钙调神经磷酸酶抑制剂对Aβ_(1-42)所致阿尔茨海默病大鼠学习记忆及细胞凋亡的影响

Effect of calcineurin inhibitor on apoptosis and ability of learning and memorizing in Aβ_(1-42)-induced Alzheimer's disease rats

目的探讨钙调神经磷酸酶抑制剂对β-淀粉样蛋白(Aβ1-42)所致阿尔茨海默病(AD)大鼠学习记忆及海马区细胞凋亡的影响及可能作用机制。方法 36只SD大鼠随机分为AD模型组、FK506组及对照组,每组12只。AD模型组和FK506组采用Aβ1-42海马注射建立AD大鼠模型,FK506组以钙调神经磷酸酶抑制剂他克莫司(FK506)干预。用Morris水迷宫检测大鼠学习记忆能力,原位末端凋亡法(TUNEL)检测凋亡细胞,实时定量PCR(RT-PCR)、免疫组化检测海马区促凋亡蛋白(Bad)、细胞凋亡蛋白酶-3(Caspase-3)的表达。结果与对照组相比,AD模型组大鼠学习记忆能力明显减退(P<0.01),海马CA1区神经元细胞凋亡率增高(P<0.05),而FK506可改善AD大鼠的学习记忆能力,并能减少海马CA1区神经元细胞凋亡率(P<0.05);Bad基因转录及其蛋白表达在AD模型组与FK506组中无明显差异(P>0.05),而FK506可显著减少AD大鼠海马区Caspase-3的表达(P<0.05)。结论抑制钙调神经磷酸酶激活可改善AD大鼠的学习记忆能力。AD的发病机制可能为,活化的钙调神经磷酸酶可能通过介导Bad去磷酸化而激活Caspase-3,最终导致细胞凋亡。钙调神经磷酸酶抑制剂可通过阻断该途径来治疗AD。

Objective To investigate the impact of calcineurin inhibitor on the ability of learning and memorizing as well as hippocampal apoptosis in Aβ1-42-induced Alzheimer′s disease （AD） rats and its potential mechanisms.Methods Thirty-six SD rats were randomly divived into AD model group,FK506 group and control group,with 12 rats in each group.AD rat model was developed by intra-hippocampal injection of Aβ1-42 in the AD model group and FK506 group,and the calcineurin inhibitor（FK506） was administered additionally in the FK506 group.The ability of learning and memorizing of rats was evaluated by Morris water maze test.The apoptotic neurons were detected by terminal dexynucleotidyl transferase-mediated dUTP nick end labelling（TUNEL）.Real-time quantitative PCR（RT-PCR） and immunochemistry were used to detect the expressions of Bad and Caspase-3 in hippocampus.Results The ability of learning and memorizing decreased significantly（P〈0.01） and the apoptotic rate of hippocampal neurons in CA1 subregion increased in the AD model group compared with the controls（P〈0.05）. FK506 might be able to improve the ability of learning and memorizing in AD rats and reduce the apoptotic rate of hippocampal neurons in CA1 subregion（P〈0.05）.There was no significant difference in the Bad gene transcription and its protein expression between AD model group and FK506 group（P〉0.05）.FK506 could significantly down-regulate the expression level of Caspase-3 in hippocampal regions （P〈0.05）.Conclusion The inhibition of calcineurin activation might improve the ability of learning and memorizing of AD rats. AD′mechanism might be that activated calcineurin induces Caspase-3 activation by the Bad-mediated dephosphorylation,which leads to the cell apoptosis.Calcineurin inhibitor could be used to cure AD by blocking this pathway.