N-甲基-D-天冬氨酸受体抑制剂盐酸美金刚对老年性痴呆大鼠β-淀粉样前体蛋白及β分泌酶表达的影响

Effect of NMDA on the expression of APP and BACE1 in Alzheimer's disease rats

目的探讨N-甲基-D-天冬氨酸(NMDA)受体抑制剂盐酸美金刚对老年性痴呆(AD)大鼠β-淀粉样前体蛋白(APP)及β分泌酶(BACE1)表达的影响。方法 30只SD大鼠随机数字表法分为假手术组、模型组、治疗组(盐酸美金刚组);除假手术组外,其余两组大鼠海马注射10μgβ-淀粉样蛋白(Aβ)1-40构建AD大鼠模型,治疗组大鼠腹腔注射10 mg·kg^(-1)·d^(-1)盐酸美金刚,其余两组给予等量生理盐水,连续给药14 d,并于第1、3、7、14天采用Morris水迷宫实验检测大鼠的空间学习记忆能力,于14 d处死大鼠取血及海马组织。ELISA法检测血清及海马组织中Aβ含量,western blot及RT-PCR法检测海马组织中APP和BACE1蛋白及mRNA表达量。结果与假手术组比较,模型组大鼠水迷宫潜伏期延长,Aβ含量显著提高,APP及BACE1蛋白及mRNA含量显著提高,均差异有统计学意义(P<0.01);与模型组比较,治疗组大鼠水迷宫潜伏期缩短,Aβ含量显著降低,APP及BACE1蛋白及mRNA含量显著下降,均差异有统计学意义(P<0.01)。结论盐酸美金刚能通过阻断APP裂解,从而抑制AD大鼠海马组织中Aβ沉积。

Objective To explore the effect of N-methyl-D-aspartate（ NMDA） receptor inhibitor（ memantine） on the expression of amyloid precursor protein（ APP） and β-secretase（ BACE1） in Alzheimer＇s disease（ AD） rats. Methods Thirty SD rats were randomized into three groups： sham operation group（ n = 10）,model group（ n = 10）,treatment group（ memantine group）（ n = 10）. The AD rats model was built by injecting 10 μg β-amyloid protein（ Aβ） 1- 40 to hippocampus. The rats received intraperitoneal injection of 10 mg·kg^-1·d^-1 memantine for 8 d in treatment group,while the rats were given the same amount of normal saline in normal and model group. The spatial learning and memory ability of rats was detected by Morris water maze test in 1,3,7,and14 d. The level of Aβ in serum and hippocampus was examined by ELISA method. The expressions of APP and BACE1 protein and mRNA in hippocampus were assayed by Western blot and RT-PCR. Results Compared with ham operation group,the escape latency in the water maze training prolonged,the level of Aβ in serum and hippocampus increased,and the expressions of APP and BACE1 protein and mRNA in hippocampus were upregulated in model group with statistically significant difference（ P〈0. 01）. Compared with model group,the escape latency in the water maze training decreased,the level of Aβ in serum and hippocampus decreased,and the expressions of APP and BACE1 protein and mRNA in hippocampus were downregulated in treatment group with statistically significant difference（ P〈0. 01）. Conclusions These results suggested that memantine could inhibit the APP cleavage,thereby inhibiting Aβ deposition of hippocampal tissue in AD rats.