Expression Of RBP-4 In Adipose Tissue Of Rats With IR Induced By Different Diets

Objective:To observe the high saturated fatty acid diet and high trans fatty acids diet on the insulin resistance and the expression of retinol-binding protein 4(RBP4) mRNA and glucose transporter 4(GLUT4) mRNA in adipose tissue of rats.Discuss the relationship between RBP4 and insulin resistance and lipid metabolism.Methods:Male SD rats were divided into 3 groups and were fed with chow,highsaturated fatty acid and high- trans fatty acids diets,respectively.After 8 weeks,oral glucose tolerance test were performed and plasma fasting glucose,lipid profile,and insulin were measured.HOMA-IR and insulin sensitive index(ISI) were calculated. Epididymal and kidney peripheral adipose tissue were weighed and fat-body ratio was calculated.RBP4 mRNA and GLUT4 mRNA were determined by reverse transcript polymerase chain reaction(RT-PCR).Results:The rats fed with high saturated fatty acid diet and high trans fatty acids diets had impaired glucose tolerance,higher fasting insulin levels,HOMA-IR, triglyceride,larger fat-body ratio,and lower ISI than those fed with chow diet.RBP4 mRNA expression level in adipose tissue of rats fed with high saturated fatty acid diet and high trans fatty acids diet were higher than those fed with chow diet,respectively (P<0.05),whereas GLUT4 mRNA expression levels were lower(P<0.05).Single factor analysis showed that the level of RBP4 mRNA in adipose tissue of rats is positive correlated to total cholesterol(r=0.525),insulin(r=0.456),HOMA-IR (r=0.462),low density lipoprotein-cholesterol(r=0.595),fat-body ratio(r=0.603), triglyceride(r=0.38),plasma fasting glucose(r=0.39) and free fatty acid(r=0.41,P <0.05),while negative correlated to GLUT4 mRNA(r=—0.56),ISI(r=—0.472,P<0.05).And it had no relationship with body weight and the weight of epididymal peripheral adipose tissue.Multiple linear regression found that adipose tissue weight,body fat ratio,HOMA-IR,free fatty acid,ISI,triglyceride influence the level of RBP-4 mRNA.Besides,compared with rats that fed with high saturated fatty acid diet,the level of body fat ratio,fasting insulin,HOMA-IR and ISI are higher in rats fed with high trans fatty acids diets.Its free fatty acid is also higher,but the level of high density lipoprotein-cholesterol is much lower than rats fed with high trans fatty acids diets(P<0.05).Conclusion:High saturated fatty acid diet and high trans fatty acids diet both induce insulin resistance of rats and also induced RBP4 mRNA over expression in adipose tissue,and the fuction of the latter is stronger.RBP4 is closely related with plasma fasting glucose,lipid profile,the weight of adipose tissue and insulin resistance.It might be a marker of metabolic syndrome and may associated with visceral obesity.