Investigation Into The Relationship Between The Very Low Density Lipoprotein And The Type 2 Diabetes Mellitus

Part 1 Expression and distribution of VLDLR and its subtypes in various tissues of type 2 diabetic rat.Objective : To investigate the distribution and expression of total amount and two subtypes of VLDLR in various tissues (heart, cerebrum, kidney, muscle, adipose)of normal SD rats and type 2 diabetic SD rats.Method: Various tissues were collected from normal SD rats and diabetic SD rats, the mRNA from various tissues were amplified by semi-quantitative RT-PCR.Result: These findings suggest that, the expression level of VLDLR almost reduced in all collected tissues compared with normal ones, especially in cerebrum, kidney, muscle, adipose. (p<0.01).the type I and type II VLDLR were all decreased in cerebrum and kidney, in muscle, type I VLDLR sharply reduced(P<0.001), but in adipose, type II VLDLR were greatly decreased(P<0.001).Conclusion: The state of insulin-resistant and disorder of lipid metabolism in type 2 diabetes can affect the expression and distribution of VLDLR in tissues. Part 2 Insulin effects on VLDLR gene expression in 3T3-L1 adipocytesObjective : To study the effects of different concentration of insulin and chronic insulin stimulation on the very low density lipoprotein receptor (VLDLR) gene expression in the differentiations of 3T3-L1 preadipocytes, and in mature adipocytes.Method: 3T3-L1 cells were induced to differentiate by using IBMX, dexamethasone and different concentration of insulin. Fully differentiated adipocytes were chronically stimulated by various concentration of insulin. And the relatively quantitative RT-PCR was used to detect the expression of VLDLR during 3T3-LI cells differentiation and mature adipocytes. The microscale way of GOD-PAP was used to detect glucose remained in medium.Result: Compared with control, the increasing insulin concentration boosted the gene expression of VLDLR (p<0.05). VLDLR gene expression was dramatically changed under chronic insulin stimulation in adipocytes, it depended on the concentration of insulin.Conclusion: Insulin plays an important role in induction of 3T3-L1 cells, and it has great effect on VLDLR gene expression. Insulin resistance caused by Chronic high insulin stimulation can down-regulate VLDLR gene expression in mature adipocytes (p<0.001). These provide evidence to further establish a mechanism through which insulin regulate the VLDLR gene expression in adipocytes.