Pain
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Recent studies have shown that leptin (an adipocytokine) played an important role in nociceptive behavior induced by nerve injury, but the cellular mechanism of this action remains unclear. Using the whole-cell patch-clamp recording from rat's spinal cord slices, we showed that superfusion of leptin onto spinal cord slices dose-dependently enhanced N-methyl-d-aspartate (NMDA) receptor-mediated currents in spinal cord lamina II neurons. At the cellular level, the effect of leptin on spinal NMDA-induced currents was mediated through the leptin receptor and the JAK2/STAT3 (but not PI3K or MAPK) pathway, as the leptin effect was abolished in leptin receptor-deficient (db/db) mice and inhibited by a JAK/STAT inhibitor. ⋯ Our data demonstrate a relationship between leptin and NMDA receptor-mediated spinal neuronal excitation and its functional role in nociceptive behavior. Since leptin contributes to nociceptive behavior induced by nerve injury, the present findings suggest an important cellular link between the leptin's spinal effect and the NMDA receptor-mediated cellular mechanism of neuropathic pain. A functional link is demonstrated between leptin, an adipocytokine, and the cellular mechanisms of neuropathic pain via enhancement of function and expression of spinal N-methyl-d-aspartate receptors.
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Randomized Controlled Trial
Pregabalin in severe burn injury pain: a double-blind, randomised placebo-controlled trial.
This randomised, double-blind, placebo-controlled trial assessed the efficacy and tolerability of pregabalin to alleviate the neuropathic component of moderate to severe burn pain. Patients aged 18 to 65 years admitted to a burns unit with a 5% or greater total body surface area burn injury were screened to participate in the trial. Using the Neuropathic Pain Scale (NPS), patients scoring 4 or higher on 'hot' pain or 'sharp' pain were invited to participate. ⋯ There was no significant difference between the pregabalin and placebo treatment groups with respect to opioid consumption, duration of hospital stay, or pain at 6 months. Pregabalin was efficacious and well tolerated in patients after severe burn injury and whose pain was characterised by features of acute neuropathic pain. In this study, pregabalin was well tolerated and significantly reduced several elements of the neuropathic pain scale including hot pain, unpleasantness of the pain, surface pain, and itch, and also significantly reduced procedural pain.
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It has been proposed that goal pursuit plays a role in the development of chronic pain disorders. On the basis of (affective) motivational theories, it was hypothesized that both long-term achievement goals and short-term hedonic goals would be related to increased levels of pain and disability, particularly in patients with high negative affect. Participants with musculoskeletal pain complaints (N=299) completed a battery of questionnaires including a novel goal pursuit questionnaire (GPQ) measuring the extent to which participants preferred hedonic goals (mood-management or pain-avoidance goals) over achievement goals in various situations. ⋯ These findings provide support for the validity of an affective-motivational approach to chronic pain, suggesting that the experience of pain and the interference of pain on daily life activities depends on goal pursuit and negative affect. Interventions aimed at improving disability in chronic pain should address both patient's goal pursuit and negative affect. An affective-motivational approach to chronic pain indicates that achievement and pain-avoidance goals are associated with pain severity and disability, particularly in patients with high negative affect.
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Problems in diagnosing fibromyalgia syndrome (FM) among motor vehicle collision (MVC) patients with whiplash (WL) include the following: the predominance of tender points (TPs) in the neck/shoulder girdle region; the 3-month duration of widespread pain criterion; and, the stability of diagnosis. The present study examined the prevalence of FM in a cohort (N = 326) patients with persistent neck pain 3 months after WL injury who were enrolled in a treatment program. Physical examinations were performed at baseline and at the end of treatment. ⋯ In conclusion, present criteria used in determining FM may result in spuriously inflated rates of diagnosis among WL patients because of persistent localized tenderness after an MVC. Furthermore, the transient nature of FM "symptoms" among WL patients should be taken into account before making a final diagnosis. The present criteria used in determining fibromyalgia may result in spuriously inflated rates of diagnosis among whiplash patients because of persistent localized tenderness after motor vehicle collisions.
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Sensory gain (i.e., hyperalgesia) and sensory loss (ie, hypoalgesia) are key features of neuropathic pain syndromes. Previously, we showed that conditioning electrical stimuli may provoke either sensory gain or decline in healthy subjects, depending on the stimulation frequencies applied. In the present study we sought to determine whether sensory decline induced by 20-Hz electrical stimulation preferentially of peptidergic C-nociceptors induces antihyperalgesic effects in a transdermal electrical pain model. ⋯ We conclude that 20-Hz noxious electrical stimulation may represent a neurostimulatory paradigm with antihyperalgesic properties. These findings may thus be of relevance for the future therapy of neuropathic pain syndromes as well. Sensory decline induced by 20-Hz electrical stimulation of peptidergic C-nociceptors induces antihyperalgesic effects in a transdermal electrical pain model.