父母肥胖对后代非酒精性脂肪肝生成的影响

发布时间：2018-08-18 09:43

【摘要】：过去几十年,儿童非酒精性脂肪肝(nonalcoholic fatty liver disease, NAFLD)的发病率在急剧增加,而这种患病率的快速增加并不单单是由儿童对高脂食物的过量摄取造成的。近来有关实验动物的研究表明,对高脂食物喂养的肥胖母亲的子代持续给予高脂食物喂养,这些子代在成年后会比给予正常食物喂养的同窝子代更容易发生非酒精性脂肪肝炎。这表明：高脂食物喂养在一定条件下,可以通过代代传递的形式对代谢综合症的发生和发展产生扩大和加剧的作用。通过建立高脂食物连续喂养三代的母系肥胖小鼠模型,本论文作者对母系肥胖后代小鼠中NAFLD的产生进行了研究。另外,流行病学研究表明,肥胖及其相关疾病如NAFLD的发生过程中存在着性别差异。因此,论文作者进一步检测了在持续母系营养过剩的条件下,后代小鼠中NAFLD的发生是否也存在性别差异。而且,父系肥胖也被证明对子代成年后疾病发生有一定影响,所以论文作者还建立了高脂食物连续喂养三代的父系肥胖小鼠模型来初步研究父系肥胖对其后代小鼠NAFLD产生的影响。在母系肥胖和父系肥胖小鼠模型中,C57BL/6小鼠被分别用正常和高脂食物连续喂养三代：即FO代、F1代和F2代。论文作者对母系肥胖模型中后代小鼠的体重、食物摄取量、肝脏的组织学变化和血清中胰岛素、瘦素、甘油三酯、肝脏功能指标和雌激素等水平、以及肝脏中甘油三酯含量水平进行了检测；并且对其肝脏中脂肪生成、葡萄糖代谢、内质网应激途径相关因子的表达情况,细胞增殖和巨噬细胞标志物的蛋白水平以及组蛋白修饰状态进行了研究。另外,父系肥胖雄鼠后代的体重、肝脏的组织学变化、肝脏中糖脂代谢通路相关基因的mRNA水平以及肝糖原的含量也都得到了检测。结果显示：1)在持续高脂食物喂养条件下,随着代数的增加,母系肥胖的雄鼠后代肥胖发生的时间更早且肥胖程度也更加严重,同时还伴随着肝脏脂肪变性的逐渐加重(F2F1FO)。血清中的胰岛素和瘦素水平也在持续高脂食物喂养的F2代雄鼠中最高。除此以外,脂肪生成和内质网应激途径也在这种母系肥胖模型的雄鼠后代中有着传代积累的现象。而且,这两个信号通路中的重要调控蛋白如LXRα(肝脏X受体α)和ERO1-α(内质网应激氧化物蛋白1α)在这些雄鼠后代中呈现一定传代性变化的趋势,并伴随着组蛋白甲基化水平和组蛋白H3K9双甲基化水平的一定传代性变化的趋势。CHIP实验也进一步表明,在持续高脂食物喂养的F2代雄鼠中,组蛋白的甲基化水平在LXRα和IERO1-α基因的启动子区域上显著下降。2)在持续高脂食物喂养条件下,母系肥胖的后代在肝脏脂肪变性过程中累积的信号通路存在性别差异。在连续的高脂食物喂养条件下,虽然肝脏病理变化以及血清中ALT和AST的水平在持续高脂食物喂养的F2代雄鼠和雌鼠之间是相似的,但是,雄鼠后代而并非雌鼠后代的肝脏中,细胞增殖和炎症发生表现出传代性积累；同时,雌鼠后代而并非雄鼠后代的肝脏中雌激素受体α的磷酸化水平表现出传代性积累。3)在持续高脂食物喂养的父系肥胖条件下,2个月和4个月大的雄鼠后代的体重和肝脏重量等都没有发生传代性增加的变化；然而,在4个月大的雄鼠后代中,肝脏脂肪变性却呈现出一定的传代性恶化的现象。因此,本论文的研究表明：在持续高脂食物喂养条件下,肥胖和NAFLD在母系肥胖的后代中都表现出传代性加剧。而在雄鼠后代中,导致这种现象产生的原因可能是肝脏中组蛋白甲基化修饰的传代性变化引起脂肪生成途径和内质网应激信号通路激活的传代性积累。而且,母系肥胖的雄鼠后代和雌鼠后代中NAFLD的发生机制可能是不同的。细胞增殖和炎症发生通路在雄鼠后代而并非在雌鼠后代中存在着传代性积累,可能是为什么男性NAFLD患者更容易发展成恶性肝病的原因之一。另外,在较长时间的持续高脂食物喂养刺激下,父系肥胖对其雄鼠后代NAFLD的产生具有一定的传代性影响,但这种影响的机制还需要进一步的研究。
[Abstract]:The incidence of nonalcoholic fatty liver disease (NAFLD) in children has increased dramatically in the past few decades, and this rapid increase is not solely due to children's excessive intake of high-fat foods. Recent studies in laboratory animals have shown that the offspring of obese mothers fed high-fat foods support this rapid increase. These offspring were more likely to develop non-alcoholic steatohepatitis in adulthood than the offspring fed normal food, suggesting that high-fat food feeding, under certain conditions, could play an expanding and intensifying role in the development of metabolic syndrome in the form of progeny transmission. In this paper, we studied the production of NAFLD in maternal obese offspring of mice fed with high-fat diet for three generations. In addition, epidemiological studies have shown that there are gender differences in the development of obesity and related diseases such as NAFLD. Therefore, the authors further examined the continuing maternal nutrition. In addition, paternal obesity has also been shown to have an effect on the development of disease in offspring, so the authors have established a paternal obesity mouse model fed with high-fat food for three generations to study the effect of paternal obesity on NAFLD in offspring. Ringing.
C57BL/6 mice were fed with normal and high-fat diets for three successive generations: FO, F1 and F2 in maternal obesity and paternal obesity mice, respectively. The levels of estrogen and triglyceride in the liver were measured, and the fatty production, glucose metabolism, the expression of endoplasmic reticulum stress pathway related factors, the levels of cell proliferation, macrophage markers and histone modification in the liver were studied. Generation weight, histological changes in the liver, mRNA levels of glycolipid metabolism pathway-related genes in the liver and glycogen content in the liver were also measured.
The results showed that: 1) With the increase of algebra, the offspring of maternal obese male rats were obese earlier and more severely, accompanied by progressive liver steatosis (F2F1FO). Serum insulin and leptin levels were also found in F2 male offspring fed continuously with high fat diet. In addition, adipogenesis and endoplasmic reticulum stress pathways also accumulated in the offspring of male mice with this maternal obesity model. Moreover, important regulatory proteins such as LXRalpha (liver X receptor alpha) and ERO1-alpha (endoplasmic reticulum stress oxide protein 1alpha) in these two signaling pathways exhibited certain transmission in these offspring of male mice. CHIP experiments also showed that histone methylation levels decreased significantly in the promoter regions of LXRalpha and IERO1-alpha genes in F2 male rats fed on high-fat diets. Sex differences in signal pathways accumulated during hepatic steatosis in maternal obese offspring fed on high-fat diets were observed. Proliferation and inflammation in the liver of offspring but not female mice showed passage accumulation; and phosphorylation of estrogen receptor alpha in the liver of offspring of female mice but not male mice showed passage accumulation. There was no change in body weight or liver weight, however, in the offspring of four-month-old male mice, liver steatosis showed a certain degree of deterioration.
Therefore, the present study suggests that obesity and NAFLD in maternal obese offspring increase in passage under continuous high-fat diet. In male offspring, this phenomenon may be due to histone methylation modification in the liver caused by the passage of fat production pathways and endoplasmic reticulum stress. The mechanism of NAFLD in maternal obese male offspring and female offspring may be different. Proliferation and inflammation pathways are present in male offspring, not in female offspring. This may be why male NAFLD patients are more likely to develop malignant liver disease. In addition, paternal obesity has a certain effect on the generation of NAFLD in male offspring, but the mechanism of this effect needs further study.
【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：R575.5

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