Pain
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Peripheral injury or inflammation leads to a release of mediators capable of binding to a variety of ion channels and receptors. Among these are the 7-transmembrane receptors (G protein-coupled receptors) coupling to G(s), G(i/o), G₁₂/₁₃, or G(q/11) G proteins. Each of the G protein-coupled receptor pathways is involved in nociceptive modulation and pain processing, but the relative contribution of individual signaling pathways in vivo has not yet been worked out. ⋯ Surprisingly, our behavioral and electrophysiological experiments also indicated defects in basal mechanical sensitivity in G(q/11) mutant mice, suggesting a novel function for G(q/11) in tonic modulation of acute nociception. Patch-clamp recordings revealed changes in voltage-dependent tetrodotoxin-resistant and tetrodotoxin-sensitive sodium channels in nociceptors upon a loss of G(q/11), whereas potassium currents remained unchanged. Our results indicate that the functional role of the G(q)/G₁₁ branch of G-protein signaling in nociceptors in vivo not only spans sensitization mechanisms in pathological pain states, but is also operational in tonic modulation of basal nociception and acute pain.
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Impairment of spinal GABAergic inhibition is demonstrated to contribute to pathologic chronic pain states. We investigated spinal and peripheral GABAergic regulation of incisional pain in rats. We found that intrathecal but not peripheral administration of muscimol (GABA-A receptor agonist) and baclofen (GABA-B receptor agonist) reduced mechanical and thermal hyperalgesia after plantar incision in rats. ⋯ However, expression of GABA-A receptor subunits α2 and α3 and GABA-B receptor subunits within the dorsal horn of the spinal cord were unchanged after incision, indicating that receptor expression cannot explain a possible modulation of GABAergic inhibition after incision. Thus, other mechanisms need to be considered. In conclusion, GABA-A and GABA-B receptors are promising targets for postoperative, incisional pain in humans.
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Randomized Controlled Trial Multicenter Study
The CONECSI trial: results of a randomized controlled trial of a multidisciplinary cognitive behavioral program for coping with chronic neuropathic pain after spinal cord injury.
Many people with spinal cord injury (SCI) rate chronic neuropathic pain as one of the most difficult problems to manage. The aim of the CONECSI (COping with NEuropathiC Spinal cord Injury pain) trial was to evaluate a multidisciplinary cognitive behavioral treatment program for persons with chronic neuropathic pain after SCI. The intervention consisted of educational, cognitive, and behavioral elements. ⋯ Significant intervention effects (Time*Group interactions) were found for anxiety and participation in activities, but not for the primary outcomes. Subsequent paired t tests showed significant changes in the intervention group that were not seen in the control group: decrease of pain intensity, pain-related disability, anxiety, and increase of participation in activities. This study implies that a multidisciplinary cognitive behavioral program might have beneficial effects on people with chronic neuropathic SCI pain.