| Background Cerebral ischemia is the most common cause of death and disability in the elderly is a kind of disease, However, cerebral ischemia treatment effect is still unsatisfactory. In recent years, studies have found that erythropoietin(EPO) has certain protective effect on cerebral ischemia/reperfusion injury, But the EPO on cyclin-dependent kinase 5(Cdk5) expression in brain after cerebral ischemia/reperfusion injury in rats whether to have influence at home and abroad has not been reported.Objective To studying the effects of EPO on expression of Cdk5 in brain after focal cerebral ischemia/reperfusion injury in rats, to investigate the protective effects and possible mechanisms of EPO on cerebral ischemia/reperfusion injury in Sprague-Dawley (SD) rats.Methods Seventy-two male SD rats were divided into four groups randomly:normal group, sham-operated group, cerebral ischemia/reperfusion (I/R) group and EPO+I/R group. The left temporary middle cerebral artery occlusion (MCAO) model was established by Zea Longa line-embolism method. The EPO+I/R group was intraperitoneal injection 3000u/Kg EPO when ischemia occurred, The I/R group and sham-operated group and normal group were intraperitoneal injection the same dosed saline when ischemia occurred. After two hours of ischemia, line-embolism of I/R group and EPO+I/R group were pulled and reperfusion was performed. After rats were suffered 2h/24h ischemia/reperfusion stress, the mortality rate were evaluated, and the nervous functional defect degree were evaluated by Longe scoring were observed, and the volumes of cerebral infarction were evaluated by 2,3,5 -triphenyl four azole nitrogen chloride (TTC) staining, and the expression of CDK5 receptor protein in the cerebral cortex and hippocampus tissue were detected by the immunohistochemical and Western blotting.Result1. The effects of EPO on the mortality rate and the nervous defect scores after ischemia/reperfusion injury in brain of rats.After rats were suffered 2h/24h ischemia/reperfusion stress, The mortality rate in EPO +I/R group (21.74%) were obviously lower than that of I/R group (33.33%). And the nervous defect scores in EPO+I/R group (1.94±0.73) were significant lower than that of I/R group (2.50±0.52) (P<0.05). The normal group and sham-operated group mortality rate and the nervous defect scores was 0 points.2. The effects of EPO on the volume of cerebral infarction after ischemia-reperfusion injury in brain of rats.The results of TTC stain showed that the normal group and sham-operated group bilateral brain hemispheres homogeneously were dyed red, The I/R group and EPO+I/R group normal brain tissue were dyed red, the left side of the cerebral infarction tissue were loss of dye showed pale colour, and compared with I/R group (36.38%±3.30%), the volumes of cerebral infarction in EPO+I/R group (21.88%±2.96%) were significant decreased (P<0.05).3. The effect of EPO on Cdk5 protein expression in the cerebral cortex after ischemia/reperfusion injury in brain of rats.(1) The results of immunofiuorescence showed that positive expression cells of CDK5 protein in cerebral cortex of each groups, and positive cell membrane and cytoplasm were showed red. Compared with normal group (10.83±3.06), the positive expression cells of Cdk5 protein in left side cerebral cortex of sham-operated group (11.33±3.50) was no significant difference. Compared with sham-operated group (11,33±3.50), the positive expression cells of CDK5 protein in left side cerebral cortex of I/R group (40.33±5.34) was significantly increased (P<0.05). However, compared with I/R group (40.33±5.34), the positive expression cells of Cdk5 protein in left side cerebral cortex of EPO+ I/R group (24.17±5.81) was significantly decreased (P<0.05).(2) The gray value of western blot electrophoresis banding analysis showed that there was no significant difference of the Cdk5 protein expression in left side cerebral cortex between normal group (0.502±0.093) and sham-operated group (0.540±0.099) was detected. Compared with sham-operated group (0.540±0.099), the protein expression of Cdk5 in left side cerebral cortex of I/R group(1.227±0.115) was significantly increased (P<0.05). However, compared with I/R group(1.227±0.115), the protein expression of Cdk5 in left side cerebral cortex of EPO+I/R group (0.592±0.113) was significantly decreased (P<0.05).4. The effect of EPO on Cdk5 protein expression in the hippocampus after ischemia/reperfusion injury in brain of rats.(1) The results of immunofluorescence showed that positive expression cells of CDK5 protein in hippocampal of each groups, and positive cell membrane and cytoplasm were showed red. Compared with normal group (9.33±2.80), the positive expression cells of Cdk5 protein in left side hippocampal CA1 area of sham-operated group (9.50±1.87) was no significant difference. Compared with sham-operated group (9.50±1.87), the positive expression cells of CDK5 protein in left side hippocampal CA1 area of I/R group (31.33±6.62) was significantly increased (P<0.05). However, compared with I/R group (31.33±6.62), the positive expression cells of Cdk5 protein in left side hippocampal CA1 area of EPO+I/R group (13.17±3.31) was significantly decreased (P<0.05).(2) The gray value of western blot electrophoresis banding analysis showed that there was no significant difference of the protein expression of Cdk5 in left side hippocampal between normal group (0.410±0.067) and sham-operated group (0.390±0.085) was detected. Compared with sham-operated group (0.390±0.085), the protein expression of Cdk5 in left side hippocampal CA1 area of I/R group(1.228±0.074) was significantly increased (P<0.05). However, compared with I/R group(1.228±0.074), the protein expression of Cdk5 in left side hippocampal CA1 area of EPO+I/R group (0.890±0.079) was significantly decreased (P<0.05).Conclusion1. These results suggest that EPO is capable of neuroprotective effect on cerebral ischemia/reperfusion injury in rats, decreasing the volume of cerebral infarction and nervous defect scores.2. The Cdk5 protein expression up regulation after ischemia/reperfusion injury in rats, the neuroprotective effect is one of the mechanism of EPO might be associated with inhibitioned the expression of Cdk5 protein in brain after cerebral ischemia/reperfusion injury in rats... |
PDF Full Text Request