Articles: neuralgia.
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This study aimed to establish a practical method for assessing pain symptomatology and develop criteria for quantifying small fiber functions using laser speckle contrast analysis (LASCA). ⋯ Pain-related small fiber functions and symptomatology (two-in-one method) can be assessed via histamine- or capsaicin-evoked axon flare responses in as little as 15 minutes. The reduction of small fiber functions are characterized by decrease in flare size/intensity at 5 minutes after stimulation and prolongation/abolishment of the latency to reach 3-fold higher levels of baseline skin microcirculation. LASCA may be applied in the clinic to aid early diagnosis, monitor disease progression, and objectively assess treatment efficacy in patients with neuropathic pain.
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Current models of somatosensory perception emphasize transmission from primary sensory neurons to the spinal cord and on to the brain1-4. Mental influence on perception is largely assumed to occur locally within the brain. Here we investigate whether sensory inflow through the spinal cord undergoes direct top-down control by the cortex. ⋯ Tactile stimulation activates somatosensory CSNs, and their corticospinal projections facilitate light-touch-evoked activity of cholecystokinin interneurons in the deep dorsal horn. This touch-driven feed-forward spinal-cortical-spinal sensitization loop is important for the recruitment of spinal nociceptive neurons under tactile allodynia. These results reveal direct cortical modulation of normal and pathological tactile sensory processing in the spinal cord and open up opportunities for new treatments for neuropathic pain.
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Opioid receptor like 1 (ORL1) receptor activation displayed an anti-nociceptive effect at spinal level for acute and neuropathic pain. SCH221510, an orally active non-peptide ORL1 agonist, was reported to be effective in treating neuropathic pain. The present study used ORL1 antagonist and siRNA to investigate that ORL1 activation mediates intrathecal SCH221510 analgesia in neuropathic pain induced by chronic constrictive injury (CCI) to rat sciatic nerve. ⋯ Intrathecal siRNA blocked SCH221510 analgesia in neuropathic pain at spinal level. Conclusively, ORL1 activation mediates SCH221510 analgesia in neuropathic pain at spinal level. The results warrant a potential clinically applicable drug in treating neuropathic pain.