The Role Of Short-chain Fatty Acids In The Induction Of Adult Insulin Resistance In Offspring By Bisphenol A Exposure During Pregnancy

Background Bisphenol A(BPA)is a typical environmental endocrine disruptor that is widely exposed to humans and has a wide range of reproductive toxicity,endocrine disruption,and neurodevelopmental toxicity.Most studies in recent years have shown that BPA exposure increases the risk of obesity and diabetes in children and adults.The pathogenesis of diabetes is not yet fully understood and involves complex genetic as well as environmental factors,mostly related to insulin secretion dysfunction of pancreatic β-cells and insulin resistance.Recent studies have shown that short-chain fatty acid(SCFA),a metabolite produced by intestinal flora,may protect against the development of obesity by regulating body metabolism.However,the effects of BPA exposure during pregnancy on offspring pancreatic β-cells and the role of short-chain fatty acids in this regard are unknown.Objective The effects of maternal low-dose BPA exposure during pregnancy on the levels of short-chain fatty acids,the metabolites of maternal intestinal flora,the development of islet β-cells and insulin resistance in offspring during pregnancy and offspring at different times were elucidated through animal experiments;the mechanism of SCFA-GPCR axis regulating islet β-cell development was further explored through high-fiber dietary intervention experiments.The experiment further explored the mechanism of SCFA-GPCR axis regulating pancreatic β-cell development through high fiber dietary intervention.Research methods1.Effects of BPA exposure during pregnancy on maternal and offspring SCFA,offspring pancreatic β-cells,and their relationship with offspring IR in adulthoodAfter acclimatization of 8-week-old C57BL/6N wild type(WT)specific pathogen free(SPF)grade mice for 1 week,male and female mice were caged together and on the second day,pregnant females were randomly divided into DMSO,10 n M BPA,100 n M BPA,and 1000 n M BPA groups to ensure At least 10 pregnant mice in each group.Pregnant mice were exposed to BPA via drinking water from pregnancy to delivery,and the offspring were breastfed for 3 weeks after birth by a surrogate mother fed a normal chew diet(NCD)without BPA exposure during pregnancy until weaning.After weaning,mice were fed NCD and high fat diet(HFD)until 19 weeks.The following experiments were performed during this period.(1)The sera of maternal rats were collected and separated at gestational day(GD)0,GD12,GD18.5 and embryonic day(ED)18.5,3W at weaning and 19 W at adulthood,and the SCFA levels were measured by gas chromatography-mass spectrometry(GCMS),GC-MS technique was used to detect SCFA levels.(2)The pancreas of fetal rats ED18.5 and offspring rats WD3 and WD19 were collected and stained by histopathologic(HP)staining to observe the size of islets and pancreatic development;the percentage of insulin and glucagon positive cells in islets were detected by immunofluorescence(IF);q RT-PCR analysis The expression levels of Insulin,Fox O1,Pdx1,Maf A,Neuro D,GPR41 and GPR43 were analyzed by q RT-PCR.(3)The offspring were reared to 19 W and blood was collected from the tail vein for glucose tolerance tests(GTT)and insulin tolerance tests(ITT);blood was collected to determine fasting glucose(FG),enzyme-linked immunosorbent assay(Enzyme-linked immunosorbent assay(ELISA)was performed to detect fasting insulin(FI)levels.2.Intervention study of HFi D on SCFA alterations induced by BPA exposure during pregnancy,β-cell abnormalities in offspring and IR in adulthoodHigh-fiber diet(HFi D)intervention groups were set up for the DMSO control group and the 1000 n M BPA group by adding inulin to the diet of pregnant rats:DMSO+HFi D group and 1000 n M BPA+HFi D group,respectively.The physiological and biochemical parameters of all pregnant rats and offspring were measured as above.Results1.Effects of BPA exposure during pregnancy on maternal and offspring SCFACompared with the DMSO control group,the serum levels of the three SCFAs decreased with increasing doses of BPA exposure during pregnancy in pregnant rats GD12,GD18.5,and fetal rats ED18.5,and at weaning(3W)in offspring.The serum SCFA levels in adult NCD and after HFD feeding(19W)still maintained a decreasing trend with increasing doses of BPA exposure during pregnancy,and the serum SCFAs levels in HFD-fed offspring were lower than those in NCD-fed offspring in all groups.2.Effects of BPA exposure during pregnancy on offspring pancreatic islet beta cellsFetal mice had abnormal pancreatic development,smaller islets,reduced expression of pancreatic development genes Insulin,Fox O1,Pdx1 and Maf A in the pancreas;reduced expression levels of SCFAs receptors GPR41 and GPR43 in the pancreas of fetal mice;smaller islet size,reduced percentage of pancreatic β-cells,reduced expression of pancreatic β-cell proliferation and differentiation-related genes Insulin,Neuro D,Pdx1 and Maf A in mice after weaning(3W)and after HFD feeding in adulthood(19W);reduced expression levels of pancreatic GPR41 and GPR43.3.Effects of BPA exposure during pregnancy on offspring IR in adulthoodOffspring of BPA-exposed dams during pregnancy and HFD-fed compared to NCDfed mice showed increased adult FG,FI,insulin resistance index(Homeostasis model assessment,HOMA)-IR,impaired glucose tolerance,reduced insulin sensitivity,and faster weight gain.Compared with the DMSO control group,the offspring of 1000 n M BPA group4.Intervention study of HFi D on SCFA alterations induced by BPA exposure during pregnancy,offspring beta-cell effects and IR in adulthoodCompared with the offspring mice in the BPA-exposed group during pregnancy,serum levels of the three SCFAs increased in pregnant mice at GD12 and GD18.5 and in fetal mice at ED18.5,and the expression levels of pancreatic SCFAs receptors GPR41 and GPR43 were upregulated;pancreatic development was restored,islets became larger,and pancreatic development genes Insulin,Fox O1,Pdx1,and Maf A were upregulated in the fetal mice pancreas.Pdx1,Maf A expression was upregulated;meanwhile,serum SCFAs levels remained higher in mice after 3W and high-fat feeding up to 19 W compared with the BPA-exposed group during pregnancy,and pancreatic GPR41 and GPR43 expression levels were elevated;islets became larger in size,therelated genes Insulin,Neuro D,Pdx1,Maf A expression was up-regulated;FG,FI and HOMA-IR decreased significantly in adult mice after high-fat diet feeding,glucose tolerance impairment improved significantly in mice,insulin sensitivity was restored,and body weight increased slowly.Conclusions1.Environmental low-dose BPA exposure during pregnancy reduced the levels of maternal SCFAs,affected offspring embryonic pancreatic development,led to a decrease in the number of offspring pancreatic β-cells,and promoted offspring adult obesity and insulin resistance.2.Dietary fiber supplementation improved offspring embryonic pancreatic development by upregulating the levels of maternal SCFAs,promoted the expression of genes related to islet β-cell proliferation and differentiation,such as Maf A,and increased the number of islet β-cells in offspring mice,thereby improving adult obesity and insulin resistance in offspring induced by BPA exposure during pregnancy.