Pharmacology, biochemistry, and behavior
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Pharmacol. Biochem. Behav. · Sep 2012
Analgesic effect of iridoid glycosides from Paederia scandens (LOUR.) MERRILL (Rubiaceae) on spared nerve injury rat model of neuropathic pain.
Iridoid glycosides of Paederia scandens (IGPS) is a major active component isolated from traditional Chinese herb P. scandens (LOUR.) MERRILL (Rubiaceae). The aim of the present study was to investigate the analgesic effect of IGPS on spared nerve injury (SNI) model of neuropathic pain. The SNI model in rats was established by complete transection of the common peroneal and tibial distal branches of the sciatic nerve, leaving the sural branch intact. ⋯ Treatment with IGPS (70, 140, 280 mg/kg) significantly alleviated SNI-induced mechanical hypersensitivity response evidenced by increased MWT; as well as markedly decreased NOS activity, NO and cGMP levels. At the same time, IGPS (70, 140, 280 mg/kg) could also inhibit mRNA expression of iNOS, PKG Ια and PKG Iβ in the spinal cord. The results suggested that IGPS possesses antinociceptive effect, which may be partly related to the inhibition of NO/cGMP/PKG signaling pathway in the rat SNI model of neuropathic pain.
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Pharmacol. Biochem. Behav. · Sep 2012
5-HT induces temporomandibular joint nociception in rats through the local release of inflammatory mediators and activation of local β adrenoceptors.
The 5-hydroxytryptamine (serotonin, 5-HT) is an important inflammatory mediator found in high levels in the synovial fluid of the temporomandibular joint (TMJ) of patients with inflammatory pain. In this study, we used the nociceptive behavior responses, measured as flinching the head and rubbing the orofacial region, as a nociceptive assay. ⋯ These results demonstrated that 5-HT induces nociception in the TMJ region by the activation of β₁ and β₂ adrenoceptors located in the TMJ region and local release of sympathetic amines and prostaglandins. Therefore, the high levels of 5-HT in the synovial fluid of patients with TMJ inflammatory pain may contribute to TMJ pain by similar mechanisms.