Transcutaneous electrical nerve stimulation attenuates CFA-induced hyperalgesia and inhibits spinal ERK1/2-COX-2 pathway activation in rats

Persistent peripheral inflammation and pain induces immediate early gene activation in supraspinal nuclei in rats

Pain is a public health concern worldwide and can present simultaneously with anxiety and depression. c-Fos is a marker used to identify activated cells in response to various stimuli. Specifically, it can be used as a brain marker of pain. We examined whether peripheral inflammation produces mechanical allodynia, anxiety- and depression-related behaviors in male rats (Rattus norvegicus, Wistar strain) and if these behaviors can have an impact on c-Fos expression in the supraspinal nuclei involved in pain control. We assessed mechanical thresholds by von Frey monofilaments, depression-like behaviors in the forced swimming test (FST) and anxiety-related behaviors in the open field test (OFT) after the administration of the inflamogen Complete Freund´s Adjuvant (CFA) in rats. We found that CFA increased paw diameter is all rats, however, CFA treatment resulted in a subgroup of rats developing allodynia [CFA- mechanical allodynia (CFA-MA)] and a subgroup of rats not developing allodynia [CFA-no mechanical allodynia (CFA-NMA)]. At the peak of tactile allodynia and inflammation, results were coupled with an increase in c-Fos expression in several supraspinal brain nuclei, i.e. basolateral amygdala, periaqueductal gray matter and rostroventromedial medulla in CFA-MA rats. Moreover, we found a correlation between c-Fos levels and mechanical thresholds. No modification in c-Fos expression was observed in CFA-NMA rats. CFA did not modulate behaviors in the OFT or FST. In summary, we show that mechanical allodynia but not peripheral inflammation activates c-Fos in several supraspinal nuclei, which sheds new light on brain regions involved in the control of pain following peripheral injury and decouples this effect from mere peripheral inflammation. This model may be used to study resistance to pain development in future studies.

Transcutaneous electrical nerve stimulation for pelvic pain: A scoping review of treatment protocols, practical indications, and caveats

BACKGROUND

Neuromodulation (NM) is a family of therapies based on electrical stimulation to target specific nerves that control LUTS (Lower Urinary Tract Symptoms) and pain. The aim is to modulate what is happening within the nervous system to achieve therapeutic effects. A particular type of neuromodulation, called TENS (Transcutaneous Electrical Nerve Stimulation), has proven effective for treating pelvic pain. The available evidence provides indications regarding the many aspects of TENS that influence therapeutic effects, but a comprehensive review has yet to be conducted.

METHODS

Scoping review on Pubmed, CINAHL, Embase, Scopus, and Web of Science, including clinical trials, reviews, case studies or series, and other descriptive studies, according to the Joanna Briggs and PRISMA methodology.

RESULTS

The 31 papers retrieved allowed the formulation of precise indications about the DOs and DON'Ts of electrode placement, waveform, pulse duration, pulse frequency, amplitude, session duration, and frequency of sessions. This paper also discusses the biochemical and neuro urological mechanisms of TENS.

CONCLUSION

TENS effectiveness is influenced by many factors, some self-evident, others subtle, which this paper elucidates. Pelvic pain requires a multimodal approach, of which TENS is just a part. TENS should therefore be viewed as one of the components of the rehabilitation program in the frame of thorough and continuous patient assessment.

AAV-glycine receptor α3 alleviates CFA-induced inflammatory pain by downregulating ERK phosphorylation and proinflammatory cytokine expression in SD rats

BACKGROUND

Glycine receptors (GlyRs) play key roles in the processing of inflammatory pain. The use of adeno-associated virus (AAV) vectors for gene therapy in human clinical trials has shown promise, as AAV generally causes a very mild immune response and long-term gene transfer, and there have been no reports of disease. Therefore, we used AAV for GlyRα1/3 gene transfer in F11 neuron cells and into Sprague-Dawley (SD) rats to investigate the effects and roles of AAV-GlyRα1/3 on cell cytotoxicity and inflammatory response.

METHODS

In vitro experiments were performed using plasmid adeno-associated virus (pAAV)-GlyRα1/3-transfected F11 neurons to investigate the effects of pAAV-GlyRα1/3 on cell cytotoxicity and the prostaglandin E2 (PGE2)-mediated inflammatory response. In vivo experiment, the association between GlyRα3 and inflammatory pain was analyzed in normal rats after AAV-GlyRα3 intrathecal injection and after complete Freund's adjuvant (CFA) intraplantar administration. Intrathecal AAV-GlyRα3 delivery into SD rats was evaluated in terms of its potential for alleviating CFA-induced inflammatory pain.

RESULTS

The activation of mitogen-activated protein kinase (MAPK) inflammatory signaling and neuronal injury marker activating transcription factor 3 (ATF-3) were evaluated by western blotting and immunofluorescence; the level of cytokine expression was measured by ELISA. The results showed that pAAV/pAAV-GlyRα1/3 transfection into F11 cells did not significantly reduce cell viability or induce extracellular signal-regulated kinase (ERK) phosphorylation or ATF-3 activation. PGE2-induced ERK phosphorylation in F11 cells was repressed by the expression of pAAV-GlyRα3 and administration of an EP2 inhibitor, GlyRαs antagonist (strychnine), and a protein kinase C inhibitor. Additionally, intrathecal AAV-GlyRα3 administration to SD rats significantly decreased CFA-induced inflammatory pain and suppressed CFA-induced ERK phosphorylation, did not induce obvious histopathological injury but increased ATF-3 activation in dorsal root ganglion (DRGs).

CONCLUSIONS

Antagonists of the prostaglandin EP2 receptor, PKC, and glycine receptor can inhibit PGE2-induced ERK phosphorylation. Intrathecal AAV-GlyRα3 administration to SD rats significantly decreased CFA-induced inflammatory pain and suppressed CFA-induced ERK phosphorylation, did not significantly induce gross histopathological injury but elicited ATF-3 activation. We suggest that PGE2-induced ERK phosphorylation can be modulated by GlyRα3, and AAV-GlyRα3 significantly downregulated CFA-induced cytokine activation.

Microfluidic Electroceuticals Platform for Therapeutic Strategies of Intervertebral Disc Degeneration: Effects of Electrical Stimulation on Human Nucleus Pulposus Cells under Inflammatory Conditions

The degeneration of an intervertebral disc (IVD) is a major cause of lower back pain. IVD degeneration is characterized by the abnormal expression of inflammatory cytokines and matrix degradation enzymes secreted by IVD cells. In addition, macrophage-mediated inflammation is strongly associated with IVD degeneration. However, the precise pathomechanisms of macrophage-mediated inflammation in IVD are still unknown. In this study, we developed a microfluidic platform integrated with an electrical stimulation (ES) array to investigate macrophage-mediated inflammation in human nucleus pulposus (NP). This platform provides multiple cocultures of different cell types with ES. We observed macrophage-mediated inflammation and considerable migration properties via upregulated expression of interleukin (IL)-6 (p < 0.001), IL-8 (p < 0.05), matrix metalloproteinase (MMP)-1 (p < 0.05), and MMP-3 (p < 0.05) in human NP cells cocultured with macrophages. We also confirmed the inhibitory effects of ES at 10 μA due to the production of IL-6 (p < 0.05) and IL-8 (p < 0.01) under these conditions. Our findings indicate that ES positively affects degenerative inflammation in diverse diseases. Accordingly, the microfluidic electroceutical platform can serve as a degenerative IVD inflammation in vitro model and provide a therapeutic strategy for electroceuticals.

The effects of TENS, interferential stimulation, and combined interferential stimulation and pulsed ultrasound on patients with disc herniation-induced radicular pain

BACKGROUND

Electrotherapy is part of a physician's toolbox for treating various musculoskeletal conditions, including radicular pain, but the preferred modality is yet unclear.

OBJECTIVE

To compare the short-term efficacy of three electrotherapeutic modalities in relieving lumbar disc herniation (LDH)-induced radicular pain.

METHODS

Fourteen patients with LDH-induced radicular pain attended a single session of electrotherapy, which included four 10-min consecutive treatments: transcutaneous electrical nerve stimulation (TENS), interferential (IF) stimulation, a combined treatment with pulsed ultrasound and IF current (CTPI), and a sham control. Treatments were randomized and the straight leg raise (SLR) degree was measured immediately before and after each treatment.

RESULTS

Each of the three active modalities significantly improved the SLR score. The most prominent improvement was observed in the CTPI condition, followed by IF and, finally, TENS. The sham stimulation did not affect the SLR scores.

CONCLUSIONS

A single session with either TENS, IF current or CTPI is sufficient to improve the range of motion and degree of radicular pain associated with LDH. CTPI appears to be the most effective modality of the three, possibly due to greater penetration efficiency of the induced current. The effects of a long-term treatment schedule are yet to be identified.

Benefits of electroacupuncture and a swimming association when compared with isolated protocols in an osteoarthritis model

Background and aim

Osteoarthritis (OA) is characterized by pain and inflammation. Electroacupuncture (EA) and swimming (SW) are non-pharmacological interventions recommended for treating OA. The study evaluated the benefits of electroacupuncture (EA) and swimming (SW) association when compared with isolated protocols in an OA rodent model. Experimental.

Procedures

An ankle monoarthritis model was induced in rats by applying Complete Freund's Adjuvant (CFA). After seven days of induced OA, the groups were submitted to EA (ST36 and the GB 30 Acupoint), SW, or the EA + SW protocol. The nociceptive behavior was measured by the Von Frey test, the Cold Stimulation test, and the Paw Flick Immersion test. Inflammatory activity was evaluated by measuring TNF levels, myeloperoxidase, NAGase, immunological parameters and the histology from the subcutaneous tissue.

Results

Compared to CFA group, EA decreased the nociceptive scores in the cold stimulation test (p < 0.05), and it also increased the latency time in thermal cold (p < 0.01) and heat hyperalgesia (p < 0.001). Also, EA reduced NAGase (p < 0.01). SW reduced the edema (p < 0.05) and did not increase the inflammatory infiltrates or congestion, neither in the histological measurements nor by analyzing the levels of TNF. The association of EA + SW decreased the neutrophils and the monocytes, MPO (p < 0.05), and the glutamate levels in the cerebrospinal fluid (CSF, p < 0.001).

Conclusion

There were statistical differences between combination therapy and monotherapy as seen by the inflammatory parameters, which could be associate to the delay of the chronification osteoarthritis retardation. However, EA + SW did not show benefits when compared to isolated protocols in nociceptive behavior.

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Electroacupuncture (EA) extended the latency time in the thermal hyperalgesia assay.

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The swimming protocol did not increase the inflammatory infiltrates.

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EA and swimming decreased the glutamate levels in the cerebral spinal fluid.

Resolving Long-Standing Uncertainty about the Clinical Efficacy of Transcutaneous Electrical Nerve Stimulation (TENS) to Relieve Pain: A Comprehensive Review of Factors Influencing Outcome

Pain is managed using a biopsychosocial approach and pharmacological and non-pharmacological treatments. Transcutaneous electrical nerve stimulation (TENS) is a technique whereby pulsed electrical currents are administered through the intact surface of the skin with the intention of alleviating pain, akin to 'electrically rubbing pain away'. Despite over 50 years of published research, uncertainty about the clinical efficacy of TENS remains. The purpose of this comprehensive review is to critically appraise clinical research on TENS to inform future strategies to resolve the 'efficacy-impasse'. The principles and practices of TENS are described to provide context for readers unfamiliar with TENS treatment. The findings of systematic reviews evaluating TENS are described from a historical perspective to provide context for a critical evaluation of factors influencing the outcomes of randomized controlled trials (RCTs); including sample populations, outcome measures, TENS techniques, and comparator interventions. Three possibilities are offered to resolve the impasse. Firstly, to conduct large multi-centered RCTs using an enriched enrolment with randomized withdrawal design, that incorporates a 'run-in phase' to screen for potential TENS responders and to optimise TENS treatment according to individual need. Secondly, to meta-analyze published RCT data, irrespective of type of pain, to determine whether TENS reduces the intensity of pain during stimulation, and to include a detailed assessment of levels of certainty and precision. Thirdly, to concede that it may be impossible to determine efficacy due to insurmountable methodological, logistical and financial challenges. The consequences to clinicians, policy makers and funders of this third scenario are discussed. I argue that patients will continue to use TENS irrespective of the views of clinicians, policy makers, funders or guideline panel recommendations, because TENS is readily available without prescription; TENS generates a pleasant sensory experience that is similar to easing pain using warming and cooling techniques; and technological developments such as smart wearable TENS devices will improve usability in the future. Thus, research is needed on how best to integrate TENS into existing pain management strategies by analyzing data of TENS usage by expert-patients in real-world settings.

Repeated administration of a flavonoid-based formulated extract from citrus peels significantly reduces peripheral inflammation-induced pain in the rat

Depression-related disorders are the first cause of disability worldwide according to the World Health Organization, and there is limited availability of effective antidepressant medications without side effects. Similarly, pain management is a public health concern particularly due to the increase in use of opioid medications, which have a significant side effect profile. Flavonoids can modulate numerous physiological functions including emotional and anti-nociceptive processes. Gold lotion (GL) is a natural product based on the extract of six citrus peels rich in flavonoids (0.45 mg/ml) with numerous reported biological activities. In the present study, we investigated the effect of repeated administration of GL in a battery of behavioral tests, including the open field test (OFT), forced swim test (FST), and von Frey test (vFT), in rats. While the OFT measured anxiolytic-related effects, the FST evaluated depression-related behavior. The vFT evaluated mechanical allodynia in two rat models of peripheral inflammation induced by carrageenan or complete Freund's adjuvant (CFA) administration. Treatment with GL reduced mechanical allodynia after either carrageenan or CFA administration. On the other hand, repeated GL administration did not modulate any behavior evaluated by OFT or FST. Consumption of GL inhibits behavioral signs of inflammatory pain. Therefore, GL may be a valuable analgesic product to be used for inflammatory pain.

Efficacy of Transcutaneous Electronic Nerve Stimulation in Postoperative Analgesia After Pulmonary Surgery: A Systematic Review and Meta-Analysis

OBJECTIVE

The aim of the study was to identify the analgesic efficacy and safety of transcutaneous electronic nerve stimulation in postoperative pain after pulmonary surgery.

DESIGN

Electronic databases (PubMed, Embase, Web of Science, and CENTRAL) were systematically searched from their inception to June 2019. The continuous variables were pooled as the weighted mean difference with correlated 95% confidence interval. Results were recognized as significant when a P value is less than 0.05. Subgroup analyses, sensitivity analyses, and quality assessment were performed.

RESULTS

Altogether, 10 studies were included. The pooled results indicated that transcutaneous electronic nerve stimulation group conferred lower pain intensity score on the first postoperative day (weighted mean difference = -0.93, 95% confidence interval = -1.56 to -0.30, P = 0.004), postoperative day 2 (weighted mean difference = -1.00, 95% confidence interval = -1.64 to -0.35, P = 0.002), postoperative day 3 (weighted mean difference = -0.92, 95% confidence interval = -1.76 to -0.09, P = 0.03), postoperative day 4 (weighted mean difference = -0.90, 95% confidence interval = -1.24 to -0.56, P < 0.001), and postoperative day 5 (weighted mean difference = -1.39, 95% confidence interval = -2.20 to -0.57, P < 0.001) compared with the placebo transcutaneous electronic nerve stimulation group. No publication bias was found. No significant discovery was obtained in sensitivity analyses.

CONCLUSIONS

Transcutaneous electronic nerve stimulation might be an effective supplementary analgesic regimen in multimodal analgesia to decrease pain intensity after pulmonary surgery.

Electrical impulse effects on degenerative human annulus fibrosus model to reduce disc pain using micro-electrical impulse-on-a-chip

Electrical stimulation of cells and tissues for therapeutic benefit is a well-established method. Although animal studies can emulate the complexity of an organism’s physiology, lab-on-a-chip platforms provide a suitable primary model for follow-up animal studies. Thus, inexpensive and easy-to-use platforms for in vitro human cell studies are required. In the present study, we designed a micro-electrical impulse (micro-EI)-on-a-chip (micro-EI-chip), which can precisely control electron density and adjust the frequency based on a micro-EI. The micro-EI-chip can stimulate cells at various micro-EI densities (0–500 mV/mm) and frequencies (0–300 Hz), which enables multiple co-culture of different cell types with or without electrical stimulation. As a proof-of-concept study, a model involving degenerative inflamed human annulus fibrosus (hAF) cells was established in vitro and the effects of micro-EI on inflamed hAF cells were evaluated using the micro-EI-chip. Stimulation of the cells (150 mV/mm at 200 Hz) inhibited the secretion of inflammatory cytokines and downregulated the activities of extracellular matrix-modifying enzymes and matrix metalloproteinase-1. These results show that micro-EI stimulation could affect degenerative diseases based on inflammation, implicating the micro-EI-chip as being useful for basic research of electroceuticals.

Inhibition of lncRNA X inactivate-specific transcript ameliorates inflammatory pain by suppressing satellite glial cell activation and inflammation by acting as a sponge of miR-146a to inhibit Nav 1.7

Long noncoding RNAs (lncRNA) has been validated to participate in nociception in inflammatory pain, presenting as a potential target against anesthesia. Previous research work confirmed the correlation between lncRNA X inactivate-specific transcript (XIST) and inflammation. However, its role in inflammatory pain is undefined. In animal pain models, voltage-gated sodium channels (VGSCs) reportedly participate in neural excitation. In this study, we observed the high expression of XIST and VGSC 1.7 (Na_v 1.7) in the dorsal root ganglion (DRG) of the complete Freund's adjuvant (CFA)-induced rat inflammatory pain model. Furthermore, XIST inhibition alleviated pain behavior and the activation of DRG satellite glial cells by suppressing glial fibrillary acidic protein (GFAP) expression, as well as inflammatory cytokine levels of interleukin-6 and tumor necrosis factor-α. XIST downregulation increased the mechanical pain threshold in an inflammatory pain model. Moreover, the expression of miR-146a was decreased in CFA rats. In vitro, XIST acted as a sponge of miR-146a, which targeted Na_v 1.7 via bioinformatic prediction, luciferase reporter, and pull-down assay. More importantly, activation of the Na_v 1.7 pathway or miR-146 depression both reversed XIST knockdown-inhibited satellite glial cell activation and inflammatory pain in CFA rats. These results suggest that cessation of XIST may ameliorate inflammatory pain by acting as a sponge of miR-146a to inhibit Nav1.7, implying a promising strategy against inflammatory pain.

Analgesic Effect of Moxibustion with Different Temperature on Inflammatory and Neuropathic Pain Mice: A Comparative Study

The aim of this study was to determine whether variation of temperature during moxibustion would generate division of analgesic effect. The moxibustion with different temperatures (37°C, 42°C, 47°C, and 52°C) was applied to ST36 acupoint for 30 minutes in chronic inflammatory or neuropathic pain mice. The analgesic effect was evaluated by thermal hyperalgesia test in chronic inflammatory pain and by mechanical allodynia in neuropathic pain, respectively. The results indicated that interventions of moxibustion with different temperature caused different analgesic effect on either chronic inflammatory induced by injection of complete Freund's adjuvant (CFA) or neuropathic pain induced by spared nerve injury (SNI). In chronic inflammatory pain, different moxibustion temperature generated different intensity of analgesic effect: the higher the better. In chronic neuropathic pain, stronger analgesic effect was found in moxibustion with temperature 47°C or 52°C other than 37°C and 42°C. However, there is no significant difference displayed between moxibustion temperatures 47°C and 52°C or 37°C and 42°C. It implies that the temperature should be taken into account for moxibustion treatment to chronic inflammatory or neuropathic pain.

TENS-like Stimulation Downregulates Inflammatory Cytokines in a PC-12 Cell Line

OBJECTIVES

The purpose of this study was to evaluate the effects of transcutaneous electrical nerve stimulation (TENS)-like stimulation on the expression of the proinflammatory cytokines tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β), and IL-6 in PC-12 cells, which are commonly used as neuronal cell models.

METHODS

Nerve growth factor-differentiated PC-12 cells were exposed to electrical stimulation for 15 minutes at 1 mA, 200 μs, and 100 Hz. Cell lysate from stimulated and control cells was assayed for TNF-α, IL-1β, and IL-6. In 6 trials, cells were preincubated with the L-type ion channel blocker nicardipine. Cultured cells were also incubated with Alexa Fluor 488 and visualized by fluorescence microscopy to determine the nuclear vs cytoplasmic distribution of the p65 sub-unit of NF-κB RESULTS: Compared with control (unstimulated) cells, the stimulated cells had a downregulation of the assayed cytokines. However, preincubation with the L-type ion channel blocker nicardipine blocked this effect of stimulation. Additionally, it was noted that TENS-like stimulation promoted a relative sequestration of the p65 subunit of NF-κB in the cytoplasm vs the nucleus.

CONCLUSIONS

It appears that in this cell line and with these stimulation parameters, TENS-like stimulation attenuated the expression of the assayed proinflammatory cytokines, in part by promoting the relative sequestration of the p65 subunit of NF-κB in the cytoplasm, and that voltage-dependent calcium channels have a role in the cascade of events initiated by the TENS-like stimulation.

Anti-arthritic property of crude extracts of Piptadeniastrum africanum (Mimosaceae) in complete Freund's adjuvant-induced arthritis in rats

BACKGROUND

Rheumatoid arthritis, disease of unknown causes is a rheumatic and autoimmune pathology, recognised for its increasing frequency and its adverse consequences. It is a disease that occurs in most cases between 50 and 60 years and women are more affected than men. This study aimed at evaluating immunomodulatory and anti-arthritis capacity of aqueous and methanol extracts of stem bark of Piptadeniastrum africanum (Mimosaceae).

METHODS

ROS production from phagocytes, proliferation of T-cells, TNF-α and IL-1β production and cytotoxicity were performed by using chemiluminescence technique, liquid scintillation counter, ELISA and MTT assay, respectively. Anti-arthritic activity was evaluated using a model of adjuvant induced arthritis.

RESULTS

Methanol and aqueous extracts of Piptadeniastrum africanum significantly (P < 0.001) inhibited extracellular and intracellular ROS production. These extracts also possess significant (P < 0.001) inhibitory activity on T-cell proliferation other than reduced TNF-α and IL-1β production. Piptadeniastrum africanum also significantly exhibited antiarthritic activity in complete Freund's adjuvant induced arthritis in rat associated with a significant anti-inflammatory and anti-hyperalgesia activity.

CONCLUSIONS

Immunomodulatory, anti-inflammatory, antihyperalgesia and anti-arthritis potential revealed in this study approve that, Piptadeniastrum africanum is a plant rich in compounds with anti-arthritic properties.

Anti-inflammatory and anti-arthritic activity of a methanol extract from Vitellaria paradoxa stem bark

BACKGROUND

Vitellaria paradoxa is a traditional medicinal plant of Cameroon. Several studies on this plant have focused on the cosmetic profile of its fruits. The present study focuses on the anti-inflammatory potency of stem barks extract of this plant.

OBJECTIVE

The objective was to evaluate the effect of methanolic extract of V. paradoxa (VPME) stem barks on inflammatory response in rats.

MATERIALS AND METHODS

Anti-inflammatory effects of VPME were evaluated in acute and chronic (28 days) inflammation induced in Wistar albino rats. The effects on hyperalgesia and locomotors activity were also quantified. The relative weight of lymphoid organs was obtained as well as some hematological parameters.

RESULTS

In the carrageenan-induced inflammation, VPME (75 mg/kg) exhibited a significant (66.67%) inhibition after 1 h. On the complete Freund's adjuvant-induced rheumatoid arthritis, VPME showed a significant protective effect with 8.12% inflammation against 25.00% for the control group after 2 days of the treatment. The extract (75 and 150 mg/kg) significantly reduced the score of arthritis with a maximum obtained on day 19(th) of the experimentation. There was a significant increase in the reaction time of rats on the hot plate as well as the exploratory activities of the animals in the open field. This extract significantly prevented weight, hemoglobin and red blood cells losses, and spleen hypertrophy. A protective action against skin destruction and cartilage erosion was evident. Liquid chromatography-mass spectrometry analysis of the extract revealed the presence of catechins.

CONCLUSIONS

These findings suggested that V. paradoxa may contribute to the reduction of the inflammatory response.

A comparison study of immune-inflammatory response in electroacupuncture and transcutaneous electrical nerve stimulation for patients undergoing supratentorial craniotomy

OBJECTIVE

The effect of transcutaneous electrical nerve stimulation (TENS) on immuno-inflammatory response was tested and the differences between electroacupuncture (EA) and TENS in immuno-inflammatory response in patients undergoing supratentorial craniotomy were explored.

METHODS

51 patients received craniotomy were divided randomly into 3 groups: control (group C, n=18), EA (group A, n=19) and TENS (group T, n=14) groups. Blood samples were collected before anesthesia (T0) and 30 min (T1), 2 h (T2) and 4 h (T3) after induction of anesthesia to measure the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-8, IL-10, IgM, IgA and IgG..

RESULTS

No significant difference existed between groups A and group T during craniotomy. IgM and IgA decreased significantly in group C compared with groups A and T at T2 and T3 time points. Compared with group C, there were significant difference in TNF-α, IgM and IgA level at T0 in groups A and T; no significant difference was found in the levels of IgG, IL-10 and IL-8.

CONCLUSION

EA and TENS could reduce immunosuppression in patients undergoing supratentorial craniotomy and it has significance in choice of treatment in immunosuppressive therapy.

Decreased low back pain intensity and differential gene expression following Calmare®: results from a double-blinded randomized sham-controlled study

In this double-blinded, randomized controlled trial we evaluated the effects of Calmare®, a non-invasive neurocutaneous electrical pain intervention, on lower back pain intensity as measured by the "worst" pain score and on pain interference using the Brief Pain Inventory-Short Form, on measures of pain sensitivity assessed by quantitative sensory testing, and on mRNA expression of pain sensitivity genes. Thirty participants were randomized to receive up to 10 sessions of Calmare® treatment (n = 15) or a sham treatment (n = 15) using the same device at a non-therapeutic threshold. At 3 weeks after conclusion of treatment, compared with the sham group, the Calmare® group reported a significant decrease in the "worst" pain and interference scores. There were also significant differences in pain sensitivity and differential mRNA expression of 17 pain genes, suggesting that Calmare® can be effective in reducing pain intensity and interference in individuals with persistent low back pain by altering the mechanisms of enhanced pain sensitivity. Further study of long-term pain outcomes, particularly functional status, analgesic use and health care utilization, is warranted.

A comparison study of immune-inflammatory response in electroacupuncture and transcutaneous electrical nerve stimulation for patients undergoing supratentorial craniotomy

OBJECTIVE

The effect of transcutaneous electrical nerve stimulation (TENS) on immuno-inflammatory response was tested and the differences between electroacupuncture (EA) and TENS in immuno-inflammatory response in patients undergoing supratentorial craniotomy were explored.

METHODS

51 patients received craniotomy were randomly divided into 3 groups: control (group C, n=18), EA (group A, n=19) and TENS (group T, n=14) groups. Blood samples were collected before anesthesia (T0) and 30 min (T1), 2 h (T2) and 4 h (T3) after induction of anesthesia to measure the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-8, IL-10, IgM, IgA and IgG.

RESULTS

No significant difference existed between group A and group T during craniotomy. IgM and IgA decreased significantly in group C compared with groups A and T at T2 and T3 time points. Compared with group C, there were significant differences in TNF-α, IgM and IgA levels at T0 in groups A and T; no significant difference was found in the levels of IgG, IL-10 and IL-8.

CONCLUSION

EA and TENS could reduce immunosuppression in patients undergoing supratentorial craniotomy and it has significance in choice of treatment in immunosuppressive therapy.

Electroacupuncture mediates extracellular signal-regulated kinase 1/2 pathways in the spinal cord of rats with inflammatory pain

Background

Activation of extracellular signal-regulated kinase1/2 (ERK1/2) in dorsal horn of the spinal cord by peripheral inflammation is contributed to inflammatory pain hypersensitivity. Although electroacupuncture (EA) has been widely used to alleviate various kinds of pain, the underlying mechanism of EA analgesia requires further investigation. This study investigated the relationship between EA-induced analgesia and ERK signaling involved in pain hypersensitivity.

Methods

The rats were randomly divided into control, model, EA and sham EA groups. Inflammatory pain model was induced by injecting of 100 μl Complete Freund’s adjuvant (CFA) into the plantar surface of a hind paw. Rats in the EA group were treatment with EA (constant aquare wave, 2 Hz and 100 Hz alternating frequencies, intensities ranging from 1-2 mA) at 5.5 h, 24.5 h and 48.5 h. Paw withdrawal thresholds (PWTs) were measured before modeling and at 5 h, 6 h, 25 h and 49 h after CFA injection. Rats were killed and ipsilateral side of the lumbar spinal cords were harvested for detecting the expressions of p-ERK1/2, Elk1, COX-2, NK-1 and CREB by immunohistochemistry, real-time PCR, western blot analysis and EMSA. Finally, the analgesic effect of EA plus U0126, a MEK (ERK kinase) inhibitor, on CFA rats was examined.

Results

Inflammatory pain was induced in rats by hindpaw injection of CFA and significantly increased phospho-ERK1/2 positive cells and protein levels of p-ERK1/2 in the ipsilateral spinal cord dorsal horn (SCDH). CFA up-regulated of cyclooxygenase-2 (COX-2) mRNA and protein expression at 6 h after injection and neurokinin-1 receptor (NK-1) expression at 49 h post-injection, in the SCDH. EA, applied to Zusanli (ST36) and Kunlun (BL60), remarkably increased the pain thresholds of CFA injected rats, significantly suppressed ERK1/2 activation and COX-2 protein expression after a single treatment, and decreased NK-1 mRNA and protein expression at 49 h. EA decreased the DNA binding activity of cAMP response element binding protein (CREB), a downstream transcription factor of ERK1/2, at 49 h after CFA injection. Moreover, EA and U0126 synergistically inhibited CFA-induced allodynia.

Conclusions

The present study suggests that EA produces analgesic effect by preventing the activation of ERK1/2-COX-2 pathway and ERK1/2-CREB-NK-1 pathway in CFA rats.

Activation of extracellular signal-regulated kinase1/2 in the medial prefrontal cortex contributes to stress-induced hyperalgesia

Stressful stimuli can exacerbate persistent pain disorder. However, the underlying mechanism is still unknown. Here, to reveal the underlying mechanism for stressful stimuli-induced hyperalgesia in chronic pain, we investigated the effect of extracellular signal-regulated kinase1/2 (ERK1/2) activation on pain hypersensitivity using single-prolonged stress (SPS) model, complete Freund's adjuvant (CFA) model and SPS + CFA model. The experimental results revealed significantly reduced paw withdrawal threshold in the SPS, CFA, and SPS + CFA group compared with the control group. However, the increased phosphorylation of ERK1/2 in the medial prefrontal cortex (mPFC) was observed in the SPS- or SPS + CFA-exposed group but not the CFA group compared with control group. There was also a significant increase in mPFC ERK1/2 phosphorylation and mechanical allodynia after SPS + CFA treatment compared to SPS or CFA treatment alone. Furthermore, inhibiting ERK1/2 phosphorylation by microinjection of U0126, a MAPK kinase (MEK) inhibitor, into the mPFC attenuated SPS + CFA- and SPS- but not CFA-induced mechanical allodynia, anxiety-like behavior, and cognitive impairments. These results suggest that the activation of ERK1/2 in the mPFC may contribute to the process of stress-induced cognitive and emotional disorders, leading to an increase in pain sensitivity.

ERK MAP kinase activation in spinal cord regulates phosphorylation of Cdk5 at serine 159 and contributes to peripheral inflammation induced pain/hypersensitivity

Cyclin-dependent kinase 5 is a proline-directed serine/threonine kinase and its activity participates in the regulation of nociceptive signaling. Like binding with the activators (P35 or P25), the phosphorylation of Cdk5 plays a critical role in Cdk5 activation. However, it is still unclear whether Cdk5 phosphorylation (p-Cdk5) contributes to pain hyperalgesia. The aim of our current study was to identify the roles of p-Cdk5 and its upstream regulator in response to peripheral inflammation. Complete Freund's adjuvant (CFA) injection induced acute peripheral inflammation and heat hyperalgesia, which was accompanied by sustained increases in phospho-ERK1/2 (p-ERK1/2) and phospho-Cdk5^S159 (p-Cdk5^S159) in the spinal cord dorsal horn (SCDH). CFA-induced p-ERK primarily colocalized with p-Cdk5^S159 in superficial dorsal horn neurons. Levels in p-ERK and p-Cdk5 were also increased in the 2^nd phase of hyperalgesia induced by formalin injection, which can produce acute and tonic inflammatory pain. MAP kinase kinase inhibitor U0126 intrathecal delivery significantly suppressed the elevation of p-Cdk5^S159, Cdk5 activity and pain response behavior (Heat hyperalgesia, Spontaneous flinches) induced by CFA or formalin injection. Cdk5 inhibitor roscovitine intrathecal administration also suppressed CFA-induced heat hyperalgesia and Cdk5 phosphorylation, but did not attenuate ERK activation. All these findings suggested that p-Cdk5^S159 regulated by ERK pathway activity may be a critical mechanism involved in the activation of Cdk5 in nociceptive spinal neurons contributes to peripheral inflammatory pain hypersensitivity.