Title: The effect of the inhibitor of extracellular signal-regulated kinase on pain hypersensitivity in rats with chronic constriction injury
Abstract: ObjectiveTo determine the role of spinal cord’s extracellular signal-regulated kinase(ERK) in neuropathic pain. MethodsIn this study, model were established chronic constriction injury (CCI) in rats. 48 rats were divided into 6 group randomly (n=8): sham+DMSO(group S), CCI+DMSO(group C) and CCI+different doses of U0126 (0.2,0.5,1,5μg/10μl, group U0.2,U0.5,U1,U5). The changes of mean withdral threshold (MWT) and thermal withdral latency(TWL) were observed at 0.5,2,6,12,24h timepoints after injection. Another 50 CCI5d rats were randomly divided into 5 groups: G1,G2,G3,G4,G5,which were received a bolus of 5.0μg U0126 and were killed at 0.5,2,6,12,24h after injection respectively. The expression of spinal cord phospho-ERK (pERK) were assessed by Immunohistochemistry(n=6) and western blot(n=4). ResultsThe MWT of 0.5, 2, 6h of group U0.5; 0.5,2,6,12h of group U1; 0.5,2,6,12,24h of group U5 was 12.3±2.8g, 11.9±3.3g, 9.5±2.7g, 14.6±1.1g, 13.4±1.6g, 12.3±2.8g, 11.7±2.7g, 10.8±2.5g, 12.6±2.6g, 13.3±3.2g, 11.4±3.3g, 10.5±3.7g respectively. Compared with group C were significantly promoted (P0.05 or P0.01). The TWL of 0.5, 2, 6h of group U0.5; 0.5,2,6,12h of group U1; 0.5,2,6,12,24h of group U5 was 15.8±2.6s, 15.8±2.4s, 17.7±3.8s, 16.9±4.2s, 15.6±5.3s, 20.7 ±4.4s, 17.1±5.8s, 16.6±4.6s, 17.7±5.5s, 15.4±3.8s respectively. Compared with group C were significantly promoted (P 0.05 or P0.01). The numbers of positive neurons of G1,G2,G3 group were 2.0±1.4、9.7±4.4、15.5±4.2. Compared with CCI group(23.8±4.2) were markedly decreased (P0.05). Similarly result can be obtained in western blot. The cytosolic and nuclear pERK1 of G1 group were 0.64±0.2,0.88±0.3. The cytosolic and nuclear pERK2 of G1 group were 0.83±0.5、0.92±0.3. Compared with CCI group were significantly decreased (P0.05). ConclusionThese data suggested that ERK caspase may involve in the signal transductor of dorsal horn in neuropathic pain.
Publication Year: 2006
Publication Date: 2006-01-01
Language: en
Type: article
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