Analgesic effect of mibefradil on diabetic neuropathic pain in rats

Objective To evaluate the analgesic effect of mibefradil on diabetic neuropathic pain in rats. Methods Twenty-one rats were used to establish the models of diabetic neuropathic pain. The rats were randomly divided into 3 groups(n=7 each): group A, 3 ml normal saline was intraperitoneally injected; group B,0.5 mg mibefradil was intraperitoneally injected; group C,1.5 mg mibefradil was intraperitoneally given. The mechanical withdrawal threshold(MWT)and thermal withdrawal latency(TWL) were measured before and 0.5,1.0,2.0,4.0 and 8.0 h after administration respectively. Results In group B, MWT at each time point[0.5 h:(6.2±2.3)g;1.0 h:(9.7±3.1)g;2.0 h:(8.8±3.4)g;4.0 h:(7.2±2.7)g;8.0 h: (4.4±0.4)g],and TWL[0.5 h:(12.2±2.1)s; 1.0 h:(13.9±2.3)s; 2.0 h:(13.2±2.4)s; 4.0 h: (11.9±2.2)s;8.0 h:(9.9±0.9)s] were significantly increased as compare with those in group A(P< 0.05).In group C, MWT at each time point[0.5 h:(10.6±3.1)g;1.0 h:(12.9±2.7)g;2.0 h:(10.9± 4.2)g;4.0 h:(9.2±3.1)g; 8.0 h:(5.2±0.6)g], and TWL[0.5 h:(14.6±3.0)s; 1.0 h:(17.1± 3.2)s;2.0 h:(16.5±3.6)s;4.0 h:(13.0±3.4)s;8.0 h:(10.9±2.3)s]were singnificantly increased as compared with those in group A(P< 0.01). Conclusion Mibefradil administrered intraperitioneally can produce a better analgesic effect in rats model of diabetic neuropathic pain. Key words: Mibefradil; Neuropathic pain