European journal of pain : EJP
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Fibromyalgia (FMS) has a prevalence of approximately 2% in the population. Central alterations have been described in FMS, but there is not consensus with respect to the role of peripheral factors for the maintenance of FMS. 31P magnetic resonance spectroscopy (31P-MRS) has been used to investigate the metabolism of phosphagens in muscles of FMS patients, but the results in the literature are not in consensus. The aim was to investigate the quantitative content of phosphagens and pH in resting quadriceps muscle of patients with FMS (n = 19) and in healthy controls (CONTROLS; n = 14) using (31) P-MRS. It was also investigated whether the concentrations of these substances correlated with measures of pain and/or physical capacity. ⋯ Alterations in intramuscular ATP, PCr and fat content in FMS probably reflect a combination of inactivity related to pain and dysfunction of muscle mitochondria.
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Platelet-activating factor (PAF) has been implicated in the pathology of neuropathic pain. Previous studies reported that PAF receptor (PAF-R) antagonists have varied anti-allodynia effects by route of administration and nerve injury models in rats. ⋯ The present results revealed the effectiveness in anti-allodynia of PAF antagonists in different nerve injury models, and the unique mode of action; long-lasting anti-allodynia effects mediated by spinal GlyRα3 with a competitive manner at the initial stage and the following non-competitive manner of inhibition.
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Previous studies have identified neuromedin U receptor 2 (NMUR2) as the subtype mediating the effects of neuromedin U on acute chemo-nociception induced by capsaicin or formalin injection. The aims of this study were to determine whether NMUR2 is required for the development of mechanical hypersensitivity after nerve injury or heat hypersensitivity after inflammation and whether there is a gender difference in the contribution of NMUR2 to nociception. ⋯ The present data do not support a significant contribution of NMUR2 to the development of hypersensitivity after nerve injury or tissue inflammation, suggesting that pharmacological intervention aimed at the NMUR2 receptor might not be a valuable approach for the treatment of chronic pain.
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Neuropathic pain is severely debilitating and resistant to pharmacological approaches; therefore, the study of therapies to complement its treatment is especially relevant. In a case report study, light-emitting diode therapy (LEDT) has shown analgesic activity as well as reduced the expression of pro-inflammatory cytokines in a rabbit osteoarthritis model and in calcaneal tendinitis in rats. Although LEDT stimulated morphofunctional recovery after nerve injury in rats, its effect against neuropathic pain has not been tested. ⋯ Taken together, these data provide first-hand evidence of LEDT effectiveness against neuropathic pain induced by SNC, with corresponding decrease of pro-inflammatory cytokine levels, both in the sciatic nerve and in the spinal cord, although at a small analgesic dose, LEDT failed to accelerate nerve regeneration.