| Objective To evaluate the effects of Sinomenine on expression of spinal dorsal cord P2X3 receptor and cyclooxygenase-2 in chronic constriction injury model of rats and to clarify its underlying mechanism of interventional treatment for neuropathic pain using Sinomenine.Methods Fifty-four male Wistar rats, aged 6-8 weeks, weighing 180-220g, were randomly assigned into 3 groups (n=18 each):sham operation group (group SHAM), chronic constriction injury group (group CCI) and the group of neuropathic pain by invention treatment of Sinomenine (group SIN). In group CCI and SIN, the classic rats model of neuropathic pain, chronic sciatic nerve constriction injury model was applied, while in group SHAM the right sciatic nerve were exposed, but not ligated. In group SIN, Sinomenine 40mg/kg · d was immediately injected intraperitoneally from the day of operation to the day before rats were sacrificed, while the equal volume of normal saline was received the same way in group SHAM and CCI. The mechanical witdrawl threshold (MWT) and thermal witdrawl latency (TWL) were evaluated using a von Frey test and paw withdrawal test respectively at the day before surgery and 3、7、4 day after that. If the test was finished, six rats in each group were randomly sacrificed only at 3、7、14 days and their lumbar segments 4-6 of spinal dorsal cord were immediately removed to be tested. Also, the expression of P2X3R and COX-2 mRNA in the spinal dorsal cord was analyzed using real-time quantitative PCR.Results Compared with group SHAM, MWT and TWL in groups CCI and SIN were significantly deceased, and the expression of P2X3R and COX-2 mRNA at the spinal dorsal cord level was upregulated (P<0.05). Compared with group CCI, MWT and TWL in group SIN were significantly increased, and the expression of P2X3R and COX-2 mRNA at spinal dorsal cord level was downregulated (P<0.05). Compared with the time point of 3 days, MWT and TWL in groups CCI and SIN were decreased at the time point of 7、14 days, and the expression of P2X3R and COX-2 mRNA at the spinal dorsal cord level was upregulated (P<0.05). Compared with the time point of 7 days, MWT and TWL in groups CCI and SIN were increased at the time point of 14 days, the expression of P2X3R and COX-2 mRNA at the spinal dorsal cord level was downregulated(P<0.05).Conclusion Intraperitoneal injection of Sinomenine has significant analgesic effects in the CCI rats model possiblly though inhibiting the expression of P2X3R mRNA and COX-2 mRNA at the spinal dorsal cord level. |
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