大鼠妊娠期缺氧造成子鼠宫内生长受限对子鼠出生后脂肪肝的影响

Prenatal Hypoxia in Rats Leads to Fetal Growth Restriction and Programs an Effect on Fatty Liver in Adult Offspring

目的探讨大鼠妊娠期缺氧造成子代宫内生长受限(fetal growth restriction,FGR)及其对子代出生后肝脏脂肪变性的影响及机制。方法健康雌性SD大鼠经正常交配受孕,受孕第7天时,根据大鼠是否缺氧及子鼠是否高脂饮食,采用随机数字表法将大鼠分为4组:(1)大鼠缺氧+子鼠高脂饮食组(实验组);(2)大鼠缺氧+子鼠正常饮食组(缺氧对照组);(3)大鼠不缺氧+子鼠高脂饮食组(高脂对照组);(4)大鼠不缺氧+子鼠正常饮食组(正常对照组)。每组含大鼠4只及子鼠8只。建立SD大鼠妊娠期缺氧模型,进行大鼠动脉血气分析。子鼠出生后,观察体重的变化,两高脂饮食组子鼠在8周龄后增加高脂饮食,高脂饮食12周后取各组大鼠进行实验分析。取子鼠肝组织进行组织病理学检查及电镜检查观察脂肪变性程度。采用蛋白质印迹法检测各组肝组织过氧化物酶体增殖物活化受体-α(PPAR-α)和肉毒碱棕榈酰转移酶1(CPT-1)蛋白的表达。结果第1次缺氧后(缺氧3h后),与正常对照组相比,实验组大鼠动脉血PaO2、SaO2明显下降(均P<0.05),而血PaCO2和pH值无显著变化(均P>0.05)。出生后第1天,实验组子鼠体重为(4.67±0.48)g,显著低于正常对照组的(5.98±0.35)g(P<0.01),出现FGR现象;出生后第3周,实验组子鼠体重为(53.6±6.3)g,与正常对照组的(54.1±7.0)g相近(P>0.05),子鼠出现"追赶生长"现象。实验组子鼠高脂饮食后肝脏脂肪变程度较其他3组均显著加重,FGR与高脂饮食引起的肝脂肪变性效应具有协同促进作用。母体大鼠妊娠期缺氧可引起子鼠成年期肝脏PPAR-α和CPT-1蛋白相对表达量明显下调(均P<0.05)。子鼠高脂饮食同样引起上述蛋白相对表达量的下降(均P<0.05)。大鼠妊娠期缺氧与子鼠高脂血症对子鼠肝脏PPAR-α和CPT-1蛋白相对表达水平的影响存在交互作用(P<0.05)。表明母体大鼠妊娠期缺氧与子鼠高脂饮食两因素具有协同抑制肝脏脂质氧化分解的作用。结论妊娠期母体大鼠缺氧造成子代FGR,并能诱导子代出生后肝脏脂肪变性,PPAR-α和CPT-1蛋白表达可能在FGR及高脂饮食诱导的子鼠肝脏脂肪变性中发挥作用。大鼠缺氧造成子代FGR与子鼠成年期高脂饮食具有协同作用。

Objective To investigate the effect of fetal growth restriction(FGR)on the subgeneration of FGR and the mechanism of hepatic steatosis after the birth of the progeny of the rat.Methods The healthy female SD rats were pregnant with normal mating.On the seventh day of pregnancy,the rats were divided into4groups according to whether the rats were anoxic and/or given the high fat diet of the rats.The rats were divided into4groups.①hypoxia+high fat diet group(experimental group);②hypoxia+normal diet group(hypoxia control group);③no hypoxia+high fat diet group(high fat control group);④no hypoxia+normal diet group(normal control group).SD rat model of hypoxia during pregnancy was established to monitor arterial blood gas in rats.After the birth of the offspring,the weight changes were observed.High fat diet was increased in the offspring of the two high fat diet groups after8weeks of age.After12weeks of high fat diet,the offspring were analyzed.The liver tissues of the offspring were taken for histopathological examination and the degree of steatosis was observed by electron microscopy.The expression levels of peroxisome proliferator activated receptor-α(PPAR-α)and botuline palmityl transferase1(CPT-1)protein were detected by Western blotting.Results After first hypoxia(3h after hypoxia),compared with the normal control group,the arterial blood PaO2and SaO2in the experimental group were significantly decreased(P<0.05),but there were no significant changes in the blood PaCO2and pH values(P>0.05).First days after birth,the weight of the offspring in the experimental group was(4.67±0.48)g,significantly lower than that of the normal control group(5.98±0.35)g(P<0.01),and the FGR phenomenon appeared.The weight of the offspring in the experimental group was(53.6±6.3)g,which was similar to that of the normal control group(54.1±7.0)g(P>0.05),and“chasing growth”appeared in the offspring.Steatosis was significantly aggravated in the experimental group than in the other three groups.FGR had synergistic effect with high fat diet-induced liver stenosis.Maternal hypoxia in pregnant rats significantly decreased the relative expression of PPAR-alpha and CPT-1protein in adult offspring rats(P<0.05)The high fat diet of offspring also decreased the relative expression of these proteins(all P<0.05).There was an interaction between the effects of hypoxia during pregnancy and the hyperlipidemia on the expression of PPAR-αand CPT-1in the liver of offspring rats(P<0.05).It is suggested that the two factors of maternal hypoxia during pregnancy and high fat diet of offspring rats had synergistic inhibition of lipid oxidation and decomposition in liver.Conclusion The hypoxia of the pregnant female rats causes the offspring FGR,and can induce hepatic steatosis after birth.The expression of PPAR-αand CPT-1protein may play a role in the liver fatty degeneration induced by FGR and high fat diet.Hypoxia-induced offspring FGR has a synergistic effect with high fat diet in adult offspring rats.