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Lou W, Li X, Jin R, Peng W. Time-varying phase synchronization of resting-state functional magnetic resonance imaging reveals a shift toward self-referential processes during sustained pain. Pain 2024; 165:1493-1504. [PMID: 38193830 DOI: 10.1097/j.pain.0000000000003152] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 11/20/2023] [Indexed: 01/10/2024]
Abstract
ABSTRACT Growing evidence has suggested that time-varying functional connectivity between different brain regions might underlie the dynamic experience of pain. This study used a novel, data-driven framework to characterize the dynamic interactions of large-scale brain networks during sustained pain by estimating recurrent patterns of phase-synchronization. Resting-state functional magnetic resonance imaging signals were collected from 50 healthy participants before (once) and after (twice) the onset of sustained pain that was induced by topical application of capsaicin cream. We first decoded the instantaneous phase of neural activity and then applied leading eigenvector dynamic analysis on the time-varying phase-synchronization. We identified 3 recurrent brain states that show distinctive phase-synchronization. The presence of state 1, characterized by phase-synchronization between the default mode network and auditory, visual, and sensorimotor networks, together with transitions towards this brain state, increased during sustained pain. These changes can account for the perceived pain intensity and reported unpleasantness induced by capsaicin application. In contrast, state 3, characterized by phase-synchronization between the cognitive control network and sensory networks, decreased after the onset of sustained pain. These results are indicative of a shift toward internally directed self-referential processes (state 1) and away from externally directed cognitive control processes (state 3) during sustained pain.
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Affiliation(s)
- Wutao Lou
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Xiaoyun Li
- School of Psychology, Shenzhen University, Shenzhen, Guangdong, China
| | - Richu Jin
- Research Institute of Trustworthy Autonomous Systems, Southern University of Science and Technology, Shenzhen, China
- Department of Computer Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Weiwei Peng
- School of Psychology, Shenzhen University, Shenzhen, Guangdong, China
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2
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Wong F, Reddy A, Rho Y, Vollert J, Strutton PH, Hughes SW. Responders and nonresponders to topical capsaicin display distinct temporal summation of pain profiles. Pain Rep 2023; 8:e1071. [PMID: 37731476 PMCID: PMC10508395 DOI: 10.1097/pr9.0000000000001071] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 12/15/2022] [Accepted: 02/02/2023] [Indexed: 09/22/2023] Open
Abstract
Introduction Topical application of capsaicin can produce an ongoing pain state in healthy participants. However, approximately one-third report no pain response (ie, nonresponders), and the reasons for this are poorly understood. Objectives In this study, we investigated temporal summation of pain (TSP) profiles, pain ratings and secondary hyperalgesia responses in responders and nonresponders to 1% topical capsaicin cream. Methods Assessments were made at baseline and then during an early (ie, 15 minutes) and late (ie, 45 minutes) time points post-capsaicin in 37 healthy participants. Results Participants reporting a visual analogue scale (VAS) rating of >50 were defined as responders (n = 24) and those with <50 VAS rating were defined as nonresponders (n = 13). There was a facilitation of TSP during the transition from an early to the late time point post-capsaicin (P<0.001) and the development of secondary hyperalgesia (P<0.05) in the responder group. Nonresponders showed no changes in TSP or secondary hyperalgesia during the early and late time points. There was an association between baseline TSP scores and the later development of a responder or nonresponder phenotype (r = 0.36; P = 0.03). Receiver operating characteristic analysis revealed that baseline TSP works as a good response predictor at an individual level (area under the curve = 0.75). Conclusion These data suggest that responders and nonresponders have different facilitatory pain mechanisms. The assessment of TSP may help to identify participants with stronger endogenous pain facilitation who may be more likely to respond to topical capsaicin.
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Affiliation(s)
- Felyx Wong
- The Nick Davey Laboratory, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Aditi Reddy
- The Nick Davey Laboratory, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Yeanuk Rho
- The Nick Davey Laboratory, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Jan Vollert
- Pain Research, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Paul H. Strutton
- The Nick Davey Laboratory, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, United Kingdom
| | - Sam W. Hughes
- The Pain Modulation Laboratory, Brain Research and Imaging Centre (BRIC), School of Psychology, Faculty of Health, University of Plymouth, Plymouth, United Kingdom
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André-Obadia N, Hodaj H, Hodaj E, Simon E, Delon-Martin C, Garcia-Larrea L. Better Fields or Currents? A Head-to-Head Comparison of Transcranial Magnetic (rTMS) Versus Direct Current Stimulation (tDCS) for Neuropathic Pain. Neurotherapeutics 2023; 20:207-219. [PMID: 36266501 PMCID: PMC10119368 DOI: 10.1007/s13311-022-01303-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2022] [Indexed: 10/24/2022] Open
Abstract
While high-frequency transcranial magnetic stimulation (HF-rTMS) is now included in the armamentarium to treat chronic neuropathic pain (NP), direct-current anodal stimulation (a-tDCS) to the same cortical targets may represent a valuable alternative in terms of feasibility and cost. Here we performed a head-to-head, randomized, single-blinded, cross-over comparison of HF-rTMS versus a-tDCS over the motor cortex in 56 patients with drug-resistant NP, who received 5 daily sessions of each procedure, with a washout of at least 4 weeks. Daily scores of pain, sleep, and fatigue were obtained during 5 consecutive weeks, and functional magnetic resonance imaging (fMRI) to a motor task was performed in a subgroup of 31 patients. The percentage of responders, defined by a reduction in pain scores of > 2 SDs from pre-stimulus levels, was similar to both techniques (42.0% vs. 42.3%), while the magnitude of "best pain relief" was significantly skewed towards rTMS. Mean pain ratings in responders decreased by 32.6% (rTMS) and 29.6% (tDCS), with half of them being sensitive to only one technique. Movement-related fMRI showed significant activations in motor and premotor areas, which did not change after 5 days of stimulation, and did not discriminate responders from non-responders. Both HF-rTMS and a-tDCS showed efficacy at 1 month in drug-resistant NP, with magnitude of relief slightly favoring rTMS. Since a significant proportion of patients responded to one procedure only, both modalities should be tested before declaring a patient as unresponsive.
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Affiliation(s)
- Nathalie André-Obadia
- Neurophysiology & Epilepsy Unit, Neurological Hospital P. Wertheimer, Hospices Civils de Lyon, 59 Boulevard Pinel, 69677, Bron Cedex, France.
- University Hospital Pain Center (CETD), Neurological Hospital P. Wertheimer, Hospices Civils de Lyon, Lyon, France.
- NeuroPain Lab, INSERM U1028, UMR5292, Lyon Neuroscience Research Center, CNRS, University Claude Bernard Lyon 1, Lyon, France.
| | - Hasan Hodaj
- Pain Center, Department of Anaesthesia and Intensive Care, Grenoble Alpes University Hospital, Grenoble, France
- University Grenoble Alpes, Inserm U1216, Grenoble Institut Neurosciences, 38000, Grenoble, France
| | - Enkelejda Hodaj
- Clinical Pharmacology Department, Inserm CIC1406, Grenoble Alpes University Hospital, Grenoble, France
| | - Emile Simon
- University Hospital Pain Center (CETD), Neurological Hospital P. Wertheimer, Hospices Civils de Lyon, Lyon, France
- NeuroPain Lab, INSERM U1028, UMR5292, Lyon Neuroscience Research Center, CNRS, University Claude Bernard Lyon 1, Lyon, France
- Functional and Stereotactic Neurosurgical Unit, Neurological Hospital P. Wertheimer, Hospices Civils de Lyon, Lyon, France
| | - Chantal Delon-Martin
- University Grenoble Alpes, Inserm U1216, Grenoble Institut Neurosciences, 38000, Grenoble, France
| | - Luis Garcia-Larrea
- University Hospital Pain Center (CETD), Neurological Hospital P. Wertheimer, Hospices Civils de Lyon, Lyon, France
- NeuroPain Lab, INSERM U1028, UMR5292, Lyon Neuroscience Research Center, CNRS, University Claude Bernard Lyon 1, Lyon, France
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Li X, Lou W, Zhang W, Tong RKY, Hu L, Peng W. Ongoing first-hand pain facilitates somatosensory resonance but inhibits affective sharing in empathy for pain. Neuroimage 2022; 263:119599. [PMID: 36049698 DOI: 10.1016/j.neuroimage.2022.119599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 08/05/2022] [Accepted: 08/28/2022] [Indexed: 10/31/2022] Open
Abstract
Alterations of empathy for others' pain among patients with chronic pain remained inconsistent. Here, applying a capsaicin-based ongoing pain model on healthy participants, this study investigated how ongoing first-hand pain influences empathic reactions to vicarious pain stimuli. Healthy participants were randomly treated with topical capsaicin cream (capsaicin group) or hand cream (control group) on the left forearm. Video clips showing limbs in painful and non-painful situations were used to induce empathic responses. The capsaicin group showed greater empathic neural responses in the right primary somatosensory cortex (S1) than the control group but smaller responses in the left anterior insula (AI) accompanied with smaller empathic pain-intensity ratings. Notably, the intensity of ongoing pain negatively correlated with empathy-related neural responses in the left AI. Inter-subject phase synchronization analysis was used to assess stimulus-dependent dynamic functional connectivity within or between brain regions engaged in pain empathy. The capsaicin group showed greater empathy-related neural synchronization within S1 and between S1 and AI, but less synchronization within AI and between AI and MCC. Behaviorally, the differential inter-subject pain-intensity rating alignment between painful and non-painful videos was more positive for the capsaicin group than for the control group, and this effect was partially mediated by the inter-subject neural synchronization between S1 and AI. These results suggest that ongoing first-hand pain facilitates neural activation and synchronization within brain regions associated with empathy-related somatosensory resonance at the cost of inhibiting activation and synchronization within brain regions engaged in empathy-related affective sharing.
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Affiliation(s)
- Xiaoyun Li
- School of Psychology, Shenzhen University, Shenzhen, China
| | - Wutao Lou
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Wenyun Zhang
- School of Psychology, Shenzhen University, Shenzhen, China
| | - Raymond Kai-Yu Tong
- Department of Biomedical Engineering, The Chinese University of Hong Kong, Hong Kong, China
| | - Li Hu
- CAS Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, Beijing, China; Department of Psychology, University of Chinese Academy of Sciences, Beijing, China
| | - Weiwei Peng
- School of Psychology, Shenzhen University, Shenzhen, China.
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Mehesz E, Karoui H, Strutton PH, Hughes SW. Exposure to an Immersive Virtual Reality Environment can Modulate Perceptual Correlates of Endogenous Analgesia and Central Sensitization in Healthy Volunteers. THE JOURNAL OF PAIN 2021; 22:707-714. [PMID: 33465506 DOI: 10.1016/j.jpain.2020.12.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 12/14/2020] [Accepted: 12/29/2020] [Indexed: 11/26/2022]
Abstract
Virtual reality (VR) has been shown to produce analgesic effects during different experimental and clinical pain states. Despite this, the top-down mechanisms are still poorly understood. In this study, we examined the influence of both a real and sham (ie, the same images in 2D) immersive arctic VR environment on conditioned pain modulation (CPM) and in a human surrogate model of central sensitization in 38 healthy volunteers. CPM and acute heat pain thresholds were assessed before and during VR/sham exposure in the absence of any sensitization. In a follow-on study, we used the cutaneous high frequency stimulation model of central sensitization and measured changes in mechanical pain sensitivity in an area of heterotopic sensitization before and during VR/sham exposure. There was an increase in CPM efficiency during the VR condition compared to baseline (P < .01). In the sham condition, there was a decrease in CPM efficiency compared to baseline (P < .01) and the real VR condition (P < .001). Neither real nor sham VR had any effect on pain ratings reported during the conditioning period or on heat pain threshold. There was also an attenuation of mechanical pain sensitivity during the VR condition indicating a lower sensitivity compared to sham (P < .05). We conclude that exposure to an immersive VR environment has no effect over acute pain thresholds but can modulate dynamic CPM responses and mechanical hypersensitivity in healthy volunteers. PERSPECTIVE: This study has demonstrated that exposure to an immersive virtual reality environment can modulate perceptual correlates of endogenous pain modulation and secondary hyperalgesia in a human surrogate pain model. These results suggest that virtual reality could provide a novel mechanism-driven analgesic strategy in patients with altered central pain processing.
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Affiliation(s)
- Erzsebet Mehesz
- The Nick Davey Laboratory, Department of Surgery and Cancer, Imperial College London, London, UK
| | - Hajer Karoui
- The Nick Davey Laboratory, Department of Surgery and Cancer, Imperial College London, London, UK
| | - Paul H Strutton
- The Nick Davey Laboratory, Department of Surgery and Cancer, Imperial College London, London, UK
| | - Sam W Hughes
- The Pain Neuroplasticity and Modulation Laboratory, Brain Research and Imaging Centre (BRIC), School of Psychology, Faculty of Health, University of Plymouth, Plymouth, UK.
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Meeker TJ, Schmid AC, Liu Y, Keaser ML, Dorsey SG, Seminowicz DA, Greenspan JD. During capsaicin-induced central sensitization, brush allodynia is associated with baseline warmth sensitivity, whereas mechanical hyperalgesia is associated with painful mechanical sensibility, anxiety and somatization. Eur J Pain 2021; 25:1971-1993. [PMID: 34051016 DOI: 10.1002/ejp.1815] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 05/23/2021] [Indexed: 12/17/2022]
Abstract
BACKGROUND Mechanical hyperalgesia and allodynia incidence varies considerably amongst neuropathic pain patients. This study explored whether sensory or psychological factors associate with mechanical hyperalgesia and brush allodynia in a human experimental model. METHODS Sixty-six healthy volunteers (29 male) completed psychological questionnaires and participated in two quantitative sensory testing (QST) sessions. Warmth detection threshold (WDT), heat pain threshold (HPT) and suprathreshold mechanical pain (STMP) ratings were measured before exposure to a capsaicin-heat pain model (C-HP). After C-HP exposure, brush allodynia and STMP were measured in one session, whilst mechanical hyperalgesia was measured in another session. RESULTS WDT and HPT measured in sessions separated by 1 month demonstrated significant but moderate levels of reliability (WDT: ICC = 0.5, 95%CI [0.28, 0.77]; HPT: ICC = 0.62, 95%CI [0.40, 0.77]). Brush allodynia associated with lower WDT (z = -3.06, p = 0.002; ϕ = 0.27). Those with allodynia showed greater hyperalgesia intensity (F = 7.044, p = 0.010, ηp 2 = 0.107) and area (F = 9.319, p = 0.004, ηp 2 = 0.163) than those without allodynia. No psychological self-report measures were significantly different between allodynic and nonallodynic groups. Intensity of hyperalgesia in response to lighter mechanical stimuli was associated with lower HPT, higher STMP ratings and higher Pain Sensitivity Questionnaire scores at baseline. Hyperalgesia to heavier probe stimuli associated with state anxiety and to a lesser extent somatic awareness. Hyperalgesic area associated with lower baseline HPT and higher STMP ratings. Hyperalgesic area was not correlated with allodynic area across individuals. CONCLUSIONS These findings support research in neuropathic pain patients and human experimental models that peripheral sensory input and individual sensibility are related to development of mechanical allodynia and hyperalgesia during central sensitization, whilst psychological factors play a lesser role. SIGNIFICANCE We evaluated differential relationships of psychological and perceptual sensitivity to the development of capsaicin-induced mechanical allodynia and hyperalgesia. Fifty percent of healthy volunteers failed to develop mechanical allodynia. Baseline pain sensitivity was greater in those developing allodynia and was related to the magnitude and area of hyperalgesia. State psychological factors, whilst unrelated to allodynia, were related to mechanical hyperalgesia. This supports that the intensity of peripheral sensory input and individual sensibility are related to development of mechanical allodynia and hyperalgesia during central sensitization, whilst psychological factors play a lesser role.
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Affiliation(s)
- Timothy J Meeker
- Department of Neural and Pain Sciences, School of Dentistry and Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD, USA.,Department of Neurosurgery, Johns Hopkins University, Baltimore, MD, USA
| | - Anne-Christine Schmid
- Department of Neural and Pain Sciences, School of Dentistry and Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD, USA.,Department of Neurosurgery, Johns Hopkins University, Baltimore, MD, USA.,Clinical Neuroengineering, BrainMind Institute and Centre of Neuroprosthetics (CNP), Swiss Federal Institute of Technology (EPFL), Geneva, Switzerland.,Swiss Federal Institute of Technology Valais (EPFL Valais), Sion, Switzerland.,WyssCenter of Bio and Neuroengineering, Geneva, Switzerland
| | - Yiming Liu
- Department of Neural and Pain Sciences, School of Dentistry and Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD, USA.,Department of Pain Medicine, Peking University People's Hospital, Beijing, China
| | - Michael L Keaser
- Department of Neural and Pain Sciences, School of Dentistry and Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD, USA
| | - Susan G Dorsey
- Department of Pain and Translational Symptom Science, School of Nursing and Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD, USA
| | - David A Seminowicz
- Department of Neural and Pain Sciences, School of Dentistry and Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD, USA
| | - Joel D Greenspan
- Department of Neural and Pain Sciences, School of Dentistry and Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD, USA
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7
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Modality-specific facilitation of noninjurious sharp mechanical pain by topical capsaicin. Pain 2021; 162:275-286. [PMID: 32701656 DOI: 10.1097/j.pain.0000000000002020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We had previously shown that a "blunt blade" stimulator can mimic the noninjurious strain phase of incisional pain, but not its sustained duration. Here, we tested whether acute sensitization of the skin with topical capsaicin can add the sustained phase to this noninvasive surrogate model of intraoperative pain. Altogether, 110 healthy volunteers (55 male and 55 female; 26 ± 5 years) participated in several experiments using the "blunt blade" (0.25 × 4 mm) on normal skin (n = 36) and on skin pretreated by a high-concentration capsaicin patch (8%, Qutenza; n = 36). These data were compared with an experimental incision (n = 40) using quantitative and qualitative pain ratings by numerical rating scale and SES Pain Perception Scale descriptors. Capsaicin sensitization increased blade-induced pain magnitude and duration significantly (both P < 0.05), but it failed to fully match the sustained duration of incisional pain. In normal skin, the SES pattern of pain qualities elicited by the blade matched incision in pain magnitude and pattern of pain descriptors. In capsaicin-treated skin, the blade acquired a significant facilitation only of the perceived heat pain component (P < 0.001), but not of mechanical pain components. Thus, capsaicin morphed the descriptor pattern of the blade to become more capsaicin-like, which is probably explained best by peripheral sensitization of the TRPV1 receptor. Quantitative sensory testing in capsaicin-sensitized skin revealed hyperalgesia to heat and pressure stimuli, and loss of cold and cold pain sensitivity. These findings support our hypothesis that the blade models the early tissue-strain-related mechanical pain phase of surgical incisions.
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Epidermal expression of human TRPM8, but not of TRPA1 ion channels, is associated with sensory responses to local skin cooling. Pain 2020; 160:2699-2709. [PMID: 31343541 DOI: 10.1097/j.pain.0000000000001660] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Human cold perception and nociception play an important role in persisting pain. However, species differences in the target temperature of thermosensitive ion channels expressed in peripheral nerve endings have fueled discussions about the mechanism of cold nociception in humans. Most frequently implicated thermosensors are members of the transient receptor potential (TRP) ion channel family TRPM8 and TRPA1. Regularly observed, distinct cold pain phenotype groups suggested the existence of interindividually differing molecular bases. In 28 subjects displaying either high or medium sensitivity to local cooling of the skin, the density at epidermal nerve fibers of TRPM8, but not that of TRPA1 expression, correlated significantly with the cold pain threshold. Moreover, reproducible grouping of the subjects, based on high or medium sensitivity to cooling, was reflected in an analogous grouping based on high or low TRPM8 expression at epidermal nerve fibers. The distribution of TRPM8 expression in epidermal nerve fibers provided an explanation for the previously observed (bi)modal distribution of human cold pain thresholds which was reproduced in this study. In the light of current controversies on the role of human TRPA1 ion channels in cold pain perception, the present observations demonstrating a lack of association of TRPA1 channel expression with cold sensitivity-related measures reinforce doubts about involvement of this channel in cold pain in humans. Since TRP inhibitors targeting TRPM8 and TRPA1 are currently entering clinical phases of drug development, the existence of known species differences, in particular in the function of TRPA1, emphasizes the increasing importance of new methods to directly approach the roles of TRPs in humans.
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Furman AJ, Prokhorenko M, Keaser ML, Zhang J, Chen S, Mazaheri A, Seminowicz DA. Sensorimotor Peak Alpha Frequency Is a Reliable Biomarker of Prolonged Pain Sensitivity. Cereb Cortex 2020; 30:6069-6082. [PMID: 32591813 DOI: 10.1093/cercor/bhaa124] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 03/29/2020] [Accepted: 04/21/2020] [Indexed: 01/28/2023] Open
Abstract
Previous research has observed that the speed of alpha band oscillations (8-12 Hz range) recorded during resting electroencephalography is slowed in chronic pain patients. While this slowing may reflect pathological changes that occur during the chronification of pain, an alternative explanation is that healthy individuals with slower alpha oscillations are more sensitive to prolonged pain, and by extension, more susceptible to developing chronic pain. To test this hypothesis, we examined the relationship between the pain-free, resting alpha oscillation speed of healthy individuals and their sensitivity to two models of prolonged pain, Phasic Heat Pain and Capsaicin Heat Pain, at two visits separated by 8 weeks on average (n = 61 Visit 1, n = 46 Visit 2). We observed that the speed of an individual's pain-free alpha oscillations was negatively correlated with sensitivity to both models and that this relationship was reliable across short (minutes) and long (weeks) timescales. Furthermore, the speed of pain-free alpha oscillations can successfully identify the most pain sensitive individuals, which we validated on data from a separate, independent study. These results suggest that alpha oscillation speed is a reliable biomarker of prolonged pain sensitivity with potential for prospectively identifying pain sensitivity in the clinic.
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Affiliation(s)
- Andrew J Furman
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201, USA.,Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD 21201, USA.,Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD 21201, USA
| | - Mariya Prokhorenko
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Michael L Keaser
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD 21201, USA.,Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD 21201, USA
| | - Jing Zhang
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD 21201, USA
| | - Shuo Chen
- Department of Epidemiology and Public Health, University of Maryland Baltimore, Baltimore, MD 21201, USA
| | - Ali Mazaheri
- School of Psychology, University of Birmingham, Birmingham, B15 2TT, UK.,Centre for Human Brain Health, University of Birmingham, Birmingham, B15 2TT, UK
| | - David A Seminowicz
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD 21201, USA.,Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD 21201, USA
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Parker T, Huang Y, Gong C, Chen Y, Wang S, Green A, Aziz T, Li L. Pain-Induced Beta Activity in the Subthalamic Nucleus of Parkinson’s Disease. Stereotact Funct Neurosurg 2020; 98:193-199. [DOI: 10.1159/000507032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2019] [Accepted: 02/27/2020] [Indexed: 11/19/2022]
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11
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Schaffler K, He W, Passier P, Tracy K, Fakhoury A, Paul J. A Phase I, Randomized, Double-Blind, Laser-Evoked Potential Study to Evaluate the Analgesic/Antihyperalgesic Effect of ASP9226, a State-Dependent N-Type Voltage-Gated Calcium Channel Inhibitor, in Healthy Male Subjects. PAIN MEDICINE 2019; 19:2246-2255. [PMID: 29378016 PMCID: PMC6217710 DOI: 10.1093/pm/pnx338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Objective Evaluate the analgesic/antihyperalgesic effects of ASP9226, a state-dependent N-type voltage-gated calcium channel inhibitor, in healthy male subjects. Design Randomized, double-blind, double-dummy, placebo- and active comparator–controlled crossover study. Setting HPR Dr. Schaffler GmbH, Munich, Germany. Subject Healthy male subjects aged 18–55 years. Methods Twenty-four eligible subjects were randomly assigned to one of four treatment sequences and received single doses of ASP9226 (30 mg or 50 mg), pregabalin (150 mg), or placebo during four treatment periods. Laser-evoked potentials (LEP) and postlaser pain visual analog scales (VAS) on capsaicin-treated skin were assessed during main assessment days (the first day of each study period). Primary and secondary end points were the differences in LEP N2-P2 peak-to-peak (PtP) amplitudes and VAS score, respectively, in all subjects. Results Overall, treatment with pregabalin resulted in a significantly lower LEP N2-P2 PtP amplitude vs placebo (–3.30 μV, P < 0.0001). There were no clinically relevant differences in N2-P2 PtP amplitudes between placebo and either ASP9226 dose (–0.31 μV and –0.27 μV). Furthermore, subjects reported significantly lower VAS pain scores with pregabalin vs placebo (–9.90%, P < 0.0001) in contrast to ASP9226 30 mg (–2.1%) and ASP9226 50 mg (1.2%) vs placebo. Subgroup analysis of LEP and VAS pain in participants with positive prestudy capsaicin response (n = 13) were in keeping with results in all subjects. Conclusions ASP9226 was well tolerated; however, there was no improvement in LEP and VAS pain scores with ASP9226 at either dose vs placebo.
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Affiliation(s)
- Klaus Schaffler
- HPR (Human Pharmacodynamic Research) Dr. Schaffler GmbH, Munich, Germany
| | - Weizhong He
- Astellas Pharma Global Development, Northbrook, Illinois, USA
| | - Paul Passier
- Astellas Pharma Europe B.V., Leiden, the Netherlands
| | - Katherine Tracy
- Astellas Pharma Global Development, Northbrook, Illinois, USA
| | - Allam Fakhoury
- Astellas Pharma Global Development, Northbrook, Illinois, USA
| | - Jeffrey Paul
- Astellas Pharma Global Development, Northbrook, Illinois, USA
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12
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Schaffler K, Yassen A, Reeh P, Passier P. A Randomized, Double-Blind, Placebo- and Active Comparator-Controlled Phase I Study of Analgesic/Antihyperalgesic Properties of ASP8477, a Fatty Acid Amide Hydrolase Inhibitor, in Healthy Female Subjects. PAIN MEDICINE 2019; 19:1206-1218. [PMID: 29228247 PMCID: PMC5998989 DOI: 10.1093/pm/pnx281] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Objectives To evaluate the analgesic/antihyperalgesic effect of ASP8477. Design Randomized, double-blind, double-dummy, cross-over, placebo- and active comparator-controlled study. Setting HPR Dr. Schaffler GmbH, Munich, Germany. Subjects Healthy female subjects aged 18–65 years. Methods Eligible subjects were randomly assigned to one of six treatment sequences and received multiple ascending doses of ASP8477, duloxetine, and placebo over three treatment periods (each consisting of 21-day dosing separated by 14-day washout periods). On the last day of each dose level, laser evoked potentials (LEPs) and visual analog scales (VAS pain) on capsaicin-treated skin at baseline and at multiple postdose time points were assessed. The primary end point was the difference in LEP N2-P2 peak-to-peak (PtP) amplitudes for ASP8477 100 mg vs placebo. Results Twenty-five subjects were randomized. In all subjects, LEP N2-P2 PtP amplitudes were numerically lower for ASP8477 100 mg vs placebo (P = 0.0721); in subjects who demonstrated positive capsaicin skin effects, a greater mean difference of –2.24 µV (P = 0.0146) was observed. Across all doses, LEP N2-P2 PtP amplitudes were lower for duloxetine compared with ASP8477 (mean difference –3.80 µV; P < 0.0001) or placebo (mean difference –5.21 µV; P < 0.0001). The effect of ASP8477 (all doses) on down-scoring the VAS pain score was significant compared with placebo (mean difference –2.55%; P < 0.0007). Conclusions ASP8477 was well tolerated in this study. Analysis of all subjects did not demonstrate a significant difference in LEP for ASP8477 100 mg over placebo but did in subjects who demonstrated positive capsaicin skin effects.
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Affiliation(s)
- Klaus Schaffler
- Human Pharmacodynamic Research (HPR) Dr. Schaffler GmbH, Munich, Germany
| | | | - Peter Reeh
- Institute for Physiology and Pathophysiology, University Erlangen-Nuremberg, Erlangen, Germany
| | - Paul Passier
- Astellas Pharma Europe B.V., Leiden, Netherlands
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A randomised, double-blind, placebo-controlled crossover trial of the influence of the HCN channel blocker ivabradine in a healthy volunteer pain model: an enriched population trial. Pain 2019; 160:2554-2565. [DOI: 10.1097/j.pain.0000000000001638] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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14
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Meeker TJ, Keaser ML, Khan SA, Gullapalli RP, Seminowicz DA, Greenspan JD. Non-invasive Motor Cortex Neuromodulation Reduces Secondary Hyperalgesia and Enhances Activation of the Descending Pain Modulatory Network. Front Neurosci 2019; 13:467. [PMID: 31139047 PMCID: PMC6519323 DOI: 10.3389/fnins.2019.00467] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 04/24/2019] [Indexed: 11/29/2022] Open
Abstract
Central sensitization is a driving mechanism in many chronic pain patients, and manifests as hyperalgesia and allodynia beyond any apparent injury. Recent studies have demonstrated analgesic effects of motor cortex (M1) stimulation in several chronic pain disorders, yet its neural mechanisms remain uncertain. We evaluated whether anodal M1 transcranial direct current stimulation (tDCS) would mitigate central sensitization as measured by indices of secondary hyperalgesia. We used a capsaicin-heat pain model to elicit secondary mechanical hyperalgesia in 27 healthy subjects. In an assessor and subject-blind randomized, sham-controlled, crossover trial, anodal M1 tDCS decreased the intensity of pinprick hyperalgesia more than cathodal or sham tDCS. To elucidate the mechanism driving analgesia, subjects underwent fMRI of painful mechanical stimuli prior to and following induction of the pain model, after receiving M1 tDCS. We hypothesized that anodal M1 tDCS would enhance engagement of a descending pain modulatory (DPM) network in response to mechanical stimuli. Anodal tDCS normalized the effects of central sensitization on neurophysiological responses to mechanical pain in the medial prefrontal cortex, pregenual anterior cingulate cortex, and periaqueductal gray, important regions in the DPM network. Taken together, these results provide support for the hypothesis that anodal M1-tDCS reduces central sensitization-induced hyperalgesia through the DPM network in humans.
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Affiliation(s)
- Timothy J. Meeker
- Department of Neurosurgery, Johns Hopkins Medicine, Baltimore, MD, United States
- Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, United States
- Program in Neuroscience, University of Maryland, Baltimore, Baltimore, MD, United States
- Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Baltimore, MD, United States
| | - Michael L. Keaser
- Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, United States
| | - Shariq A. Khan
- Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, United States
| | - Rao P. Gullapalli
- Program in Neuroscience, University of Maryland, Baltimore, Baltimore, MD, United States
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland, Baltimore, Baltimore, MD, United States
| | - David A. Seminowicz
- Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, United States
- Program in Neuroscience, University of Maryland, Baltimore, Baltimore, MD, United States
- Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Baltimore, MD, United States
| | - Joel D. Greenspan
- Department of Neural and Pain Sciences, School of Dentistry, University of Maryland, Baltimore, Baltimore, MD, United States
- Program in Neuroscience, University of Maryland, Baltimore, Baltimore, MD, United States
- Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Baltimore, MD, United States
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15
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16
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TRPA1 Sensitization Produces Hyperalgesia to Heat but not to Cold Stimuli in Human Volunteers. Clin J Pain 2019; 35:321-327. [DOI: 10.1097/ajp.0000000000000677] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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17
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Quantitative sensory testing response patterns to capsaicin- and ultraviolet-B-induced local skin hypersensitization in healthy subjects: a machine-learned analysis. Pain 2019; 159:11-24. [PMID: 28700537 PMCID: PMC5737455 DOI: 10.1097/j.pain.0000000000001008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The comprehensive assessment of pain-related human phenotypes requires combinations of nociceptive measures that produce complex high-dimensional data, posing challenges to bioinformatic analysis. In this study, we assessed established experimental models of heat hyperalgesia of the skin, consisting of local ultraviolet-B (UV-B) irradiation or capsaicin application, in 82 healthy subjects using a variety of noxious stimuli. We extended the original heat stimulation by applying cold and mechanical stimuli and assessing the hypersensitization effects with a clinically established quantitative sensory testing (QST) battery (German Research Network on Neuropathic Pain). This study provided a 246 × 10-sized data matrix (82 subjects assessed at baseline, following UV-B application, and following capsaicin application) with respect to 10 QST parameters, which we analyzed using machine-learning techniques. We observed statistically significant effects of the hypersensitization treatments in 9 different QST parameters. Supervised machine-learned analysis implemented as random forests followed by ABC analysis pointed to heat pain thresholds as the most relevantly affected QST parameter. However, decision tree analysis indicated that UV-B additionally modulated sensitivity to cold. Unsupervised machine-learning techniques, implemented as emergent self-organizing maps, hinted at subgroups responding to topical application of capsaicin. The distinction among subgroups was based on sensitivity to pressure pain, which could be attributed to sex differences, with women being more sensitive than men. Thus, while UV-B and capsaicin share a major component of heat pain sensitization, they differ in their effects on QST parameter patterns in healthy subjects, suggesting a lack of redundancy between these models.
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18
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Machine-learned analysis of the association of next-generation sequencing-based human TRPV1 and TRPA1 genotypes with the sensitivity to heat stimuli and topically applied capsaicin. Pain 2019; 159:1366-1381. [PMID: 29596157 PMCID: PMC6012053 DOI: 10.1097/j.pain.0000000000001222] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Heat pain and its modulation by capsaicin varies among subjects in experimental and clinical settings. A plausible cause is a genetic component, of which TRPV1 ion channels, by their response to both heat and capsaicin, are primary candidates. However, TRPA1 channels can heterodimerize with TRPV1 channels and carry genetic variants reported to modulate heat pain sensitivity. To address the role of these candidate genes in capsaicin-induced hypersensitization to heat, pain thresholds acquired before and after topical application of capsaicin and TRPA1/TRPV1 exomic sequences derived by next-generation sequencing were assessed in n = 75 healthy volunteers and the genetic information comprised 278 loci. Gaussian mixture modeling indicated 2 phenotype groups with high or low capsaicin-induced hypersensitization to heat. Unsupervised machine learning implemented as swarm-based clustering hinted at differences in the genetic pattern between these phenotype groups. Several methods of supervised machine learning implemented as random forests, adaptive boosting, k-nearest neighbors, naive Bayes, support vector machines, and for comparison, binary logistic regression predicted the phenotype group association consistently better when based on the observed genotypes than when using a random permutation of the exomic sequences. Of note, TRPA1 variants were more important for correct phenotype group association than TRPV1 variants. This indicates a role of the TRPA1 and TRPV1 next-generation sequencing-based genetic pattern in the modulation of the individual response to heat-related pain phenotypes. When considering earlier evidence that topical capsaicin can induce neuropathy-like quantitative sensory testing patterns in healthy subjects, implications for future analgesic treatments with transient receptor potential inhibitors arise.
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Ferland CE, Villemure C, Michon PE, Gandhi W, Ma ML, Chouchou F, Parent AJ, Bushnell MC, Lavigne G, Rainville P, Ware MA, Jackson PL, Schweinhardt P, Marchand S. Multicenter assessment of quantitative sensory testing (QST) for the detection of neuropathic-like pain responses using the topical capsaicin model. Can J Pain 2018; 2:266-279. [PMID: 35005384 PMCID: PMC8730652 DOI: 10.1080/24740527.2018.1525682] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Background The use of quantitative sensory testing (QST) in multicenter studies has been quite limited, due in part to lack of standardized procedures among centers. Aim The aim of this study was to assess the application of the capsaicin pain model as a surrogate experimental human model of neuropathic pain in different centers and verify the variation in reports of QST measures across centers. Methods A multicenter study conducted by the Quebec Pain Research Network in six laboratories allowed the evaluation of nine QST parameters in 60 healthy subjects treated with topical capsaicin to model unilateral pain and allodynia. The same measurements (without capsaicin) were taken in 20 patients with chronic neuropathic pain recruited from an independent pain clinic. Results Results revealed that six parameters detected a significant difference between the capsaicin-treated and the control skin areas: (1) cold detection threshold (CDT) and (2) cold pain threshold (CPT) are lower on the capsaicin-treated side, indicating a decreased in cold sensitivity; (3) heat pain threshold (HPT) was lower on the capsaicin-treated side in healthy subjects, suggesting an increased heat pain sensitivity; (4) dynamic mechanical allodynia (DMA); (5) mechanical pain after two stimulations (MPS2); and (6) mechanical pain summation after ten stimulations (MPS10), are increased on the capsaicin-treated side, suggesting an increased in mechanical pain (P < 0.002). CDT, CPT and HPT showed comparable effects across all six centers, with CPT and HPT demonstrating the best sensitivity. Data from the patients showed significant difference between affected and unaffected body side but only with CDT. Conclusion These results provide further support for the application of QST in multicenter studies examining normal and pathological pain responses.
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Affiliation(s)
- Catherine E Ferland
- Quebec Pain Research Network, Université de Sherbrooke, Sherbrooke, QC, Canada.,Research Centre, Shriners Hospitals for Children-Canada, Montreal, QC, Canada.,Department of Anesthesia, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - Chantal Villemure
- Alan Edwards Pain Management Unit, McGill University Health Centre, Montreal, QC, Canada
| | - Pierre-Emmanuel Michon
- Division des Neurosciences cliniques et cognitives, centre de recherche CERVO, Université Laval, Quebec, QC, Canada
| | - Wiebke Gandhi
- Centre for Integrative Neuroscience and Neurodynamics, School of Psychology and Clinical Language Sciences, University of Reading, Reading, UK
| | - My-Linh Ma
- Research Centre, Shriners Hospitals for Children-Canada, Montreal, QC, Canada
| | - Florian Chouchou
- Département santé buccale, Faculté de médecine dentaire, Université de Montréal, Montreal, QC, Canada
| | - Alexandre J Parent
- Quebec Pain Research Network, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - M Catherine Bushnell
- National Centre for Complementary and Integrative Health, NIH, Bethesda, MD, USA
| | - Gilles Lavigne
- Quebec Pain Research Network, Université de Sherbrooke, Sherbrooke, QC, Canada.,Département santé buccale, Faculté de médecine dentaire, Université de Montréal, Montreal, QC, Canada
| | - Pierre Rainville
- Quebec Pain Research Network, Université de Sherbrooke, Sherbrooke, QC, Canada.,Centre de recherche de l'Institut universitaire de gériatrie de Montréal (CRIUGM), Montreal, QC, Canada.,Département de stomatologie, Faculté de médecine dentaire, Université de Montréal, Montreal, QC, Canada
| | - Mark A Ware
- Quebec Pain Research Network, Université de Sherbrooke, Sherbrooke, QC, Canada.,Alan Edwards Pain Management Unit, McGill University Health Centre, Montreal, QC, Canada
| | - Philip L Jackson
- Quebec Pain Research Network, Université de Sherbrooke, Sherbrooke, QC, Canada.,Division des Neurosciences cliniques et cognitives, centre de recherche CERVO, Université Laval, Quebec, QC, Canada.,School of Psychology, Université Laval, Quebec, QC, Canada
| | - Petra Schweinhardt
- Quebec Pain Research Network, Université de Sherbrooke, Sherbrooke, QC, Canada.,Department of Neurology and Neurosurgery, Faculty of Medicine, McGill University, Montreal, QC, Canada
| | - Serge Marchand
- Quebec Pain Research Network, Université de Sherbrooke, Sherbrooke, QC, Canada.,Centre de recherche du CHUS, Sherbrooke, QC, Canada.,Department of Surgery, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, QC, Québec, Canada
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Weyer-Menkhoff I, Lötsch J. Human pharmacological approaches to TRP-ion-channel-based analgesic drug development. Drug Discov Today 2018; 23:2003-2012. [PMID: 29969684 DOI: 10.1016/j.drudis.2018.06.020] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 06/07/2018] [Accepted: 06/27/2018] [Indexed: 12/19/2022]
Abstract
The discovery of novel analgesic drug targets is an active research topic owing to insufficient treatment options for persisting pain. Modulators of temperature-sensing transient receptor potential ion channels (thermoTRPs), in particular TRPV1, TRPV2, TRPM8 and TRPA1, have reached clinical development. This requires access for TRP channels and the effects of specific modulators in humans. This is currently possible via (i) the study of TRP channel function in human-derived cell lines, (ii) immunohistochemical visualization of TRP channel expression in human tissues, (iii) human experimental pain models employing sensitization by means of topical application of TRP channel activators including capsaicin (TRPV1), menthol (TRPM8), mustard oil and cinnamaldehyde (TRPA1), and (iv) the study of phenotypic consequences of human TRP gene variants.
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Affiliation(s)
- Iris Weyer-Menkhoff
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany
| | - Jörn Lötsch
- Institute of Clinical Pharmacology, Goethe-University, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany; Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596 Frankfurt am Main, Germany.
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21
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Lötsch J, Lerch F, Djaldetti R, Tegder I, Ultsch A. Identification of disease-distinct complex biomarker patterns by means of unsupervised machine-learning using an interactive R toolbox (Umatrix). BIG DATA ANALYTICS 2018. [DOI: 10.1186/s41044-018-0032-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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22
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Vollert J, Magerl W, Baron R, Binder A, Enax-Krumova EK, Geisslinger G, Gierthmühlen J, Henrich F, Hüllemann P, Klein T, Lötsch J, Maier C, Oertel B, Schuh-Hofer S, Tölle TR, Treede RD. Pathophysiological mechanisms of neuropathic pain: comparison of sensory phenotypes in patients and human surrogate pain models. Pain 2018; 159:1090-1102. [DOI: 10.1097/j.pain.0000000000001190] [Citation(s) in RCA: 56] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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23
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Moskal D, Maisto SA, De Vita M, Ditre JW. Effects of experimental pain induction on alcohol urge, intention to consume alcohol, and alcohol demand. Exp Clin Psychopharmacol 2018; 26:65-76. [PMID: 29323505 PMCID: PMC5794517 DOI: 10.1037/pha0000170] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Research suggests one determinant of alcohol consumption may be physical pain, but there is no empirical evidence that pain has a causal effect on drinking. Therefore, the primary aim of this study was to test experimental pain as a determinant of several alcohol consumption proxies: self-reported urge to drink, intention to consume alcohol, and alcohol demand. This study also was designed to test negative affect as a mediator of the effects of pain on alcohol use proxies. We hypothesized that participants randomized to experimental pain induction (vs. no pain) would report greater urge, intention, and alcohol demand, and that these effects would be mediated by increased negative affect. Participants were healthy undergraduates who were moderate-heavy drinkers (N = 61). Experimental pain was induced using a novel capsaicin-heat model intended to approximate key features of clinical pain. Results indicated that participants in the pain condition subsequently endorsed greater urge and intention to drink. Furthermore, these effects were mediated by pain-induced negative affect. We observed no effect of pain on alcohol demand. This is the first study to demonstrate a causal effect of acute pain on urge and intention to drink. Given the close association between alcohol consumption, urge and intention to drink, these findings suggest that pain may influence alcohol consumption, which can have implications for individuals with co-occurring pain and alcohol use disorder (AUD). Specifically, individuals with co-occurring pain and AUD may drink to alleviate pain-related negative affect. Therefore, improving pain-coping skills may enhance pain-management abilities, subsequently reducing coping-motivated drinking. (PsycINFO Database Record
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Using a Standardized Clinical Quantitative Sensory Testing Battery to Judge the Clinical Relevance of Sensory Differences Between Adjacent Body Areas. Clin J Pain 2017; 33:37-43. [PMID: 27300723 DOI: 10.1097/ajp.0000000000000372] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Skin sensitivity to sensory stimuli varies among different body areas. A standardized clinical quantitative sensory testing (QST) battery, established for the diagnosis of neuropathic pain, was used to assess whether the magnitude of differences between test sites reaches clinical significance. METHODS Ten different sensory QST measures derived from thermal and mechanical stimuli were obtained from 21 healthy volunteers (10 men) and used to create somatosensory profiles bilateral from the dorsum of the hands (the standard area for the assessment of normative values for the upper extremities as proposed by the German Research Network on Neuropathic Pain) and bilateral at volar forearms as a neighboring nonstandard area. The parameters obtained were statistically compared between test sites. RESULTS Three of the 10 QST parameters differed significantly with respect to the "body area," that is, warmth detection, thermal sensory limen, and mechanical pain thresholds. After z-transformation and interpretation according to the QST battery's standard instructions, 22 abnormal values were obtained at the hand. Applying the same procedure to parameters assessed at the nonstandard site forearm, that is, z-transforming them to the reference values for the hand, 24 measurements values emerged as abnormal, which was not significantly different compared with the hand (P=0.4185). CONCLUSIONS Sensory differences between neighboring body areas are statistically significant, reproducing prior knowledge. This has to be considered in scientific assessments where a small variation of the tested body areas may not be an option. However, the magnitude of these differences was below the difference in sensory parameters that is judged as abnormal, indicating a robustness of the QST instrument against protocol deviations with respect to the test area when using the method of comparison with a 95 % confidence interval of a reference dataset.
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Furman AJ, Meeker TJ, Rietschel JC, Yoo S, Muthulingam J, Prokhorenko M, Keaser ML, Goodman RN, Mazaheri A, Seminowicz DA. Cerebral peak alpha frequency predicts individual differences in pain sensitivity. Neuroimage 2017; 167:203-210. [PMID: 29175204 DOI: 10.1016/j.neuroimage.2017.11.042] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2017] [Revised: 11/15/2017] [Accepted: 11/19/2017] [Indexed: 10/18/2022] Open
Abstract
The identification of neurobiological markers that predict individual predisposition to pain are not only important for development of effective pain treatments, but would also yield a more complete understanding of how pain is implemented in the brain. In the current study using electroencephalography (EEG), we investigated the relationship between the peak frequency of alpha activity over sensorimotor cortex and pain intensity during capsaicin-heat pain (C-HP), a prolonged pain model known to induce spinal central sensitization in primates. We found that peak alpha frequency (PAF) recorded during a pain-free period preceding the induction of prolonged pain correlated with subsequent pain intensity reports: slower peak frequency at pain-free state was associated with higher pain during the prolonged pain condition. Moreover, the degree to which PAF decreased between pain-free and prolonged pain states was correlated with pain intensity. These two metrics were statistically uncorrelated and in combination were able to account for 50% of the variability in pain intensity. Altogether, our findings suggest that pain-free state PAF over relevant sensory systems could serve as a marker of individual predisposition to prolonged pain. Moreover, slowing of PAF in response to prolonged pain could represent an objective marker for subjective pain intensity. Our findings potentially lead the way for investigations in clinical populations in which alpha oscillations and the brain areas contributing to their generation are used in identifying and formulating treatment strategies for patients more likely to develop chronic pain.
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Affiliation(s)
- Andrew J Furman
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, 21201, United States; Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD, 21201, United States; Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD, 21201, United States
| | - Timothy J Meeker
- Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD, 21201, United States; Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD, 21201, United States; Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD, 21201, United States
| | - Jeremy C Rietschel
- Maryland Exercise and Robotics Center of Excellence, Veterans Health Administration, Baltimore, MD, United States
| | - Sooyoung Yoo
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD, 21201, United States
| | - Janusiya Muthulingam
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD, 21201, United States
| | - Mariya Prokhorenko
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD, 21201, United States
| | - Michael L Keaser
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD, 21201, United States; Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD, 21201, United States
| | - Ronald N Goodman
- Maryland Exercise and Robotics Center of Excellence, Veterans Health Administration, Baltimore, MD, United States
| | - Ali Mazaheri
- Center for Human Brain Health, School of Psychology, University of Birmingham, B15 2TT, United Kingdom.
| | - David A Seminowicz
- Department of Neural and Pain Sciences, University of Maryland School of Dentistry, Baltimore, MD, 21201, United States; Center to Advance Chronic Pain Research, University of Maryland Baltimore, Baltimore, MD, 21201, United States.
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Characterization of a novel capsaicin/heat ongoing pain model. Eur J Pain 2017; 22:370-384. [DOI: 10.1002/ejp.1126] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2017] [Indexed: 12/27/2022]
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van Amerongen G, de Boer MW, Groeneveld GJ, Hay JL. A literature review on the pharmacological sensitivity of human evoked hyperalgesia pain models. Br J Clin Pharmacol 2016; 82:903-22. [PMID: 27203797 DOI: 10.1111/bcp.13018] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 05/13/2016] [Accepted: 05/18/2016] [Indexed: 02/06/2023] Open
Abstract
AIMS Human evoked pain models can be used to determine the efficacy of new and existing analgesics and to aid in the identification of new targets. Aspects of neuropathic pain can be simulated by inducing hyperalgesia resulting from provoked sensitization. The present literature review aimed to provide insight into the sensitivity of different hyperalgesia and allodynia models of pharmacological treatment. METHODS A literature search was performed to identify randomized, double-blind, placebo-controlled studies that included human hyperalgesia pain models and investigated the pharmacodynamic effects of different classes of drugs. RESULTS Three hyperalgesia models [ultraviolet B (UVB) irradiation, capsaicin and thermode burn] have been used extensively. Assessment of hyperalgesia/allodynia and pharmacological effect are measured using challenge tests, which generally comprise thermal (heat/cold) or mechanical stimulation (pin-prick, stroking or impact). The UVB model was sensitive to the antihyperalgesic effects of nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids. The capsaicin model was partially sensitive to opioids. The burn model did not detect any antihyperalgesic effects when NSAIDs or local anaesthetics were administered but responded to the effects of N-methyl D-aspartate (NMDA) receptor antagonists by moderately reducing mechanical hyperalgesia. CONCLUSIONS Based on pharmacological sensitivity, the UVB model adequately reflects inflammatory pain and was sensitive to NSAIDs and opioids. Findings from the capsaicin and burn models raised questions about the translatability of these models to the treatment of neuropathic pain. There is a need for a reproducible and predictive model of neuropathic pain, either in healthy subjects or in patients.
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Affiliation(s)
| | | | | | - Justin L Hay
- Centre for Human Drug Research (CHDR), Leiden, The Netherlands
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Schunke O, Grashorn W, Kahl U, Schöttle D, Haggard P, Münchau A, Bingel U, Ganos C. Quantitative Sensory Testing in adults with Tourette syndrome. Parkinsonism Relat Disord 2016; 24:132-6. [DOI: 10.1016/j.parkreldis.2016.01.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Revised: 12/10/2015] [Accepted: 01/06/2016] [Indexed: 11/25/2022]
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Identification of Molecular Fingerprints in Human Heat Pain Thresholds by Use of an Interactive Mixture Model R Toolbox (AdaptGauss). Int J Mol Sci 2015; 16:25897-911. [PMID: 26516852 PMCID: PMC4632832 DOI: 10.3390/ijms161025897] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 09/28/2015] [Accepted: 10/21/2015] [Indexed: 12/14/2022] Open
Abstract
Biomedical data obtained during cell experiments, laboratory animal research, or human studies often display a complex distribution. Statistical identification of subgroups in research data poses an analytical challenge. Here were introduce an interactive R-based bioinformatics tool, called “AdaptGauss”. It enables a valid identification of a biologically-meaningful multimodal structure in the data by fitting a Gaussian mixture model (GMM) to the data. The interface allows a supervised selection of the number of subgroups. This enables the expectation maximization (EM) algorithm to adapt more complex GMM than usually observed with a noninteractive approach. Interactively fitting a GMM to heat pain threshold data acquired from human volunteers revealed a distribution pattern with four Gaussian modes located at temperatures of 32.3, 37.2, 41.4, and 45.4 °C. Noninteractive fitting was unable to identify a meaningful data structure. Obtained results are compatible with known activity temperatures of different TRP ion channels suggesting the mechanistic contribution of different heat sensors to the perception of thermal pain. Thus, sophisticated analysis of the modal structure of biomedical data provides a basis for the mechanistic interpretation of the observations. As it may reflect the involvement of different TRP thermosensory ion channels, the analysis provides a starting point for hypothesis-driven laboratory experiments.
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Lötsch J, Dimova V, Ultsch A, Lieb I, Zimmermann M, Geisslinger G, Oertel BG. A small yet comprehensive subset of human experimental pain models emerging from correlation analysis with a clinical quantitative sensory testing protocol in healthy subjects. Eur J Pain 2015; 20:777-89. [PMID: 26492152 DOI: 10.1002/ejp.803] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/06/2015] [Indexed: 11/11/2022]
Abstract
BACKGROUND Picturing the complexity of pain in human experimental settings has increased the predictivity for clinical pain but requires increasingly complex test batteries. This raises problems in studies in which time is objectively limited, for example by the course of action of an analgesic drug. We addressed the selection of a small yet comprehensive set of pain tests for the use in such a situation. METHOD Nineteen different pain measures from 'classical' pain models (n = 9) and a clinically established QST-pain test battery (n = 10), were obtained from 72 healthy volunteers (34 men). The nonparametric correlation structure among the various pain measures was analysed using Ward clustering. RESULTS Four clusters emerged, each consisting of highly correlated pain measures. The pain model groups emerged comprised (I) pain thresholds and tolerances to blunt pressure or electrical pain; (II) pain thresholds to thermal stimuli; (III) pain measures obtained following application of punctate mechanical, intranasal CO2 chemical or cutaneous laser heat stimuli; and (IV) detection thresholds to thermal stimuli. The first three clusters agreed with an immediate mechanistic interpretation as reflecting C-fibre mediated pain, thermal pain and Aδ-fibre mediated pain, respectively, whereas the last cluster contained non-painful measures and was disregarded. CONCLUSIONS When basing a selection of a small comprehensive set of pain models on the assumption that highly correlated pain measures account for redundant results and therefore, one member of each group suffices an economic yet comprehensive pain study, results suggest inclusion of established C-fibre, Aδ-fibre mediated and thermal pain measures.
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Affiliation(s)
- J Lötsch
- Institute of Clinical Pharmacology, Goethe - University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.,Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
| | - V Dimova
- Institute of Clinical Pharmacology, Goethe - University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.,Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - A Ultsch
- DataBionics Research Group, University of Marburg, Hans-Meerwein-Straße, 35032, Marburg, Germany
| | - I Lieb
- Institute of Clinical Pharmacology, Goethe - University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - M Zimmermann
- DataBionics Research Group, University of Marburg, Hans-Meerwein-Straße, 35032, Marburg, Germany
| | - G Geisslinger
- Institute of Clinical Pharmacology, Goethe - University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.,Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
| | - B G Oertel
- Institute of Clinical Pharmacology, Goethe - University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.,Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
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Dimova V, Oertel BG, Kabakci G, Zimmermann M, Hermens H, Lautenbacher S, Ultsch A, Lötsch J. A more pessimistic life orientation is associated with experimental inducibility of a neuropathy-like pain pattern in healthy individuals. THE JOURNAL OF PAIN 2015; 16:791-800. [PMID: 26056011 DOI: 10.1016/j.jpain.2015.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 04/27/2015] [Accepted: 05/19/2015] [Indexed: 01/31/2023]
Abstract
UNLABELLED The clinical pattern of neuropathic pain, diagnosed using the quantitative sensory testing (QST) battery (German Research Network on Neuropathic Pain), could be partly mimicked in healthy volunteers after topical capsaicin application. However, similar to clinical neuropathic pain that develops in only a subgroup of patients who have a neurologic lesion, this attempt to mimick a neuropathic pain pattern succeeded only in a small fraction (18%) of healthy individuals. In the present assessment, we pursued the hypothesis that the inducible subgroup differed from the other healthy participants with respect to their psychological phenotype. Therefore, in an observational study, participants were assessed using a comprehensive set of psychological variables comprising general psychological and pain-related cognitive-emotional mechanisms. The sum scores of the questionnaires were significantly linearly correlated with each other. Principal component analysis indicated that a major source of variance (46%) could be attributed to dispositional optimism examined via the Life Orientation Test (LOT). The LOT score significantly differed between the groups of participants, either those in whom a neuropathy-like pattern of pain assessed via QST could be partly (50-60% of the 11 QST parameters) induced (n = 20) or not (n = 90; P = .0375). It emerged again as the main selection criterion in a classification and regression tree predicting a participant's group assignment (inducible neuropathy-like QST pattern versus noninducible neuropathy-like QST pattern) at a cross-validated accuracy of 95.5 ± 2.1%. Thus, the few participants in a random sample of healthy volunteers who, after topical capsaicin application, partly resemble (to a degree of about 60%) the clinical pattern of neuropathic pain in the QST test battery, are preselectable on the basis of psychological factors, with a particular emphasis on pessimistic life attitudes. PERSPECTIVE In a small fraction of 18% of healthy volunteers, topical capsaicin application resulted in a neuropathy-like pattern in 50 to 60% of the components of a clinical test battery. These individuals displayed a more pessimistic life attitude as assessed by means of the LOT.
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Affiliation(s)
- Violeta Dimova
- Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany; Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Bruno G Oertel
- Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany; Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Frankfurt am Main, Germany
| | - Gülden Kabakci
- Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany
| | - Michael Zimmermann
- Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Hanneke Hermens
- Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany
| | - Stefan Lautenbacher
- Physiological Psychology, Otto-Friedrich University Bamberg, Bamberg, Germany
| | - Alfred Ultsch
- DataBionics Research Group, University of Marburg, Marburg, Germany
| | - Jörn Lötsch
- Institute of Clinical Pharmacology, Goethe-University, Frankfurt am Main, Germany; Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Frankfurt am Main, Germany.
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Lötsch J, Dimova V, Lieb I, Zimmermann M, Oertel BG, Ultsch A. Multimodal distribution of human cold pain thresholds. PLoS One 2015; 10:e0125822. [PMID: 25992576 PMCID: PMC4439151 DOI: 10.1371/journal.pone.0125822] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 03/19/2015] [Indexed: 01/21/2023] Open
Abstract
Background It is assumed that different pain phenotypes are based on varying molecular pathomechanisms. Distinct ion channels seem to be associated with the perception of cold pain, in particular TRPM8 and TRPA1 have been highlighted previously. The present study analyzed the distribution of cold pain thresholds with focus at describing the multimodality based on the hypothesis that it reflects a contribution of distinct ion channels. Methods Cold pain thresholds (CPT) were available from 329 healthy volunteers (aged 18 – 37 years; 159 men) enrolled in previous studies. The distribution of the pooled and log-transformed threshold data was described using a kernel density estimation (Pareto Density Estimation (PDE)) and subsequently, the log data was modeled as a mixture of Gaussian distributions using the expectation maximization (EM) algorithm to optimize the fit. Results CPTs were clearly multi-modally distributed. Fitting a Gaussian Mixture Model (GMM) to the log-transformed threshold data revealed that the best fit is obtained when applying a three-model distribution pattern. The modes of the identified three Gaussian distributions, retransformed from the log domain to the mean stimulation temperatures at which the subjects had indicated pain thresholds, were obtained at 23.7 °C, 13.2 °C and 1.5 °C for Gaussian #1, #2 and #3, respectively. Conclusions The localization of the first and second Gaussians was interpreted as reflecting the contribution of two different cold sensors. From the calculated localization of the modes of the first two Gaussians, the hypothesis of an involvement of TRPM8, sensing temperatures from 25 – 24 °C, and TRPA1, sensing cold from 17 °C can be derived. In that case, subjects belonging to either Gaussian would possess a dominance of the one or the other receptor at the skin area where the cold stimuli had been applied. The findings therefore support a suitability of complex analytical approaches to detect mechanistically determined patterns from pain phenotype data.
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Affiliation(s)
- Jörn Lötsch
- Institute of Clinical Pharmacology, Goethe—University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
- * E-mail:
| | - Violeta Dimova
- Institute of Clinical Pharmacology, Goethe—University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
- Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Isabel Lieb
- Institute of Clinical Pharmacology, Goethe—University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Michael Zimmermann
- Department of Anesthesiology, Intensive Care Medicine and Pain Therapy, University Hospital Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
| | - Bruno G. Oertel
- Institute of Clinical Pharmacology, Goethe—University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology TMP, Theodor-Stern-Kai 7, 60596, Frankfurt am Main, Germany
| | - Alfred Ultsch
- DataBionics Research Group, University of Marburg, Hans-Meerwein-Straße, 35032, Marburg, Germany
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