Expression Of PI3Kp85α And AKT2 In Liver And Perinephric Adipose Tissue In High-fat-sucrose Diet Pregnant Rats And Its Association With Insulin Resistance

BackgroundGestational diabetes mellitus(GDM) is a special kind of diabetes mellitus.GDM is associated with serious hazardes to pregnant women, fetal and newborns.GDM morbidity has increased dramatically in recent years.GDM appears to result from the same spectrum of physiological and genetic abnormality that characterize diabetes outside of pregnancy. So GDM provides a unique chance to study pathogenesis of diabetes and to develop early interventions to prevent the type 2 diabetes.Severe insulin resistance is a defining attribute of GDM.The etiology and pathogenesis of insulin resistance is unclear,which may be induced by abnormal insulin signaling pathway.In currently studies,the relations between abnormal insulin signaling pathway and pregnancy insulin resistance became a focus.It was kown that the key reason of pregnancy insulin resistance was dysfunction afer insulin receptor of insulin signaling transmission.Phosphoinositide 3-kinase p85 alpha and Akt2/PKB beta are two importance molecules proteins in phosphatidylinositol 3-kinase-dependent signaling pathways,which was the major pathway in insulin-signaling transmission afer insulin receptor. ObjectiveIn the study,we made the model of pregnancy insulin resistance rats by sucrose and fat diet.the model is similar to human in insulin resistance of gestational diabetes mellitus.we discussed the expression of PI3Kp85 alpha and AKT2 in liver and perinephric adipose in model.The aim of this study was to determine whether the expression of p85 alpha and Akt2 were associated with insulin resistance in normal pregnancy and gestational diabetes mellitus.Subjects and MethodsForty female SD rats were divided into four groups:sucrose and fat diet pregnant rats (SFP),sucrose and fat diet virgin rats (SFV), normal diet pregnant rats (NP),normal diet virgin rats (NV). (n=10 per group).High-sucrose-fat diet or normal diet were given according to group. Oral Glucose Tolerance Test (OGTT)were performed at 18 days of gestation.On days 20 of gestation, we measured followed serologic parameters such as FPG,FINS,triglyceride,cholerterol,and free fatty acids.Then executed rats, Liver and perinephric adipose were divided into two parts:one was used to observed the morphological changes in liver,perinephric adipose and pancreatic tissue by HE staining,another was used to measure the level of PI3KP85alpha mRNA and AKT2 mRNA by RT-PCR.Fasting plasma glucose (FPG) and fasting insulin(FINS)were measured by oxidized assay and ELISA.Insulin resistance index (HOMA-IR) was calculated according FPG and FINS.All statistical analyses were carried out with the SPSS 13.0.Results1 OGTT:In the SPF group,the levels of glucose at 0min,30min,60min and120min were higher than other groups.In the SFV and NP group the levels of glucose are higher than control group (NV) at 60min(P<0.05).But the levels of glucose at 0,30,120min glucose were no difference among the three groups (P>0.05)2 In the SFP group,the levels of FIN,TG,TC,FFA and HOMA-IR were significantly higher than that of other groups(P<0.01),these were higher than control group(NV) in the SFV and NP group (P<0.05),but no difference between each other (P>0.05).The levels of FBG in the SFP group was significantly higher than other groups(P<0.01); But fasting blood glucose was no difference among the SFV,NP and NVgroups.3 HE stain analysis:Examined under microscope,in liver of the SFP group, hepatic cells were different in size and volume compare with other groups. Lots of hepatic cell were getting fatty degeneration, translucent spaces and vacuoles in cytoplasm. In the NP and SFV group, a few hepatic cell were getting fatty degeneration and cell size are arranged disorders.4 In liver and perinephric adipose tissue, the expression levels of P85 alpha mRNA in SPF group were obviously higher than that of other groups (P<0.01); The level of P85 alpha mRNA in SFV group and NP group were higher than that of NV group (P<0.05).No differences were found in mRNA expression of p85 alpha between SFV and NP group(P>0.05); The mRNA expression levels of AKT2 in liver and perinephric adipose tissue were significally lower in SFP group than other groups (P<0.01),The mRNA expression of AKT2 was decreased in SFV or NP compared to NV group(P<0.05),However,expression of AKT2 mRNA were no differ between SFV and NP group(P>0.05).5 In liver and perinephric adipose,the expression levels of p85 alpha mRNA was significantly correlated positively with HOMA-IR in the SFP,NP and SFV groups (P<0.01 or P<0.05);The expression levels of AKT2 mRNA was significantly correlated negatively with HOMA-IR in the SFP,NP and SFV groups (P<0.01 or P<0.05); However,expression levels of p85 alpha and AKT2 mRNA were not correlated with HOMA-IR in the NV group(P>0.05).In the SFP,NP and SFV groups, the expression levels of P85 alpha mRNA was correlated positively with the levels of FFA(P<0.01 or P<0.05) and the expression levels of AKT2 mRNA was correlated negatively with the levels of FFA(P<0.01 or P<0.05);However,expression levels of p85 alpha and AKT2 mRNA were not correlated with the levels of FFA in the NV group(P>0.05). Conclusions1 We made a success of the pregnancy insulin resistance rats model induced by high-sucrose-fat diet.The model was similar to human gestational diabetes mellitus in insulin resistance and metabolic characters of glucose and lipid;2.The overexpression p85amRNA and low expression AKT2mRNA may be one of the molecular mechanisms leading to insulin resistance of gestational diabetes mellitus;3 High-Sucrose-fat diet and pregnancy may contribute to increase the expression of p85a and decrease the expression of AKT2, leading to insulin resistance;4 FFA may contribute to the insulin resistance of gestational diabetes mellitus by increasing the expression of p85a and decreasing the expression of AKT2...