Atorvastatin prevents type 2 diabetes mellitus—An experimental study

Association of PPARγ gene expression with postprandial hypertriglyceridaemia and risk of type 2 diabetes mellitus

PURPOSE

Peroxisome proliferator-activated receptor γ (PPARγ) gene is strongly associated with type 2 diabetes mellitus, as well as postprandial lipemia, and plays an important role in Wnt dependent adipogenesis in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT). We aimed to study the expression of PPARγ gene in SAT and VAT to find out its correlation with postprandial hypertriglyceredemia and glucose intolerance.

METHODS

Thirty subjects who were scheduled to undergo abdominal surgery were recruited in three groups (n = 10 in NGT, n = 10 in prediabetes, and n = 10 in T2DM). A standardized oral fat challenge was performed. Anthropometry, plasma glucose, HbA1c, and fasting serum insulin were also measured. SAT and VATs were collected during surgery for PPARγ gene expression studies by real-time PCR.

RESULTS

PPARγ gene expression was 5.5-fold lower in T2DM and 1.7-fold lower in prediabetes as compared with NGT subjects in VAT. There was a significant negative correlation of expression of PPARγ gene in VAT {Tgauc (r = -0.57, p < 0.007), Peak Tg (r = -0.51, p < 0.01)} as well as in subcutaneous adipose tissue {Tgauc (r = -0.45, p < 0.02)} with PPTg responses measures.

CONCLUSION

Reduced adipocyte expression of PPARγ gene and the resultant postprandial hypertriglyceredemia is associated with greater risk of diabetes and prediabetes.

Efficacy and adverse reaction to different doses of atorvastatin in the treatment of type II diabetes mellitus

Background: Type II diabetes mellitus (T2DM), a persistent metabolic disorder, is primarily characterized by insulin resistance, relative insulin deficiency and dyslipidemia. Here, we aimed to investigate whether different doses of atorvastatin (ATV) affect rats with T2DM. A total of 110 Sprague–Dawley rats were successfully established as T2DM models. Methods: First, the total cholesterol, triglyceride (TG), high-/low-/very-low-density lipoprotein cholesterol (HDL-c/LDL-c/VLDL-c), alanine transaminase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), creatinine (Cr), apolipoprotein Al (ApoA1) and apolipoprotein B (ApoB) levels in rat serum were analyzed. In addition, cholesteryl ester transfer protein (CETP) and retinol-binding protein 4 (RBP4) were also measured. Then, the incidence of adverse reactions was noted. Finally, the pathological study of liver and pancreatic tissues was performed. Results: Rats administered ATV at the doses of 40 and 80 mg/(kg·day) showed down-regulated TG, LDL-c, ApoB, CETP and RBP4 levels yet up-regulated HDL-c and ApoAl levels. Rats administered ATV at a dose of 80 mg/(kg·day) exhibited a higher incidence of adverse reactions and higher ALT and AST levels but lower BUN and Cr levels, which might affect liver and kidney function. Rats administered ATV at the doses of 40 and 80 mg/(kg·day) demonstrated significantly improved liver injury and pancreatic injury induced by T2DM. Conclusion: These data revealed that ATV could improve the lipid metabolism in T2DM rats and 40 mg/(kg·day) may serve as the optimal dose for the reduction of lipid levels and the incidence of adverse effects.

Atorvastatin Treatment for Carotid Intima-Media Thickness in Chinese Patients With Type 2 Diabetes: A Meta-Analysis

Impact of atorvastatin on carotid intima-media thickness (CIMT) in patients with type 2 diabetes is still debating.The aim of our study is to investigate atorvastatin as adjuvant treatment on CIMT in Chinese patients with type 2 diabetes by conducting a meta-analysis based on the randomized controlled trials (RCTs).A systematic search of electronic database of the Pubmed, EMBASE, Cochrane Library, VIP database, China National Knowledge Infrastructure, and Wangfang up to January 2015 was conducted. Randomized controlled trials (RCTs) comparing atorvastatin adjuvant treatment to the hypoglycemic therapies or high-dose atorvastatin versus low-dose atorvastatin therapies for patients with type 2 diabetes were selected.A total of 14 RCTs involving 1345 patients were included. Adjuvant treatment with atorvastatin was associated with a significant reduction in CIMT (weighted mean difference [WMD] = -0.17 mm; 95% confidence interval [CI] -0.22 to -0.12). Compared with the low-dose atorvastatin, high-dose atorvastatin treatment was associated with a significant reduction in CIMT (WMD = -0.17 mm; 95% CI: -0.32 to -0.02). Adjuvant treatment with atorvastatin reduced serum total cholesterol, triglyceride, low-density lipoproteins, and high sensitivity C-reactive protein levels. However, atorvastatin had no significant impact on blood glucose levels.This meta-analysis demonstrated that treatment with atorvastatin significantly reduced CIMT in Chinese patients with type 2 diabetes. Moreover, high-dose atorvastatin appeared to have additional benefits in reducing CIMT than the low-dose atorvastatin.

Vascular injury in diabetic db/db mice is ameliorated by atorvastatin: role of Rac1/2-sensitive Nox-dependent pathways

Oxidative stress [increased bioavailability of reactive oxygen species (ROS)] plays a role in the endothelial dysfunction and vascular inflammation, which underlie vascular damage in diabetes. Statins are cholesterol-lowering drugs that are vasoprotective in diabetes through unknown mechanisms. We tested the hypothesis that atorvastatin decreases NADPH oxidase (Nox)-derived ROS generation and associated vascular injury in diabetes. Lepr(db)/Lepr(db) (db/db) mice, a model of Type 2 diabetes and control Lepr(db)/Lepr(+) (db/+) mice were administered atorvastatin (10 mg/kg per day, 2 weeks). Atorvastatin improved glucose tolerance in db/db mice. Systemic and vascular oxidative stress in db/db mice, characterized by increased plasma TBARS (thiobarbituric acid-reactive substances) levels and exaggerated vascular Nox-derived ROS generation respectively, were inhibited by atorvastatin. Cytosol-to-membrane translocation of the Nox regulatory subunit p47(phox) and the small GTPase Rac1/2 was increased in vessels from db/db mice compared with db/+ mice, an effect blunted by atorvastatin. The increase in vascular Nox1/2/4 expression and increased phosphorylation of redox-sensitive mitogen-activated protein kinases (MAPKs) was abrogated by atorvastatin in db/db mice. Pro-inflammatory signalling (decreased IκB-α and increased NF-κB p50 expression, increased NF-κB p65 phosphorylation) and associated vascular inflammation [vascular cell adhesion molecule-1 (VCAM-1) expression and vascular monocyte adhesion], which were increased in aortas of db/db mice, were blunted by atorvastatin. Impaired acetylcholine (Ach)- and insulin (INS)-induced vasorelaxation in db/db mice was normalized by atorvastatin. Our results demonstrate that, in diabetic mice, atorvastatin decreases vascular oxidative stress and inflammation and ameliorates vascular injury through processes involving decreased activation of Rac1/2 and Nox. These findings elucidate redox-sensitive and Rac1/2-dependent mechanisms whereby statins protect against vascular injury in diabetes.