Effects Of High-energy Diet Before And During Pregnancy On Maternal And Fetal Metabolism And The Regulatory Mechanisms

Maternal diet before and during pregnancy is very important to the growth and development of herself and fetus.Epidemiological and experimental studies have shown that there is a strong correlation between maternal high-energy diet before and during pregnancy and fetal birth weight,obesity and metabolic syndrome.The placenta is an important hub between the mother and the fetus,and the development of the fetus in the maternal uterus completely depends on the supply of nutrients between the placenta and the fetus.At the same time,studies have shown that circRNAs and miRNAs play an important role in the regulation of maternal placental nutrient transport.Studies on mice have shown that maternal energy levels affect fetal growth and development,but the specific mechanism is not clear.Our previous studies showed that high energy levels can increase the expression of circ-Amotl1 in NIH-3T3 cells,which is beneficial to the proliferation and survival of NIH-3T3 cells.However,there are few studies on the effects of high-energy diet before and during pregnancy on maternal and fetal metabolism and the regulation of placental nutrient transport by circRNAs.Therefore,this study systematically revealed the effects of high-energy diet before and during pregnancy on maternal and fetal metabolism and its regulatory mechanism in C57/6L mice.the purpose of this study is to provide a reference for determining the appropriate dietary energy level for maternal and fetal growth and development before and after pregnancy and early fetal growth and development in animal husbandry production.Thirty C57/6L mice weighing nearly 7 weeks were randomly divided into three groups,namely,Control group(CON),High sucrose group(HSD)and High fat group(HFD),each with 10 mice,which were reared in a single cage.The CON group was fed with 10%fat,the HFD group was fed with 60%fat,and the HSD group was fed with10%fat plus 20%sucrose water.Before the trial,the energy intake of HSD group and HFD group were basically the same.After 4 weeks of feeding,the male and female mice were closed at 1:1,and continued feeding for 18.5 days after successful mating.During the experiment,the food intake and drinking water of mice were recorded every day,and the weight changes of mice during pregnancy were measured every week.At the end of the experiment,maternal blood,placenta,fetus,intestine,fat and intestinal contents were collected to detect the growth performance,histomorphology,intestinal microflora and differential expression of circRNAs in placenta.The results show that:(1)With the increase of the number of days of pregnancy,there were similarities between HSD group and HFD group in improving the growth performance of mice.During the whole experiment,the final weight,daily gain,fat weight,average energy intake and blood glucose levels of mice in HSD group and HFD group were significantly higher than those in CON group(P<0.01),The contents of triglyceride(TG),free fatty acids(FFAs),glucocorticoid(GC),total cholesterol(TC),leptin,insulin(INS)and low density lipoprotein(LDP)in serum were significantly higher than those in CON group(P<0.01),adiponectin(ADP)decreased significantly(P<0.01),and the contents of fasting blood glucose(FBG),abdominal fat and LDP in HFD group were significantly higher than those in HSD group(P<0.01);The content of serum ADP in HSD group was significantly higher than that in HFD group(P<0.01).In addition,the glucose tolerance test showed that the insulin resistance index of the mice in the HSD group and the HFD group was significantly higher than that of the CON group(P<0.01).(2)Liver weight,liver index,spleen index and kidney index in HSD group and HFD group were significantly higher than those in CON group(P<0.01),and liver weight,liver index,spleen index and kidney index in HFD group were significantly higher than those in HSD group(P<0.05).(3)The litter size,litter weight,total weight of placenta and total weight of placenta+fetal complex in HSD group and HFD group were significantly higher than those in CON group,(P<0.05),while the number of stillbirths in HFD group was significantly higher than that in CON group and HSD group(P<0.01).(4)The expression of IGF-II,Stat3,Slc2a1,Slc2a3,SLC27A1,FATP4,FABP3 and CD36 m RNA in placenta and fetus of HSD group and HFD group was significantly higher than that of CON group(P<0.01),while the expression of H19 was significantly down-regulated(P<0.01).The expression of IGF-II,Stat3,Slc2a3 and FABP3 in placenta of HFD group was significantly higher than that of HSD group(P<0.01),and the expression of Slc2a1 in placenta of HSD group was significantly higher than that of HFD group(P<0.01).In addition,the expression of Slc2a3 and FATP4 in fetal liver in HFD group was significantly higher than that in HSD group(P<0.01).(5)The pathological changes of liver and placenta in HSD group and HFD group were more serious than those in CON group,and the height of intestinal villi,the depth of crypt,the number of V/C,goblet cells,lymphocytes and Ki67~+cells in placenta trophoblast in HSD group and HFD group were significantly higher than those in CON group(P<0.01),and the villus height,the ratio of villus height to crypt depth and the number of goblet cells in HSD group were significantly higher than those in HFD group(P<0.01).(6)The diameter and area of adipocytes in abdomen and back in HFD group were significantly higher than those in CON group and HSD group,and the brown fat in abdomen and back was significantly transformed into white fat.(7)At the phylum level,the intestinal flora of each group were mainly Firmicutes,Bacteroides and Proteobacteria,and the ratio of Firmicutes to Bacteroides in HFD group was significantly higher than that in HSD group and CON group(P<0.01);at the class level,the intestinal flora of each group was mainly Proteobacteria,Clostridium and Bacteroidetes,while the content of Bacteroidetes in CON group and HSD group was similar and significantly higher than that in HFD group(P<0.01),while that in CON group and HSD group was Clostridium to and significantly lower than that in HFD group(P<0.01);at the eye level,the intestinal flora of each group were mainly Desulfovibrionales,Clostridiales,Bacteroidetes and Lactobacillales,the content of Clostridiales in HSD group and CON group was similar to and significantly lower than that in HFD group(P<0.01),and the content of Bacteroidetes in HSD group and CON group was similar and significantly higher than that in HFD group(P<0.01);the analysis of the main differential microflora in colon showed that Staphylococcus,Rrtmdtdbt4ccus and Brachybacterium were dominant in HFD group,while Bifidobacterium,Sutterella and Eurasian bacteria were dominant in HSD group,the intestinal flora structure of HSD group was similar to that of CON group,but different from that of HFD group.(8)11176 circRNAs expression abundances were identified in placental circRNAs library,among which 53 were up-regulated and 64 down-regulated between HSD group and CON group,67 circRNAs were up-regulated and 66down-regulated between HFD group and CON group,and 80 differentially expressed circRNAs were up-regulated and down-regulated between HFD group and HSD group,of which 41 were up-regulated and 39 down-regulated.(9)Pathway enrichment analysis showed that differentially expressed circRNAs can regulate a variety of biological processes,cellular components and molecular functions through a variety of energy metabolic pathways.CircRNAs function prediction showed that mmu-let-7g-5p could bind to a variety of differentially expressed circRNAs.In addition,this study predicted that 10 kinds of circRNAs,with protein-coding function were found in all the differentially expressed circRNAs.These circRNAs may directly encode proteins to regulate maternal placental nutrient transport.To sum up,high-energy diet before and during pregnancy can improve the growth performance of mice and promote fetal development.at the same time,high-energy diet can change the morphological structure and function of liver,placenta,intestine and fat in the mouse to a certain extent,seriously affect maternal health,and may even endanger offspring.In addition,high-energy diet before and during pregnancy can lead to the disorder of intestinal microflora and affect the maternal utilization and transport of energy.sequencing results show that there are many differentially expressed circRNAs,in the placenta of high-energy diet mice.These circRNAs play a very important role in placental nutrient transport and fetal development,and are also an important breakthrough in in-depth study of maternal placental nutrient transport and fetal development.