Aging, Abdominal Obese And Diabetes Affect On IGFBP2 Expression In Adipose Tissue

OBJECTIVE:obesity is a complex, non-communicable chronic disease which arise from many factors. obesity contributes to metabolic disorders that increased the risk for the development of cardiovascular diseases,and there are epidemiological studys reveal that the obese are more likely to performance impared glucose tolerance and insulin resistance than the normal body weight.IGF binding protein 2(IGFBP2) is secreted by white adipocytes and contributes to the prevention of diet-induced obesity and age-related insulin resistance in mice.However, the expression levels of IGFBP2 in insulin resistance disorders have not been evaluated.The present study was aimed at determining IGFBP2 m RNA levels in adipose tissue in conditions of insulin resistance such as aging and obesity and the relation between IGFBP2 m RNA levels and plasma IGFBP-2 levels. Methods:Male C57BL/6 mice aged 4, 12 and 24 months old(n=12); Male ob/ob, db/ db(aged 4 months) and their respective controls(wild-type C57BL6 mice of the same age),(n=6);high-fat sucrose-fed(diet-induced) obese C57BL6 mice(aged 4 months, on the feeding regimen since weaning) and their respective controls(chow-fed wild-type C57BL6 mice of the same age),(n=6). After an overningt,mice were sacrificed by breaking the neck and blood(cardiac puncture) and white adipose tissue(WAT) samples were immediately harvested. WAT tissues were snap frozen in liquid nitrogen. Blood was kept on ice until centrifugation(1 500 g, 15 min at 4 ° C), and the plasma was stored at-20 ° C.After RNA extraction,reverse transcribed as c DNA and real-time Quantitative PCR was carried out to mesure the expression of m IGFBP-2.Plasma concentrations of IGFBP2 were quantified by ELISA using commercial kits.Data are presented as mean ± S.E.M.The data were analyzed by ANOVA,t-test and simple regression.All statistics were performed with SPSS17 software. A p-value of < 0.05 was considered significant. Results:(1)The influence of age on the visceral adipose tissue:in the non-obesity group, 12 mouths old and 24 mouths old mice showed a significant reduction of IGFBP2 m RNA levels in the epididymal adipose depot compared to that of their younger 4 months old counterparts(p<0.05). These changes were specific to the visceral depot, as no statistical diff erence was observed in subcutaneous fat;(2)The influence of obesity and diabetes on the visceral adipose tissue:in the 4 mouths old mices,IGFBP2 expression was lower in visceral WAT from ob / ob,HFD-ob and db / db compared to that in wild-type littermates. In contrast, IGFBP2 expression was found to be unaltered in the subcutaneous fat depot of obese animals;(3)plasma IGFBP2 concentrations were associated with IGFBP2 m RNA expression in visceral but not in subcutaneous WAT among all the mices.