贝沙罗汀对小鼠脑缺血再灌注损伤神经元的保护作用及机制

Protective effect and mechanism of Bexarotene on neuronal injury induced by cerebral ischemia reperfusion in mice

目的探讨贝沙罗汀(Bexarotene)对脑缺血再灌注(CIR)损伤神经元的保护作用及机制。方法将45只C57BL/6雄性小鼠随机分为假手术组、模型组及贝沙罗汀组(5 mg/kg),每组15只。采用线栓法建立短暂小鼠中动脉栓塞(t MCAO)模型,再灌注后通过神经行为学评分观察小鼠神经功能缺损情况;HE染色观察脑部皮层损伤侧神经元病理变化;TUNEL染色检测脑部皮层损伤侧神经元凋亡;免疫荧光染色检测损伤部位Cleaved Caspase-3表达;Western blot检测小鼠损伤脑组织中JNK信号通路相关蛋白P-C-Jun、P-JNK及Cleaved Caspase-3的表达情况。结果与假手术组相比,模型组和贝沙罗汀组小鼠神经功能缺损明显较重(P <0.05),皮层神经元损伤分级明显增加(P <0.05),损伤部位TUNEL阳性细胞数及Cleaved Caspase-3的表达明显较高(P <0.05),同时损伤侧小鼠脑组织JNK、C-Jun、Cleaved Caspase-3的蛋白表达水平显著上调(P <0.05);与模型组相比,贝沙罗汀组小鼠神经行为学评分较低(P <0.05),贝沙罗汀可有效阻止t MCAO后脑组织形态学的改变(P <0.05),降低小鼠损伤侧脑组织TUNEL染色阳性细胞数及P-JNK、P-C-Jun、Cleaved Caspase-3蛋白表达水平(P <0.05)。结论贝沙罗汀对CIR神经元损伤具有保护作用,且该作用可能通过抑制JNK/Caspase-3信号通路的激活来实现。

Objective To investigate the protective effect of Bexarotene on neuronal injury induced by cerebral ischemia reperfusion( CIR) and its mechanism. Methods A total of 45 C57 BL/6 male mice were randomly divided into sham group,model group and Bexarotene group( 5 mg/kg),with 15 mice in each group. The transient middle cerebral artery occlusion( t MCAO) model in mice was established by the thread technique. After reperfusion,the effect of Bexarotene on the neurological function of mice was measured by the neurologic deficit score.The morphological changes of neurons in damaged cerebral cortex were observed by HE staining. The neuronal apoptosis of damaged cerebral cortex was assessed by TUNEL staining. The expression of Cleaved Caspase-3 was detected by immunofluorescence staining. The levels of P-C-Jun,P-JNK,Cleaved Caspase-3 in damaged brain tissue were analyzed by Western blot. Results Compared with the sham group,the nerve function injury of mice was more serious( P < 0. 05),the cortical neuron damage was aggravated( P < 0. 05),the number of TUNEL positive cells and the expression of Cleaved Caspase-3 were higher( P < 0. 05),the expression levels of P-JNK,P-C-Jun and Cleaved Caspase-3 were up-regulated in the model group and the Bexarotene group( P < 0. 05). Compared with the model group,Bexarotene treatment significantly reduced the neurobehavioral score of t MCAO mice( P < 0. 05),which effectively prevented the brain morphological changes,reduced the number of TUNEL positive cells,down-regulated the expression levels of P-JNK,P-C-Jun and Cleaved Caspase-3( P < 0. 05).Conclusion Bexarotene has protective effect on neuron injury induced by cerebral ischemia-reperfusion,which may be achieved by inhibiting the activation of JNK/Caspase-3 signaling pathway.