Influence of acute pain on valence rating of words.

Numerous studies showed the effect of negative affective and pain-related semantic primes enhancing the perceived intensity of successive painful stimuli. It remains unclear whether and how painful primes are able to influence semantic stimuli in a similar way. Therefore, we investigated the effects of noxious primes on the perception of the valence of subsequent semantic stimuli. In two experiments, 48 healthy subjects were asked to give their valence ratings regarding different semantic stimuli (pain-related, negative, positive, and neutral adjectives) after they were primed with noxious electrical stimuli of moderate intensity. Experiment 1 focused on the existence of the effect, experiment 2 focused on the length of the effect. Valence ratings of pain-related, negative, and positive words (not neutral words) became more negative after a painful electrical prime was applied in contrast to no prime. This effect was more pronounced for pain-related words compared to negative, pain-unrelated words. Furthermore, the priming effect continued to affect the valence ratings even some minutes after the painful priming had stopped. So, painful primes are influencing the perception of semantic stimuli as well as semantic primes are influencing the perception of painful stimuli.

Peripheral Nerve Stimulation in Pain Management: A Systematic Review.

BACKGROUND: Peripheral nerve stimulation (PNS) has been increasingly used to manage acute and chronic pain. However, the level of clinical evidence to support its use is not clear. OBJECTIVES: To assess the clinical evidence of PNS in the treatment of acute or chronic pain. STUDY DESIGN: A systematic review of the efficacy and safety of PNS in managing acute or chronic pain. METHODS: Data sources were PubMed, Cochrane Library, Scopus, CINAHL Plus, Google Scholar, and reference lists. The literature search was performed up to December 2019. Study selection included randomized trials, observational studies, and case reports of PNS in acute or chronic pain. Data extraction and methodological quality assessment were performed utilizing Cochrane review methodologic quality assessment and Interventional Pain Management Techniques-Quality Appraisal of Reliability and Risk of Bias Assessment (IPM-QRB) and Interventional Pain Management Techniques-Quality Appraisal of Reliability and Risk of Bias Assessment for Nonrandomized Studies (IPM-QRBNR). The evidence was summarized utilizing principles of best evidence synthesis on a scale of 1 to 5. Data syntheses: 227 studies met inclusion criteria and were included in qualitative synthesis. RESULTS: Evidence synthesis based on randomized controlled trials (RCTs) and observational studies showed Level I and II evidence of PNS in chronic migraine headache; Level II evidence in cluster headache, postamputation pain, chronic pelvic pain, chronic low back and lower extremity pain; and Level IV evidence in peripheral neuropathic pain, and postsurgical pain. Peripheral field stimulation has Level II evidence in chronic low back pain, and Level IV evidence in cranial pain. LIMITATIONS: Lack of high-quality RCTs. Meta-analysis was not possible due to wide variations in experimental design, research protocol, and heterogeneity of study population. CONCLUSIONS: The findings of this systematic review suggest that PNS may be effective in managing chronic headaches, postamputation pain, chronic pelvic pain, and chronic low back and lower extremity pain, with variable levels of evidence in favor of this technique.

Convergent neural representations of experimentally-induced acute pain in healthy volunteers: A large-scale fMRI meta-analysis.

Characterizing a reliable, pain-related neural signature is critical for translational applications. Many prior fMRI studies have examined acute nociceptive pain-related brain activation in healthy participants. However, synthesizing these data to identify convergent patterns of activation can be challenging due to the heterogeneity of experimental designs and samples. To address this challenge, we conducted a comprehensive meta-analysis of fMRI studies of stimulus-induced pain in healthy participants. Following pre-registration, two independent reviewers evaluated 4,927 abstracts returned from a search of 8 databases, with 222 fMRI experiments meeting inclusion criteria. We analyzed these experiments using Activation Likelihood Estimation with rigorous type I error control (voxel height p < 0.001, cluster p < 0.05 FWE-corrected) and found a convergent, largely bilateral pattern of pain-related activation in the secondary somatosensory cortex, insula, midcingulate cortex, and thalamus. Notably, these regions were consistently recruited regardless of stimulation technique, location of induction, and participant sex. These findings suggest a highly-conserved core set of pain-related brain areas, encouraging applications as a biomarker for novel therapeutics targeting acute nociceptive pain.

The analgesic effect of refeeding on acute and chronic inflammatory pain.

Pain is susceptible to various cognitive factors. Suppression of pain by hunger is well known, but the effect of food intake after fasting (i.e. refeeding) on pain remains unknown. In the present study, we examined whether inflammatory pain behavior is affected by 24 h fasting and 2 h refeeding. In formalin-induced acute inflammatory pain model, fasting suppressed pain behavior only in the second phase and the analgesic effect was also observed after refeeding. Furthermore, in Complete Freund's adjuvant-induced chronic inflammatory pain model, both fasting and refeeding reduced spontaneous pain response. Refeeding with non-calorie agar produced an analgesic effect. Besides, intraperitoneal (i.p.) administration of glucose after fasting, which mimics calorie recovery following refeeding, induced analgesic effect. Administration of opioid receptor antagonist (naloxone, i.p.) and cannabinoid receptor antagonist (SR 141716, i.p.) reversed fasting-induced analgesia, but did not affect refeeding-induced analgesia in acute inflammatory pain model. Taken together, our results show that refeeding produce analgesia in inflammatory pain condition, which is associated with eating behavior and calorie recovery effect.

The efficacy of muscle energy techniques in symptomatic and asymptomatic subjects: a systematic review.

Background: Muscle energy techniques are applied to reduce pain and increase range of motion. These are applied to a variety of pathological conditions and on asymptomatic subjects. There is however limited knowledge on their effectiveness and which protocol may be the most beneficial. Objective: The aim of this review is to determine the efficacy of muscle energy techniques (MET) in symptomatic and asymptomatic subjects. Design: Systematic Review. Methods: A literature search was performed using the following database: Cochrane Library, MEDLINE, NLM Pubmed and ScienceDirect. Studies regarding MET in asymptomatic and symptomatic patients were considered for investigation. The main outcomes took into account range of motion, chronic and acute pain and trigger points. Two trained investigators independently screened eligible studies according to the eligibility criteria, extracted data and assessed risk of bias. Randomized control trials (RCT's) were analyzed for quality using the PEDro scale. Results: A total of 26 studies were considered eligible and included in the quantitative synthesis: 14 regarding symptomatic patients and 12 regarding asymptomatic subjects. Quality assessment of the studies through the PEDro scale observed a "moderate to high" quality of the included records. Conclusions: MET are an effective treatment for reducing chronic and acute pain of the lower back. MET are also effective in treating chronic neck pain and chronic lateral epicondylitis. MET can be applied to increase range of motion of a joint when a functional limitation is present. Other techniques seem to be more appropriate compared to MET for trigger points.

Evaluation of clinical efficacy of silver-needle warm acupuncture in treating adults with acute low back pain due to lumbosacral disc herniation: study protocol for a randomized controlled trial.

BACKGROUND: As a common cause of low back pain, lumbosacral disc herniation (LDH) is usually dealt with using non-surgical interventions. In the face of concerns about prescription opioid abuse, alternative and complementary treatments may be promising, among which silver-needle warm acupuncture is considered as an upgrading option for its potential anti-inflammatory and strong analgesic effect for patients with chronic pain. In this proposed study, we aim to assess its clinical efficacy in comparison with conventional stainless steel filiform-needle warm acupuncture. METHODS/DESIGN: This is a randomized, two-armed, patient- and assessor-blinded trial. One hundred and sixty eligible patients recruited from December 2018 to June 2020 in three centers will be assigned for warm acupuncture treatment with either stainless steel filiform or silver needles. Nine sessions of 20-min treatment will be conducted during 3 consecutive weeks. Assessments with instruments including the Oswestry Disability Index, the visual analog scale, and the Japanese Orthopedic Association Back Pain Evaluation Questionnaire will be performed at four time points to explore the difference of clinical efficacy between two groups. DISCUSSION: If the results show that participants treated with silver-needle warm acupuncture gain a greater improvement in terms of pain intensity, physical function, and quality of life, this study is expected to offer reliable evidence to widely push this treatment for LDH in clinical practice. TRIAL REGISTRATION: Chinese Clinical Trial Registry, ChiCTR1800019051 . Registered on 24 October 2018.

The Neuroscience of Pain: Biobehavioral, Developmental, and Psychosocial Mechanisms Relevant to Intervention Targets.

Chronic pain is a major problem in clinical medicine and public health, affecting approximately one in five adults, and is associated with significant societal and familial burden. Early-life adversities, psychological, and biobehavioral factors are associated with an elevated risk of the subsequent development of chronic pain. In this special issue of Psychosomatic Medicine, articles address the neuroscientific, psychological, and biobehavioral processes involved in acute and chronic pain. We focus on the following themes that emerged in this special issue: (a) risk factors and early adversity as related to chronic pain; (b) the role of expectations in shaping pain perception; and (c) mechanisms of interventions targeting pain modulation. This article concludes by outlining important new targets for research, including the neurobiology of pain, important methodological challenges, and targets for personalized pain interventions.

A Dedicated Acute Pain Service Is Associated With Reduced Postoperative Opioid Requirements in Patients Undergoing Cytoreductive Surgery With Hyperthermic Intraperitoneal Chemotherapy.

BACKGROUND: The Acute Pain Service (APS) was initially introduced to optimize multimodal postoperative pain control. The aim of this study was to evaluate the association between the implementation of an APS and postoperative pain management and outcomes for patients undergoing cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). METHODS: In this propensity-matched retrospective cohort study, we performed a before-after study without a concurrent control group. Outcomes were compared among patients undergoing CRS-HIPEC when APS was implemented versus historical controls (non-APS). The primary objective was to determine if there was a decrease in median total opioid consumption during postoperative days 0-3 among patients managed by the APS. Secondary outcomes included opioid consumption on each postoperative day (0-6), time to ambulation, time to solid intake, and hospital length of stay. RESULTS: After exclusion, there were a total of 122 patients, of which 51 and 71 were in the APS and non-APS cohort, respectively. Between propensity-matched groups, the median (quartiles) total opioid consumption during postoperative days 0-3 was 27.5 mg intravenous morphine equivalents (MEQs) (7.6-106.3 mg MEQs) versus 144.0 mg MEQs (68.9-238.3 mg MEQs), respectively. The median difference was 80.8 mg MEQs (95% confidence interval, 46.1-124.0; P < .0001). There were statistically significant decreases in time to ambulation and time to solid diet intake in the APS cohort. CONCLUSIONS: After implementing the APS, CRS-HIPEC patients had decreased opioid consumption by >50%, as well as shorter time to ambulation and time to solid intake. Implementation of an APS may improve outcomes in CRS-HIPEC patients.

Joint nociceptor nerve activity and pain in an animal model of acute gout and its modulation by intra-articular hyaluronan.

The mechanisms whereby deposition of monosodium urate (MSU) crystals in gout activates nociceptors to induce joint pain are incompletely understood. We tried to reproduce the signs of painful gouty arthritis, injecting into the knee joint of rats suspensions containing amorphous or triclinic, needle MSU crystals. The magnitude of MSU-induced inflammation and pain behavior signs were correlated with the changes in firing frequency of spontaneous and movement-evoked nerve impulse activity recorded in single knee joint nociceptor saphenous nerve fibers. Joint swelling, mechanical and cold allodynia, and hyperalgesia appeared 3 hours after joint injection of MSU crystals. In parallel, spontaneous and movement-evoked joint nociceptor impulse activity raised significantly. Solutions containing amorphous or needle-shaped MSU crystals had similar inflammatory and electrophysiological effects. Intra-articular injection of hyaluronan (HA, Synvisc), a high-MW glycosaminoglycan present in the synovial fluid with analgesic effects in osteoarthritis, significantly reduced MSU-induced behavioral signs of pain and decreased the enhanced joint nociceptor activity. Our results support the interpretation that pain and nociceptor activation are not triggered by direct mechanical stimulation of nociceptors by MSU crystals, but are primarily caused by the release of excitatory mediators by inflammatory cells activated by MSU crystals. Intra-articular HA decreased behavioral and electrophysiological signs of pain, possibly through its viscoelastic filtering effect on the mechanical forces acting over sensitized joint sensory endings and probably also by a direct interaction of HA molecules with the transducing channels expressed in joint nociceptor terminals.

The experience of patients admitted to hospital with acute low back pain: a qualitative study.

AIM: To understand the patient experience of being admitted to hospital with acute low back pain (LBP), with a view to developing suggestions for care and LBP management guidelines. METHOD: Interpretive phenomenological analysis (IPA) was adopted to examine semi-structured interviews from patients admitted to hospital with acute LBP. Sampling continued until thematic saturation was reached (n = 14). Data were analyzed using the Framework Method, so that data from multiple participants could be systematically summarized, compared, and analyzed. RESULTS: Four themes were identified: pain and helplessness, desire for validation, interactions with healthcare teams, and a return to pre-morbid identity and roles. Patients' initial presentation to hospital was characterized by severe pain, disability and difficulty in communicating their illness experience. Patients expected doctors to investigate for an underlying cause of the back pain. To recover, they were required to navigate a system they did not understand, interacting with healthcare workers who seemed to operate independently rather than as a team. Patients viewed medical treatment as a means of returning to pre-morbid activities of daily living, roles and relationships. Using these themes, a model of the inpatient journey was developed. CONCLUSION: We have described new patient insights which highlight how the hospital environment adds unique challenges to managing acute LBP. Several suggestions for acute LBP management guidelines are made: developing lay summaries for patients, including methods for communicating the team structure and roles to patients, and ensuring all members of treating teams are educated to ensure guidelines are consistently implemented.

Electroencephalographic assessment of oral meloxicam, topical anaesthetic cream and cautery iron for mitigating acute pain in pigs (Sus scrofa) undergoing tail docking.

OBJECTIVE: To evaluate the efficacy of oral meloxicam, topical anaesthetic cream and cautery iron in mitigating acute nociceptive responses of pigs to tail docking. STUDY DESIGN: A prospective, randomized, controlled experimental study. ANIMALS: A total of 40 healthy Large WhitexLandrace pigs aged 21±1 days, weighing 6.1±0.9 kg. METHODS: Pigs were randomly assigned to one of four treatments (n=10 per treatment): CONTROL: docked using clippers without analgesia; MEL: docked using clippers after administration of oral meloxicam; EMLA: docked using clippers after application of topical anaesthetic cream; and CAUT: docked using a cautery iron without analgesia. Anaesthesia was induced and maintained with halothane in oxygen. Following induction, end-tidal halothane was stabilized at 0.95-1.05% and electroencephalograph (EEG) recording commenced. After 5 minutes of baseline data collection, tail docking was performed and recording continued for a further 10 minutes. The EEG summary variables median frequency (F50), 95% spectral edge frequency (F95) and total power (PTOT) were calculated for the baseline period and for consecutive 30-second intervals following docking. RESULTS: Following docking, F50 increased and PTOT decreased significantly in CONTROL and MEL pigs. EMLA pigs exhibited no change in any variable, whilst CAUT pigs exhibited a reduction in PTOT but no change in F50. F50 was higher in control pigs than in EMLA pigs 30-60 seconds after docking (p≤0.01). PTOT was lower in CONTROL than in EMLA pigs 30-90 seconds after docking (p<0.03) and in CAUT pigs 60 seconds after docking (p=0.01). CONCLUSIONS AND CLINICAL RELEVANCE: Prior application of EMLA cream abolished EEG indicators of nociception in pigs docked using clippers. Docking using a cautery iron without analgesia ameliorated EEG indicators of nociception, relative to using clippers without analgesia. Prior administration of EMLA cream or the use of cautery instead of clippers may reduce the acute pain experienced by pigs undergoing tail docking.

Breaking barriers to novel analgesic drug development.

Acute and chronic pain complaints, although common, are generally poorly served by existing therapies. This unmet clinical need reflects a failure to develop novel classes of analgesics with superior efficacy, diminished adverse effects and a lower abuse liability than those currently available. Reasons for this include the heterogeneity of clinical pain conditions, the complexity and diversity of underlying pathophysiological mechanisms, and the unreliability of some preclinical pain models. However, recent advances in our understanding of the neurobiology of pain are beginning to offer opportunities for developing novel therapeutic strategies and revisiting existing targets, including modulating ion channels, enzymes and G-protein-coupled receptors.

Music as an Adjunct to Opioid-Based Analgesia.

Epidemic increases in opioid use in the USA and globally highlight the need for effective adjunctive therapies to opioid-based analgesia. Given the shortcomings of behavioral adjuncts to opioid-based pain treatment, an urgent need exists for pain-related behavioral interventions that resonate with broad patient populations, can be delivered confidentially in any environment, and can incorporate new content automatically. Understanding the potential for automated behavioral therapies like music therapy in modulating the experience of pain may unlock methods to transition patients to lower doses of pharmacologic therapy or provide alternatives to opioids during acute exacerbations of pain. This manuscript describes the neurologic mechanism of action, theoretical basis, and potential applications of personalized music as a smartphone-based mHealth intervention for acute and chronic pain management.

A clinical trial comparing Lanconone® with ibuprofen for rapid relief in acute joint pain.

BACKGROUND: To study the effect of Lanconone® (1000 mg) on acute pain on exertion as compared to the standard of care, Ibuprofen (400 mg). METHOD: The study recruited 72 subjects diagnosed with mild to moderate knee joint pain on exertion. Subjects with Pain Visual Analogue Scale of more than 40 mm were included. Uphill walking was provided as the stressor using Naughton's protocol on a treadmill. The subjects walked for 10 minutes continuously followed by a rest period and baseline pain score for index knee joint was recorded. Subjects were administered a single dose of Lanconone® (1000 mg)/Ibuprofen (400 mg). Thereafter the same stressor was provided at 0.5, 1, 2, 3, 4, and 6 hours, subsequently, pain scores were recorded on a visual analogue scale. Double stopwatch method was used to evaluate the onset of pain relief and time taken to meaningful pain relief. RESULT: Both Lanconone® and Ibuprofen showed the first perceived pain relief at 65.31 ± 35.57 mins as compared to 60.82 ± 32.56 mins respectively. The mean time taken to experience meaningful pain relief in Lanconone® group was 196.59 ± 70.85 mins compared to 167.13 ± 71.41 mins amongst Ibuprofen group. The meaningful pain relief continued for 6 hours. CONCLUSION: The current study successfully demonstrated rapid pain-relieving potential of Lanconone® which was comparable to Ibuprofen. No adverse event related to the interventions was reported in the study. TRIAL REGISTRATION: Clinical trials.gov NCT02417506 . 21 January 2015.

Synthesis and characterization of a disubstituted piperazine derivative with T-type channel blocking action and analgesic properties.

BACKGROUND: T-type calcium channels are important contributors to signaling in the primary afferent pain pathway and are thus important targets for the development of analgesics. It has been previously reported that certain piperazine-based compounds such as flunarizine are able to inhibit T-type calcium channels. Thus, we hypothesized that novel piperazine compounds could potentially act as analgesics. RESULTS: Here, we have created a series of 14 compound derivatives around a diphenyl methyl-piperazine core pharmacophore. Testing their effects on transiently expressed Cav3.2 calcium channels revealed one derivative (3-((4-(bis(4-fluorophenyl)methyl)piperazin-1-yl)methyl)-4-(2-methoxyphenyl)-1,2,5-oxadiazole 2-oxide, compound 10e) as a potent blocker. 10e mediate tonic block of these channels with an IC50 of around 4 micromolar. 10e also blocked Cav3.1 and Cav3.3 channels, but only weakly affected high-voltage-activated Cav1.2 and Cav2.2 channels. Intrathecal delivery of 10e mediated relief from formalin and complete Freund's adjuvant induced inflammatory pain that was ablated by genetic knockout of Cav3.2 channels. CONCLUSIONS: Altogether, our data identify a novel T-type calcium channel blocker with tight structure activity relationship (SAR) and relevant in vivo efficacy in inflammatory pain conditions.

Acupuncture Reduces Pain and Autonomic Distress During Injection of Local Anesthetic in Children: A Pragmatic Crossover Investigation.

OBJECTIVES: Stimulation of acupoint LI4 has been shown to result in analgesic effects in patients experiencing acute pain. We aimed to study the effectiveness of LI4 stimulation for pain relief in children receiving an injection of a local anesthetic (LA). MATERIALS AND METHODS: Children scheduled for dental treatment using LA received bilateral acupuncture at LI4 using indwelling fixed needles. During the treatment, the parents of the patients stimulated the needles by massage. Two different treatment regimes were compared: a standardized LA injection given 5 minutes after acupuncture, and an LA injection without acupuncture. The order of treatment was randomized, with the 2 treatments performed in a crossover manner on different days. Pain intensity during LA injection, assessed by the patient with the Verbal Rating Scale or Faces Pain Scale (0 to 10), was used as the primary endpoint. Parent-assessed and dentist-assessed pain intensity and agitation, heart rate, and the patients' satisfaction with the therapy were also recorded. RESULTS: Data were obtained from 49 patients (22 female; mean age 10 y). Patients reported less pain when acupuncture was used: mean 2.3 (95% confidence interval, 1.5-3.1) versus 3.9 (95% confidence interval, 3.0-4.7); P<0.001. The patients' heart rate remained low throughout the dental treatment after LI4 stimulation, when compared with treatment without acupuncture (P<0.05). LI4 stimulation was safe and increased satisfaction levels in both the patients and their parents, when compared with LA injection alone (P<0.05). DISCUSSION: Stimulation of acupoint LI4 reduces pain and autonomic distress in children during LA injection in dental procedures.

Effect of manual versus mechanically assisted manipulations of the thoracic spine in neck pain patients: study protocol of a randomized controlled trial.

BACKGROUND: Neck pain is a common musculoskeletal condition with a point prevalence of around 15% in males and 23% in females that often presents in physiotherapy practice. Physical therapy and/or manipulation therapy is generally the first management option for patients with mechanical neck pain. Physical therapists treat mechanical neck pain with a number of interventions including joint mobilization and/or manipulation, therapeutic exercises or education. However, manipulation of the cervical spine carries some risks. Treating the thoracic spine for neck pain is an alternative approach. Emerging evidence suggests that it may be effective for treating neck pain without the risks associated with cervical spine manipulation. A new electromechanical device has recently been developed and tested for delivering multiple high velocity, low amplitude thrust manipulations to the spine. This device incorporates both auditory and visual systems that provide real time feedback on the applied treatment. The objective of this study is to compare the short- and long-term effects of manual versus mechanically assisted manipulations of the thoracic spine for neck pain patients. METHODS/DESIGN: A 6-month, randomized controlled trial consisting of 54 patients with acute or chronic neck pain patients will be conducted. Patients with no signs of major pathology and with little or no interference with daily activities will be recruited. Three treatment sessions with 4-day intervals will be carried out. The patients will be randomly assigned to receive either manually performed manipulations or electromechanical manipulations at the thoracic spine. The primary outcome is pain intensity as measured by the Visual Analogue Pain Rating Scale. The secondary outcome measures are neck physical disability using the Neck Disability Index, quality of life measured by the European Quality of Life 5 Dimensions 5 Levels and patients' improvement using the Patient's Global Impression of Change Scale. DISCUSSION: It is expected that both interventions will improve neck pain. This would be a significant finding, as thoracic spine manipulation for neck pain does not carry the same risk of injury as cervical spine manipulation. In addition, the results may provide useful information about therapeutic options for health care providers and patients for the problem of neck pain. TRIAL REGISTRATION: Current Controlled Trials ISRCTN88585962, registered January 2013.

Thalamic Kv 7 channels: pharmacological properties and activity control during noxious signal processing.

BACKGROUND AND PURPOSE: The existence of functional K(v)7 channels in thalamocortical (TC) relay neurons and the effects of the K(+)-current termed M-current (I(M)) on thalamic signal processing have long been debated. Immunocytochemical evidence suggests their presence in this brain region. Therefore, we aimed to verify their existence, pharmacological properties and function in regulating activity in neurons of the ventrobasal thalamus (VB). EXPERIMENTAL APPROACH: Characterization of K(v)7 channels was performed by combining in vitro, in vivo and in silico techniques with a pharmacological approach. Retigabine (30 µM) and XE991 (20 µM), a specific K(v)7 channel enhancer and blocker, respectively, were applied in acute brain slices during electrophysiological recordings. The effects of intrathalamic injection of retigabine (3 mM, 300 nL) and/or XE991 (2 mM, 300 nL) were investigated in freely moving animals during hot-plate tests by recording behaviour and neuronal activity. KEY RESULTS: K(v)7.2 and K(v)7.3 subunits were found to be abundantly expressed in TC neurons of mouse VB. A slow K(+)-current with properties of IM was activated by retigabine and inhibited by XE991. K(v)7 channel activation evoked membrane hyperpolarization, a reduction in tonic action potential firing, and increased burst firing in vitro and in computational models. Single-unit recordings and pharmacological intervention demonstrated a specific burst-firing increase upon I(M) activation in vivo. A K(v)7 channel-mediated increase in pain threshold was associated with fewer VB units responding to noxious stimuli, and increased burst firing in responsive neurons. CONCLUSIONS AND IMPLICATIONS: K(v)7 channel enhancement alters somatosensory activity and may reflect an anti-nociceptive mechanism during acute pain processing.

Epigenetic regulation of acute inflammatory pain.

Acute pain is associated with tissue damage, which results in the release of inflammatory mediators. Recent studies point to the involvement of epigenetic mechanisms (DNA methylation) in the development of pain. We have found that during acute inflammatory pain induced by the application of 10% mustard oil on the tongues of rats, levels of DNMT3a and 3b were elevated markedly (36 and 42 % respectively), whereas the level of DNMT1 was not changed significantly. Previous injection of Xefocam with 0,4 mg/kg dose decreased levels of DNMT3a and 3b (25 and 24% respectively). The level of DNMT1 was not changed significantly compared to the control group. The findings support the idea that inhibitors of DNA-methyltransferases could be useful for pain management. Our data suggest that NSAIDs (alone or in combination with DNMT inhibitors) may be proposed as possible epigenetic regulatory agents, which may play a role in epigenetic mechanisms indirectly through altering the activity of inflammatory mediators involved in pain development.