产前应激促进慢性应激诱导的子代鼠海马β-淀粉样蛋白形成

Prenatal stress promotes formation of chronic stress-induced hippocampal amyloid β protein in offspring mice

目的探讨产前应激是否能促进慢性应激诱导的6月龄雄性子代鼠海马β-淀粉样蛋白（A13）形成及其作用机制。方法以APPswe／PSldE9双转基因小鼠为研究对象，将雄性APPswe／PSldE9双转基因子代鼠根据产前是否应激和子代鼠是否慢性应激分为产前应激-子代慢性应激（TT）组、产前应激．子代正常处理（TC）组、产前正常处理．子代慢性应激（CT）组和产前正常处理．子代正常处理（CC）组，每组18只。采用刚果红染色检查子代鼠脑组织的淀粉样斑块；采用Westernblotting检测海马组织磷酸化真核翻译起始因子2的α亚单位（p-eIF2α）、磷酸化蛋白激酶R样内质网激酶（p-PERK）、葡萄糖调节蛋白78（Grp78）和淀粉样前体蛋白β位点分裂酶1（BACE1）的表达水平；采用ELISA法检测Aβ1-40和Aβ1-42表达水平；采用荧光酶标仪检测BACE1活性。结果与CC组相比，CT组、TT组、TC组小鼠脑组织淀粉样斑块数目增多。与CC组相比，CT组小鼠海马组织P-eIF2α、P-PERK、Grp78、BACE1、Aβ1-40和Aβ1-42表达水平明显升高，差异均有统计学意义（P〈0．05）。与CT组相比，TT组海马组织P-eIF2α、P-PERK、Grp78、BACE1、Aβ1-40和Aβ1-42表达水平进一步升高，差异均有统计学意义（P〈0．05）。各组小鼠海马组织BACE1活性比较差异无统计学意义（P〉0．05）。结论产前应激可促进慢性应激诱导的6月龄雄性APPswe／PS1dE9双转基因小鼠子代鼠AB生成增多，其机制可能是产前应激通过促进子代鼠海马神经元内质网应激，激活PERK，引起eIF2α磷酸化，促进BACE1表达增加．从而促进Aβ生成。

Objective To explore whether prenatal stress promotes formation of chronic stress-induced hippocampal amyloid β （Aβ） protein in 6-month-old male offspring mice and its mechanism. Methods The APPswe/PSldE9 double transgenic mice were divided into 4 groups according to the prenatal stress and offspring mice stress： prenatal control-offspring control group （CC group）, prenatal control-chronic offspring stress group （CT group）, chronic prenatal stress-offspring control group （TC group）, and chronic prenatal stress-chronic offspring stress group （TT group） （n=18）. The number of amyloid plaques in brains was checked using Congo red staining. ELISA was used to examine the hippocampus levels ofamyloid-βproteins （Aβ1-42 and Aβ1-40） in the offspring mice; β-site APP-cleaving enzyme 1 （BACE1） activity was detected using fluorospectrophotometry. Additionally, Western blotting were used to observe the expression levels ofphosphorylated eukaryotic initiation factor 2α （p-eIF2α）, phosphorylated protein kinase R [PKR]-like ER kinase （p-PERK）, glucose-regulated protein 78 （Grp78） and β-site BACE1 in the hippocampus. Results As compared with that in the CC group, the number of amyloid plaques in brain in CT, TT and TC groups was increased. The expressions of p-eIF2α, p-PERK, Grp78, BACE1, Aβ1-40 and Aβ1-42 in the hippocampus of CT group weresignificantly increased as compared with those in the CC group （P〈0.05）. The expressions ofp-eIF2α, p-PERK, Grp78, BACE1, Aβ1-40 and Aβ1.42 in the hippocampus of TT group were further significantly increased as compared with those in the CT group （P〈0.05）. There was no significant difference in BACE1 activity among the different groups （P〉0.05）. Conclusion The prenatal stress can promote the formation of hippocampal Aβ protein induced by chronic stress in 6-month-old male offspring mice, whose mechanism may be that prenatal stress aggravates hippocampal neurons endoplasmic reticulum stress, activates the PERK, then causes eIF2αlpha phosphorylation, and finally promotes BACE1 expression.