二苯乙烯苷调控MKK7/JNK信号通路改善阿尔茨海默病大鼠神经元损伤作用及机制研究

The effect and mechanism of stilbene glycosides on improving neuronal injury in Alzheimer's disease rats by regulating ASK/MKK7/JNK pathway

目的:探讨二苯乙烯苷(TSG)通过调控MKK7/JNK通路改善阿尔茨海默病大鼠神经元损伤中的作用机制。方法:采用24月龄的雄性老年大鼠42只,随机分为正常组,假手术组,模型组,阳性药组(0.15mg/kg石杉碱甲),以及TSG低剂量组(0.033 g/kg)、TSG中剂量组(0.1 g/kg)、TSG高剂量组(0.3 g/kg),每组6只。模型组、TSG各剂量组采用立体定位Aβ_(25-35)溶液构建老年痴呆模型,于造模28 d后经被动回避实验筛选造模成功的大鼠。筛选后阳性药物组、TSG各剂量组按照对应剂量灌胃给药,给药28 d后进行实验。采HE染色镜下观察每组大鼠大脑内海马区神经元细胞形态学变化;IHC检测各组大鼠脑组织MKK7、JNK蛋白的表达情况;qRT-PCR检测各大鼠脑组织内MKK7、JNK mRNA的表达情况。结果:(1)HE染色观察,与正常组,假手术组相比,模型组神经细胞数量减少且排列紊乱无规则,细胞膜发生皱缩,细胞核溶解变形。与模型组比较,阳性药组以及TSG各组神经细胞数量增多且排列相对整齐。(2)TUNEL染色阳性细胞比值结果:与正常组、假手术组相比,模型组凋亡细胞数量明显上调;与模型组相比,阳性药物组、TSG各组染色凋亡细胞减少(P<0.05)。(3)免疫组化测定结果表明:与正常组和假手术组相比,模型中MKK7、JNK在大鼠脑中的蛋白表达含量显著增加(P<0.05);与模型组比较,阳性药及TSG各剂量组蛋白表达量均有不同程度降低(P<0.05)。(4)qRT-PCR结果显示,与正常组、假手术组相比,模型组大鼠脑组织中MKK7、JNK mRNA水平明显上升(P<0.05);与模型组相比,各组给药大鼠脑组织中MKK7、JNK mRNA的表达含量均明显下调(P<0.05)。结论:二苯乙烯苷对神经元的损伤修复有一定的作用效果,其作用机制可能与下调MKK7、JNK激酶的mRNA转录及蛋白的表达有关。

Objective:To investigate the mechanism of action of tetrahydroxy stilbene glycosides(TSG)in ameliorating neuronal damage in Alzheimer's disease rats by regulating MKK7 and JNK kinases.Methods:A total of 24⁃month⁃old 42 SD rats were randomly selected for the experiment in 7 groups:normal group,sham⁃operated group,model group,positive drug group,low,medium and high dose TSG group at 0.033 g/kg,0.1 g/kg,0.3 g/kg.The model group and the TSG groups were established by stereotaxic Aβ25⁃35 solution.After 28 days,the model rats were selected by passive avoidance test.After screening,each dosage group of TSG and positive drug group was given intragastrically according to the corresponding dosage,and the experiment was carried out after 28 days.The pathological changes of hippocampal CA1 region were observed by tissue staining,and the amount of MKK7 and JNK proteins and the expression content of MKK7 and JNK mRNA by histochemical method of protein,and qRT⁃PCR assay.Results:(1)HE staining observation:Compared with the normal group and the sham⁃operated group,the num⁃ber of nerve cells in the model group decreased and arranged irregularly,the cell membrane shrank,and the nucleus deformed and dissolved.The number of neurons in the positive drug group and TSG group also increased significantly,the order is also relatively well.(2)From the results of the tunel staining experiments:The positive apoptotic cells in the model group were higher than con⁃trol group and sham⁃operated group,positive drug group and TSG drugs group was significantly smaller than that in the model group(P<0.05).(3)Compared with the control group and the virtual operation group,the MKK7 and JNK protein concentra⁃tions in the brain of the model group were increased(P<0.05)by data analysis of immunohistochemistry:Compared with the mod⁃el group,the protein expression of positive drug and TSG each dose group were reduced(P<0.05).(4)The results of QRT⁃PCR data showed that the levels of MKK7 and JNK mRNA in the brain tissue of the model group were increased compared with the nor⁃mal group and sham⁃operated groups(P<0.05).Conclusion:Stilbene glycoside has a certain effect on neuronal injury and repair which may be related to the changes of mRNA transcription and protein expression of MKK7 and JNK kinases.