European journal of pain : EJP
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It is well known that neuropeptide Y (NPY) participates in the modulation of chronic pain, but its exact role has not yet been fully explained. In this study, we explored whether targeted delivery of NPY and its antagonists into dorsal root ganglion (DRG) modulates pain-related behaviour in rats with experimentally induced inflammatory nociception. ⋯ These findings indicate an important link between pain-related behaviour and neuroimmune actions of NPY Y1 and Y2 receptors.
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Injection of nerve growth factor (NGF) produces mechanical and thermal hypersensitivity in rodents and humans. Treatment with sequestering antibodies demonstrates the importance of NGF in various pain states, with efficacy seen in a number of animal pain models and in painful human conditions. However, these phenomena have not been evaluated in the context of using NGF-induced hypersensitivities as a model of pain. ⋯ The results reported here suggest that effects of NGF on thermal and mechanical sensitivity in rats are similar to those reported in human and are partially driven by TRPV1. The rat NGF model may serve as a potential translational model for exploring the effects of novel analgesic agents.
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Unusual symptoms such as digit misidentification and neglect-like phenomena have been reported in complex regional pain syndrome (CRPS), which we hypothesized could be explained by parietal lobe dysfunction. ⋯ In patients with chronic CRPS, detailed clinical examination may reveal parietal dysfunction, with severity relating to the extent of allodynia.
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The painDETECT questionnaire (PD-Q) has been used as a tool to characterize sensory abnormalities in patients with persistent pain. This study investigated whether the self-reported sensory descriptors of patients with painful cervical radiculopathy (CxRAD) and patients with fibromyalgia (FM), as characterized by responses to verbal sensory descriptors from PD-Q (sensitivity to light touch, cold, heat, slight pressure, feeling of numbness in the main area of pain), were associated with the corresponding sensory parameters as demonstrated by quantitative sensory testing (QST). ⋯ Clinicians and researchers should be cautious about relying on PD-Q as a stand-alone screening tool to determine sensory abnormalities in patients with FM.
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Peripheral nerve injury induces up-regulation of the calcium channel alpha-2-delta-1 proteins in the dorsal root ganglia and dorsal spinal cord that correlates with neuropathic pain development. Similar behavioural hypersensitivity was also observed in injury-free transgenic (TG) mice over-expressing the alpha-2-delta-1 proteins in neuronal tissues. To investigate pathways regulating alpha-2-delta-1 protein-mediated behavioural hypersensitivity, we examined whether spinal serotonergic 5-HT3 receptors are involved similarly in the modulation of behavioural hypersensitivity induced by either peripheral nerve injury in a nerve injury model or neuronal alpha-2-delta-1 over-expression in the TG model. ⋯ Our data suggest that spinal 5-HT3 receptors are likely to play a role in alpha-2-delta-1-mediated behavioural hypersensitivities through a descending serotonergic facilitation.