Effect Of Maternal LPS Exposure During Pregnancy On Blood Lipids In Offspring Rats And Its Mechanism

Circulation system disease would be the most important reason of death in the world for its high morbidity,disability and mortality.However,with the development of society,people suffer from such disease won’t be reduced,the fatality rate of this disease is increasing year by year,and the number of death from this related disease reaches 15 million per year,even though proper precautions would decrease the morbidity of this disease largely.Hence earlier treatments for this disease would be more important and useful.In our study,we use animal model of maternal LPS exposure during pregnancy to explore the mechanism of such disease in earlier life.For a better understand of how maternal LPS exposure during pregnancy works on the circulation system di sease,we detected the blood lipid,liver structure,mitochondrial structure and functions,cholesterol related gene transcriptions and some key proteins in the metabolism of lipid.Meanwhile we feed the offspring with high fat diet,and try to uncover the mechanism of such disease with the determinations gained by above detections.Our studies try to explore the mechanism of circulation system disease in a totally new degree,and it would offer a new effective therapeutic method for circulation system disease.Methods1.Group dividing of model animalsPregnant rats were randomly divided into two groups,control group and LPS stimulation group.Control group: Rats were intraperitoneally administered sterilizing saline 0.5ml from 8th-14 th days since gestation;LPS stimulation group: Rats were intraperitoneally administered sterilizing saline 0.5ml on 9th,11 th,13th,14 th day of gestation,and intraperitoneally administered LPS 0.79mg/kg on 8th,10 th,12th day of gestation.After 4 weeks from the birth,offspring were divided into two groups in each group,control group and high fat diet group,LPS stimulation group and LPS stimulation and high fat diet combined group.Control and LPS stimulation groups were raised with normal food,while high fat diet and LPS stimulation and high fat diet combined groups were raised with high fat diet.2.Related indexes detections of model animal offspring.Weighted offspring weekly since delivery.Detected blood lipid and liver function indexes when the offspring grow up to 8 weeks.Photograph the histopathological alterations of the liver with hematoxylin-eosin staining by microscopy and changes in liver cells by transmission electron microscopy.Measured related proteins expressed in liver mitochondria by western blot.Use cholesterol related genome chips to analyze related gene transcriptions.Measured mitochondrial membrane potential,cytochrome c oxidase activity and ATP content in liver cells.Results1.Blood lipid disorderIn normal diet,offspring in LPS stimulation group had a higher TC(p<0.01),TG(p<0.01)and LDL-C(p<0.05)than control group.Offspring in high fat diet group had a higher TC(p<0.01),TG(p<0.01)and LDL-C(p<0.05)than control group.Offspring in LPS stimulation and high fat diet combined group had a higher TC(p<0.01),TG(p<0.01)and LDL-C(p<0.05)than LPS stimulation group;Meanwhile,offspring in LPS stimulation group had a higher weight than control group(p<0.01).High fat diet improved the rate of weight gained in offspring(p<0.05).LPS stimulation group had the same rate of weight increasing gained in offspring with high fat diet group.2.Liver impairmentLiver with hematoxylin-eosin staining in control group had a completed structure and apparent cell boundary,while liver cells in LPS stimulation group were swelling and the cell boundary decreased,some lipid empty bubbles would be found in cells,and some inflammatory cells would be found among liver cells.High fat diet would induce light cell swelling and lipid empty bubbles,and it would made liver cells worse which were damaged from LPS stimulation;High fat diet would increase the level of ALT in offspring(p<0.01).Offspring in high fat diet and LPS stimulation combined group had a higher ALT(42.00±13.11U/L)than control group(22.67±2.66U/L)(p<0.01);Offspring in LPS stimulation group had a higher AST(74.17±5.04U/L)than control group(61±5.14U/L)(p<0.05).Offspring in LPS stimulation and high fat diet combined group had a higher AST(105.83±18.88U/L)than control group(61.00±5.14U/L)(p<0.01)(standard ALT,AST levels: ATL: 23.5-71.9U/L,AST: 76.2-137.5U/L).3.Cholesterol metabolism related genes dysregulationCholesterol related genome chips analysis showed 12 genes’ changes among the total 88 genes in LPS stimulation group.They were Apoc1,Apoc3,Cyp46a1,Cyp7b1,Dhcr24,Lipe,Olr1,Ppard,Prkaa2,Tm7sf2,Vldlr and Sor11.4.Mitochondria dysfunctionPhotographed by transmission electron microscopy mitochondria in control group had a completed bilayer membrane structure,and the inner membrane folded into inner space to over many times and formed matrix,the shape and structure of matrix would be observed clearly in the oval mitochondria.Mitochondria in LPS stimulation group swelled into balls and some of the matrix were ruined,the number of mitochondria increased largely while the bilayer membrane structure of mitochondria was damaged partly,and there were just partial mitochondria structure damage in high fat diet group.In the LPS stimulation and high fat diet combined group,mitochondria had a remarkable damages and histopathological alterations;Mitochondrial membrane potential in LPS stimulation group had an apparent decrease than control group(p<0.01),and seems to had a same potential level with high fat diet group.Mitochondrial in LPS stimulation and high fat diet combined group had a lower membrane potential than mitochondria in LPS stimulation group;High fat diet would increase the ATP content in liver cells(p<0.01)while LPS stimulation would decrease the level of ATP(p<0.05);Cytochrome c oxidase activity in high fat diet decreased largely(p<0.05),but LPS stimulation would increase the activity;Complex I level in LPS stimulation group was higher than control group,while the level of complex III and complex V had no significant change.Complex II in LPS stimulation group had a lower expression than the control group.High fat diet would decrease the level of complex I,II,III and V;LPS stimulation would increase deletion of mtDNA4977 bp,LPS stimulation had a higher deletion than control group(p<0.01),LPS stimulation and high fat diet combined group had a significant increase of mtDNA4977 deletion than LPS stimulation group(P<0.01).Conclusion1.Maternal LPS exposure during pregnancy would disorder the metabolism of lipid,makethe offspring more sensitive to high-fat diet and aggravate the liver impairment.2.Cholesterol metabolism related genes dysregulation and mitochondria dysfunction may be the mechanism of lipid disorder of offspring of maternal LPS exposure during pregnancy.