Effects Of Perinatal Folic Acid Supplementation On Glucose Metabolism Disorders In Male Offspring Induced By Lipopolysaccharide Exposure During Pregnancy

Background: Adverse environmental factors in the early stage of life can change the gene phenotype of cells through epigenetic mechanisms such as DNA methylation,and ultimately affect the occurrence and development of fetogenic diseases such as diabetes and hypertension.Folic acid is an important methyl donor involved in DNA replication and methylation.Therefore,to explore the effect of folic acid supplementation on adult diabetes from the perspective of primary prevention was helpful for nursing staff to do a good job in pregnancy health care,reasonably regulate the nutrition and behavior of pregnant women,and reduce the risk of adult diabetes in their offspring.The preliminary experimental results of our group demonstrated that low-dose Lipopolysaccharide（LPS）exposure during pregnancy could lead to the disorder of glucose metabolism in male offspring.However,the effect of folic acid supplementation on glucose metabolism disorders in male offspring induced by LPS exposure is not clear.Objective: The aim of this study was to investigate the effects of folic acid supplementation on glucose metabolism disorder in male offsprng induced by LPS exposure during pregnancy and its potential mechanism.Methods: Pregnant mice were divided into 6 groups according to body weight S type,namely normal saline（Ctrl）+ low dose folic acid group（FA2）,normal saline（Ctrl）+ medium dose folic acid group（FA5）,normal saline（Ctrl）+ high dose folic acid group（FA40）,LPS+ low dose folic acid group（FA2）,LPS+ medium dose folic acid group（FA5）,LPS+ high dose folic acid group（FA40）.The offspring were Ctrl（2mg）,Ctrl（5mg）,Ctrl（40mg）,LPS（2mg）,LPS（5mg）,LPS（40mg）respectively.Normal saline and LPS were injected intraperitoneally at 15-17 days of pregnancy at a dose of 50μg/kg/d.FA2,FA5 and FA40 were diets containing different doses of folic acid（2mg/kg,5mg/kg and 40mg/kg）,and the feeding time was from the adaptive feeding period to the end of lactation.All pregnant mice delivered naturally.The offspring were weaned 21 days after birth（PD21）,after which they were all given FA2 diet.Glucose tolerance test was performed at PD60,PD90 and PD120,and insulin tolerance test was performed at PD120.After fasting for 12 hours,the serum was taken to detect serum insulin,triglyceride and total cholesterol content.The protein expression of P-PI3 K,PI3K,P-Akt,AKT,PGSK3β and GSK3β and m RNA expression of dnmt1,dnmt3 a,dnmt3b,pparγ,igf2 and peg3 were detected in liver tissues.Results:（1）Male offspring in LPS（2mg）groups had higher higher glucose after glucose injection and area under glucose curve at PD120,decreased fasting serum insulin,downregulated PI3K/AKT signaling pathway,upregulated m RNA levels of dnmt3 a and peg3 and downregulated m RNA levels of dnmt3 b,pparγ and igf2 compared to Ctrl（2mg）.Compared with Ctrl（40mg）,male offspring in LPS（40mg）group showed higher glucose after glucose injection and glucose area under the curve at PD60,PD90 and PD120,higher glucose after insulin injection at PD120,decreased fasting serum insulin,downregulated PI3K/AKT signaling pathway,upregulated m RNA levels of dnmt3 a and peg3 and downregulated m RNA levels of dnmt3 b,pparγ and igf2.（2）When pregnant mice were not exposed to low dose LPS（intraperitoneal injection of normal saline at GD15-17）in the late stage of pregnancy,there were no significant differences in blood glucose,area under curve,fasting serum insulin,PI3K/AKT signaling pathway and gene m RNA expression among male offspring of Ctrl（2mg）,Ctrl（5mg）and Ctrl（40mg）groups.（3）When pregnant mice were exposed to low doses of LPS at the late stage of pregnancy,glucose tolerance and insulin tolerance of male offspring in LPS（5mg）group were not significantly impaired compared to LPS（2mg）and LPS（40mg）groups.LPS（5mg）group had lower fasting serum insulin levels,upregulated PI3K/AKT signaling pathway,downregulated m RNA levels of dnmt3 a and peg3 and upregulated m RNA levels of dnmt3 b,pparγ and igf2.Conclusion: Low doses of LPS exposure during pregnancy could cause glucose metabolism disorders in male offspring,however we found that supplementation of 5mg/kg folic acid in pregnant mice could improve the glucose metabolism disorder of male offspring.This may be related to the up-regulation of dnmt3 b m RNA expression,which increased peg3 methylation level,decreased peg3 m RNA expression and promote cell growth and proliferation,and the downregulation of dnmt3 a m RNA expression,which decreased pparγ and igf2 methylation levels,increased pparγ and igf2 m RNA expression and promoted the secretion of insulin.Thus,glucose homeostasis was improved.To explore the effect of folic acid supplementation on adult diabetes from the perspective of primary prevention was beneficial to health education of nursing staff,reduce the risk of adult diabetes in offspring,and provide a new idea for pregnant women to supplement the dose of folic acid.