The Analgesia Effect Of Corydaline And TMP On Neuropathic Pain, And Its Relation With TRPV-1Expression

Background:Neuralgia is a modern disease, the most traditional pain medications are not to achieve a significant treatment effect. Previous studies have shown that corydaline and tetrahydropalmatme (TMP) extracted from Corydalis W. T.(yanbusuo) have analgesic effects, its mechanism of action is achieved through the inhibition of striatal D2dopamine receptor. Corydaline and TMP whether used in the treatment of neuralgia is still a lack of rigorous scientific research. In recent years, studies have shown that transient receptor potential cation channel, vanilloid receptor1(TRPV-1) expression and neuropathic pain is highly correlated. Therefore, yanhusuo, the. mechanism of action is related to this worth exploring.Purpose:Assessment the analgesia effect of corydaline and TMP on neuropathic pain, and its relation with TRPV-1expressionMethods:We use the chronic constriction injury of sciatica nerve model (CCI). Rats were divided into control group, vehicle group and treatment group. On day4,7,11,14,16after operation, the all rats receive the tests of noxious heat paw withdrawal latency, the numbers of cold plate induced leg raising and tactile allodynia. On postoperative11,14.16day, the treatment group were used in corydaline5mg/kg,10mg/kg and TMP5mg/kg.1Omg/kg.15mg/kg by intra-peritoneal injection. We observe and compare the difference of responses between all groups. Then the rats were sacrificed, followed by immunohistochemistrical staining to observe the TRPV-1expression changes of spinal cord L5-L6dorsal horn area in the different groups Results:The study found that Corydaline10mg/kg on day11,14,16can effectively extend the radiant heat-induced paw withdrawal latency and decrease the cold plate-induced leg raising times. On day11.14.16the TMP10mg/kg and15mg/kg also can extend the radiant heat-induced paw withdrawal latency and decrease the cold plate-induced paw-raising times. Tetrahydropalmatine10mg/kg, on day14, can reduce tactile allodynia. We further compared the analgesia effect of corydaline with TMP. We found that both have the same effect to extend the radiant heat-induced paw withdrawal latency and reduce cold plate-induced paw withdrawal times in the same10mg/kg dose. In immunohistochemical staining, the control group, and vehicle group can be seen TRPV-1receptor expression is significantly increased in the ipsilateral spinal cord dorsal hom region, the treatment group under corydaline10mg/kg and TMP10.15mg/kg: the TRPV-1expression was significantly inhibited.Conclusion:The corydaline and TMP can effectively inhibit the thermal hyperalgesia cold allodynia and highly related to inhibition of TRPV-1expression. We first found that the corydaline and TMP reduce neuropathic pain mechanism is by inhibiting the performance of the TRPV-1receptors in the spinal cord dorsal hom area, fulfilled that role in the level of the spinal cord. It is different with the traditional understanding of pain mechanisms is subject to supra-spinal descending modulation by the inhibition of striatal dopamine (D2) receptors.