过表达脑红蛋白抑制双转基因AD小鼠脑中Aβ诱导的凋亡

目的:研究AD双转基因(APPswe/PS1d E9)小鼠侧脑室注射质粒p NGB后,过表达脑红蛋白(neuroglobin,NGB)对Aβ诱导的AD小鼠脑中细胞凋亡的影响及其潜在机制。方法:将24只鉴定后的13月龄AD双转基因阳性小鼠(雌雄各半)随机分为对照组、侧脑室注射生理盐水+pc DNA3.1(1 g/L)组和侧脑室注射pc DNA3.1(1 g/L)+p NGB组。采用免疫组化检测鼠脑Aβ1-42表达情况,TUNEL染色检测脑内细胞的凋亡情况;Western blot检测鼠脑内与凋亡密切相关的cleaved caspase-3、caspase-9以及PI3K、p-Akt、Akt的蛋白水平。结果:与对照组和注射生理盐水组比较,注射p NGB组小鼠脑内Aβ1-42的表达明显受到抑制(P0.01),TUNEL染色阳性细胞数也明显减少(P0.01);过表达NGB能够明显抑制脑组织内cleaved caspase-3和caspase-9的蛋白表达(P0.01),促进Akt磷酸化水平的增强(P0.01)。结论:p NGB过表达能够明显抑制Aβ的生成并抑制Aβ诱导的细胞凋亡,其机制可能与激活PI3K/Akt通路进而抑制与凋亡密切相关的cleaved caspase-3和caspase-9的表达有关。

Overexpression of neuroglobin attenuates Aβ-induced apoptosis in brains of double transgenic AD mice

AIM: To observe the effects of neuroglobin(NGB) overexpression on the apoptosis induced by Aβ in the brains of double transgenic AD(APPswe/PS1dE9) mice and to explore its potential mechanisms.METHODS: Twenty-four 13-month-old double transgenic AD mice were randomly divided into 3 groups:intracerebroventricular injection with normal saline(NS) group, intracerebroventricular injection with pcDNA3.1 and NS group, and intracerebroventricular injection with pcDNA3.1 and pNGB group. Immunohistochemistry was used to detect the expression of Aβ_1-42 in the brains. TUNEL staining was used for analyzing the apoptosis, and the protein levels of cleaved caspase-3, caspase-9, PI3K, Akt and p-Akt were determined by Western blot.RESULTS: After intracerebroventricular injection with pNGB, the areas of Aβ_1-42 in the hippocampus and cortex were decreased compared with NS group and pcDNA3.1+NS group(P<0.01). The TUNEL-positive staining cells in the pNGB group were less than those in NS group and pcDNA3.1 group(P<0.01). NGB overexpression attenuated the protein levels of cleaved caspase-3 and caspase-9(P<0.01), but induced the production of PI3K and p-Akt(P<0.01).CONCLUSION: Overexpression of pNGB significantly inhibits the generation of Aβ and attenuates the apoptosis induced by Aβ, indicating that NGB overexpression activates PI3K/Akt pathway and inhibits the production of cleaved caspase-3 and caspase-9, which were tightly related with apoptosis.