The Research On Mechanisms Between Insulin Resistance And Adipocyte Dysfunction In Catch-growth Intrauterine Growth Retardation Rats

Objective Intrauterine growth retardation (IUGR) is associated with insulin resistance, hypertension,hyperlipidemia and Type2diabetes. Insulin resistance is the key link of metabolic disorders. Research show that IUGR catch-up growth(IUGR-CG) especially in adipose tissue after born may be related to its insulin resistance.This study is aimed to explore the adipocyte function of IUGR-CG pup for4weeks and changes of related key enzymes for lipid metabolism, for further research on the molecular mechanism of insulin resistance in IUGR-CG adipocytes.Methods maternal nutrition restriction was used to establish IUGR-CG animal model during pregnancy.5newborns that BW<5.1g from experimental group were breast-fed by a maternal and8normal newborns from the control group were breast-fed by a maternal. Measure the body weight and body length at birth and the last4weeks.20IUGR-CG pups and24AGA pups randomly selected were to fast overnight and then test fasting plasma glucose,insulin,triglyceride,ASP,adiponection levels. HOMA-IR indexes (IRI) of two group were calculated. Glucose tolerance was measured by intraperitoneal injection of glucose (2g/kg) after an overnight fast. Preadipocytes isolated from epididymal and perirenal adipose tissues of4-week-old offspring by collagenase digestion. Investigated the proliferation of preadipocytes with crystal violet. Preadipocytes were differentiated With classic "cocktail" method, observe morphology of adipocytes and the protein expression level of DGAT and LPL in the mature process of preadipocytes.Results IUGR-CG rats was significantly lower in Body weight, Body length than normal control (AGA) rats at birth and1-week-old, but body weight of IUGR-CG rats were significantly higher than AGA rats at2to4-week-old. Body length of2-week-old in IUGR-CG rats had no significant difference with AGA rats, even higher than AGA rats at3-week-old, but lower than AGA rats at4-week-old. BMI of IUGR-CG rats were significantly lower than AGA rats at birth, but significantly higher than AGA rats at4-week-old. Fasting plasma glucose had no difference between IUGR-CG and AGA. However, IUGR-CG rats have higher fasting plasma TC, insulin, ASP and IRI than AGA rats. Plasma glucose of IUGR-CG rats was higher than AGA rats after30min in glucose tolerance test. Contrast to AGA, the proliferation of preadipocytes of IUGR-CG rats had an increasing trend. During the differentiation mature process of adipocytes, LPL protein expression level in IUGR-CG from4th differentiation day are significantly higher than these in AGA group. And DGAT protein expression level appear earlier and express higher from the second differentiation day than that in the AGA. Western blot shows that in mature adipocyte cell, the IRS1/2, PI3K's expression was downregulated and SOCS1/3was upregulated.Conclusions The body weight, body length and BMI of IUGR-CG rats had a significantly change. There were overweight, hypertriglyceridemia, insulin resistance, impaired glucose tolerance, higher level of ASP and lower level of adiponectin. The proliferation of preadipocytes had a increasing trend in IUGR-CG rats.During the mature process of preadipocyte, the protein expression of DGAT and LPL which are the key enzymes of lipid metabolism increase is related with the disfunction of adipocytes in IUGR. Objective:To observe the relationship between IRS1/2, SOCS1/3gene silence and C/EBPα,PPARy's expression when preadipose cell turn to mature cell; To research the affection of PI3K inhibtion on C/EBPα, PPARy. Then to find out how the molecular changes in the insulin signal pathway effect the preadipocyte's differentiation.Methods:1) cell culture:pre-adipose cell were cultured and inducted into mature cell by insulin DEX and IBMX (0.5mmol/L IBMX,1.0μmol/LDEX,10μg/LINS)2) RNA inference:shRNA of IRS1/2, SOCS1/3were designed and infect the pre-adipose cell through plasmid to research the C/EBPα PPARy expression changes3) use PI3K inhibitors LY294002in pre-adipocyte cell's differentiation, then exam the expression changes of C/EBPaα,PPARy.Results:compare with the negative group:1) IRS1/2gene silence make the C/EBPα, PPARy down regulated, there is significant difference at3d(p<0.05), WB and Real-time PCR show the same result;2) SOCS1/3gene silence make the C/EBPα, PPARy's expression down-regulated; WB show that there is significant difference at3d(p<0.01), as well as the Real-time PCR results.3) with PI3K inhibitor LY294002, C/EBPα, PPARy's expression was downregulated at4days after inhibitor was added.Conclusion:during pre-adipose cell's differentiation process, IRS1/2-. SOCS1/3was positive-related with C/EBPa, PPARy's expression:PI3K inhibition also down regulated the expression of C/EBPα, PPARγ.