右美托咪定通过MAPK/STAT3通路对Aβ1-42致大鼠海马神经元凋亡的影响

Impact of dexmedetomidine on apoptosis of rat hippocampal neurons induced by Aβ1-42 via MAPK/STAT3 pathway

目的探讨右美托咪定(Dexmedetomidine,Dex)通过丝裂原活化蛋白激酶(Mitogen-activated protein kinase,MAPK)/信号转导和转录激活子3(Signal transduction and transcriptional activators 3,STAT3)通路对β-淀粉样蛋白(Amyloidβ-protein,Aβ)1-42致大鼠海马神经元凋亡的影响。方法将60只大鼠随机分为假手术组、Aβ1-42组、Dex低剂量(Dex-L)组(Dex,12.5μg/kg)、Dex高剂量(Dex-H)组(Dex,50μg/kg)、Dex-H+Anisomycin(MAPK通路激活剂)组(Dex,50μg/kg;Anisomycin,5.0 mg/kg)、Dex-H+Colivelin(STAT3激活剂)组(Dex,50μg/kg;Colivelin,0.5 mg/kg)。除假手术组外,其余各组大鼠均给予Aβ1-42制作阿尔茨海默病(Alzheimer’s disease,AD)大鼠模型;给药4周后水迷宫实验检验大鼠空间学习能力;静脉取血,检测炎性因子[白细胞介素(Interleukin,IL)-1β、IL-6、肿瘤坏死因子-α(Tumor necrosis factor-α,TNF-α)]水平;分离大鼠海马组织,Nissl染色、甲醇刚果红染色、脱氧核糖核苷酸末端转移酶介导的缺口末端标记法(Terminal deoxynucleotidyl transferase dUTP nick end labeling,TUNEL)试剂盒分别检测海马组织结构变化、Aβ沉积状况、细胞凋亡数目;Western blot检测海马组织中MAPK/STAT3通路相关蛋白磷酸化-丝裂原活化蛋白激酶p38抗体(Phosphorylated p38 mitogen-activated protein kinases,p-p38 MAPK)、p38 MAPK、磷酸化信号转导和转录激活因子3(Phosphorylated STAT3,p-STAT3)、STAT3、B淋巴细胞瘤-2(B lymphocytoma-2,Bcl-2)、激活型Caspase-3(Cleaved caspase-3)表达水平。结果Aβ1-42组大鼠海马组织神经元结构疏松,胞体形态异常,Aβ沉积严重,逃避潜伏期、炎性因子(IL-1β,IL-6,TNF-α)水平、细胞凋亡数目、p-p38 MAPK/p38 MAPK、p-STAT3/STAT3、Cleaved caspase-3表达较假手术组均显著增加,穿越原平台次数、Bcl-2表达显著减少(P<0.05);经不同剂量Dex干预后均可逆转上述指标水平(P<0.05);MAPK通路激活剂及STAT3激活剂可抑制Dex对AD大鼠海马组织的保护作用(P<0.05)。结论Dex可以通过降低炎性因子水平以及减少Aβ沉积来减轻海马细胞损伤和凋亡,保护大鼠海马神经元,其机制可能与抑制MAPK/STAT3通路有关。

Objective To explore the impact of dexmedetomidine(Dex)on the apoptosis of rat hippocampal neurons induced byβ-amyloid(Aβ)1-42 via mitogen-activated protein kinase(MAPK)/signal transduction and transcriptional activators 3(STAT3)pathway.Methods Sixty rats were randomly divided into sham operation group,Aβ1-42 group,Dex low-dose(Dex-L,12.5μg/kg)group,Dex high-dose(Dex-H,50μg/kg)group,Dex-H+Anisomycin(MAPK pathway activator,50μg/kg Dex-H+5.0 mg/kg Anisomycin)group,and Dex-H+Colivelin(STAT3 activator,50μg/kg Dex-H+0.5 mg/kg Colivelin)group.Besides the sham-operated group,rats in other groups were given Aβ1-42 to replicate the Alzheimer's disease(AD)rat model.After 4 weeks of administration,the spatial learning ability of rats was tested by Morris water maze.Venous blood was collected to detect the levels of inflammatory factors(IL-1β,IL-6,TNF-α).The Nissl staining,methanol Congo red staining,and TUNEL staining were performed to detect the pathological changes of hippocampus,Aβdeposition status,and the number of apoptosis.Western blot were performed to detect the expression of MAPK/STAT3 pathway-related proteins including p-p38 MAPK,p38 MAPK,p-STAT3,STAT3,Blymphocytoma-2(Bcl-2)and cleaved caspase-3.Results In the Aβ1-42 group,the neuronal structure of the hippocampus was lost,the cell morphology was abnormal,and the Aβdeposition was increased,the escape latency,the levels of inflammatory factors(IL-1β,IL-6,TNF-α),the number of apoptotic cells,the expressions of p-p38 MAPK/p38 MAPK,p-STAT3/STAT3,and cleaved caspase-3 were unusually higher than those in the sham operation group,the times of crossing the original platform and the expression of Bcl-2 were lower(P<0.05);the above indicators could be reversed after intervention by different doses of Dex(P<0.05);MAPK pathway activators and STAT3 activators could alleviate the protective effect of Dex on AD rats(P<0.05).Conclusion Dex may reduce the level of inflammatory factors and Aβdeposits to relieve cellular lesions and apoptosis,protecting rat hippocampal neurons,which may be related to the inhibition of MAPK/STAT3 pathway.