胰岛素样生长因子1对β样淀粉蛋白引起的神经元凋亡和tau蛋白磷酸化的作用(英文)

本研究的目的是阐明胰岛素样生长因子1(IGF-1)对β样淀粉蛋白(Aβ)引起的神经元凋亡的保护作用,以及tau蛋白磷酸化的作用。用MTT(四甲基偶氮唑盐)方法检测细胞活性,用流式细胞学结合Annexin V-FITC和PI(碘化丙锭)双染的方法检测早期凋亡和晚期凋亡/坏死,用Hoechst 33342染色观察凋亡细胞形态学,用免疫细胞化学的方法检测tau蛋白磷酸化。IGF-1阻止了Aβ25-35引起的培养的大鼠海马神经元的毒性,MTT值显著增加,从54.51%增至61.8%,Hoechst 33342阳性细胞的百分比从30.77%减少到22.81%。Aβ25-35孵育使Annexin V单标记细胞(Annexin V+/PI-)以及Annexin V/PI双标记细胞(An-nexin V+/PI +)的百分比显著增加(分别为3.41%和19.47%),应用100 ng/ml的IGF-1可显著减少Annexin V单标记细胞和Annexin V/PI双标记细胞的百分比分别至2.98%和15.16%。Aβ25-35可增加tau蛋白磷酸化,AT8阳性细胞占41.84%,而IGF-1则可抑制这一效应。我们的结果表明IGF-1可保护神经元,降低Aβ的细胞毒性,减少早期和晚期凋亡/坏死细胞的比例,抑制tau蛋白磷酸化,这可能是IGF-1神经保护作用的细胞机制。

EFFECTS OF INSULIN-LIKE GROWTH FACTOR 1 ON β-AMYLOID INDUCED NEURON APOPTOSIS AND TAU PHOSPHORYLATION

The aim of this study is to elucidate the protective and anti-apoptotic effects of insulin-like growth factor 1 ( IGF-1 ) against β-amyloid (Aβ) and investigate the effect of IGF-1 on Aβ-induced tau phosphorylation. Cell viability was measured using the MTT (3-(4,5-dimethylthiazolyl-2 )-2,5-diphenyltetrazolium bromide) assay, early apoptosis and late apoptosis/necrosis were analyzed by flow cytometry using Annexin V-FITC and propidium iodide (PI) double staining, and morphology was examined by Hoechst 33342 staining. Tau phosphorylation was detected using AT8 immunostaining. Preincubation of cultured rat hippocampal neurons with IGF-1 for 24 h prevented cytotoxicity induced by Aβ25-35 for 48 h. The MTT value significantly increased from 54.51% to 61.8% of the control group, and the percentage of Hoechst 33342-positive cells decreased from 30.77% to 22.81%. Incubation with Aβ25-35 for 48 h caused a marked increase in the percentages of Annexin V-FITC single-labeled cells (Annexin V +/PI-) and Annexin V/PI double-stained cells (Annexin V +/PI + ) (3.41% and 19.47% , respectively), which were significantly decreased by pretreatment with 100 ng/ml of IGF-1 for 24 h (to 2.98% and 15.16% , respectively). Aβ25-35 treatment increased tau phosphorylation and AT8 positive cells were 41.84%. This effect could be inhibited by different concentrations of IGF-1. Our findings showed that IGF-1 protected against Aβ-induced cytotoxicity, decreased the percentage of early and late apoptosis/necrosis cells, and inhibited tau phosphorylation, which may be the cellular mechanisms for its neuroprotective action.