protein level compared with EA alone, while SR141716 induced the opposite results. The present study suggests that EA alleviates hyperalgesia induced by IT injection of morphine partially through the inhibition of ERK1/2 activation. Activation of the CB1 receptor enhances the antinociceptive effect of EA in rats with MIH partly through the regulation of the spinal CB1-ERK1/2 signaling pathway.

Expression profiles of TRPV1, TRPV4, TLR4 and ERK1/2 in the dorsal root ganglionic neurons of a cancer-induced neuropathy rat model

Background

The spread of tumors through neural routes is common in several types of cancer in which patients suffer from a moderate-to-severe neuropathy, neural damage and a distorted quality of life. Here we aim to examine the expression profiles of transient receptor potential vanilloid 1 (TRPV1) and of transient receptor potential vanilloid 4 (TRPV4), toll-like receptor 4 (TLR4) and extracellular signal-regulated kinase (ERK1/2), and to assess the possible therapeutic strategies through blockade of transient receptor potential (TRP) channels.

Methods

Cancer was induced within the sciatic nerves of male Copenhagen rats, and tissues from dorsal root ganglia (DRG) were collected and used for measurements of immunofluorescence and Western blotting. The TRPV1 antagonist capsazepine, the selective TRPV4 antagonist HC-067047 and the calcium ions inhibitor ruthenium red were used to treat thermal and/or mechanical hyperalgesia.

Results

Transient receptor potential vanilloid 1 showed a lower expression in DRGs on days 7 and 14. The expression of TRPV4, TLR4 and ERK1/2 showed an increase on day 3 then a decrease on days 7 and 14. TRPV1 and TLR4 as well as TRPV4 and ERK1/2 co-existed on the same neuronal cells. The neuropathic pain was reversed in dose-dependent manners by using the TRP antagonists and the calcium ions inhibitor.

Conclusion

The decreased expression of TRPV1 and TRPV4 is associated with high activation. The increased expression of TLR4 and ERK1/2 reveals earlier immune response and tumor progression, respectively, and their ultimate decrease is an indicator of nerve damage. We studied the possible role of TRPV1 and TRPV4 in transducing cancer-induced hyperalgesia. The possible treatment strategies of cancer-induced thermal and/or mechanical hyperalgesia using capsazepine, HC-067047 and ruthenium red are examined.

Role of Transient Receptor Potential Vanilloid 1 in Electroacupuncture Analgesia on Chronic Inflammatory Pain in Mice

Chronic inflammatory pain may result from peripheral tissue injury or inflammation, increasing the release of protons, histamines, adenosine triphosphate, and several proinflammatory cytokines and chemokines. Transient receptor potential vanilloid 1 (TRPV1) is known to be involved in acute to subacute neuropathic and inflammatory pain; however, its exact mechanisms in chronic inflammatory pain are not elucidated. Our results showed that EA significantly reduced chronic mechanical and thermal hyperalgesia in the chronic inflammatory pain model. Chronic mechanical and thermal hyperalgesia were also abolished in TRPV1-/- mice. TRPV1 increased in the dorsal root ganglion (DRG) and spinal cord (SC) at 3 weeks after CFA injection. The expression levels of downstream molecules such as pPKA, pPI3K, and pPKC increased, as did those of pERK, pp38, and pJNK. Transcription factors (pCREB and pNFκB) and nociceptive ion channels (Nav1.7 and Nav1.8) were involved in this process. Inflammatory mediators such as GFAP, S100B, and RAGE were also involved. The expression levels of these molecules were reduced in EA and TRPV1-/- mice but not in the sham EA group. Our data provided evidence to support the clinical use of EA for treating chronic inflammatory pain.

Alleviating Mechanical Allodynia and Modulating Cellular Immunity Contribute to Electroacupuncture's Dual Effect on Bone Cancer Pain

Hypothesis: Electroacupuncture (EA) has been used as an alternative analgesic therapy for hundreds of years, yet its analgesic potency and therapeutic advantage against bone cancer pain (BCP) in comparison with morphine remains unclear. This study aimed to investigate the effects of EA on mechanical allodynia and cellular immunity of BCP rats, and to further explore the potential mechanism. Methods: The BCP model was established by implanting Walker 256 mammary gland carcinoma cells into the left tibia of adult female Sprague-Dawley rats. EA (dilatational wave, 2/100 Hz, 0.5 mA–1mA–1.5 mA for 10 minutes each intensity) was applied bilaterally to Zusanli (ST 36) and Kunlun (BL 60) for 30 minutes. Both EA stimulation and morphine (10 mg/kg, intraperitoneally) was given once every other day. Naloxone (0.3 mg/kg, intraperitoneally) was injected at 30 minutes prior to EA. Mechanical allodynia were demonstrated by paw withdrawal thresholds (PWTs) which measured by dynamic plantar aesthesiometer. T cell proliferation, percentage of CD3⁺, CD4⁺ and CD8⁺ T lymphocytes in spleen as well as expression of interleukin-2 (IL-2) in plasma were detected by WST-8, flow cytometry, and enzyme-linked immunosorbent assay technique, respectively. Results: An intratibial inoculation of Walker 256 mammary gland carcinoma cells significantly decreased PWTs to mechanical stimuli. EA stimulation alleviated mechanical allodynia in BCP rats, and the analgesic potency of EA was weaker than that of morphine. In contrast to morphine, EA stimulation of BCP rats increased splenic concanavalin A (Con A)-induced T cell proliferation and plasma IL-2 content, as well as increased the percentages of splenic CD₃⁺CD₄⁺ and CD₃⁺CD₈⁺ T cell subsets. Moreover, both the analgesic effect and the partial immunomodulation of EA were suppressed by an intraperitoneal injection of naloxone. Conclusion: EA could significantly alleviate BCP-induced mechanical allodynia. Although the analgesic effect of EA was weaker than that of morphine, EA had an immunomodulation effect on cellular immunity. Both analgesic and immunomodulatory effect of EA might share the same mechanism via the opioid-mediated pathway, which needs further investigation.

Intraoperative electroacupuncture relieves remifentanil-induced postoperative hyperalgesia via inhibiting spinal glial activation in rats

Background Accumulating studies have suggested that remifentanil, the widely-used opioid analgesic in clinical anesthesia, can activate the pronociceptive systems and enhance postoperative pain. Glial cells are thought to be implicated in remifentanil-induced hyperalgesia. Electroacupuncture is a complementary therapy to relieve various pain conditions with few side effects, and glial cells may be involved in its antinociceptive effect. In this study, we investigated whether intraoperative electroacupuncture could relieve remifentanil-induced postoperative hyperalgesia by inhibiting the activation of spinal glial cells, the production of spinal proinflammatory cytokines, and the activation of spinal mitogen-activated protein kinases. Methods A rat model of remifentanil-induced postoperative hyperalgesia was used in this study. Electroacupuncture during surgery was conducted at bilateral Zusanli (ST36) acupoints. Behavior tests, including mechanical allodynia and thermal hyperalgesia, were performed at different time points. Astrocytic marker glial fibrillary acidic protein, microglial marker Iba1, proinflammatory cytokines, and phosphorylated mitogen-activated protein kinases in the spinal cord were detected by Western blot and/or immunofluorescence. Results Mechanical allodynia and thermal hyperalgesia were induced by both surgical incision and remifentanil infusion, and remifentanil infusion significantly exaggerated and prolonged incision-induced pronociceptive effects. Glial fibrillary acidic protein, Iba1, proinflammatory cytokines (interleukin-1β and tumor necrosis factor-α), and phosphorylated mitogen-activated protein kinases (p-p38, p-JNK, and p-ERK1/2) were upregulated after surgical incision, remifentanil infusion, and especially after their combination. Intraoperative electroacupuncture significantly attenuated incision- and/or remifentanil-induced pronociceptive effects, spinal glial activation, proinflammatory cytokine upregulation, and phosphorylated mitogen-activated protein kinase upregulation. Conclusions Our study suggests that remifentanil-induced postoperative hyperalgesia can be relieved by intraoperative electroacupuncture via inhibiting the activation of spinal glial cells, the upregulation of spinal proinflammatory cytokines, and the activation of spinal mitogen-activated protein kinases.

Acupuncture for Pain Management in Cancer: A Systematic Review and Meta-Analysis

Objective. To evaluate the effectiveness and safety of acupuncture for cancer-related pain. Methods. A systematic review of literatures published from database inception to February 2015 was conducted in eight databases. RCTs involving acupuncture for treatment of cancer-related pain were identified. Two researchers independently performed article selection, data extraction, and quality assessment of data. Results. 1,639 participants in twenty RCTs were analyzed. All selected RCTs were associated with high risk of bias. Meta-analysis indicated that acupuncture alone did not have superior pain-relieving effects as compared with conventional drug therapy. However, as compared with the drug therapy alone, acupuncture plus drug therapy resulted in increased pain remission rate, shorter onset time of pain relief, longer pain-free duration, and better quality of life without serious adverse effects. However, GRADE analysis revealed that the quality of all outcomes about acupuncture plus drug therapy was very low. Conclusions. Acupuncture plus drug therapy is more effective than conventional drug therapy alone for cancer-related pain. However, multicenter high-quality RCTs with larger sample sizes are needed to provide stronger evidence for the effectiveness of acupuncture in cancer-related pain due to the low data quality of the studies included in the current meta-analysis.

MiRNAs are involved in chronic electroacupuncture tolerance in the rat hypothalamus

Acupuncture tolerance is the gradual decrease in analgesic effect due to its prolonged application. However, its mechanism in terms of miRNA is still unknown. To explore the role of miRNAs in electroacupuncture (EA) tolerance of rats using deep sequencing, rats with more than a 50 % increase in tail flick latency (TFL) in response to EA were selected for this experiment. EA tolerance was induced by EA once daily for eight consecutive days. The hypothalami were harvested for deep sequencing. As a result, 49 differentially expressed miRNAs were identified and validated by real-time PCR. Of them, let-7b-5p, miR-148a-3p, miR-124-3p, miR-107-3p, and miR-370-3p were further confirmed to be related to EA tolerance by an intracerebroventricular injection of agomirs or antagomirs of these miRNAs. Potential targets of the 49 miRNAs were enriched in 9 pathways and 282 gene ontology (GO) terms. Five miRNAs were confirmed to participate in EA tolerance probably through the functional categories related to nerve impulse transmission, receptor signal pathways, and gene expression regulation, as well as pathways related to MAPK, neurotrophin, fatty acid metabolism, lysosome, and the degradation of valine, leucine, and isoleucine. Our findings reveal a characterized panel of the differentially expressed miRNAs in the hypothalamus in response to EA and thus provide a solid experimental framework for future analysis of the mechanisms underlying EA-induced tolerance.

The Effects of Yin, Yang and Qi in the Skin on Pain

The most effective and safe treatment site for pain is in the skin. This chapter discusses the reasons to treat pain in the skin. Pain is sensed in the skin through transient receptor potential cation channels and other receptors. These receptors have endogenous agonists (yang) and antagonists (yin) that help the body control pain. Acupuncture works through modulation of these receptor activities (qi) in the skin; as do moxibustion and liniments. The treatment of pain in the skin has the potential to save many lives and improve pain therapy in most patients.

Analgesic Effect of Electroacupuncture in a Mouse Fibromyalgia Model: Roles of TRPV1, TRPV4, and pERK

Fibromyalgia (FM) is among the most common chronic pain syndromes encountered in clinical practice, but there is limited understanding of FM pathogenesis. We examined the contribution of transient receptor potential vanilloid 1 (TRPV1) and TRPV4 channels to chronic pain in the repeated acid injection mouse model of FM and the potential therapeutic efficacy of electroacupuncture. Electroacupuncture (EA) at the bilateral Zusanli (ST36) acupoint reduced the long-lasting mechanical hyperalgesia induced by repeated acid saline (pH 4) injection in mouse hindpaw. Isolated L5 dorsal root ganglion (DRG) neurons from FM model mice (FM group) were hyperexcitable, an effect reversed by EA pretreatment (FM + EA group). The increase in mechanical hyperalgesia was also accompanied by upregulation of TRPV1 expression and phosphoactivation of extracellular signal regulated kinase (pERK) in the DRG, whereas DRG expression levels of TRPV4, p-p38, and p-JNK were unaltered. Blockade of TRPV1, which was achieved using TRPV1 knockout mice or via antagonist injection, and pERK suppressed development of FM-like pain. Both TRPV1 and TRPV4 protein expression levels were increased in the spinal cord (SC) of model mice, and EA at the ST36 acupoint decreased overexpression. This study strongly suggests that DRG TRPV1 overexpression and pERK signaling, as well as SC TRPV1 and TRPV4 overexpression, mediate hyperalgesia in a mouse FM pain model. The therapeutic efficacy of EA may result from the reversal of these changes in pain transmission pathways.

Recurrent Oligodendroglioma Treated with Acupuncture and Pharmacopuncture

Acupuncture and pharmacopuncture have been shown to be effective in tumor treatment. However, their effectiveness for treating oligodendroglioma has not been reported yet. The purpose of this study was to provide an initial report on the effectiveness of acupuncture and pharmacopuncture for the treatment of an oligodendroglioma by presenting a case that was treated successfully. A 54-year-old man, who had experienced intracranial hemorrhage, was diagnosed with recurrent oligodendroglioma. His expected survival period was 3-6 months. The patient received daily acupuncture and weekly pharmacopuncture of mountain ginseng and bee venom. After treatment for 18 months, the tumor size was decreased markedly on brain magnetic resonance imaging, and severe seizures had disappeared. In this case, a combination of acupuncture and pharmacopuncture was shown to be effective for the treatment of recurrent oligodendroglioma.

Role of Nrf2/ARE pathway in protective effect of electroacupuncture against endotoxic shock-induced acute lung injury in rabbits

NF-E2 related factor 2 (Nrf2) is a major transcription factor and acts as a key regulator of antioxidant genes to exogenous stimulations. The aim of current study was to determine whether Nrf2/ARE pathway is involved in the protective effect of electroacupuncture on the injured lung in a rabbit model of endotoxic shock. A dose of lipopolysaccharide (LPS) 5 mg/kg was administered intravenously to replicate the model of acute lung injury induced by endotoxic shock. Electroacupuncture pretreatment was handled bilaterally at Zusanli and Feishu acupoints for five consecutive days while sham electroacupuncture punctured at non-acupoints. Fourty anesthetized New England male rabbits were randomized into normal control group (group C), LPS group (group L), electroacupuncture + LPS group (group EL) and sham electroacupuncture + LPS (group SEL). At 6 h after LPS administration, the animals were sacrificed and the blood samples were collected for biochemical measurements. The lungs were removed for calculation of wet-to-dry weight ratios (W/D), histopathologic examination, determination of heme oxygenase (HO)-1 protein and mRNA, Nrf2 total and nucleoprotein, as well as Nrf2 mRNA expression, and evaluation of the intracellular distribution of Nrf2 nucleoprotein. LPS caused extensive morphologic lung damage, which was lessened by electroacupuncture treatment. Besides, lung W/D ratios were significantly decreased, the level of malondialdehyde was inhibited, plasma levels of TNF-α and interleukin-6 were decreased, while the activities of superoxide dismutase, glutathione peroxidase and catalase were enhanced in the electroacupucnture treated animals. In addition, electroacupuncture stimulation distinctly increased the expressions of HO-1 and Nrf2 protein including Nrf2 total protein and nucleoprotein as well as mRNA in lung tissue, while these effects were blunted in the sham electroacupuncture group. We concluded that electroacupuncture treatment at ST36 and BL13 effectively attenuates lung injury in a rabbit model of endotoxic shock through activation of Nrf2/ARE pathway and following up-regulation of HO-1 expression.

Mechanisms of acupuncture-electroacupuncture on persistent pain

In the last decade, preclinical investigations of electroacupuncture mechanisms on persistent tissue injury (inflammatory), nerve injury (neuropathic), cancer, and visceral pain have increased. These studies show that electroacupuncture activates the nervous system differently in health than in pain conditions, alleviates both sensory and affective inflammatory pain, and inhibits inflammatory and neuropathic pain more effectively at 2 to 10 Hz than at 100 Hz. Electroacupuncture blocks pain by activating a variety of bioactive chemicals through peripheral, spinal, and supraspinal mechanisms. These include opioids, which desensitize peripheral nociceptors and reduce proinflammatory cytokines peripherally and in the spinal cord, and serotonin and norepinephrine, which decrease spinal N-methyl-D-aspartate receptor subunit GluN1 phosphorylation. Additional studies suggest that electroacupuncture, when combined with low dosages of conventional analgesics, provides effective pain management which can forestall the side effects of often-debilitating pharmaceuticals.

Electroacupuncture Stimulation at CV12 Inhibits Gastric Motility via TRPV1 Receptor

Gastric dysmotility is one of the major pathophysiological factors in functional gastrointestinal disorders. Acupuncture, as one of the alternative approaches, is efficacious in the treatment of gastrointestinal motility disorders; however, the mechanism underlying its action is unclear. In the present study, we used both capsazepine, a TRPV1 antagonist, and TRPV1 knockout mice. Animals were divided into wild-type group (WT), capsazepine injection group (CZP, 0.5 mg/kg, i.p.), and TRPV1 knockout mice group (TRPV1^−/−). Each of these three groups was divided into three subgroups, which were subjected to EA stimulation at acupoint Zhongwan (CV12) at a different intensity (1, 2, or 4 mA). We demonstrated that electroacupuncture at Zhongwan (CV12) markedly inhibited gastric motility at 2 and 4 mA in an intensity-dependent manner in wild-type mice. The inhibitory effect was also observed in capsazepine-injected and TRPV1^−/− mice but was no longer intensity dependent, indicating that TRPV1 is partially involved in the electroacupuncture-mediated modulation of gastric motility.

Molecular mechanisms underlying the effects of acupuncture on neuropathic pain

Acupuncture has been used to treat neuropathic pain for a long time, but its mechanisms of action remain unknown. In this study, we observed the effects of electroacupuncture and manual acu-puncture on neuropathic pain and on ephrin-B/EphB signaling in rats models of chronic constriction injury-induced neuropathic pain. The results showed that manual acupuncture and elec-puncture significantly reduced mechanical hypersensitivity following chronic constriction injury, es-pecially electroacupuncture treatment. Real-time PCR results revealed that ephrin-B1/B3 and EphB1/B2 mRNA expression levels were significantly increased in the spinal dorsal horns of chronic constriction injury rats. Electroacupuncture and manual acupuncture suppressed the high sion of ephrin-B1 mRNA, and elevated EphB3/B4 mRNA expression. Electroacupuncture signifi-cantly enhanced the mRNA expression of ephrin-B3 and EphB3/B6 in the dorsal horns of neuro-pathic pain rats. Western blot results revealed that electroacupuncture in particular, and manual acupuncture, significantly up-regulated ephrin-B3 protein levels in rat spinal dorsal horns. The re-sults of this study suggest that acupuncture could activate ephrin-B/EphB signaling in neuropathic pain rats and improve neurological function.

Low Frequency Electroacupuncture Alleviated Spinal Nerve Ligation Induced Mechanical Allodynia by Inhibiting TRPV1 Upregulation in Ipsilateral Undamaged Dorsal Root Ganglia in Rats

Neuropathic pain is an intractable problem in clinical practice. Accumulating evidence shows that electroacupuncture (EA) with low frequency can effectively relieve neuropathic pain. Transient receptor potential vanilloid type 1 (TRPV1) plays a key role in neuropathic pain. The study aimed to investigate whether neuropathic pain relieved by EA administration correlates with TRPV1 inhibition. Neuropathic pain was induced by right L5 spinal nerve ligation (SNL) in rats. 2 Hz EA stimulation was administered. SNL induced mechanical allodynia in ipsilateral hind paw. SNL caused a significant reduction of TRPV1 expression in ipsilateral L5 dorsal root ganglia (DRG), but a significant up-regulation in ipsilateral L4 and L6 DRGs. Calcitonin gene-related peptide (CGRP) change was consistent with that of TRPV1. EA alleviated mechanical allodynia, and inhibited TRPV1 and CGRP overexpressions in ipsilateral L4 and L6 DRGs. SNL did not decrease pain threshold of contralateral hind paw, and TRPV1 expression was not changed in contralateral L5 DRG. 0.001, 0.01 mg/kg TRPV1 agonist 6'-IRTX fully blocked EA analgesia in ipsilateral hind paw. 0.01 mg/kg 6'-IRTX also significantly decreased pain threshold of contralateral paw. These results indicated that inhibition of TRPV1 up-regulation in ipsilateral adjacent undamaged DRGs contributed to low frequency EA analgesia for mechanical allodynia induced by spinal nerve ligation.

Acupuncture for cancer pain and related symptoms

Cancer pain is one of most prevalent symptoms in patients with cancer. Acupuncture and related techniques have been suggested for the management of cancer pain. The National Comprehensive Cancer Network guidelines for adult cancer pain recommends acupuncture, as one of several integrative interventions, in conjunction with pharmacologic intervention as needed. This review presents the latest available evidence regarding the use of acupuncture for cancer pain. It also provides "actionable" acupuncture protocols for specific cancer pain conditions and related symptoms in order to provide more clinically relevant solutions for clinicians and cancer patients with pain. These conditions include postoperative cancer pain, postoperative nausea and vomiting, postsurgical gastroparesis syndrome, opioid-induced constipation, opioid-induced pruritus, chemotherapy-induced neuropathy, aromatase inhibitor-associated joint pain, and neck dissection-related pain and dysfunction.

Electroacupuncture inhibition of hyperalgesia in rats with adjuvant arthritis: involvement of cannabinoid receptor 1 and dopamine receptor subtypes in striatum

Electroacupuncture (EA) has been regarded as an alternative treatment for inflammatory pain for several decades. However, the molecular mechanisms underlying the antinociceptive effect of EA have not been thoroughly clarified. Previous studies have shown that cannabinoid CB1 receptors are related to pain relief. Accumulating evidence has shown that the CB1 and dopamine systems sometimes interact and may operate synergistically in rat striatum. To our knowledge, dopamine D1/D2 receptors are involved in EA analgesia. In this study, we found that repeated EA at Zusanli (ST36) and Kunlun (BL60) acupoints resulted in marked improvements in thermal hyperalgesia. Both western blot assays and FQ-PCR analysis results showed that the levels of CB1 expression in the repeated-EA group were much higher than those in any other group (P = 0.001). The CB1-selective antagonist AM251 inhibited the effects of repeated EA by attenuating the increases in CB1 expression. The two kinds of dopamine receptors imparted different actions on the EA-induced CB1 upregulation in AA rat model. These results suggested that the strong activation of the CB1 receptor after repeated EA resulted in the concomitant phenomenon of the upregulation of D1 and D2 levels of gene expression.

Electroacupuncture improves thermal and mechanical sensitivities in a rat model of postherpetic neuralgia

Background

Electroacupuncture (EA) is effective in relieving pain in patients with postherpetic neuralgia (PHN). However, the mechanism underlying the therapeutic effect of EA in PHN is still unclear. Systemic injection of resiniferatoxin (RTX), an ultrapotent analog of TRPV1 agonist, in adult rats can reproduce the clinical symptoms of PHN by ablating TRPV1-expressing sensory neurons. In this study, we determined the beneficial effect of EA and the potential mechanisms in this rat model of PHN.

Methods

PHN was induced in rats by a single injection of RTX. Thermal hyperalgesia was tested with a radiant heat stimulus, and mechanical allodynia was quantified with von Frey filaments. TRPV1 receptors were shown by using immunofluorescence labeling. The ultrastructural changes of the sciatic nerve were assessed by electron microscopic examination. The sprouting of myelinated primary afferent terminals into the spinal dorsal horn was mapped by using the transganglionic tracer cholera toxin B-subunit (CTB).

Results

RTX injection diminished thermal sensitivity and gradually induced tactile allodynia within 3 weeks. EA applied to GB30 and GB34 at 2 and 15 Hz, but not 100 Hz, significantly increased the thermal sensitivity 4 weeks after treatment and decreased the tactile allodynia 2 weeks after treatment in RTX-treated rats. EA treatment at 2 and 15 Hz recovered the loss of TRPV1-positive dorsal root ganglion neurons and their central terminals of afferent fibers in the spinal superficial dorsal horn of RTX-treated rats. Moreover, EA significantly reduced the loss of unmyelinated fibers and the damage of the myelinated nerve fibers of RTX-treated rats. Furthermore, EA at 2 and 15 Hz inhibited the sprouting of myelinated primary afferent terminals into the spinal lamina II of RTX-treated rats.

Conclusions

EA treatment improves thermal perception by recovering TRPV1-positive sensory neurons and nerve terminals damaged by RTX. EA Also reduces RTX-induced tactile allodynia by attenuating the damage of myelinated afferent nerves and their abnormal sprouting into the spinal lamina II. Our study provides new information about the mechanisms of the therapeutic actions of EA in the treatment of PHN.

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

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

Effects of different electroacupuncture scheduling regimens on murine bone tumor-induced hyperalgesia: sex differences and role of inflammation

Previous studies have shown that electroacupuncture (EA) is able to reduce hyperalgesia in rodent models of persistent pain, but very little is known about the analgesic effects and potential sex differences of different EA treatment regimens. In the present study, we examined the effects of five different EA treatments on tumor-induced hyperalgesia in male and female mice. EA applied to the ST-36 acupoint either twice weekly (EA-2X/3) beginning on postimplantation day (PID) 3 or prophylactically three times prior to implantation produced the most robust and longest lasting antinociceptive effects. EA treatment given once per week beginning at PID 7 only produced an antinociceptive effect in female animals. The analgesic effect of EA-2X/3 began earlier in males, but lasted longer in females indicating sex differences in EA. We further demonstrate that EA-2X/3 elicits a marked decrease in tumor-associated inflammation as evidenced by a significant reduction in tumor-associated neutrophils at PID 7. Moreover, EA-2X/3 produced a significant reduction in tumor-associated PGE(2) as measured in microperfusate samples. Collectively, these data provide evidence that EA-2X/3 treatment reduces tumor-induced hyperalgesia, which is associated with a decrease in tumor-associated inflammation and PGE(2) concentration at the tumor site suggesting possible mechanisms by which EA reduces tumor nociception.

Attenuation of TRPV1 and TRPV4 Expression and Function in Mouse Inflammatory Pain Models Using Electroacupuncture

Although pain is a major human affliction, our understanding of pain mechanisms is limited. TRPV1 (transient receptor potential vanilloid subtype 1) and TRPV4 are two crucial receptors involved in inflammatory pain, but their roles in EA- (electroacupuncture-) mediated analgesia are unknown. We injected mice with carrageenan (carra) or a complete Freund's adjuvant (CFA) to model inflammatory pain and investigated the analgesic effect of EA using animal behavior tests, immunostaining, Western blotting, and a whole-cell recording technique. The inflammatory pain model mice developed both mechanical and thermal hyperalgesia. Notably, EA at the ST36 acupoint reversed these phenomena, indicating its curative effect in inflammatory pain. The protein levels of TRPV1 and TRPV4 in DRG (dorsal root ganglion) neurons were both increased at day 4 after the initiation of inflammatory pain and were attenuated by EA, as demonstrated by immunostaining and Western blot analysis. We verified DRG electrophysiological properties to confirm that EA ameliorated peripheral nerve hyperexcitation. Our results indicated that the AP (action potential) threshold, rise time, and fall time, and the percentage and amplitude of TRPV1 and TRPV4 were altered by EA, indicating that EA has an antinociceptive role in inflammatory pain. Our results demonstrate a novel role for EA in regulating TRPV1 and TRPV4 protein expression and nerve excitation in mouse inflammatory pain models.