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Regnath F, Biersack K, Jäger N, Glasauer S, Lehnen N. Not a general, symptom-unspecific, transdiagnostic marker for functional symptoms: sensorimotor processing of head control is intact in chronic pain. Front Neurol 2023; 14:1294702. [PMID: 38174100 PMCID: PMC10762802 DOI: 10.3389/fneur.2023.1294702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 11/22/2023] [Indexed: 01/05/2024] Open
Abstract
Introduction Functional disorders are prevalent in all medical fields and pose a tremendous public health problem, with pain being one of the most common functional symptoms. Understanding the underlying, potentially unifying mechanism in functional (pain) disorders is instrumental in facilitating timely diagnosis, stigma reduction, and adequate treatment options. Neuroscientific models of perception suggest that functional symptoms arise due to dysregulated sensorimotor processing in the central nervous system, with brain-based predictions dominating the eventual percept. Experimental evidence for this transdiagnostic mechanism has been established in various functional symptoms. The goal of the current study was to investigate whether erroneous sensorimotor processing is an underlying transdiagnostic mechanism in chronic (functional) pain. Method A total of 13 patients with chronic (functional) pain [three patients with chronic (functional) pain disorder, F45.40, ICD-10; 10 patients with chronic pain disorder with somatic and psychological factors, F45.41, ICD-10]; and 15 healthy controls performed large combined eye-head gaze shifts toward visual targets, naturally and with increased head moment of inertia. We simultaneously measured participants' eye and head movements to assess head oscillations at the end of the gaze shift, which are an established indicator of (transdiagnostic) sensorimotor processing deficits of head control. Results Using a Bayesian analysis protocol, we found that patients with chronic (functional) pain and control participants stabilized their heads equally well (Bayes Factor 01 = 3.7, Bayes Factor exclusion = 5.23; corresponding to substantial evidence) during all sessions of the experiment. Conclusion Our results suggest that patients with chronic (functional) pain do not show measurable symptom-unspecific sensorimotor processing deficits. We discuss outcome parameter choice, organ system specificity, and selection of patient diagnoses as possible reasons for this result and recommend future avenues for research.
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Affiliation(s)
- Franziska Regnath
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Rechts der Isar, Technical University of Munich, Munich, Germany
- TUM Graduate School, Graduate Center of Medicine and Health (GC MH), Technical University of Munich, Munich, Germany
| | - Katharina Biersack
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Rechts der Isar, Technical University of Munich, Munich, Germany
- TUM Graduate School, Graduate Center of Medicine and Health (GC MH), Technical University of Munich, Munich, Germany
| | - Nina Jäger
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Rechts der Isar, Technical University of Munich, Munich, Germany
- TUM Graduate School, Graduate Center of Medicine and Health (GC MH), Technical University of Munich, Munich, Germany
| | - Stefan Glasauer
- Computational Neuroscience, Institute of Medical Technology, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
- Faculty of Health Sciences Brandenburg, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
| | - Nadine Lehnen
- Department of Psychosomatic Medicine and Psychotherapy, University Hospital Rechts der Isar, Technical University of Munich, Munich, Germany
- Institute of Medical Technology, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany
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Fan Y, Ni Y, Cheng M, Guo W, Gao H, Hu W, Shu C, Ding L. The metabolite profiling of YR-1702 injection in human plasma, urine and feces by HPLC-Q-TOF-MS/MS. Xenobiotica 2023; 53:536-546. [PMID: 37850428 DOI: 10.1080/00498254.2023.2272193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2023] [Accepted: 10/14/2023] [Indexed: 10/19/2023]
Abstract
YR-1702, a hybrid μ/κ/δ receptor agonist, is modified from the traditional opioid analgesic dezocine. It had shown both excellent analgesic effect and lower addiction in phase I clinical trial in China, however, the metabolic pathway of YR-1702 in humans remains unelucidated.The goals of this study are to characterise the metabolism of YR-1702 in human liver microsomes (HLMs) and patients with chronic non-cancer pain by high performance liquid chromatography-coupled with quadrupole-time-of-flight mass spectrometry (HPLC-Q-TOF-MS/MS).The results showed that a total of twelve metabolites were identified in HLMs, in which 7, 6 and 5 metabolites were also found in human plasma, urine and feces, respectively. And the major metabolic pathways include mono-hydroxylation, di-hydroxylation, dehydrogenation and glucuronidation. The locations of hydroxylation and dehydrogenation were identified by the signature fragments of the metabolites.The relative contents of the metabolites in human plasma were also evaluated, in which the main metabolite M1 notably accounting for more than 14% of the total drug exposure. This study would contribute to the understanding of the in vivo metabolite profile of YR-1702 injection for future use.
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Affiliation(s)
- Yuxuan Fan
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
| | - Yufeng Ni
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
- Yangtze River Pharmaceutical Group Co., Ltd, Taizhou, China
| | - Minlu Cheng
- Nanjing Clinical Tech Laboratories Inc, Nanjing, China
| | - Wenjing Guo
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
| | - Huaye Gao
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
| | - WenHui Hu
- Nanjing Jiening Pharmaceutical Technology Co., Ltd, Nanjing, China
| | - Chang Shu
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
| | - Li Ding
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing, China
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Retrospective Analysis of Functional Pain among Professional Climbers. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12052653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Climbing became one of the official Olympic sports in 2020. The nociplastic pain mechanism is indicated as important in professional sports. Functional pain, which has not been examined in climbers until now, can be an example of nociplastic pain. This study aimed to determine functional pain locations in climbers according to gender and dominant climbing style. Climbers (n = 183) and healthy subjects (n = 160) completed an online survey focused on functional pain occurrence in the head, spine, and upper limbs. The logistic regression showed that climbing predisposes one to functional pain at: Gleno-humeral joint (odds ratio (OR): 3.06; area under the curve (AUC): 0.635), elbow (OR: 2.86; AUC: 0.625), fingers (OR: 7.74; AUC: 0.733), all (p < 0.05). Among the climbers, the female gender predisposed one to pain at: GHJ (OR: 3.34; AUC: 0.638), thoracic spine (OR: 1.95; AUC: 0.580), and lumbosacral spine (OR: 1.96; AUC: 0.578), all (p < 0.05). Climbing predisposes one to functional pain development in the upper limb. While the male climbers mainly suffered from finger functional pain, the female climbers reported functional pain in the GHJ and the thoracic and lumbosacral spine. Further studies on functional pain occurrence are recommended.
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Childers WE, Abou-Gharbia MA. "I'll Be Back": The Resurrection of Dezocine. ACS Med Chem Lett 2021; 12:961-968. [PMID: 34141081 DOI: 10.1021/acsmedchemlett.1c00233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Accepted: 05/07/2021] [Indexed: 12/25/2022] Open
Abstract
Beginning with opium itself, natural and synthetic opioids have been used as analgesics for over 8000 years and were likely abused as drugs of recreation for that long as well. However, the "opioid crisis" resulted in attempts to avoid or limit opioid analgesics in favor of other therapies and methods. Mu opioid agonists can be effective analgesics but suffer from addiction, tolerance, and dangerous, sometimes fatal, side effects. One exception to this generalization is dezocine (Dalgan), a mixed mu/kappa opioid partial agonist. Dezocine is at least as effective as morphine in reducing acute pain in animal models and clinical applications such as postoperative pain. And while dezocine was discontinued in western markets in 2011, it has become the favored opioid analgesic in China, capturing over 40% of the market. Additionally, dezocine possesses norepinephrine uptake inhibitory activity, which may synergize with mu agonism in the case of acute pain treatment and possibly endow the drug with antinociceptive activity in neuropathic pain conditions. This Innovations article summarizes the history and properties of dezocine and presents evidence and rationale for why dezocine has undergone a resurrection.
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Affiliation(s)
- Wayne E. Childers
- The Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, 3307 N. Broad Street, Philadelphia, Pennsylvania 19140, United States
| | - Magid A. Abou-Gharbia
- The Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, 3307 N. Broad Street, Philadelphia, Pennsylvania 19140, United States
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Kano M, Oudenhove LV, Dupont P, Wager TD, Fukudo S. Imaging Brain Mechanisms of Functional Somatic Syndromes: Potential as a Biomarker? TOHOKU J EXP MED 2020; 250:137-152. [PMID: 32132323 DOI: 10.1620/tjem.250.137] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
When patients present with persistent bodily complaints that cannot be explained by a symptom-linked organic pathology (medically unexplained symptoms), they are diagnosed with 'functional' somatic syndromes (FSS). Despite their prevalence, the management of FSS is notoriously challenging in clinical practice. This may be because FSS are heterogeneous disorders in terms of etiopathogenesis. They include patients with primarily peripheral dysfunction, primarily centrally driven somatic symptoms, and a mix of both. Brain-imaging studies, particularly data-driven pattern recognition methods using machine learning algorithms, could provide brain-based biomarkers for these clinical conditions. In this review, we provide an overview of our brain imaging data on brain-body interactions in one of the most well-known FSS, irritable bowel syndrome (IBS), and discuss the possible development of a brain-based biomarker for FSS. Anticipation of unpredictable pain, which commonly elicits fear in FSS patients, induced increased activity in brain areas associated with hypervigilance during rectal distention and non-distention conditions in IBS. This was coupled with dysfunctional inhibitory influence of the medial prefrontal cortex (mPFC) and pregenual anterior cingulate cortex (pACC) on stress regulation systems, resulting in the activated autonomic nervous system (ANS) and neuroendocrine system stimulated by corticotropin-releasing hormone (CRH). IBS subjects with higher alexithymia, a risk factor for FSS, showed stronger activity in the insula during rectal distention but reduced subjective sensitivity. Reduced top-down regulation of the ANS and CRH system by mPFC and pACC, discordance between the insula response to stimulation and subjective sensation of pain, and stronger threat responses in hypervigilance-related areas may be a candidate brain-based biomarker.
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Affiliation(s)
- Michiko Kano
- Sukawa Clinic, Kirari Health-Coop.,Behavioral Medicine, Tohoku University Graduate School of Medicine
| | - Lukas Van Oudenhove
- Laboratory for Brain-Gut Axis Studies (LaBGAS), Translational Research Center for Gastrointestinal Disorders (TARGID), KU Leuven
| | | | - Tor D Wager
- Cognitive and Affective Neuroscience Lab, Department of Psychological and Brain Sciences, Dartmouth College
| | - Shin Fukudo
- Behavioral Medicine, Tohoku University Graduate School of Medicine.,Department of Psychosomatic Medicine, Tohoku University Hospital
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Manion J, Waller MA, Clark T, Massingham JN, Neely GG. Developing Modern Pain Therapies. Front Neurosci 2019; 13:1370. [PMID: 31920521 PMCID: PMC6933609 DOI: 10.3389/fnins.2019.01370] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 12/04/2019] [Indexed: 12/24/2022] Open
Abstract
Chronic pain afflicts as much as 50% of the population at any given time but our methods to address pain remain limited, ineffective and addictive. In order to develop new therapies an understanding of the mechanisms of painful sensitization is essential. We discuss here recent progress in the understanding of mechanisms underlying pain, and how these mechanisms are being targeted to produce modern, specific therapies for pain. Finally, we make recommendations for the next generation of targeted, effective, and safe pain therapies.
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Affiliation(s)
- John Manion
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Matthew A. Waller
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Teleri Clark
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - Joshua N. Massingham
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
| | - G. Gregory Neely
- The Dr. John and Anne Chong Lab for Functional Genomics, Charles Perkins Centre and School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW, Australia
- Genome Editing Initiative, The University of Sydney, Sydney, NSW, Australia
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Castañeda AM, Lee CS, Kim YC, Lee D, Moon JY. Addressing Opioid-Related Chemical Coping in Long-Term Opioid Therapy for Chronic Noncancer Pain: A Multicenter, Observational, Cross-Sectional Study. J Clin Med 2018; 7:E354. [PMID: 30322212 PMCID: PMC6210168 DOI: 10.3390/jcm7100354] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 10/10/2018] [Accepted: 10/13/2018] [Indexed: 11/30/2022] Open
Abstract
Opioid consumption has increased worldwide, which carries the risk of opioid use disorder (OUD). However, the literature on OUD and opioid-related chemical coping (OrCC) in chronic noncancer pain (CNCP) is heterogeneous, with most studies conducted in the United States. We performed a multicenter, observational, cross-sectional study to address OrCC in long-term opioid therapy (LtOT) for CNCP in South Korea. The objectives were to determine the frequency and predictors of OrCC. We included 258 patients. Among them, fifty-five (21%) patients showed OrCC. The sample had high pain catastrophizing (≥30 points; 66%), moderate-severe insomnia (≥15 points; 63%), low resilience (68 points), and high suicidal ideation (67%). OrCC patients had greater pain interference (85.18% vs. 58.28%, p = 0.017) and lower satisfaction with the LtOT (56.4% vs. 78.3%, p = 0.002). In multivariable analysis, alcohol abuse (OR = 6.84, p = 0.001), prescription drugs abuse (OR = 19.32, p = 0.016), functional pain (OR = 12.96, p < 0.001), head and neck pain (OR = 2.48, p = 0.039), MEDD (morphine equivalent daily dose) ≥ 200 mg/day (OR = 3.48, p = 0.006), and ongoing litigation (OR = 2.33, p = 0.047) were significant predictors of OrCC. In conclusion, the break-out of OrCC in CNCP in South Korea was comparable to those in countries with high opioid consumption, such as the United States, regardless of the country's opioid consumption rate.
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Affiliation(s)
- Anyela Marcela Castañeda
- Department of Anesthesiology and Pain Medicine, Seoul National University Hospital College of Medicine, 101Daehak-ro, Jongno-gu, Seoul 03080, Korea.
| | - Chang-Soon Lee
- Department of Anesthesiology and Pain Medicine, Seoul National University Hospital College of Medicine, 101Daehak-ro, Jongno-gu, Seoul 03080, Korea.
| | - Yong-Chul Kim
- Department of Anesthesiology and Pain Medicine, Seoul National University Hospital College of Medicine, 101Daehak-ro, Jongno-gu, Seoul 03080, Korea.
| | - Dasom Lee
- Department of Psychiatry, Seoul National University Hospital College of Medicine, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea.
| | - Jee Youn Moon
- Department of Anesthesiology and Pain Medicine, Seoul National University Hospital College of Medicine, 101Daehak-ro, Jongno-gu, Seoul 03080, Korea.
- Department of Integrated Cancer Care Center, Seoul National University Cancer Hospital, 101 Daehak-ro, Jongno-gu, Seoul 03080, Korea.
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Nation KM, Dodick DW, Navratilova E, Porreca F. Sustained exposure to acute migraine medications combined with repeated noxious stimulation dysregulates descending pain modulatory circuits: Relevance to medication overuse headache. Cephalalgia 2018; 39:617-625. [DOI: 10.1177/0333102418804157] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Background Loss of conditioned pain modulation/diffuse noxious inhibitory controls has been demonstrated in patients with migraine and medication overuse headache. We hypothesized that exposure to acute migraine medications may lead to dysregulation of central pain modulatory circuits that could be revealed by evaluating diffuse noxious inhibitory controls and that prior noxious stimulus is required for a loss of the diffuse noxious inhibitory control response in rats exposed to these medications. Methods Rats were “primed” by continuous infusion of morphine or one of two doses of sumatriptan. Diffuse noxious inhibitory control was evaluated at the end of drug-priming (day 7) and again after sensory thresholds returned to baseline (day 21). The Randall-Selitto hindpaw pressure test was used as the test stimulus and forepaw capsaicin injection served as the conditioning stimulus. Results Morphine-primed rats showed opioid-induced hyperalgesia accompanied by a loss of diffuse noxious inhibitory controls on day 7. Sumatriptan-primed rats did not develop hyperalgesia or loss of diffuse noxious inhibitory controls on day 7. Morphine-primed and high-dose sumatriptan-primed rats only had a loss of diffuse noxious inhibitory control on day 21 if they received a capsaicin injection on day 7. Conclusions Prolonged exposure to migraine treatments followed by an acute nociceptive stimulation caused long-lasting alterations in descending pain modulation, shown by a loss of diffuse noxious inhibitory controls. Morphine was more detrimental than sumatriptan, consistent with clinical observations of higher medication overuse headache risk with opioids. These data suggest a mechanism of medication overuse headache by which migraine medications combined with repeated episodes of pain may amplify the consequences of nociceptor activation and increase the probability of future migraine attacks as well as risk of medication overuse headache.
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Affiliation(s)
- Kelsey M Nation
- Department of Pharmacology, University of Arizona, Tucson, AZ, USA
| | | | - Edita Navratilova
- Department of Pharmacology, University of Arizona, Tucson, AZ, USA
- Mayo Clinic, Scottsdale, AZ, USA
| | - Frank Porreca
- Department of Pharmacology, University of Arizona, Tucson, AZ, USA
- Mayo Clinic, Scottsdale, AZ, USA
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Muddana A, Asbill DT, Jerath MR, Stuebe AM. Quantitative Sensory Testing, Antihistamines, and Beta-Blockers for Management of Persistent Breast Pain: A Case Series. Breastfeed Med 2018; 13:275-280. [PMID: 29630399 DOI: 10.1089/bfm.2017.0158] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND It is not uncommon for mothers to have persistent pain with breastfeeding beyond the first few weeks after birth. Persistent pain can be multifactorial, with neuropathic pain maintained by central sensitization being one dimension. Our knowledge in delineating categories of persistent pain is simple and not very sophisticated. METHODS We have developed and tested a Lactation Quantitative Sensory Test (L-QST) to quantify the neuropathic component of persistent breastfeeding pain. We present three case reports of neuropathic breastfeeding pain and treatment, and we discuss the potential role of histamine and catecholamines in persistent breastfeeding-associated pain. CONCLUSIONS The L-QST can be a useful tool to quantify neuropathic pain. Further studies are needed to test inter-observer reliability and reproducibility of this tool. Antihistamines can be considered for treating persistent pain in breastfeeding women with a history of allergy or atopy, and beta-blockers may be helpful in women with multiple pain disorders.
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Affiliation(s)
- Anitha Muddana
- 1 Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Diane T Asbill
- 2 Lactation Services Department, University of North Carolina Hospitals , Main Campus, North Carolina Women's Hospital, Chapel Hill, North Carolina
| | - Maya R Jerath
- 3 Division of Rheumatology, Allergy, and Immunology, Department of Medicine, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina
| | - Alison M Stuebe
- 4 Division of Maternal-Fetal Medicine, University of North Carolina at Chapel Hill School of Medicine , Chapel Hill, North Carolina
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Nation KM, DeFelice M, Hernandez PI, Dodick DW, Neugebauer V, Navratilova E, Porreca F. Lateralized kappa opioid receptor signaling from the amygdala central nucleus promotes stress-induced functional pain. Pain 2018; 159:919-928. [PMID: 29369967 PMCID: PMC5916844 DOI: 10.1097/j.pain.0000000000001167] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The response of diffuse noxious inhibitory controls (DNIC) is often decreased, or lost, in stress-related functional pain syndromes. Because the dynorphin/kappa opioid receptor (KOR) pathway is activated by stress, we determined its role in DNIC using a model of stress-induced functional pain. Male, Sprague-Dawley rats were primed for 7 days with systemic morphine resulting in opioid-induced hyperalgesia. Fourteen days after priming, when hyperalgesia was resolved, rats were exposed to environmental stress and DNIC was evaluated by measuring hind paw response threshold to noxious pressure (test stimulus) after capsaicin injection in the forepaw (conditioning stimulus). Morphine priming without stress did not alter DNIC. However, stress produced a loss of DNIC in morphine-primed rats in both hind paws that was abolished by systemic administration of the KOR antagonist, nor-binaltorphimine (nor-BNI). Microinjection of nor-BNI into the right, but not left, central nucleus of the amygdala (CeA) prevented the loss of DNIC in morphine-primed rats. Diffuse noxious inhibitory controls were not modulated by bilateral nor-BNI in the rostral ventromedial medulla. Stress increased dynorphin content in both the left and right CeA of primed rats, reaching significance only in the right CeA; no change was observed in the rostral ventromedial medulla or hypothalamus. Although morphine priming alone is not sufficient to influence DNIC, it establishes a state of latent sensitization that amplifies the consequences of stress. After priming, stress-induced dynorphin/KOR signaling from the right CeA inhibits DNIC in both hind paws, likely reflecting enhanced descending facilitation that masks descending inhibition. Kappa opioid receptor antagonists may provide a new therapeutic strategy for stress-related functional pain disorders.
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Affiliation(s)
| | - Milena DeFelice
- Department of Pharmacology, University of Arizona, Tucson, AZ
| | | | | | - Volker Neugebauer
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX
| | - Edita Navratilova
- Department of Pharmacology, University of Arizona, Tucson, AZ
- Mayo Clinic, Scottsdale, AZ
| | - Frank Porreca
- GIDP in Neuroscience, University of Arizona, Tucson, AZ
- Department of Pharmacology, University of Arizona, Tucson, AZ
- Mayo Clinic, Scottsdale, AZ
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