激活内源性肝X受体对酒精暴露致新生鼠神经前体细胞增殖障碍的保护作用

Activation of liver X receptors alleviates ethanol-mediated toxicity to neural precursor cells in the hippocampus of neonatal mice

目的探索激活肝脏X受体(liver X receptors,LXRs)对新生期小鼠酒精暴露后海马齿状回内神经前体细胞的保护作用。方法选用同窝的子鼠按随机数字表法分成3组(n=3):对照组、酒精组(分别注射等量溶剂或酒精)和LXRs激动剂(TO901317,TO)+酒精组[腹腔注射TO激动剂10 mg/kg(DMSO∶PBS=1∶3为溶剂)]。采用免疫组化方法检测与增殖细胞相关的Ki67、5-溴-2'-脱氧尿嘧啶核苷(BrdU)以及性别决定区域Y同源盒基因2(Sox2)、巢蛋白Nestin的表达水平,观察激活内源性LXRs对新生期小鼠酒精暴露后海马齿状回神经前体细胞增殖与神经前体细胞维持的影响。结果新生期小鼠酒精暴露后抑制海马齿状回神经前体细胞的增殖,包括Ki67阳性细胞数量显著减少[酒精组(24.7±5.5)vs对照组(45.9±7.1),P<0.01],BrdU阳性细胞数量显著减少[酒精组(44.9±2.9)vs对照组(54.8±6.0),P<0.01],Sox2标记的神经前体细胞数量减少[酒精组(31.1±6.4)vs对照组(46.6±6.3),P<0.01],Nestin标记的长纤维出现断裂,数量减少[酒精组(25.3±3.8)vs对照组(35.0±2.0),P<0.01]。TO901317预处理有效减轻酒精对海马齿状回前体细胞的毒性作用,TO+酒精组较酒精组Ki67阳性细胞数量增加[TO+酒精组(54.2±10.8)vs酒精组(24.7±5.5),P<0.01],BrdU阳性细胞数量显著增加[TO+酒精组(53.4±2.8)vs酒精组(44.9±2.9),P<0.01],Sox2阳性细胞增加[TO+酒精组(54.0±6.7)vs酒精组(31.1±6.4),P<0.01],Nestin标记的纤维断裂减少,数量增加[TO+酒精组(33.0±2.6)vs酒精组(25.3±3.8),P<0.05]。结论激活LXRs可减轻酒精暴露对新生期小鼠海马齿状回神经前体细胞增殖的抑制作用,从而保护海马齿状回的发育。

Objective To determine the protective effect of activating endogenous liver X receptors （LXRs） on the proliferation of dentate gyrus （DG） neural precursor cells （NPCs） in the neonatal mice exposed to ethanol. Methods Mice from the same litters were randomized into a control group （equivalent solvent）, an ethanol group and an ethanol group pretreated with LXRs agonist TO901317 （10 mg/kg, dissolved in solvent DMSO： PBS = 1： 3） （TO ＋ ethanol group）. Immunohistochemistry assay was used to detect the expression of Ki67 protein （ Ki67 ）, 5-bromo-2＇-deoxyuridine （ BrdU）, sex determining region Y-box 2 （ Sox2 ） and nestin to observe whether the activation of LXRs could promote the cell proliferation and maintain NPCs in the DG of the hippocampus of neonatal mice exposed to ethanol. Results The inhibited proliferation of NPCs in the hippocampus was proven by significant reduction in the number of Ki67-positive cells ethanol group （24.7 ＋ 5.5 ） vs control group （45.9 ±7.1 ）, P 〈 0.01 , BrdU-positive cells ethanol group （44.9 ± 2.9 ） vs control group （54.8 ±6.0）, P 〈0.01 and Sox2-1abeled cells ethanol group （31.1 ±6.4） vs control group （46.6± 6. 3）, P 〈 0.01 in the neonatal mice subjected to ethanol exposure, which could be rescued by pretreatment of TO901317 Ki67-positive cells： ethanol group （24.7 ±5.5） vs TO ＋ ethanol group （54.2 ±10.8）, P 〈0.01 ; BrdU-positive cells ： ethanol group （44.9 ±2.9 ） vs TO ＋ ethanol group （53.4 ±2.8 ）, P 〈 0. 01 ; Sox2- labeled cells： ethanol group （31.1 ±6.4） vs TO ＋ ethanol group （54.0 ±6.7）, P 〈0.01 . Meanwhile, TO901317 also rescued the number decrease of nestin-positive radial glial cell fibers caused by ethanol exposure control group （35.0 ±2.0） vs ethanol group （25.3 ±3.8 ） vs TO ＋ ethanol group （33.0 ±2.6）, P 〈 0.01 . Conclusion Activation of LXRs can rescue the decline of NPCs proliferation in the DG of the hippocampus in ethanol-exposed neonatal mice.