Experimental observation of SNI and CCI two kinds of rat neuropathic pain models

Objective To observe and compare the efficacy of 2 neuropathic pain models:spared nerve injury model(SNI) and chronic constriction injury of sciatic nerve model(CCI).Methods 30 Wistar rats were divided randomly into 3 groups:sham group(n=10),SNI group(n=10),and CCI group(n=10).In the sham group,the sciatic nerves of rats were just surgically exposed,and the SNI model and CCI model were operated on the right posterior limb.The mechanical withdrawal threshold(MWT) were tested from the 1th day preoperative to the 28th day postoperative,and GTP cyclohydrolase 1(GCH1),which is a kind of pain-related gene,in dorsal root ganglion was measured by Western blotting on the 14th and 28th days postoperative.Results The rats in sham group did not appear hyperalgia.MWT in both SNI group and CCI group were obviously declined on the 1th day postoperative compared with Sham group(P0.05).MWT of SNI rats keeped a low level to the 28th day postoperative,but MWT in CCI group rose again from the 21th day postoperative.The results of Western blotting showed that,on the 14th day after the operation,the expression of GCH1 in both SNI and CCI group increased compared with sham group(P0.05),but on the 28th day it decreased in CCI group,and there were statistical differences compared with SNI group(P0.05).Conclusion Compared with CCI model,SNI model is a more sensitive and stable neuropathic pain model.