The Correlation Between Serum Retinol Binding Protein4, Insulin Resistance, Lipid Metabolism In Rats With Type2Diabetes Mellitus

Objective: To observe the serum retinol binding protein4（RBP4) changein type2diabetes rats which induced by high-sugar and high-fat diet andintraperitoneal (ip) injection of low dose of streptozotocin(STZ),and toexplore the correlation between RBP4,insulin resistance and lipidmetabolism. Methods: Thirty healthy male Sprague-Dawley (SD) ratswere randomly divided into two groups. Rats in the model group (n=15)were injected (ip) with low dose of STZ after high-sugar and high-fat dietbeing fed for8weeks to establish type2diabetic rats with insulinresistance model, but rats in the control group (n=15) were injected (ip)with the same dose of citric acid buffer after normal diet for8weeks.Then two groups of rats were continued to feed for4weeks. The changesin appearance, behavior and weight of rats during the process ofexperiment were observed. The levels of fasting plasma glucose (FPG),fasting insulin (FINS), triglycerides (TG), total cholesterol (TC), lowdensity lipoprotein cholesterol (LDL-c) and weight were detected at theend of the experiment. The level of serum RBP4was measured by ELISA.The degree of insulin resistance was measured by insulin sensitivity index(ISI) and insulin resistance index (HOMA-IR). Results:(1) As comparedwith control group, the weight of the model group was increasedobviously in the first eight weeks, and higher obviously than that ofcontrol group (P＜0.01). But the weight of the model group was decreased continually from the9thweek, and lower obviously than that ofcontrol group at the end of the12thweek (P＜0.01).(2) The serumlevels of RBP4, FPG, FINS, TG, TC, LDL-c and HOMA-IR wereincreased significantly in model group compared with control group, butISI was significantly lower in model group compared with control group(P＜0.05or P＜0.01).(3) The correlation analysis showed that the serumRBP4was positively correlated with FPG, FINS, TG, TC, LDL-c andHOMA-IR(r values were0.453,0.816,0.733,0.699,0.747and0.817, P＜0.05or P＜0.01) but was negatively correlated to the level of ISI (r=﹣0.770, P＜0.01). The multiple stepwise regression analysis indicated thatHOMA-IR was an independent risk factor for the level of RBP4（r~2=0.668, β=0.237, P＜0.01). Conclusion：(1) High sucrose-high fatdiet can induce the fat rats, On this basis, STZ injection combined withhigh sucrose-high fat diet can establish rat model of type2diabetesmellitus with insulin resistance.(2) The level of serum RBP4issignificantly higher in type2diabetic rats, and the levels of serum FPG,FINS, HOMA-IR are also significantly higher than the normal controlgroup, the correlation analysis shows that RBP4level is positivelycorrelated with HOMA-IR, and HOMA-IR is an independent risk factorfor the level of RBP4, so RBP4is closely related with insulin resistance.(3) The levels of TG, TC and LDL-c in model group are also significantlyhigher than normal control group, and the level of serum RBP4ispositively correlated with TG, TC and LDL-c, so RBP4is also associatedwith lipid metabolism.