孕期增重过多对胎鼠肝脏脂质代谢的影响及机制研究

The impact of excessive gestational weight gain on fetal hepatic lipid metabolism and the regulatory mechanism

目的构建孕期增重过多(EGWG)大鼠模型,探讨EGWG对胎鼠肝脏脂质代谢的影响及机制。方法健康SD大鼠合笼验孕,显微镜观察到精子视为孕0.5 d。采用随机数字表法将孕鼠分为正常饮食(ND)组和高脂饮食(HFD)组,每组8只,记录孕鼠孕期体质量。于孕21.5 d行剖宫产手术,记录胎鼠出生体质量。苏木精-伊红(HE)染色、油红O染色观察孕鼠、胎鼠肝脏脂质沉积,甘油磷酸氧化酶-过氧化物酶(GPO-PAP)法检测孕鼠、胎鼠肝脏与血清三酰甘油(TG)、胆固醇(TC)水平,实时荧光定量PCR(RT-PCR)和Western blot检测胎鼠肝脏脂质代谢关键基因FASN、SREBP1c的mRNA表达水平和蛋白表达水平。采用独立样本t检验进行两组间数据比较。结果HFD组与ND组大鼠孕前体质量无差异,孕期体质量及孕期增重差异逐渐明显。孕21.5 d,HFD组孕鼠体质量[(467.75±22.05)g比(430.88±18.80)g,t=-3.600,P=0.003]、孕期增重[(181.50±9.68)g比(148.50±10.86)g,t=-6.415,P<0.001]、胎鼠体质量[(5.51±0.17)g比(4.85±0.35)g,t=-4.779,P<0.001]均较ND组显著增加。HE染色、油红O染色均提示HFD组孕鼠、胎鼠肝脏脂质沉积加重。HFD组孕鼠、胎鼠肝脏与血清TG、TC水平均较ND组显著升高(均P<0.05)。RT-PCR和Western blot结果显示,HFD组胎鼠肝脏脂质代谢关键基因FASN、SREBP1c的mRNA表达水平和蛋白表达水平均较ND组显著升高(均P<0.05)。结论孕21 d HFD可成功构建EGWG动物模型,孕鼠EGWG可导致胎鼠肝脏脂质沉积,其机制可能与胎鼠肝脏脂质代谢关键基因FASN、SREBP1c的表达改变有关。

Objective A rat model of excessive gestational weight gain(EGWG)was constructed to investigate the impact of EGWG on fetal hepatic lipid metabolism and the relevant regulatory mechanism.Methods Healthy Sprague-Dawley rats were caged together and tested for pregnancy.Rats with the sperm observed under microscope were considered pregnant for 0.5 days.Pregnant rats were divided into the normal diet(ND)group and high-fat diet(HFD)group by the random number table method,with 8 rats in each group.The body weight during pregnancy of the pregnant rats was recorded.Cesarean section was performed at day 21.5 of gestation and the birth weight of the fetal rats was recorded.Hepatic lipid deposition of the pregnant and fetal rats was examined by hematoxylin-eosin(HE)staining and oil red O staining.Triglyceride(TG)and cholesterol(TC)levels in livers and serum of the pregnant and fetal rats were detected by glycerol phosphate oxidase-peroxidase(GPO-PAP)method.The mRNA and protein expression levels of key genes FASN and SREBP1c in hepatic lipid metabolism of fetal rats were measured by real-time polyme-rase chain reaction(RT-PCR)and Western blot.Differences between the two groups were compared by independent sample t test.Results There was no difference in pre-pregnancy body weight between the HFD group and the ND group,but the differences in the weight and the weight gain during pregnancy gradually enlarged between the two groups.At day 21.5 of gestation,the weight of the pregnant rats[(467.75±22.05)g vs.(430.88±18.80)g,t=-3.600,P=0.003],the weight gain of the pregnant rats during pregnancy[(181.50±9.68)g vs.(148.50±10.86)g,t=-6.415,P<0.001]and the birth weight of the fetal rats[(5.51±0.17)g vs.(4.85±0.35)g,t=-4.779,P<0.001]of the HFD group were significantly higher than those of the ND group.Both HE staining and oil red O staining presented increased hepatic lipid deposition in the pregnant and fetal rats of the HFD group.The hepatic and serum TG and TC levels of the pregnant and fetal rats of the HFD group were significantly higher than those of the ND group(all P<0.05).RT-PCR and Western blot showed that the mRNA and protein levels of key genes FASN and SREBP1c in hepatic lipid metabolism of fetal rats of the HFD group were significantly higher than those of the ND group(all P<0.05).Conclusions An EGWG model can be successfully constructed by a 21-day HFD during pregnancy.EGWG can lead to hepatic lipid deposition in the fetal rats.The mechanism may be related to the expression changes of key genes FASN and SREBP1c in hepatic lipid metabolism of fetal rats.