The Effect Of Simvastatin On The Glucose Metabolism Of Mouse Adipose Cells And Its Mechanism

Research backgroundStatins, the 3-hydroxy-3-methyl-glut-aryl CoA reductase inhibitor,HMG CoA, which is the cornerstone of primary prevention and secondary prevention of atherosclerotic cardiovascular disease.Statins reduce the concentration of Low Density Lipoprotein- Cholesterol(LDL-C) by inhibiting the rate-limiting enzyme of cholesterol synthesis. Statins have been well known as one of the most important of lipid lowering and anti-atherosclerotic drugs. Recent studies have shown that some stains have negative effect on glucose metabolism. Consequently, some people have started to question the treatment status of statins. ObjectiveOur goal was to study the influence of different concentration of a lipophilic statin(simvastatin) on the glucose metabolism of mouse adipose cell and to explore the possible mechanisms. Method1. 3T3-L1 preadipocytes were differentiated to adipocytes by cocktail hormones(induce medium A:5 mg/L insulin,1 μmol/L dexamethasone and 0.5 mmol/L isobutyl-methylxanthine, induce medium B: 10 mg/L insulin). The morphologic changes of 3T3-L1 cells were observed by microscope. Fat droplet were observed in the cytoplasm by Oil red O staining.2. Induced mature 3T3-L1 fat cells were randomly divided into NC group(control group), group A,group B and group C,treated with 10nmol/L insulin and different concentration of simvastatin(0,2,5,10 μmol/L) respectively for 48 hours.3. CCK-8 kit analyzed the influence of different concentrations of simvastatin on 3T3-L1 adipose cell activity.4. The mature 3T3-L1 adipose cells’ glucose consumption was measured by glucose oxidase method.5. Real-Time PCR was used to detect the level of mRNA of GLUT-4,PPAR-γ and IR.6. Western blot was used to detect protein of P-PI3 K, P-Akt, total GLUT-4 and membrane GLUT-4.7. Flow cytometry(FCM) was performed to analyze the change of cell apoptosis,cells cycles,membrane IR and membrane GLUT-4. Results1. 3T3-L1 pre-adipocyte were fibroblastic,and no fat droplet was noted in cytoplasm. After fully differentiated, the adipocytes became bigger,rounder and larger of fat drops accumulated, which looked like the finger-ring.2. Compared with group NC,each treatment concentration of simvastatin had no effect on the cell activity of 3T3L1 adipocytes(all p>0.05).3. Compared with group NC,the glucose consumption was remarkably decreased in adipocyte of simvastatin groups(concentration 10 μmol/L,p<0.05).4. Induced mature 3T3-L1 fat cells were treated with different concentration of simvastatin and the level of P-Akt decreased significantly at high concentration when compared with control group(p<0.05). The level of membrane GLUT-4 was decreased significantly at middle and high concentration when compared with control group(p<0.05). The level of P-PI3 K and total membrane GLUT-4 was decreased a little, but had no significance when compared with control group.5. Induced mature 3T3-L1 fat cells were treated with different concentration of simvastatin and the level of IR m RNA decreased significantly at middle and high concentration when compared with control group(p<0.05); the level of PPAR-γ m RNA decreased significantly at high concentration when compared with control group(p<0.05); the level of GLUT-4 m RNA had changed little when compared with control group(p>0.05).6. Flow cytometry(FCM) showed that the level of membrane GLUT-4 decreased significantly at high concentration when compared with control group(p<0.05) and simvastatin had a little effect on the change of cell apoptosis, cell cycle and the level of membrane IR,but has no statistical significance(p>0.05). ConclusionOur study showed that lipophilic statins(simvastatin) inhibit transport of glucose from extracellular to intracellular by effecting pathway of Ins/IR/IRS-1/PI3-K/AKT/GLUT-4 and PPARγ/GLUT-4, consequently inhibiting the transport of GLUT-4.