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Huerta MÁ, Cisneros E, Alique M, Roza C. Strategies for measuring non-evoked pain in preclinical models of neuropathic pain: Systematic review. Neurosci Biobehav Rev 2024; 163:105761. [PMID: 38852847 DOI: 10.1016/j.neubiorev.2024.105761] [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: 05/06/2024] [Revised: 05/28/2024] [Accepted: 06/04/2024] [Indexed: 06/11/2024]
Abstract
The development of new analgesics for neuropathic pain treatment is crucial. The failure of promising drugs in clinical trials may be related to the over-reliance on reflex-based responses (evoked pain) in preclinical drug testing, which may not fully represent clinical neuropathic pain, characterized by spontaneous non-evoked pain (NEP). Hence, strategies for assessing NEP in preclinical studies emerged. This systematic review identified 443 articles evaluating NEP in neuropathic pain models (mainly traumatic nerve injuries in male rodents). An exponential growth in NEP evaluation was observed, which was assessed using 48 different tests classified in 12 NEP-related outcomes: anxiety, exploration/locomotion, paw lifting, depression, conditioned place preference, gait, autotomy, wellbeing, facial grooming, cognitive impairment, facial pain expressions and vocalizations. Although most of these outcomes showed clear limitations, our analysis suggests that conditioning-associated outcomes, pain-related comorbidities, and gait evaluation may be the most effective strategies. Moreover, a minimal part of the studies evaluated standard analgesics. The greater emphasis on evaluating NEP aligning with clinical pain symptoms may enhance analgesic drug development, improving clinical translation.
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Affiliation(s)
- Miguel Á Huerta
- Department of Pharmacology, Faculty of Medicine, University of Granada, Granada 18016, Spain; Institute of Neuroscience, Biomedical Research Center, University of Granada, 18100 Armilla, Granada, Spain; Biosanitary Research Institute ibs.GRANADA, Granada 18012, Spain
| | - Elsa Cisneros
- Health Sciences School, Centro Universitario Internacional de Madrid (CUNIMAD), Madrid, Spain; Health Sciences School, Universidad Internacional de La Rioja (UNIR), Logroño, Spain
| | - Matilde Alique
- Department of System's Biology, Medical School, University of Alcala de Henares, Alcalá de Henares, Spain; Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid 28034, Spain
| | - Carolina Roza
- Department of System's Biology, Medical School, University of Alcala de Henares, Alcalá de Henares, Spain.
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Teixeira-Santos L, Martins S, Sousa T, Albino-Teixeira A, Pinho D. The pro-resolving lipid mediator Maresin 1 ameliorates pain responses and neuroinflammation in the spared nerve injury-induced neuropathic pain: A study in male and female mice. PLoS One 2023; 18:e0287392. [PMID: 37347750 PMCID: PMC10286986 DOI: 10.1371/journal.pone.0287392] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 06/05/2023] [Indexed: 06/24/2023] Open
Abstract
Specialized pro-resolving mediators (SPMs) have recently emerged as promising therapeutic approaches for neuropathic pain (NP). We evaluated the effects of oral treatment with the SPM Maresin 1 (MaR1) on behavioral pain responses and spinal neuroinflammation in male and female C57BL/6J mice with spared nerve injury (SNI)-induced NP. MaR1, or vehicle, was administered once daily, on post-surgical days 3 to 5, by voluntary oral intake. Sensory-discriminative and affective-motivational components of pain were evaluated with von Frey and place escape/avoidance paradigm (PEAP) tests, respectively. Spinal microglial and astrocytic activation were assessed by immunofluorescence, and the spinal concentration of cytokines IL-1β, IL-6, IL-10, and macrophage colony-stimulating factor (M-CSF) were evaluated by multiplex immunoassay. MaR1 treatment reduced SNI-induced mechanical hypersensitivity on days 7 and 11 in both male and female mice, and appeared to ameliorate the affective component of pain in males on day 11. No definitive conclusions could be drawn about the impact of MaR1 on the affective-motivational aspects of pain in female mice, since repeated suprathreshold mechanical stimulation of the affected paw in the dark compartment did not increase the preference of vehicle-treated SNI females for the light side, during the PEAP test session (a fundamental assumption for PAEP's validity). MaR1 treatment also reduced ipsilateral spinal microglial and astrocytic activation in both sexes and marginally increased M-CSF in males, while not affecting cytokines IL-1β, IL-6 and IL-10 in either sex. In summary, our study has shown that oral treatment with MaR1 (i) produces antinociception even in an already installed peripheral NP mouse model, and (ii) this antinociception may extend for several days beyond the treatment time-frame. These therapeutic effects are associated with attenuated microglial and astrocytic activation in both sexes, and possibly involve modulation of M-CSF action in males.
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Affiliation(s)
- Luísa Teixeira-Santos
- Departamento de Biomedicina–Unidade de Farmacologia e Terapêutica, Faculdade de Medicina, Universidade do Porto, Porto, Portugal
- Centro de Investigação Farmacológica e Inovação Medicamentosa (MedInUP), Universidade do Porto, Porto, Portugal
| | - Sandra Martins
- Serviço de Patologia Clínica, Centro Hospitalar e Universitário São João (CHUSJ), Porto, Portugal
- EPIUnit, Instituto de Saúde Pública, Universidade do Porto, Porto, Portugal
| | - Teresa Sousa
- Departamento de Biomedicina–Unidade de Farmacologia e Terapêutica, Faculdade de Medicina, Universidade do Porto, Porto, Portugal
- Centro de Investigação Farmacológica e Inovação Medicamentosa (MedInUP), Universidade do Porto, Porto, Portugal
| | - António Albino-Teixeira
- Departamento de Biomedicina–Unidade de Farmacologia e Terapêutica, Faculdade de Medicina, Universidade do Porto, Porto, Portugal
- Centro de Investigação Farmacológica e Inovação Medicamentosa (MedInUP), Universidade do Porto, Porto, Portugal
| | - Dora Pinho
- Departamento de Biomedicina–Unidade de Farmacologia e Terapêutica, Faculdade de Medicina, Universidade do Porto, Porto, Portugal
- Centro de Investigação Farmacológica e Inovação Medicamentosa (MedInUP), Universidade do Porto, Porto, Portugal
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3
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The BDNF-TrkB signaling pathway in the rostral anterior cingulate cortex is involved in the development of pain aversion in rats with bone cancer via NR2B and ERK-CREB signaling. Brain Res Bull 2022; 185:18-27. [DOI: 10.1016/j.brainresbull.2022.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 03/15/2022] [Accepted: 04/05/2022] [Indexed: 11/19/2022]
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Morphine-Conditioned Placebo Analgesia in Female and Male Rats with Chronic Neuropathic Pain: c-Fos Expression in the Rostral Ventromedial Medulla. Neuroscience 2020; 457:51-73. [PMID: 33285237 DOI: 10.1016/j.neuroscience.2020.11.038] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 11/19/2020] [Accepted: 11/23/2020] [Indexed: 12/17/2022]
Abstract
Placebo analgesia has great potential to overcome the inadequacies of current drug therapies to treat conditions of chronic pain. The rostral ventromedial medulla (RVM) has been implicated as a critical relay in the antinociceptive pathway underpinning placebo analgesia in humans. We developed a model of opiate-conditioned placebo analgesia in rats with neuropathic injury to identify medullary nuclei active during placebo analgesia. Using female and male rats the degree of thermal allodynia was first determined following nerve injury, and a pharmacological conditioning procedure, pairing contextual cues with the experience of morphine-induced analgesia, was used to elicit placebo analgesic reactions. This protocol revealed clear subpopulations of placebo reactors (36% of males, 25% of females) and non-reactors in proportions similar to those reported in human studies. We detected injury-specific c-Fos expression in the gracile nucleus and morphine-specific c-Fos expression in the serotonergic midline raphe nuclei and the caudal nuclei of the solitary tract. However, c-Fos expression did not differ between placebo reactors and non-reactors in either serotonergic or non-serotonergic neurons of the RVM. Despite a subpopulation of rats demonstrating placebo reactions, we found no evidence for enhanced activity in the nuclei from which the classical RVM → spinal cord descending analgesic pathways emerge.
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Otis C, Guillot M, Moreau M, Pelletier JP, Beaudry F, Troncy E. Sensitivity of functional targeted neuropeptide evaluation in testing pregabalin analgesic efficacy in a rat model of osteoarthritis pain. Clin Exp Pharmacol Physiol 2019; 46:723-733. [PMID: 31046168 DOI: 10.1111/1440-1681.13100] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 03/22/2019] [Accepted: 04/28/2019] [Indexed: 12/27/2022]
Abstract
The monosodium iodoacetate (MIA)-induced joint degeneration in rats is the most used animal model to screen analgesic drugs to alleviate osteoarthritis (OA) pain. This study aimed to evaluate the analgesic efficacy of pregabalin (PGB) in an MIA-induced OA model in rodents by using functional and neuroproteomic pain assessment methods. Treatment group included PGB in curative intent over 9 days compared to gold standard therapy (positive controls) and placebo (negative control). Functional assessments of pain (quantitative sensory testing and operant test) were performed concomitantly with spinal neuropeptides quantification. At day 21 post-OA induction, PGB in MIA rats reduced tactile allodynia (P = 0.028) and improved the place escape/avoidance behaviour (P = 0.04) compared to values recorded at last time-point before initiating analgesic therapy. All spinal neuropeptide concentrations, such as substance P, calcitonin gene-related peptide, bradykinin and somatostatin, came back to normal (non-affected) rat values, compared to their increase observed in MIA rats receiving the placebo (P < 0.0001). Initiated 13 days after chemical OA induction, repeated medication with PGB provided analgesia according to quantitative sensory testing, operant test and targeted neuropeptides pain assessment methods. This report highlights the interest of using reliable and sensitive methods like targeted neuropeptide quantification to detect the analgesic effects of a test article with concomitant functional assessments of pain when studying OA pain components.
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Affiliation(s)
- Colombe Otis
- Animal Pharmacology Research Group of Quebec (GREPAQ), Department of Veterinary Biomedicine, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada
| | - Martin Guillot
- Animal Pharmacology Research Group of Quebec (GREPAQ), Department of Veterinary Biomedicine, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada.,Osteoarthritis Research Unit, University of Montreal Hospital Research Center (CRCHUM), Montreal, Quebec, Canada
| | - Maxim Moreau
- Animal Pharmacology Research Group of Quebec (GREPAQ), Department of Veterinary Biomedicine, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada.,Osteoarthritis Research Unit, University of Montreal Hospital Research Center (CRCHUM), Montreal, Quebec, Canada
| | - Jean-Pierre Pelletier
- Animal Pharmacology Research Group of Quebec (GREPAQ), Department of Veterinary Biomedicine, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada.,Osteoarthritis Research Unit, University of Montreal Hospital Research Center (CRCHUM), Montreal, Quebec, Canada
| | - Francis Beaudry
- Animal Pharmacology Research Group of Quebec (GREPAQ), Department of Veterinary Biomedicine, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada.,Osteoarthritis Research Unit, University of Montreal Hospital Research Center (CRCHUM), Montreal, Quebec, Canada
| | - Eric Troncy
- Animal Pharmacology Research Group of Quebec (GREPAQ), Department of Veterinary Biomedicine, Faculty of Veterinary Medicine, Université de Montréal, Saint-Hyacinthe, Quebec, Canada.,Osteoarthritis Research Unit, University of Montreal Hospital Research Center (CRCHUM), Montreal, Quebec, Canada
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6
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Abstract
All preclinical procedures for analgesic drug discovery involve two components: 1) a "pain stimulus" (the principal independent variable), which is delivered to an experimental subject with the intention of producing a pain state; and 2) a "pain behavior" (the principal dependent variable), which is measured as evidence of that pain state. Candidate analgesics are then evaluated for their effectiveness to reduce the pain behavior, and results are used to prioritize drugs for advancement to clinical testing. This review describes a taxonomy of preclinical procedures organized into an "antinociception matrix" by reference to their types of pain stimulus (noxious, inflammatory, neuropathic, disease related) and pain behavior (unconditioned, classically conditioned, operant conditioned). Particular emphasis is devoted to pain behaviors and the behavioral principals that govern their expression, pharmacological modulation, and preclinical-to-clinical translation. Strengths and weaknesses are compared and contrasted for procedures using each type of behavioral outcome measure, and the following four recommendations are offered to promote strategic use of these procedures for preclinical-to-clinical analgesic drug testing. First, attend to the degree of homology between preclinical and clinical outcome measures, and use preclinical procedures with behavioral outcome measures homologous to clinically relevant outcomes in humans. Second, use combinations of preclinical procedures with complementary strengths and weaknesses to optimize both sensitivity and selectivity of preclinical testing. Third, take advantage of failed clinical translation to identify drugs that can be back-translated preclinically as active negative controls. Finally, increase precision of procedure labels by indicating both the pain stimulus and the pain behavior in naming preclinical procedures.
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Affiliation(s)
- S Stevens Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
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Llorca-Torralba M, Mico JA, Berrocoso E. Behavioral effects of combined morphine and MK-801 administration to the locus coeruleus of a rat neuropathic pain model. Prog Neuropsychopharmacol Biol Psychiatry 2018. [PMID: 29524514 DOI: 10.1016/j.pnpbp.2018.03.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The persistent activation of N-methyl-d-aspartate acid receptors (NMDARs) seems to be responsible for a series of changes in neurons associated with neuropathic pain, including the failure of opioids that act through mu-opioid receptors (MORs) to provide efficacious pain relief. As the noradrenergic locus coeruleus (LC) forms part of the endogenous analgesic system, we explored how intra-LC administration of morphine, a MORs agonist, alone or in combination with MK-801, a NMDARs antagonist, affects the sensorial and affective dimension of pain in a rat model of neuropathic pain; chronic constriction injury (CCI). Intra-LC microinjection of morphine induced analgesia in CCI rats, as evident in the von Frey and cold plate test 7 and 30 days after surgery, although it was not able to reverse pain-related aversion when evaluated using the place escape/avoidance test. However, the thermal anti-nociception produced by morphine was enhanced when it was administered to the LC of CCI animals in combination with MK-801, without altering its effects on the mechanical thresholds. Furthermore, pain-related aversion was reduced by co-administration of these agents, yet only in the short-term CCI (7 day) rats. Overall the data indicate that administration of morphine to the LC produces analgesia in nerve injured animals and that this effect is potentiated in specific pain modalities by the co-administration of MK-801. While a combination of morphine and MK-801 could reduce pain-related aversion in short-term neuropathic animals, it was ineffective in the long-term, suggesting that its sensorial effects and its influence on the affective component of pain are regulated by different mechanisms.
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Affiliation(s)
- Meritxell Llorca-Torralba
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, Madrid, Spain; Instituto de Investigación e Innovación en Ciencias Biomédicas de Cádiz, INiBICA, Hospital Universitario Puerta del Mar, Cádiz, Spain; Neuropsychopharmacology and Psychobiology Research Group, University of Cádiz, Cádiz, Spain
| | - Juan A Mico
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, Madrid, Spain; Instituto de Investigación e Innovación en Ciencias Biomédicas de Cádiz, INiBICA, Hospital Universitario Puerta del Mar, Cádiz, Spain; Neuropsychopharmacology and Psychobiology Research Group, Department of Neuroscience, University of Cádiz, Cádiz, Spain
| | - Esther Berrocoso
- Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, Madrid, Spain; Instituto de Investigación e Innovación en Ciencias Biomédicas de Cádiz, INiBICA, Hospital Universitario Puerta del Mar, Cádiz, Spain; Neuropsychopharmacology and Psychobiology Research Group, Department of Psychology, University of Cádiz, Puerto Real, Cádiz, Spain.
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Yezierski RP, Hansson P. Inflammatory and Neuropathic Pain From Bench to Bedside: What Went Wrong? THE JOURNAL OF PAIN 2018; 19:571-588. [DOI: 10.1016/j.jpain.2017.12.261] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 11/29/2017] [Accepted: 12/13/2017] [Indexed: 12/31/2022]
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Shu B, Yang F, Guan Y. Intra-spinal microstimulation may alleviate chronic pain after spinal cord injury. Med Hypotheses 2017; 104:73-77. [PMID: 28673596 DOI: 10.1016/j.mehy.2017.05.028] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 05/25/2017] [Indexed: 12/30/2022]
Abstract
Chronic pain after spinal cord injury (SCI) is a form of central neuropathic pain that is debilitating and often refractory to current pharmacological treatments. Neurostimulation pain therapies, such as epidural spinal cord stimulation, have only moderate success in reducing SCI pain. The pathogenesis of SCI pain may involve a state of central neuronal hyperexcitability, especially in the spinal cord dorsal horn, that develops after injury. We hypothesize that the neuronal structures near the spinal cord injury site may be an important pain generator, and intraspinal microstimulation (ISMS) may normalize dorsal horn neuronal hyperexcitability and hence alleviate SCI pain. Specifically, ISMS may induce frequency-dependent conduction block on axons of afferent sensory neurons, in the spinothalamic tract and Lissauer's tract. ISMS may also facilitate primary afferent depolarization that elicits presynaptic inhibition of incoming afferent inputs. Together, these actions will reduce abnormal afferent inputs and ascending pain signals before they can reach the brain. Furthermore, ISMS may directly induce inhibitory postsynaptic potentials in dorsal horn neurons, and trigger the release of endogenous inhibitory neurotransmitters, opioids and serotonin to inhibit postsynaptic neurons and restore the compromised segmental pain inhibition after SCI. Finally, ISMS may alter the frequency and pattern of discharge such that the rostrally conducted impulses no longer code pain or activate brain areas concerned with pain signaling. Based on recent progress in understanding spinal learning and plasticity, we also postulate that repetitive or long-term ISMS may help the dorsal horn "reset" neuronal excitability and regain normal pain processing for a prolonged period. By finely tuning the stimulation parameters (e.g., intensity, pulse width, frequency), position, and geometry of ISMS electrode, multiple spinal structures (e.g., dorsal horn, dorsal column, spinothalamic tract) may be modulated to induce synergistic pain inhibition. Our hypothesis can be readily tested in preclinical models of SCI pain by using a combination of in vivo electrophysiological (neuronal activity) and animal behavioral (pain response) approaches. Since ISMS electrodes stimulate the spinal structures directly, we expect that the effective stimulus intensity and energy consumption can be lower than that for epidural spinal cord stimulation. The proposed hypothesis may provide insights and rationales for developing a novel neurostimulation pain therapy by directly inhibiting the pain generators in the spinal cord, and ISMS may be an alternative strategy to treat SCI pain.
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Affiliation(s)
- Bin Shu
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA; Department of Anesthesiology and Pain Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Fei Yang
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
| | - Yun Guan
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA.
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Bravo L, Mico JA, Rey-Brea R, Camarena-Delgado C, Berrocoso E. Effect of DSP4 and desipramine in the sensorial and affective component of neuropathic pain in rats. Prog Neuropsychopharmacol Biol Psychiatry 2016; 70:57-67. [PMID: 27181607 DOI: 10.1016/j.pnpbp.2016.05.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Revised: 05/08/2016] [Accepted: 05/09/2016] [Indexed: 12/13/2022]
Abstract
Previous findings suggest that neuropathic pain induces characteristic changes in the noradrenergic system that may modify the sensorial and affective dimensions of pain. We raise the hypothesis that different drugs that manipulate the noradrenergic system can modify specific domains of pain. In the chronic constriction injury (CCI) model of neuropathic pain, the sensorial (von Frey and acetone tests) and the affective (place escape/avoidance paradigm) domains of pain were evaluated in rats 1 and 2weeks after administering the noradrenergic neurotoxin [N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride] (DSP4, 50mg/kg). In other animals, we evaluated the effect of enhancing noradrenergic tone in the 2weeks after injury by administering the antidepressant desipramine (10mg/kg/day, delivered by osmotic minipumps) during this period, a noradrenaline reuptake inhibitor. Moreover, the phosphorylation of the extracellular signal regulated kinases (p-ERK) in the anterior cingulate cortex (ACC) was also assessed. The ACC receives direct inputs from the main noradrenergic nucleus, the locus coeruleus, and ERK activation has been related with the expression of pain-related negative affect. These studies revealed that DSP4 almost depleted noradrenergic axons in the ACC and halved noradrenergic neurons in the locus coeruleus along with a decrease in the affective dimension and an increased of p-ERK in the ACC. However, it did not modify sensorial pain perception. By contrast, desipramine reduced pain hypersensitivity, while completely impeding the reduction of the affective pain dimension and without modifying the amount of p-ERK. Together results suggest that the noradrenergic system may regulate the sensorial and affective sphere of neuropathic pain independently.
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Affiliation(s)
- Lidia Bravo
- Neuropsychopharmacology & Psychobiology Research Group, University of Cádiz, Spain; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, 28007 Madrid, Spain; Psychobiology Area, Department of Psychology, University of Cadiz, Spain
| | - Juan A Mico
- Neuropsychopharmacology & Psychobiology Research Group, University of Cádiz, Spain; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, 28007 Madrid, Spain; Department of Neuroscience, University of Cádiz, Spain
| | - Raquel Rey-Brea
- Neuropsychopharmacology & Psychobiology Research Group, University of Cádiz, Spain
| | | | - Esther Berrocoso
- Neuropsychopharmacology & Psychobiology Research Group, University of Cádiz, Spain; Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Instituto de Salud Carlos III, 28007 Madrid, Spain; Psychobiology Area, Department of Psychology, University of Cadiz, Spain.
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11
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Otis C, Gervais J, Guillot M, Gervais JA, Gauvin D, Péthel C, Authier S, Dansereau MA, Sarret P, Martel-Pelletier J, Pelletier JP, Beaudry F, Troncy E. Concurrent validity of different functional and neuroproteomic pain assessment methods in the rat osteoarthritis monosodium iodoacetate (MIA) model. Arthritis Res Ther 2016; 18:150. [PMID: 27338815 PMCID: PMC4918125 DOI: 10.1186/s13075-016-1047-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/09/2016] [Indexed: 11/17/2022] Open
Abstract
Background Lack of validity in osteoarthritis pain models and assessment methods is suspected. Our goal was to 1) assess the repeatability and reproducibility of measurement and the influence of environment, and acclimatization, to different pain assessment outcomes in normal rats, and 2) test the concurrent validity of the most reliable methods in relation to the expression of different spinal neuropeptides in a chemical model of osteoarthritic pain. Methods Repeatability and inter-rater reliability of reflexive nociceptive mechanical thresholds, spontaneous static weight-bearing, treadmill, rotarod, and operant place escape/avoidance paradigm (PEAP) were assessed by the intraclass correlation coefficient (ICC). The most reliable acclimatization protocol was determined by comparing coefficients of variation. In a pilot comparative study, the sensitivity and responsiveness to treatment of the most reliable methods were tested in the monosodium iodoacetate (MIA) model over 21 days. Two MIA (2 mg) groups (including one lidocaine treatment group) and one sham group (0.9 % saline) received an intra-articular (50 μL) injection. Results No effect of environment (observer, inverted circadian cycle, or exercise) was observed; all tested methods except mechanical sensitivity (ICC <0.3), offered good repeatability (ICC ≥0.7). The most reliable acclimatization protocol included five assessments over two weeks. MIA-related osteoarthritic change in pain was demonstrated with static weight-bearing, punctate tactile allodynia evaluation, treadmill exercise and operant PEAP, the latter being the most responsive to analgesic intra-articular lidocaine. Substance P and calcitonin gene-related peptide were higher in MIA groups compared to naive (adjusted P (adj-P) = 0.016) or sham-treated (adj-P = 0.029) rats. Repeated post-MIA lidocaine injection resulted in 34 times lower downregulation for spinal substance P compared to MIA alone (adj-P = 0.029), with a concomitant increase of 17 % in time spent on the PEAP dark side (indicative of increased comfort). Conclusion This study of normal rats and rats with pain established the most reliable and sensitive pain assessment methods and an optimized acclimatization protocol. Operant PEAP testing was more responsive to lidocaine analgesia than other tests used, while neuropeptide spinal concentration is an objective quantification method attractive to support and validate different centralized pain functional assessment methods.
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Affiliation(s)
- Colombe Otis
- Groupe de Recherche en Pharmacologie Animale du Québec (GREPAQ), Department of Biomedical Sciences, Faculty of veterinary medicine, Université de Montréal, 1500 des Vétérinaires Street, P.O. Box 5000, St-Hyacinthe, Quebec, J2S 7C6, Canada.,Osteoarthritis Research Unit, Research Center Hospital of Montreal University (CRCHUM), Montreal, Quebec, Canada
| | - Julie Gervais
- Groupe de Recherche en Pharmacologie Animale du Québec (GREPAQ), Department of Biomedical Sciences, Faculty of veterinary medicine, Université de Montréal, 1500 des Vétérinaires Street, P.O. Box 5000, St-Hyacinthe, Quebec, J2S 7C6, Canada
| | - Martin Guillot
- Groupe de Recherche en Pharmacologie Animale du Québec (GREPAQ), Department of Biomedical Sciences, Faculty of veterinary medicine, Université de Montréal, 1500 des Vétérinaires Street, P.O. Box 5000, St-Hyacinthe, Quebec, J2S 7C6, Canada.,Osteoarthritis Research Unit, Research Center Hospital of Montreal University (CRCHUM), Montreal, Quebec, Canada
| | - Julie-Anne Gervais
- Groupe de Recherche en Pharmacologie Animale du Québec (GREPAQ), Department of Biomedical Sciences, Faculty of veterinary medicine, Université de Montréal, 1500 des Vétérinaires Street, P.O. Box 5000, St-Hyacinthe, Quebec, J2S 7C6, Canada
| | - Dominique Gauvin
- Groupe de Recherche en Pharmacologie Animale du Québec (GREPAQ), Department of Biomedical Sciences, Faculty of veterinary medicine, Université de Montréal, 1500 des Vétérinaires Street, P.O. Box 5000, St-Hyacinthe, Quebec, J2S 7C6, Canada.,Osteoarthritis Research Unit, Research Center Hospital of Montreal University (CRCHUM), Montreal, Quebec, Canada
| | - Catherine Péthel
- Groupe de Recherche en Pharmacologie Animale du Québec (GREPAQ), Department of Biomedical Sciences, Faculty of veterinary medicine, Université de Montréal, 1500 des Vétérinaires Street, P.O. Box 5000, St-Hyacinthe, Quebec, J2S 7C6, Canada.,Department of Physiology and Biophysics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | | | - Marc-André Dansereau
- Department of Physiology and Biophysics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Philippe Sarret
- Department of Physiology and Biophysics, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Johanne Martel-Pelletier
- Osteoarthritis Research Unit, Research Center Hospital of Montreal University (CRCHUM), Montreal, Quebec, Canada
| | - Jean-Pierre Pelletier
- Osteoarthritis Research Unit, Research Center Hospital of Montreal University (CRCHUM), Montreal, Quebec, Canada
| | - Francis Beaudry
- Groupe de Recherche en Pharmacologie Animale du Québec (GREPAQ), Department of Biomedical Sciences, Faculty of veterinary medicine, Université de Montréal, 1500 des Vétérinaires Street, P.O. Box 5000, St-Hyacinthe, Quebec, J2S 7C6, Canada.,Osteoarthritis Research Unit, Research Center Hospital of Montreal University (CRCHUM), Montreal, Quebec, Canada
| | - Eric Troncy
- Groupe de Recherche en Pharmacologie Animale du Québec (GREPAQ), Department of Biomedical Sciences, Faculty of veterinary medicine, Université de Montréal, 1500 des Vétérinaires Street, P.O. Box 5000, St-Hyacinthe, Quebec, J2S 7C6, Canada. .,Osteoarthritis Research Unit, Research Center Hospital of Montreal University (CRCHUM), Montreal, Quebec, Canada.
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12
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Refsgaard L, Hoffmann-Petersen J, Sahlholt M, Pickering D, Andreasen J. Modelling affective pain in mice: Effects of inflammatory hypersensitivity on place escape/avoidance behaviour, anxiety and hedonic state. J Neurosci Methods 2016; 262:85-92. [DOI: 10.1016/j.jneumeth.2016.01.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Revised: 01/15/2016] [Accepted: 01/16/2016] [Indexed: 10/22/2022]
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13
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Bree D, Moriarty O, Broom DC, Kelly JP, Roche M, Finn DP. Characterization of the Affective Component of Acute Postoperative Pain Associated with a Novel Rat Model of Inguinal Hernia Repair Pain. CNS Neurosci Ther 2015; 22:146-53. [PMID: 26663888 DOI: 10.1111/cns.12483] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 10/09/2015] [Accepted: 10/23/2015] [Indexed: 12/17/2022] Open
Abstract
AIMS Acute postoperative pain remains a significant healthcare issue. Historically, the assessment of postoperative pain in rodents has relied on evoked withdrawal or reflexive measures. Using a recently developed, anatomically relevant rat model of acute postoperative pain (J Pain, 16, 2015, 421), the present experiments sought to investigate the affective component of acute postoperative pain associated with inguinal hernia repair. METHODS Male Lister hooded rats underwent surgery to model Lichtenstein inguinal hernia repair (without hernia induction), or a sham procedure. Postsurgical characterization involved a modified place escape/avoidance paradigm (mPEAP), as well as home cage and open field locomotor activity monitoring. In pharmacological validation studies, rats received either morphine or carprofen prior to mPEAP testing. RESULTS Surgery was associated with a significantly increased proportion of the trial duration in the light compartment of the mPEAP arena, in avoidance of the noxious stimulus, compared with sham animals. When retested in the mPEAP at day 7 postsurgery, there was no difference between sham and surgery animals for time spent in either compartment, but surgery animals displayed a persistent increase in the percentage response to noxious stimulation. Morphine and carprofen treatment in surgery animals reduced escape/avoidance behavior at discrete time points over the trial. Surgery-induced reductions in home cage and open field locomotor activity were also observed. CONCLUSION The present studies report for the first time the characterization of the affective component of acute postoperative pain using the mPEAP in a rodent model, which may facilitate development of improved understanding and treatment of postoperative pain.
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Affiliation(s)
- Dara Bree
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland, Galway, Ireland.,Physiology, School of Medicine, National University of Ireland, Galway, Ireland.,Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, Ireland
| | - Orla Moriarty
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland, Galway, Ireland.,Physiology, School of Medicine, National University of Ireland, Galway, Ireland.,Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, Ireland.,Research and Development, Covidien, North Haven, CT, USA
| | - Daniel C Broom
- Research and Development, Covidien, North Haven, CT, USA
| | - John P Kelly
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland, Galway, Ireland.,Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, Ireland
| | - Michelle Roche
- Physiology, School of Medicine, National University of Ireland, Galway, Ireland.,Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, Ireland
| | - David P Finn
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland, Galway, Ireland.,Galway Neuroscience Centre and Centre for Pain Research, NCBES, National University of Ireland, Galway, Ireland
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14
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Miller LL, Altarifi AA, Negus SS. Effects of repeated morphine on intracranial self-stimulation in male rats in the absence or presence of a noxious pain stimulus. Exp Clin Psychopharmacol 2015; 23:405-14. [PMID: 26375515 PMCID: PMC4578993 DOI: 10.1037/pha0000042] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Research on opioid analgesics such as morphine suggests that expression of abuse-related effects increases with repeated exposure. Repeated exposure to opioids often occurs clinically in the context of pain management, and a major concern for clinicians is the risk of iatrogenic addiction and dependence in patients receiving opioids for treatment of pain. This study compared abuse-related morphine effects in male rats in an intracranial self-stimulation (ICSS) procedure after repeated treatment either with morphine alone or with morphine in combination with a repeated noxious stimulus (intraperitoneal administration of dilute acid). The study also permitted comparison of morphine potency and effectiveness to block acid-induced depression of ICSS (antinociception) and to produce enhanced facilitation of ICSS (abuse-related effect). There were 3 main findings. First, initial morphine exposure to drug naïve rats did not produce abuse-related ICSS facilitation. Second, repeated daily treatment with 3.2 mg/kg/day morphine for 6 days increased expression of ICSS facilitation. This occurred whether morphine was administered in the absence or presence of the noxious stimulus. Finally, a lower dose of 1.0 mg/kg/day morphine was sufficient to produce antinociception during repeated acid treatment, but this lower dose did not reliably increase abuse-related morphine effects. Taken together, these results suggest that prior morphine exposure can increase abuse liability of subsequent morphine treatments even when that morphine exposure occurs in the context of a pain state. However, it may be possible to relieve pain with relatively low morphine doses that do not produce increases in abuse-related morphine effects.
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Affiliation(s)
- Laurence L. Miller
- Department of Psychological Science, Georgia Regents University, Augusta GA, USA
| | - Ahmad A. Altarifi
- Department of Pharmacology, Jordan University of Science and Technology, Irbid, Jordan
| | - S. Stevens Negus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond VA, USA
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15
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Higgins GA, Silenieks LB, Van Niekerk A, Desnoyer J, Patrick A, Lau W, Thevarkunnel S. Enduring attentional deficits in rats treated with a peripheral nerve injury. Behav Brain Res 2015; 286:347-55. [DOI: 10.1016/j.bbr.2015.02.050] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 02/17/2015] [Accepted: 02/24/2015] [Indexed: 12/01/2022]
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16
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Evaluation of anxiety-like behaviour in a rat model of acute postoperative pain. Eur J Anaesthesiol 2015; 32:242-7. [DOI: 10.1097/eja.0000000000000052] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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17
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Burke NN, Finn DP, Roche M. Chronic administration of amitriptyline differentially alters neuropathic pain-related behaviour in the presence and absence of a depressive-like phenotype. Behav Brain Res 2014; 278:193-201. [PMID: 25300472 DOI: 10.1016/j.bbr.2014.09.044] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Revised: 09/04/2014] [Accepted: 09/27/2014] [Indexed: 01/11/2023]
Abstract
Chronic pain and depression share a complex, reciprocal relationship. Furthermore, in addition to treating depression, antidepressants such as amitriptyline are a first-line treatment for chronic pain conditions, indicating possible common neural substrates underlying both depression and pain. However, there is a paucity of studies examining the effect of antidepressant treatment on nociceptive and neuropathic pain responding in the presence of a depressive phenotype. The current study aimed to examine the effect of chronic amitriptyline administration on neuropathic pain-related behaviour and associated neuroinflammatory processes in the olfactory bulbectomised (OB) rat model of depression. Nociceptive responding to mechanical, innocuous cold or noxious heat stimuli in sham or OB rats was not altered by chronic amitriptyline administration. The induction of neuropathic pain following L5-L6 spinal nerve ligation (SNL) resulted in robust mechanical and cold allodynia and heat hyperalgesia in both sham and OB vehicle-treated animals. Chronic amitriptyline administration attenuated SNL-induced mechanical allodynia in both sham and OB rats at day 7 post-SNL, an effect which was enhanced and prolonged in OB rats. In comparison, chronic amitriptyline administration attenuated SNL-induced cold allodynia and heat hyperalgesia in sham, but not OB, rats. Evaluating the affective/motivational aspect of pain using the place escape avoidance paradigm revealed that OB-SNL rats exhibit reduced noxious avoidance behaviour when compared with sham counterparts, an effect not altered by chronic amitriptyline administration. Chronic amitriptyline administration prevented the increased expression of GFAP, IL-10 and CCL5, and enhanced the expression of TNFα, in the prefrontal cortex of OB-SNL rats. In conclusion, these data demonstrate that chronic amitriptyline differentially alters somatic nociceptive responding following peripheral nerve-injury, depending on stimulus modality and the presence or absence of a depressive-like phenotype, an effect which may involve modulation of neuroinflammatory processes.
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Affiliation(s)
- Nikita N Burke
- Physiology, School of Medicine, National University of Ireland Galway, University Road, Galway, Ireland; Pharmacology and Therapeutics, School of Medicine, National University of Ireland Galway, University Road, Galway, Ireland; NCBES Galway Neuroscience Centre and Centre for Pain Research, National University of Ireland Galway, University Road, Galway, Ireland
| | - David P Finn
- Pharmacology and Therapeutics, School of Medicine, National University of Ireland Galway, University Road, Galway, Ireland; NCBES Galway Neuroscience Centre and Centre for Pain Research, National University of Ireland Galway, University Road, Galway, Ireland
| | - Michelle Roche
- Physiology, School of Medicine, National University of Ireland Galway, University Road, Galway, Ireland; NCBES Galway Neuroscience Centre and Centre for Pain Research, National University of Ireland Galway, University Road, Galway, Ireland.
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18
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Galan-Arriero I, Avila-Martin G, Ferrer-Donato A, Gomez-Soriano J, Bravo-Esteban E, Taylor J. Oral administration of the p38α MAPK inhibitor, UR13870, inhibits affective pain behavior after spinal cord injury. Pain 2014; 155:2188-98. [PMID: 25180015 DOI: 10.1016/j.pain.2014.08.030] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Revised: 07/03/2014] [Accepted: 08/22/2014] [Indexed: 12/15/2022]
Abstract
The p38α mitogenous activated protein kinase (MAPK) cell signaling pathway is a key mechanism of microglia activation and has been studied as a target for neuropathic pain. The effect of UR13870, a p38α MAPK inhibitor, on microglia expression in the anterior cingulate cortex (ACC) and spinal dorsal horn was addressed after T9 contusion spinal cord injury (SCI) in the rat, in addition to behavioral testing of pain-related aversion and anxiety. Administration of intravenous UR13870 (1mg/kg i.v.) and pregabalin (30 mg/kg i.v.) reduced place escape avoidance paradigm (PEAP) but did not affect open-field anxiety behavior 42 days after SCI. PEAP behavior was also reduced in animals administered daily with oral UR13870 (10mg/kg p.o.) and preserved spinal tissue 28 days after SCI. Although UR13870 (10mg/kg p.o.) failed to reduce OX-42 and glial fibrillar acid protein immunoreactivity within the spinal dorsal horn, a reduction toward the control level was observed close to the SCI site. In the anterior cingulate cortex (ACC), a significant increase in OX-42 immunoreactivity was identified after SCI. UR13870 (10mg/kg p.o.) treatment significantly reduced OX-42, metabotropic glutamate type 5 receptor (mGluR5), and NMDA (N-methyl-d-aspartate) 2B subunit receptor (NR2B) expression in the ACC after SCI. To conclude, oral treatment with a p38α MAPK inhibitor reduces the affective behavioral component of pain after SCI in association with a reduction of microglia and specific glutamate receptors within the ACC. Nevertheless the role of neuroinflammatory processes within the vicinity of the SCI site in the development of affective neuropathic pain cannot be excluded.
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Affiliation(s)
- Iriana Galan-Arriero
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain
| | - Gerardo Avila-Martin
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain
| | - Agueda Ferrer-Donato
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain
| | - Julio Gomez-Soriano
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; E.U.E. Fisioterapia de Toledo, Universidad de Castilla la Mancha, Toledo, Spain
| | - Elisabeth Bravo-Esteban
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain; IAI, Consejo Superior de Investigaciones Científicas (CSIC), Arganda del Rey, Spain
| | - Julian Taylor
- Sensorimotor Function Group, Hospital Nacional de Parapléjicos, SESCAM, Toledo, Spain.
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19
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Chu KL, Xu J, Frost J, Li L, Gomez E, Dart MJ, Jarvis MF, Meyer MD, McGaraughty S. A selective α2 B adrenoceptor agonist (A-1262543) and duloxetine modulate nociceptive neurones in the medial prefrontal cortex, but not in the spinal cord of neuropathic rats. Eur J Pain 2014; 19:649-60. [PMID: 25154730 DOI: 10.1002/ejp.586] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/16/2014] [Indexed: 12/29/2022]
Abstract
BACKGROUND The noradrenergic system contributes to pain modulation, but the roles of its specific adrenoceptors are still being defined. We have identified a novel, potent (rat EC50 = 4.3 nM) and selective α2B receptor agonist, A-1262543, to further explore this adrenoceptor subtype's contribution to pathological nociception. METHODS Systemic administration of A-1262543 (1-10 mg/kg, intraperitoneal) dose-dependently attenuated mechanical allodynia in animals with a spinal nerve ligation injury. To further explore its mechanism of action, the activity of nociceptive neurones in the spinal cord and medial prefrontal cortex (mPFC) were examined after injection of 3 mg/kg of A-1262543 (intravenous, i.v.). These effects were compared with duloxetine (3 mg/kg, i.v.), a dual noradrenaline (NA) and serotonin (5-HT) reuptake inhibitor. RESULTS Systemic administration of A-1262543 or duloxetine did not alter the spontaneous or evoked firing of spinal wide dynamic range and nociceptive-specific neurones in the neuropathic rats, indicating that neither compound engaged spinal, peripheral or descending pathways. In contrast to the lack of effect on spinal neurones, both A-1262543 and duloxetine reduced the evoked and spontaneous firing of 'pain-responsive' (PR) neurones in the mPFC. Duloxetine, but not A-1262543, also inhibited the firing of pain non-responsive (nPR) neurones in the mPFC probably reflecting duloxetine's contribution to modulating non-pain endpoints. CONCLUSIONS These data highlight that activation of the α2B adrenoceptor as well as inhibiting NA and 5-HT reuptake can result in modulating the ascending nociceptive system, and in particular, dampening the firing of PR neurones in the mPFC.
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Affiliation(s)
- K L Chu
- Neuroscience Research, AbbVie, North Chicago, USA
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20
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McNabb CT, White MM, Harris AL, Fuchs PN. The elusive rat model of conditioned placebo analgesia. Pain 2014; 155:2022-32. [PMID: 25026214 DOI: 10.1016/j.pain.2014.07.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 06/30/2014] [Accepted: 07/03/2014] [Indexed: 10/25/2022]
Abstract
Recent research on human placebo analgesia has suggested the need for rodent models to further elucidate the neural substrates of the placebo effect. This series of 3 experiments therefore was performed in an attempt to develop a model of placebo analgesia in rats. In each study, female Sprague-Dawley rats received an L5 spinal nerve ligation to induce a neuropathic pain condition. Each rat then underwent a 4-day conditioning procedure in which an active analgesic drug or its vehicle (unconditioned stimulus) was associated with the following cues (conditioned stimuli): novel testing room (environmental), vanilla scent cue (olfactory), dim incandescent lighting (visual), restraint procedure/injection (tactile), and time of day and injection-test latency (temporal). The analgesics for each experiment were as follows: Experiment 1 used 90 mg/kg gabapentin, experiment 2 used 3mg/kg loperamide hydrochloride, and experiment 3 used 6 mg/kg morphine sulfate. On the following test day, half of the animals received the opposite treatment, resulting in 4 conditioning manipulations: drug/drug, drug/vehicle, vehicle/drug, and vehicle/vehicle. Nociceptive thresholds were assessed with the mechanical paw withdrawal threshold test each day after the conditioning procedure. In all 3 experiments, no significant differences were detected on test day between control and placebo groups, indicating a lack of a conditioned placebo analgesic response. Our results contrast with prior research that implies the existence of a reliable and robust response to placebo treatment. We conclude that placebo analgesia in rats is not particularly robust and that it is difficult to achieve using conventional procedures and proper experimental design.
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Affiliation(s)
| | - Michelle M White
- Department of Psychology, University of Texas at Arlington, Arlington, TX, USA
| | - Amber L Harris
- Department of Psychology, University of Texas at Arlington, Arlington, TX, USA
| | - Perry N Fuchs
- Department of Psychology, University of Texas at Arlington, Arlington, TX, USA; Department of Biology, University of Texas at Arlington, Arlington, TX, USA.
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21
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Tappe-Theodor A, Kuner R. Studying ongoing and spontaneous pain in rodents - challenges and opportunities. Eur J Neurosci 2014; 39:1881-90. [DOI: 10.1111/ejn.12643] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Revised: 04/30/2014] [Accepted: 04/30/2014] [Indexed: 01/15/2023]
Affiliation(s)
- Anke Tappe-Theodor
- Institute of Pharmacology; Heidelberg University; Im Neuenheimer Feld 366 69120 Heidelberg Germany
| | - Rohini Kuner
- Institute of Pharmacology; Heidelberg University; Im Neuenheimer Feld 366 69120 Heidelberg Germany
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22
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Avila-Martin G, Galan-Arriero I, Ferrer-Donato A, Busquets X, Gomez-Soriano J, Escribá PV, Taylor J. Oral 2-hydroxyoleic acid inhibits reflex hypersensitivity and open-field-induced anxiety after spared nerve injury. Eur J Pain 2014; 19:111-22. [PMID: 24824524 DOI: 10.1002/ejp.528] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/06/2014] [Indexed: 12/19/2022]
Abstract
BACKGROUND Recently, fatty acids have been shown to modulate sensory function in animal models of neuropathic pain. In this study, the antinociceptive effect of 2-hydroxyoleic acid (2-OHOA) was assessed following spared nerve injury (SNI) with reflex and cerebrally mediated behavioural responses. METHODS Initial antinociceptive behavioural screening of daily administration of 2-OHOA (400 mg/kg, p.o.) was assessed in Wistar rats by measuring hindlimb reflex hypersensitivity to von Frey and thermal plate stimulation up to 7 days after SNI, while its modulatory effect on lumbar spinal dorsal horn microglia reactivity was assessed with OX-42 immunohistochemistry. In vitro the effect of 2-OHOA (120 μM) on cyclooxygenase protein expression (COX-2/COX-1 ratio) in lipopolysaccharide-activated macrophage cells was tested with Western blot analysis. Finally, the effects of 2-OHOA treatment on the place escape aversion paradigm (PEAP) and the open-field-induced anxiety test were tested at 21 days following nerve injury compared with vehicle-treated sham and pregabalin-SNI (30 mg/kg, p.o.) control groups. RESULTS Oral 2-OHOA significantly reduced ipsilateral mechanical and thermal hypersensitivity up to 7 days after SNI. Additionally 2-OHOA decreased the COX-2/COX-1 ratio in lipopolysaccharide-activated macrophage cells and OX-42 expression within the ipsilateral lumbar spinal dorsal horn 7 days after SNI. 2-OHOA significantly restored inner-zone exploration in the open-field test compared with the vehicle-treated sham group at 21 days after SNI. CONCLUSIONS Oral administration of the modified omega 9 fatty acid, 2-OHOA, mediates antinociception and prevents open-field-induced anxiety in the SNI model in Wistar rats, which is mediated by an inhibition of spinal dorsal horn microglia activation.
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Affiliation(s)
- G Avila-Martin
- Sensorimotor Function Group, SESCAM, Hospital Nacional de Parapléjicos, Toledo, Spain
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23
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Grégoire S, Wattiez AS, Etienne M, Marchand F, Ardid D. Monoarthritis-induced emotional and cognitive impairments in rats are sensitive to low systemic doses or intra-amygdala injections of morphine. Eur J Pharmacol 2014; 735:1-9. [PMID: 24747193 DOI: 10.1016/j.ejphar.2014.03.056] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Revised: 02/21/2014] [Accepted: 03/26/2014] [Indexed: 11/27/2022]
Abstract
Chronic pain is a multidimensional experience that not only includes changes in nociception but also impairments in emotional and cognitive functions, not often taken into account in preclinical research. The present study investigated emotional and cognitive impairments in an animal model of persistent inflammatory pain as well as the involvement of the basolateral complex (BLC) of the amygdala in these components. Monoarthritis was induced by intra-articular injection of complete Freund׳s adjuvant. Mechanical hypersensitivity, anxiety and depressive-like behaviours as well as cognitive capacities were assessed using several tests, such as von Frey, social interaction, open field, saccharin preference, spatial and social recognition memory tests. The effects of morphine administered systemically or into the BLC of the amygdala were also studied. Monoarthritic rats exhibited mechanical hypersensitivity, anxiety and depressive-like behaviours as well as cognitive impairments. Whereas low systemic doses and intra-BLC infusion of morphine failed to reduce mechanical hypersensitivity, they reversed monoarthritis-induced anxiety-like behaviours and cognitive impairments. Our findings further support a crucial role of amygdala in the effect of morphine on emotional/cognitive components of pain and not on mechanical hypersensitivity. Finally, our study highlights the interest of a multi-behavioural approach in the assessment of pain and the analgesic effect of drugs.
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Affiliation(s)
- Stéphanie Grégoire
- Clermont Université, Université d׳Auvergne, NEURO-DOL, BP 10448, F-63000 Clermont-Ferrand, France; Clermont-Ferrand Inserm, U1107, F-63001 Clermont-Ferrand BP 10448, F-63000 Clermont-Ferrand, France.
| | - Anne-Sophie Wattiez
- Clermont Université, Université d׳Auvergne, NEURO-DOL, BP 10448, F-63000 Clermont-Ferrand, France; Clermont-Ferrand Inserm, U1107, F-63001 Clermont-Ferrand BP 10448, F-63000 Clermont-Ferrand, France.
| | - Monique Etienne
- Clermont Université, Université d׳Auvergne, NEURO-DOL, BP 10448, F-63000 Clermont-Ferrand, France; Clermont-Ferrand Inserm, U1107, F-63001 Clermont-Ferrand BP 10448, F-63000 Clermont-Ferrand, France.
| | - Fabien Marchand
- Clermont Université, Université d׳Auvergne, NEURO-DOL, BP 10448, F-63000 Clermont-Ferrand, France; Clermont-Ferrand Inserm, U1107, F-63001 Clermont-Ferrand BP 10448, F-63000 Clermont-Ferrand, France.
| | - Denis Ardid
- Clermont Université, Université d׳Auvergne, NEURO-DOL, BP 10448, F-63000 Clermont-Ferrand, France; Clermont-Ferrand Inserm, U1107, F-63001 Clermont-Ferrand BP 10448, F-63000 Clermont-Ferrand, France.
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24
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Vilela FC, Giusti-Paiva A. Cannabinoid receptor agonist disrupts behavioral and neuroendocrine responses during lactation. Behav Brain Res 2014; 263:190-7. [DOI: 10.1016/j.bbr.2014.01.037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 01/23/2014] [Accepted: 01/27/2014] [Indexed: 12/24/2022]
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25
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Cobos EJ, Portillo-Salido E. "Bedside-to-Bench" Behavioral Outcomes in Animal Models of Pain: Beyond the Evaluation of Reflexes. Curr Neuropharmacol 2014; 11:560-91. [PMID: 24396334 PMCID: PMC3849784 DOI: 10.2174/1570159x113119990041] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2013] [Revised: 04/05/2013] [Accepted: 05/24/2013] [Indexed: 12/21/2022] Open
Abstract
Despite the myriad promising new targets and candidate analgesics recently identified in preclinical pain studies, little translation to novel pain medications has been generated. The pain phenotype in humans involves complex behavioral alterations, including changes in daily living activities and psychological disturbances. These behavioral changes are not reflected by the outcome measures traditionally used in rodents for preclinical pain testing, which are based on reflexes evoked by sensory stimuli of different types (mechanical, thermal or chemical). These measures do not evaluate the impact of the pain experience on the global behavior or disability of the animals, and therefore only consider a limited aspect of the pain phenotype. The development of relevant new outcomes indicative of pain to increase the validity of animal models of pain has been increasingly pursued over the past few years. The aim has been to translate “bedside-to-bench” outcomes from the human pain phenotype to rodents, in order to complement traditional pain outcomes by providing a closer and more realistic measure of clinical pain in rodents. This review summarizes and discusses the most important nonstandard outcomes for pain assessment in preclinical studies. The advantages and drawbacks of these techniques are considered, and their potential impact on the validation of potential analgesics is evaluated.
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Affiliation(s)
- Enrique J Cobos
- Department of Pharmacology, School of Medicine, University of Granada, Avenida de Madrid 11, 18012 Granada
| | - Enrique Portillo-Salido
- Drug Discovery and Preclinical Development, Esteve, Avenida Mare de Déu de Montserrat 221, 08041 Barcelona, Spain
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26
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Hirsch SJ, Dickenson AH. Morphine sensitivity of spinal neurons in the chronic constriction injury neuropathic rat pain model. Neurosci Lett 2013; 562:97-101. [PMID: 24128881 DOI: 10.1016/j.neulet.2013.10.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 09/26/2013] [Accepted: 10/04/2013] [Indexed: 12/20/2022]
Abstract
Opioid analgesia involves suppression of neuronal activity in central sensory pathways. We show that the classic opioid morphine reduces spinal neuronal spontaneous and evoked activity after induction of neuropathy by chronic constriction injury of the sciatic nerve in rats. The minimal effective dose of morphine was 0.3 mg/kg for most response parameters tested. Morphine sensitivity of spinal cord neurons is similar across neuropathic pain models. We therefore conclude that nerve damage per se rather than the experimental model determines the effectiveness of opioids in general and investigate several pain measurement endpoints which might be important to clinically determine morphine's efficacy in neuropathic pain.
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Affiliation(s)
- Silke J Hirsch
- Boehringer Ingelheim Pharma GmbH & Co KG, CNS Research, 88400 Biberach, Germany.
| | - Anthony H Dickenson
- Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
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Pratt D, Fuchs PN, Sluka KA. Assessment of avoidance behaviors in mouse models of muscle pain. Neuroscience 2013; 248:54-60. [PMID: 23747349 DOI: 10.1016/j.neuroscience.2013.05.058] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Revised: 05/28/2013] [Accepted: 05/30/2013] [Indexed: 11/26/2022]
Abstract
Pain encompasses both a sensory as well as an affective dimension and these are differentially processed in the cortex. Animal models typically use reflexive behaviors to test nociceptive responses; these are thought to reflect the sensory dimension of pain. While several behavioral tests are available for examining the affective dimension of pain it is unclear if these are appropriate in animal models of muscle pain. We therefore tested the utility of existing paradigms as well as new avoidance paradigms in animal models of muscle pain in mice. Specifically we used an escape-avoidance test to noxious mechanical stimuli, a learned avoidance test to noxious mechanical stimuli, and avoidance of physical activity. We used three animal models of muscle pain: carrageenan-induced inflammation, non-inflammatory muscle pain, and exercise-enhanced pain. In the carrageenan model of inflammation mice developed escape-avoidance behaviors to mechanical stimuli, learned avoidance to mechanical stimulation and avoidance of physical activity - these models are associated with unilateral hyperalgesia. When both muscles were inflamed, escape-avoidance behaviors did not develop suggesting that equivalent bilateral pain behaviors cannot be tested with an escape-avoidance test. In the non-inflammatory muscle pain model mice did not show significant changes in escape-avoidance behaviors or learned avoidance, but did avoid physical activity. In the exercise-enhanced pain model, there were no changes in escape-avoidance, learned avoidance of noxious or physical activity In conclusion, we developed several testing protocols that assess supraspinal processing of pain behaviors in models of muscle pain and that are most sensitive in animals with unilateral hyperalgesia.
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Affiliation(s)
- D Pratt
- Physical Therapy and Rehabilitation Science, Pain Research Program, University of Iowa, Iowa City, IA, United States; Department of Psychology, University of Texas Arlington, Arlington, TX, United States; Department of Biology, University of Texas Arlington, Arlington, TX, United States
| | - P N Fuchs
- Physical Therapy and Rehabilitation Science, Pain Research Program, University of Iowa, Iowa City, IA, United States; Department of Psychology, University of Texas Arlington, Arlington, TX, United States; Department of Biology, University of Texas Arlington, Arlington, TX, United States
| | - K A Sluka
- Physical Therapy and Rehabilitation Science, Pain Research Program, University of Iowa, Iowa City, IA, United States; Department of Psychology, University of Texas Arlington, Arlington, TX, United States; Department of Biology, University of Texas Arlington, Arlington, TX, United States.
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The application of conditioning paradigms in the measurement of pain. Eur J Pharmacol 2013; 716:158-68. [PMID: 23500202 DOI: 10.1016/j.ejphar.2013.03.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 02/25/2013] [Accepted: 03/03/2013] [Indexed: 12/13/2022]
Abstract
Pain is a private experience that involves both sensory and emotional components. Animal studies of pain can only be inferred by their responses, and therefore the measurement of reflexive responses dominates the pain literature for nearly a century. It has been argued that although reflexive responses are important to unveil the sensory nature of pain in organisms, pain affect is equally important but largely ignored in pain studies primarily due to the lack of validated animal models. One strategy to begin to understand pain affect is to use conditioning principles to indirectly reveal the affective condition of pain. This review critically analyzed several procedures that are thought to measure affective learning of pain. The procedures regarding the current knowledge, the applications, and their advantages and disadvantages in pain research are discussed. It is proposed that these procedures should be combined with traditional reflex-based pain measurements in future studies of pain, which could greatly benefit both the understanding of neural underpinnings of pain and preclinical assessment of novel analgesics.
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Alba-Delgado C, Llorca-Torralba M, Horrillo I, Ortega JE, Mico JA, Sánchez-Blázquez P, Meana JJ, Berrocoso E. Chronic pain leads to concomitant noradrenergic impairment and mood disorders. Biol Psychiatry 2013; 73:54-62. [PMID: 22854119 DOI: 10.1016/j.biopsych.2012.06.033] [Citation(s) in RCA: 132] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 05/31/2012] [Accepted: 06/17/2012] [Indexed: 02/07/2023]
Abstract
BACKGROUND Patients suffering chronic pain are at high risk of suffering long-lasting emotional disturbances characterized by persistent low mood and anxiety. We propose that this might be the result of a functional impairment in noradrenergic circuits associated with locus coeruleus (LC) and prefrontal cortex, where emotional and sensorial pain processes overlap. METHODS We used a chronic constriction injury of sciatic nerve as a model of neuropathic pain in male Sprague-Dawley rats to assess the time-dependent changes that might potentially precipitate mood disorders (2, 7, 14, and 28 days after injury). This was measured through a combination of behavioral, electrophysiological, microdialysis, immunohistochemical, and Western blot assays. RESULTS As expected, nerve injury produced an early and stable decrease in sensorial pain threshold over the testing period. By contrast, long-term neuropathic pain (28 days after injury) resulted in an inability to cope with stressful situations, provoking depressive and anxiogenic-like behaviors, even more intense than the aversiveness associated with pain perception. The onset of these behavioral changes coincided with irruption of noradrenergic dysfunction, evident as: an increase in LC bursting activity; in tyrosine hydroxylase expression and that of the noradrenaline transporter; and enhanced expression and sensitivity of α2-adrenoceptors in the LC. CONCLUSIONS Long-term neuropathic pain leads to anxio-depressive-like behaviors that are more predominant than the aversion of a painful experience. These changes are consistent with the impairment of noradrenergic system described in depressive disorders.
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Affiliation(s)
- Cristina Alba-Delgado
- Neuropsychopharmacology Research Group, Department of Neuroscience, University of Cadiz, Cadiz, Spain
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Allchorne AJ, Gooding HL, Mitchell R, Fleetwood-Walker SM. A novel model of combined neuropathic and inflammatory pain displaying long-lasting allodynia and spontaneous pain-like behaviour. Neurosci Res 2012; 74:230-8. [PMID: 23131427 DOI: 10.1016/j.neures.2012.10.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2012] [Revised: 09/20/2012] [Accepted: 10/15/2012] [Indexed: 11/25/2022]
Abstract
Many clinical cases of chronic pain exhibit both neuropathic and inflammatory components. In contrast, most animal models of chronic pain focus on one type of injury alone. Here we present a novel combined model of both neuropathic and inflammatory pain and characterise its distinctive properties. This combined model of chronic constriction injury (CCI) and intraplantar Complete Freund's Adjuvant (CFA) injection results in enhanced mechanical allodynia, thermal hyperalgesia, a static weight bearing deficit, and notably pronounced spontaneous foot lifting (SFL) behaviour (which under our conditions was not seen in either individual model and may reflect ongoing/spontaneous pain). Dorsal root ganglion (DRG) expression of Activating Transcription Factor-3 (ATF-3), a marker of axonal injury, was no greater in the combined model than CCI alone. Initial pharmacological characterisation of the new model showed that the SFL was reversed by gabapentin or diclofenac, typical analgesics for neuropathic or inflammatory pain respectively, but not by mexiletine, a Na(+) channel blocker effective in both neuropathic and inflammatory pain models. Static weight bearing deficit was moderately reduced by gabapentin, whereas only diclofenac reversed mechanical allodynia. This novel animal model of chronic pain may prove a useful test-bed for further analysing the pharmacological susceptibility of complicated clinical pain states.
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Affiliation(s)
- Andrew J Allchorne
- Centre for Neuroregeneration, School of Biomedical Sciences, University of Edinburgh, Chancellor's Building, Edinburgh EH16 4SB, UK
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31
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Spinal cord stimulation: neurophysiological and neurochemical mechanisms of action. Curr Pain Headache Rep 2012; 16:217-25. [PMID: 22399391 DOI: 10.1007/s11916-012-0260-4] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Chronic neuropathic pain can significantly reduce quality of life and place an economic burden on individuals and society. Spinal cord stimulation (SCS) is an alternative approach to the treatment of neuropathic pain when standard pharmacological agents have failed. However, an improved understanding of the mechanisms by which SCS inhibits pain is needed to enhance its clinical utility. This review summarizes important findings from recent studies of SCS in animal models of neuropathic pain, highlights current understanding of the spinal neurophysiological and neurochemical mechanisms by which SCS produces an analgesic effect, and discusses the potential clinical applicability of these findings and future directions for research.
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Grégoire S, Michaud V, Chapuy E, Eschalier A, Ardid D. Study of emotional and cognitive impairments in mononeuropathic rats: Effect of duloxetine and gabapentin. Pain 2012; 153:1657-1663. [DOI: 10.1016/j.pain.2012.04.023] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 04/04/2012] [Accepted: 04/25/2012] [Indexed: 10/28/2022]
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Munro G, Storm A, Hansen MK, Dyhr H, Marcher L, Erichsen HK, Sheykhzade M. The combined predictive capacity of rat models of algogen-induced and neuropathic hypersensitivity to clinically used analgesics varies with nociceptive endpoint and consideration of locomotor function. Pharmacol Biochem Behav 2012; 101:465-78. [DOI: 10.1016/j.pbb.2012.02.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 01/26/2012] [Accepted: 02/11/2012] [Indexed: 11/26/2022]
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Fuchs PN, McNabb CT. The place escape/avoidance paradigm: A novel method to assess nociceptive processing. J Integr Neurosci 2012; 11:61-72. [DOI: 10.1142/s0219635212500045] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2011] [Revised: 10/26/2011] [Indexed: 11/18/2022] Open
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Validation of an air-puff passive-avoidance paradigm for assessment of aversive learning and memory in rat models of chronic pain. J Neurosci Methods 2012; 204:1-8. [DOI: 10.1016/j.jneumeth.2011.10.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 10/24/2011] [Accepted: 10/26/2011] [Indexed: 11/20/2022]
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Ruttenl K, Vry J, Robens A, Tzschentke TM, Kam EL. Dissociation of rewarding, anti-aversive and anti-nociceptive effects of different classes of anti-nociceptives in the rat. Eur J Pain 2012; 15:299-305. [DOI: 10.1016/j.ejpain.2010.07.011] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 06/11/2010] [Accepted: 07/30/2010] [Indexed: 01/11/2023]
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McNabb CT, Uhelski ML, Fuchs PN. A direct comparison of affective pain processing underlying two traditional pain modalities in rodents. Neurosci Lett 2011; 507:57-61. [PMID: 22172927 DOI: 10.1016/j.neulet.2011.11.051] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2011] [Revised: 11/23/2011] [Accepted: 11/26/2011] [Indexed: 10/14/2022]
Abstract
In the preclinical study of pain, two commonly used pain models are the L5 spinal nerve ligation (SNL) and the injection of carrageenan. Using a modified place escape/avoidance paradigm (mPEAP), a novel behavioral test that quantifies aversive behavior evoked by painful stimuli, we directly compared the affective component of the SNL and inflammation models. Fifty three Sprague-Dawley rats underwent baseline mechanical paw withdrawal threshold (MPWT) and mPEAP testing followed by an L5 SNL or sham surgery for the left paw and then a carrageenan or saline injection for the right paw. After recovering, animals underwent post-manipulation MPWT and mPEAP tests. Both pain conditions produced mechanical hypersensitivity, and animals with a single-paw condition demonstrated escape/avoidance behavior in response to stimulation of the affected paw. Animals with the bilateral pain condition did not show a preference for stimulation of one paw versus the other paw, and the avoidance behavior was not significantly different from the sham/saline control. The results indicate that the pain models are associated with significant avoidance behavior and that they produce comparable degrees of pain affect. These findings advance the preclinical study of pain by validating the simultaneous utilization of the SNL and inflammation models and will allow future studies that combine pain conditions to more closely resemble clinical conditions.
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Affiliation(s)
- C T McNabb
- The University of Texas at Arlington, Department of Psychology, 501 S. Nedderman Dr., 313 Life Sciences Building, Box 19528, Arlington, TX 76019, USA
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Chen Y, Wang G, Xu X, Liu BF, Li J, Zhang G. Design, synthesis and biological activity evaluation of arylpiperazine derivatives for the treatment of neuropathic pain. Molecules 2011; 16:5785-806. [PMID: 21738106 PMCID: PMC6264349 DOI: 10.3390/molecules16075785] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 06/24/2011] [Accepted: 06/27/2011] [Indexed: 11/16/2022] Open
Abstract
In this work, a series of arylpiperazine derivatives were synthesized and screened by in vivo pharmacological trials. Among the tested compounds, 2-(4-(3-(trifluoromethyl)phenyl)piperazin-1-yl)-1-phenylethanone (18) and 2-(4-(2,3-dimethylphenyl)piperazin-1-yl)-1-phenylethanone (19) exhibited potent analgesic activities in both the mice writhing and mice hot plate tests. They showed more than 70% inhibition relative to controls in the writhing test, and increased latency by 116.0% and 134.4%, respectively, in the hot plate test. Furthermore, compound 18 was also active in the models of formalin pain and neuropathic pain without sedative side effects.
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Affiliation(s)
- Yin Chen
- Department of Systems Biology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Guan Wang
- Shanghai Institute of Pharmaceutical Industry, 1111 North Zhongshan Road, Shanghai, 200437, China
| | - Xiangqing Xu
- Jiangsu Nhwa Pharmaceutical Corporation, Ltd. 69# Minzhu South Road Xuzhou City, Jiangsu, 221009, China
| | - Bi-Feng Liu
- Department of Systems Biology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
| | - Jianqi Li
- Shanghai Institute of Pharmaceutical Industry, 1111 North Zhongshan Road, Shanghai, 200437, China
| | - Guisen Zhang
- Department of Systems Biology, Huazhong University of Science and Technology, 1037 Luoyu Road, Wuhan, 430074, China
- Jiangsu Nhwa Pharmaceutical Corporation, Ltd. 69# Minzhu South Road Xuzhou City, Jiangsu, 221009, China
- Author to whom correspondence should be addressed; ; Tel.: +86-27-87792235; Fax: +86-27-87792170
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Baastrup C, Jensen TS, Finnerup NB. Coexisting mechanical hypersensitivity and anxiety in a rat model of spinal cord injury and the effect of pregabalin, morphine, and midazolam treatment. Scand J Pain 2011; 2:139-145. [DOI: 10.1016/j.sjpain.2011.02.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2011] [Accepted: 02/16/2011] [Indexed: 10/18/2022]
Abstract
Abstract
Background and purpose
Spinal cord injury (SCI) has detrimental consequences that include chronic neuropathic pain, which is seen in 40-50% of patients, and symptoms of anxiety and depression, which affect 13-45% of SCI patients. The coexistence of pain, anxiety, and depression is known from other neuropathic pain conditions, but the relationship between these symptoms is not clear and has not been investigated in a preclinical model of SCI so far.
The aim of this study was to investigate anxiety-like behavior and at-level mechanical hypersensitivity following experimental spinal cord contusion (SCC) in female Sprague-Dawley rats, and the effects of analgesic and anxiolytic drugs.
Methods
Mechanical sensitivity and elevated plus maze (EPM) behavior were measured pre- and postinjury in SCC and sham animals. Pregabalin 30 mg/kg, morphine 3 mg/kg, midazolam 0.5 mg/kg, and 0.9% NaCl were evaluated in a randomly allocated, blinded balanced design.
Results
SCC animals developed persistent at-level mechanical hypersensitivity and decreased open arm activity in the EPM, which indicates an anxiety-like state. Pregabalin, a dual-acting analgesic and anxiolytic drug reduced both hypersensitivity and anxiety-like behavior, while the analgesic drug morphine only reduced hypersensitivity. The anxiolytic drug midazolam in the dose used had no effect on either parameter.
Conclusions
SCC animals developed long lasting coexisting at-level mechanical hypersensitivity and anxiety-like behavior, but there was no evidence to support a causal relationship between pain and anxiety following SCI.
Implications
The findings that at-level mechanical hypersensitivity and anxiety-like behavior develops concomitantly in the spinal cord contusion models and that both symptoms is persistent provide basis for further investigation of the mechanisms and connection behind these two clinically relevant symptoms after injury to the central nervous system.
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Affiliation(s)
- Cathrine Baastrup
- Danish Pain Research Center , Aarhus University Hospital , Norrebrogade 44, Building 1A, DK-8000 Aarhus C , Aarhus , Denmark
| | - Troels S. Jensen
- Danish Pain Research Center , Aarhus University Hospital , Norrebrogade 44, Building 1A, DK-8000 Aarhus C , Aarhus , Denmark
- Department of Neurology , Aarhus University Hospital , Norrebrogade 44, DK-8000 Aarhus C , Aarhus , Denmark
| | - Nanna B. Finnerup
- Danish Pain Research Center , Aarhus University Hospital , Norrebrogade 44, Building 1A, DK-8000 Aarhus C , Aarhus , Denmark
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Kaufling J, Waltisperger E, Bourdy R, Valera A, Veinante P, Freund-Mercier MJ, Barrot M. Pharmacological recruitment of the GABAergic tail of the ventral tegmental area by acute drug exposure. Br J Pharmacol 2011; 161:1677-91. [PMID: 21087442 DOI: 10.1111/j.1476-5381.2010.00984.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND AND PURPOSE The tail of the ventral tegmental area (tVTA), also called the rostromedial tegmental nucleus, is a newly defined brain structure and a potential control centre for dopaminergic activity. It was identified by the induction of DeltaFosB following chronic cocaine exposure. In this work, we screened 20 drugs for their ability to induce FosB/DeltaFosB in the tVTA. EXPERIMENTAL APPROACH Immunohistochemistry following systemic drug administration was used to study FosB/DeltaFosB induction in the tVTA of adult rats. Double-staining was used to determine whether dopamine or GABA neurones are involved in this induction. KEY RESULTS The acute injection of the psychostimulant drugs cocaine, D-amphetamine, (+/-)-3,4-methylenedioxymethamphetamine (MDMA), methylphenidate or caffeine, induced the expression of FosB/DeltaFosB in the tVTA GABAergic cells. No induction was observed following exposure to ethanol, diazepam, γ-hydroxybutyric acid (GHB), morphine, ketamine, phencyclidine (PCP), Δ(9)-tetrahydrocannabinol (THC), sodium valproic acid or gabapentin. To evaluate the role of monoamine transporters in the psychostimulant-induced expression of FosB/DeltaFosB, we tested the antidepressant drugs reboxetine, nortriptyline, fluoxetine and venlafaxine (which target the noradrenaline and/or the 5-hydroxytryptamine transporters), the 5-hydroxytryptamine releasing agent dexfenfluramine, and the dopamine transporter inhibitor GBR12909. Only GBR12909 was able to induce FosB/DeltaFosB expression in the tVTA, showing that this induction is mediated by dopamine. CONCLUSIONS AND IMPLICATIONS Newly described brain structures may help to increase our knowledge of brain function, pathology and targets for treatments. FosB/DeltaFosB induction in the tVTA is a common feature of drugs sharing psychostimulant properties but not of drugs sharing risk of abuse.
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Affiliation(s)
- Jennifer Kaufling
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Strasbourg, France
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Baastrup C, Jensen TS, Finnerup NB. Pregabalin attenuates place escape/avoidance behavior in a rat model of spinal cord injury. Brain Res 2010; 1370:129-35. [PMID: 21070753 DOI: 10.1016/j.brainres.2010.11.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2010] [Revised: 10/19/2010] [Accepted: 11/03/2010] [Indexed: 11/17/2022]
Abstract
Spinal cord injury (SCI) pain in humans is difficult to treat, and the lack of valid methods to measure behavior comparable to the complex human pain experience preclinically represents an important obstacle to finding better treatments for this type of central pain. The place escape/avoidance paradigm (PEAP) relies on the active choice of an animal between its natural preference for a dark environment or pain relief, and it has been suggested to measure the affective-motivational component of pain. We have modified the method to a T10 spinal cord contusion model (SCC) of at-level central neuropathic pain in Sprague-Dawley rats. In order to demonstrate sensitivity to change in escape/avoidance behavior and thus the applicability of the PEAP method to predict drug efficacy, we investigated the effect of pregabalin (30 mg/kg) treatment in a randomized design. SCC animals displayed increased escape/avoidance behavior postinjury, indicating at-level mechanical hypersensitivity. Second, we found no correlation between state anxiety levels in SCC animals (elevated plus maze) and PEAP behavior, suggesting that the PEAP measurement is not biased by differences in anxiety levels. Third, we demonstrated a decrease in escape/avoidance behavior in response to treatment with the analgesic drug pregabalin. Thus, the PEAP may be applicable as a surrogate correlate of human pain. In conclusion, the primary finding in this study was a sensitivity to change in escape/avoidance behavior induced by pharmacological modulation with analgesics, supporting the use of the PEAP as a central outcome measure in preclinical SCI pain research.
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Affiliation(s)
- Cathrine Baastrup
- Danish Pain Research Center, Aarhus University Hospital, Noerrebrogade 44, Building 1A, DK-8000 Aarhus C, Denmark.
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Baastrup C, Maersk-Moller CC, Nyengaard JR, Jensen TS, Finnerup NB. Spinal-, brainstem- and cerebrally mediated responses at- and below-level of a spinal cord contusion in rats: evaluation of pain-like behavior. Pain 2010; 151:670-679. [PMID: 20863621 DOI: 10.1016/j.pain.2010.08.024] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2010] [Revised: 08/13/2010] [Accepted: 08/18/2010] [Indexed: 11/16/2022]
Abstract
Pain is a frequent consequence of spinal cord injury (SCI) which may profoundly impair the patients' quality of life. Valid experimental models and methods are therefore desirable in the search for better treatments. Usually, experimental pain assays depend on stimulus-evoked withdrawal responses; however, this spinal-mediated reflex response may be particularly problematic when evaluating below-level SCI pain due to the development of hyperactive reflex circuitries. In this study, we applied and compared assays measuring cold (acetone), static (von Frey filaments), and dynamic mechanical (soft brush) hypersensitivity at different levels of the neuroaxis at and below the level of injury in a rat model of SCI. We induced an experimental SCI (MASCIS 25 mm weight-drop) and evaluated the development of spinal reflexes (withdrawal), spinal-brainstem-spinal reflexes (licking, guarding, struggling, vocalizing, jumping, and biting) and cerebral-dependent behavior (place escape/avoidance paradigm (PEAP)). We demonstrated increased brainstem reflexes and cerebrally mediated aversive reactions to stimuli applied at the level of SCI, suggesting development of at-level evoked pain behavior. Furthermore, stimulation below-level increased innate reflex responses without increasing brainstem reflexes or aversive behavior in the PEAP, suggesting development of the spasticity syndrome rather than pain-like behavior. While spinal reflex measures are acceptable for studying changes in the spinal reflex pathways and spinal cord, they are not suited as nociceptive behavioral measures. Measuring brainstem organized responses eliminates the bias associated with the spastic syndrome, but pain requires cortical involvement. Methods depending on cortical structures, as the PEAP, are therefore optimal endpoints in animal models of central pain.
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Affiliation(s)
- Cathrine Baastrup
- Danish Pain Research Center, Aarhus University Hospital, Aarhus, Denmark Stereology & Electron Microscopy Research Laboratory, Aarhus University Hospital, Aarhus, Denmark
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Munro G, Dyhr H, Grunnet M. Selective potentiation of gabapentin-mediated antinociception in the rat formalin test by the nicotinic acetylcholine receptor agonist ABT-594. Neuropharmacology 2010; 59:208-17. [DOI: 10.1016/j.neuropharm.2010.05.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Revised: 05/24/2010] [Accepted: 05/24/2010] [Indexed: 10/19/2022]
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Guo W, Wang H, Zou S, Wei F, Dubner R, Ren K. Long lasting pain hypersensitivity following ligation of the tendon of the masseter muscle in rats: a model of myogenic orofacial pain. Mol Pain 2010; 6:40. [PMID: 20633279 PMCID: PMC2914030 DOI: 10.1186/1744-8069-6-40] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Accepted: 07/15/2010] [Indexed: 02/28/2023] Open
Abstract
Background A major subgroup of patients with temporomandibular joint (TMJ) disorders have masticatory muscle hypersensitivity. To study myofacial temporomandibular pain, a number of preclinical models have been developed to induce myogenic pain of the masseter muscle, one of the four muscles involved in mastication. The currently used models, however, generate pain that decreases over time and only lasts from hours to weeks and hence are not suitable for studying chronicity of the myogenic pain in TMJ disorders. Here we report a model of constant myogenic orofacial pain that lasts for months. Results The model involves unilateral ligation of the tendon of the anterior superficial part of the rat masseter muscle (TASM). The ligation of the TASM was achieved with two chromic gut (4.0) ligatures via an intraoral approach. Nocifensive behavior of the rat was assessed by probing the skin site above the TASM with a series of von Frey filaments. The response frequencies were determined and an EF50 value, defined as the von Frey filament force that produces a 50% response frequency, was derived and used as a measure of mechanical sensitivity. Following TASM ligation, the EF50 of the injured side was significantly reduced and maintained throughout the 8-week observation period, suggesting the presence of mechanical hyperalgesia/allodynia. In sham-operated rats, the EF50 of the injured side was transiently reduced for about a week, likely due to injury produced by the surgery. Somatotopically relevant Fos protein expression was indentified in the subnucleus caudalis of the spinal trigeminal sensory complex. In the same region, persistent upregulation of NMDA receptor NR1 phosphorylation and protein expression and increased expression of glial markers glial fibrillary acidic protein (astroglia) and CD11b (microglia) were found. Morphine (0.4-8 mg/kg, s.c.) and duloxetine (0.4-20 mg/kg, i.p.), a selective serotonin-norepinephrine reuptake inhibitor, produced dose-dependent attenuation of hyperalgesia. Conclusions Ligation injury of the TASM in rats led to long-lasting and constant mechanical hypersensitivity of myogenic origin. The model will be particularly useful in studying the chronicity of myogenic pain TMJ disorders. The model can also be adapted to other regions of the body for studying pathology of painful tendinopathy seen in sports injury, muscle overuse, and rheumatoid arthritis.
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Affiliation(s)
- Wei Guo
- Department of Neural and Pain Sciences, Dental School & Program in Neuroscience, University of Maryland, Baltimore, MD 21201, USA
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Comparison of mechanical allodynia and the affective component of inflammatory pain in rats. Neuropharmacology 2010; 58:537-43. [DOI: 10.1016/j.neuropharm.2009.08.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Revised: 08/14/2009] [Accepted: 08/17/2009] [Indexed: 02/07/2023]
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Wu HE, Gemes G, Zoga V, Kawano T, Hogan QH. Learned avoidance from noxious mechanical simulation but not threshold semmes weinstein filament stimulation after nerve injury in rats. THE JOURNAL OF PAIN 2009; 11:280-6. [PMID: 19945356 DOI: 10.1016/j.jpain.2009.07.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Revised: 07/01/2009] [Accepted: 07/26/2009] [Indexed: 11/29/2022]
Abstract
UNLABELLED Noxious mechanical stimulation evokes a complex and sustained hyperalgesic motor response after peripheral nerve injury that contrasts with a brief and simple withdrawal seen after noxious stimulation in control animals or after threshold punctate mechanical stimulation by the von Frey technique. To test which of these behaviors indicate pain, the aversiveness of the experience associated with each was determined using a passive avoidance test in rats after sciatic nerve ligation (SNL) or skin incision alone. After 18 days, step-down latency was measured during 9 sequential trials at 10-minute intervals. At each trial, rats received either no stimulus, needle stimuli, or threshold Semmes Weinstein (SW) filament stimuli after stepping down. Reactions were either a hyperalgesic response or a brief reflexive withdrawal. In SNL animals, needle stimulation produced substantial learned avoidance when animals showed hyperalgesic responses but produced minimal prolonged latency in SNL animals that showed only simple withdrawal responses. No learned avoidance developed using threshold SW testing in SNL animals. These findings show that needle stimulation is aversive in rats responding with hyperalgesic behavior. In contrast, SW stimulation, as well as needle stimulation that produced mere withdrawal, is minimally aversive. PERSPECTIVE The validity of measures of pain in animals is open to question. We demonstrated that needle stimulation is aversive in rats that respond with hyperalgesic-type behavior and is therefore a valid indicator of pain. Stimulation by SW is minimally aversive and is a problematic indicator of pain.
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Affiliation(s)
- Hsiang-En Wu
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Rahn EJ, Hohmann AG. Cannabinoids as pharmacotherapies for neuropathic pain: from the bench to the bedside. Neurotherapeutics 2009; 6:713-37. [PMID: 19789075 PMCID: PMC2755639 DOI: 10.1016/j.nurt.2009.08.002] [Citation(s) in RCA: 208] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Neuropathic pain is a debilitating form of chronic pain resulting from nerve injury, disease states, or toxic insults. Neuropathic pain is often refractory to conventional pharmacotherapies, necessitating validation of novel analgesics. Cannabinoids, drugs that share the same target as Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the psychoactive ingredient in cannabis, have the potential to address this unmet need. Here, we review studies evaluating cannabinoids for neuropathic pain management in the clinical and preclinical literature. Neuropathic pain associated with nerve injury, diabetes, chemotherapeutic treatment, human immunodeficiency virus, multiple sclerosis, and herpes zoster infection is considered. In animals, cannabinoids attenuate neuropathic nociception produced by traumatic nerve injury, disease, and toxic insults. Effects of mixed cannabinoid CB(1)/CB(2) agonists, CB(2) selective agonists, and modulators of the endocannabinoid system (i.e., inhibitors of transport or degradation) are compared. Effects of genetic disruption of cannabinoid receptors or enzymes controlling endocannabinoid degradation on neuropathic nociception are described. Specific forms of allodynia and hyperalgesia modulated by cannabinoids are also considered. In humans, effects of smoked marijuana, synthetic Delta(9)-THC analogs (e.g., Marinol, Cesamet) and medicinal cannabis preparations containing both Delta(9)-THC and cannabidiol (e.g., Sativex, Cannador) in neuropathic pain states are reviewed. Clinical studies largely affirm that neuropathic pain patients derive benefits from cannabinoid treatment. Subjective (i.e., rating scales) and objective (i.e., stimulus-evoked) measures of pain and quality of life are considered. Finally, limitations of cannabinoid pharmacotherapies are discussed together with directions for future research.
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Affiliation(s)
- Elizabeth J. Rahn
- grid.213876.9000000041936738XNeuroscience and Behavior Program, Department of Psychology, University of Georgia, 30602-3013 Athens, GA
| | - Andrea G. Hohmann
- grid.213876.9000000041936738XNeuroscience and Behavior Program, Department of Psychology, University of Georgia, 30602-3013 Athens, GA
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Rivera-Arconada I, Roza C, Lopez-Garcia JA. Enhancing m currents: a way out for neuropathic pain? Front Mol Neurosci 2009; 2:10. [PMID: 19680469 PMCID: PMC2726036 DOI: 10.3389/neuro.02.010.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Accepted: 07/23/2009] [Indexed: 12/19/2022] Open
Abstract
Almost three decades ago, the M current was identified and characterized in frog sympathetic neurons (Brown and Adams, 1980). The years following this discovery have seen a huge progress in the understanding of the function and the pharmacology of this current as well as on the structure of the underlying ion channels. Therapies for a number of syndromes involving abnormal levels of excitability in neurons are benefiting from research on M currents. At present, the potential of M current openers as analgesics for neuropathic pain is under discussion. Here we offer a critical view of existing data on the involvement of M currents in pain processing. We believe that enhancement of M currents at the site of injury may become a powerful strategy to alleviate pain in some peripheral neuropathies.
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Affiliation(s)
- Ivan Rivera-Arconada
- Departamento de Fisiología, Edificio de Medicina, Universidad de Alcala Madrid, Spain
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Munro G. Pharmacological assessment of the rat formalin test utilizing the clinically used analgesic drugs gabapentin, lamotrigine, morphine, duloxetine, tramadol and ibuprofen: Influence of low and high formalin concentrations. Eur J Pharmacol 2009; 605:95-102. [DOI: 10.1016/j.ejphar.2009.01.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Revised: 12/11/2008] [Accepted: 01/05/2009] [Indexed: 10/21/2022]
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Animal models and the prediction of efficacy in clinical trials of analgesic drugs: a critical appraisal and call for uniform reporting standards. Pain 2008; 139:243-247. [PMID: 18814968 DOI: 10.1016/j.pain.2008.08.017] [Citation(s) in RCA: 225] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2008] [Accepted: 08/27/2008] [Indexed: 01/31/2023]
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