European journal of pain : EJP
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Distraction interventions are used clinically to relieve pain. Exposure to distracting stimuli causes withdrawal of attention from the painful stimulus and reduces perceived pain. However, the neurobiological mechanisms mediating distraction-induced analgesia are poorly understood due, in part, to a paucity of animal studies modelling this phenomenon. ⋯ Failure to detect any distractor-induced effects on plasma corticosterone levels or aversive behaviours suggests that the stimuli used were non-stressful. HPLC analysis revealed that there was a significant reduction in serotonin and dopamine metabolites in the medial prefrontal cortex in animals exposed to the novel object. These results indicate that exposure to a novel object or arena reduces nociceptive behaviour in rats, effects accompanied by discrete alterations in serotonin and dopamine metabolites in the medial prefrontal cortex.
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EphrinB-EphB receptor signaling plays diverse roles during development, but recently has been implicated in synaptic plasticity in the matured nervous system and in pain processes. The present study investigated the correlation between expression of ephrinB and EphB receptor proteins and chronic constriction injury (CCI) of the sciatic nerve and dorsal rhizotomy (DR) in dorsal root ganglion (DRG) and spinal cord (SC); and interaction of CCI and DR on expression of these signals. Adult, male Sprague-Dawley rats were employed and thermal sensitivity was determined in the sham operated CCI and DR rats. ⋯ DR suppressed CCI-induced upregulation of ephrinB1 in SC and EphB1 receptor in DRG and SC. These findings indicate that ephrinB-EphB receptor activation and redistribution in DRG and DH neurons after nerve injury could contribute to neuropathic pain. This study may also provide a new mechanism underlying DR-induced analgesia in clinic.
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Antidepressant drugs act mainly by blocking the noradrenaline and/or serotonin uptake sites and require a chronic treatment. Tricyclic antidepressants are among the first line treatments clinically recommended against neuropathic pain. As observed against depression, a chronic treatment is required for a therapeutic effect. ⋯ For comparison, we tested the anticonvulsant gabapentin and showed that it alleviates neuropathic allodynia after 3 days of treatment. Naloxone had no effect on gabapentin therapeutic benefit, showing that antidepressants and anticonvulsants alleviate neuropathic allodynia through independent mechanisms. Our work provides a clinically relevant model to understand the mechanism by which chronic antidepressant treatment can alleviate neuropathic pain.
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The term whiplash associated disorders (WAD) includes a wide range of complaints, with neck pain as predominating symptom. Living with long term pain influences quality of life. In previous studies of other chronic pain patients, subgrouping has been made according to thermal pain thresholds measured in quantitative sensory testing (QST). ⋯ Thermal pain hyperalgesia, especially for cold, seems to be a determinant for subgrouping WAD patients. These results support that such a classification of a heterogenous group could be of importance in tailoring treatment and early interventions.
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Multicenter Study Clinical Trial
Efficacy and safety of pregabalin in patients with diabetic peripheral neuropathy or postherpetic neuralgia: Open-label, non-comparative, flexible-dose study.
We assessed the efficacy and safety of a flexible-dose pregabalin regimen in patients with diabetic peripheral neuropathy (DPN) or postherpetic neuralgia (PHN) under clinical practice conditions. Further, the trial investigated the correlation of unspecific measures of change (patient and physician global impression of change, PGIC and CGIC) and specific measures of morbidity. The primary outcomes of this prospective, open-label, non-controlled study were the correlation between global status (PGIC and CGIC) and changes in pain, sleep, and anxiety scores as assessed on numerical or visual rating scales. ⋯ In conclusion, pregabalin in a flexible-dose regimen improved pain, sleep, anxiety and general state, and was well tolerated. The efficacy and safety profile of pregabalin was consistent with the data from the controlled clinical trials. The PGIC and CGIC and the specific pain and sleep scores, but not the anxiety score were generally well correlated but not synonymous.