Articles: hyperalgesia.
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Although still used by hundreds of millions of people worldwide, the mechanism of the analgesic action of the pyrazolone derivatives (PDs), dipyrone, propyphenazone and antipyrine remains unknown. The transient receptor potential ankyrin 1 (TRPA1) channel, expressed by nociceptors, is emerging as a major pain transduction pathway. We hypothesized that PDs target the TRPA1 channel and by this mechanism produce their analgesic effect. ⋯ Evidence that in rodents the nociceptive/hyperalgesic effect produced by TRPA1 activation is blocked by PDs suggests that a similar pathway is attenuated by PDs in humans and that TRPA1 antagonists could be novel analgesics, devoid of the adverse haematological effects of PDs.
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Cast immobilization induces mechanical hypersensitivity, which disturbs rehabilitation. Although vibration therapy can reduce various types of pain, whether vibration reduces immobilization-induced hypersensitivity remains unclear. ⋯ The data suggest that initiation of vibration therapy in the early phase of immobilization may inhibit the development of immobilization-induced hypersensitivity.
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Neuroscience letters · Jun 2015
Antiallodynic effect of tianeptine via modulation of the 5-HT7 receptor of GABAergic interneurons in the spinal cord of neuropathic rats.
Although tianeptine, an atypical antidepressant has been reported to have antinociceptive effects, the mode of action is different from that of tricyclic antidepressants despite structural similarities. We examined the antiallodynic effect of intrathecal tianeptine in neuropathic pain rats and determined the involvement of 5-hydroxytryptamine type 7 (5-HT7) receptor of the GABAergic interneurons in the spinal cord. Neuropathic pain was induced by spinal nerve ligation (SNL). ⋯ Both GAD65 expression and the GABA concentration in the spinal cord were decreased in neuropathic rats but were increased by tianeptine. Additionally, 5-HT7 receptor and GAD65 were co-localized in the spinal cord. Intrathecal tianeptine reduces neuropathic pain. 5-HT7 receptor of the GABAergic interneurons together with GAD65 plays a role in the activity of tianeptine at the spinal cord level.
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Proc. Natl. Acad. Sci. U.S.A. · Jun 2015
Classical conditioning of analgesic and hyperalgesic pain responses without conscious awareness.
Pain reduction and enhancement can be produced by means of conditioning procedures, yet the role of awareness during the acquisition stage of classical conditioning is unknown. We used psychophysical measures to establish whether conditioned analgesic and hyperalgesic responses could be acquired by unseen (subliminally presented) stimuli. A 2 × 2 factorial design, including subliminal/supraliminal exposures of conditioning stimuli (CS) during acquisition/extinction, was used. ⋯ The effect was significantly larger for hyperalgesic than analgesic responses (P < 0.001). Results demonstrate that conscious awareness of the CS is not required during either acquisition or extinction of conditioned analgesia or hyperalgesia. Our results support the notion that nonconscious stimuli have a pervasive effect on human brain function and behavior and may affect learning of complex cognitive processes such as psychologically mediated analgesic and hyperalgesic responses.
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World J. Gastroenterol. · Jun 2015
Effects of electroacupuncture on corticotropin-releasing hormone in rats with chronic visceral hypersensitivity.
To investigate the effect of electroacupuncture on corticotropin-releasing hormone (CRH) in the colon, spinal cord, and hypothalamus of rats with chronic visceral hypersensitivity. ⋯ Electroacupuncture at the Shangjuxu acupoint was able to significantly reduce the visceral hypersensitivity in rats, and regulated the expression of CRH protein and mRNA in the colon, spinal cord and hypothalamus at different levels, playing a therapeutic role in this model of irritable bowel syndrome.