pitavastatin and 3-nitrotyrosine

We investigated the effects of co-administration of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor and angiotensin II type 1 receptor blocker (ARB) on nitric oxide (NO) bioavailability in genetically hyperlipidemic rabbits with our newly developed NO sensor. A total of 36 myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits equally derived (n=6 per group) were treated with 1) vehicle (control), 2) hydralazine (15 mg/kg/d), 3) the HMG-CoA reductase inhibitor pitavastatin (P: 0.5 mg/kg/d), 4) the ARB valsartan (V: 5 mg/kg/d), and 5) pitavastatin+valsartan (P+V) together without or 6) with N(G)-nitro-L-arginine methyl ester (L-NAME) for 8 weeks. After treatment, acetylcholine (ACh)-induced NO production was measured as a surrogate for endothelium protective function, and vascular peroxynitrite (a product of superoxide and NO) was measured for assessing dysfunctional endothelial NO synthase activity. Plaque area was quantified by histology as well as optical coherence tomography (OCT). Intra-aortic infusion of ACh produced an increase in plasma NO concentration, which was significantly greater with all drug treatments than with the control. P+V increased ACh-induced NO by 4.1 nmol/L significantly more than either P or V singly. The vascular peroxynitrite concentration was 1.6 pmol/mg protein in the control group and significantly less than those in the P- and V-monotherapy-groups. The lowest peroxynitrite concentration was observed in the P+V group (0.4 pmol/mg protein), which was significantly lower than those in the P- and the V-monotherapy-groups. OCT and histology of the thoracic aorta revealed that the plaque area decreased significantly more with the combination than with the monotherapy. In conclusion, the combined treatment with an HMG-CoA reductase inhibitor and an ARB may have additive protective effects on endothelial function as well as atherosclerotic change.

Topics: Acetylcholine; Angiotensin II Type 1 Receptor Blockers; Animals; Atherosclerosis; Biological Availability; Drug Therapy, Combination; Echocardiography; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Hyperlipidemias; Myocardial Infarction; Nitric Oxide; Quinolines; Rabbits; Reactive Oxygen Species; Tetrazoles; Tyrosine; Valine; Valsartan

It is generally considered that 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) have renoprotective effects via a pathway independent of their cholesterol-lowering cascade. In the kidneys of diabetic nephropathy, monomeric endothelial nitric oxide synthase (eNOS) is thought to be overexpressed; and its dimerization is suppressed. In the present study, we investigated the expression of eNOS and oxidative stress in type 2 diabetes mellitus KK-Ay/Ta mice treated with pitavastatin, one of the statins. The KK-Ay/Ta mice were divided into 3 groups and given pitavastatin intraperitoneally starting at 8 weeks of age for 8 weeks: pitavastatin 3 mg/(kg d) (n=5), pitavastatin 10 mg/(kg d) (n=5), and a control group (n=10). The urinary albumin-creatinine ratio (ACR), urinary 8-hydroxy-2'-deoxyguanosine, body weight, fasting blood glucose, hemoglobin A1c, total cholesterol, and triglyceride were measured; and the intraperitoneal glucose tolerance test was performed. The eNOS, nitrotyrosine, and p47 phox were evaluated by immunohistochemical analyses and/or Western blot analyses. Guanosine triphosphate cyclohydrolase 1 messenger RNA expression in the kidneys was evaluated using a real-time polymerase chain reaction assay. Pitavastatin improved the levels of urinary ACR and 8-hydroxy-2'-deoxyguanosine, intraperitoneal glucose tolerance test, and hemoglobin A1c. Protein levels of monomeric eNOS, nitrotyrosine, and p47 phox in the kidneys were decreased in the pitavastatin-treated groups. Guanosine triphosphate cyclohydrolase 1 messenger RNA expression was significantly increased in the pitavastatin groups. There were no significant changes in body weight, levels of fasting blood glucose, serum total cholesterol, triglyceride, and blood pressure among all groups. Pitavastatin improved urinary ACR apparently because of suppression of eNOS uncoupling and its antioxidant effect in the kidneys of KK-Ay/Ta mice.

Topics: Animals; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Glycated Hemoglobin; GTP Cyclohydrolase; Hydroxymethylglutaryl-CoA Reductase Inhibitors; Immunohistochemistry; Mice; Mice, Inbred C57BL; NADPH Oxidases; Nitric Oxide Synthase Type II; Nitric Oxide Synthase Type III; Protein Kinase C; Quinolines; RNA, Messenger; Tyrosine

3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors are known to modulate carcinogenesis. In this study, we investigated whether a lipophilic HMG-CoA reductase inhibitor pitavastatin suppresses inflammation-related mouse colon carcinogenesis. Male CD-1 (ICR) mice were initiated with a single intraperitoneal injection of azoxymethane (AOM, 10 mg/kg body weight) and promoted by 2% (w/v) dextran sodium sulfate (DSS) in drinking water for 7 days. The experimental diets containing pitavastatin at 2 dose levels (1 and 10 ppm) were fed to male CD-1 (ICR) mice for 17 weeks, staring 1 week after the cessation of DSS exposure. The effects of dietary pitavastatin on colonic tumor development were assessed at Weeks 5, 10 and 20. Feeding with pitavastatin at both doses significantly inhibited the multiplicity of colonic adenocarcinoma at Week 20. Furthermore, the treatment significantly lowered the positive rates of proliferating cell nuclear antigen and increased the apoptotic index in the colonic epithelial malignancies. The treatment also reduced nitrotyrosine-positivity in the colonic mucosa. Our findings thus show that pitavastatin is effective in inhibiting colitis-related colon carcinogenesis through modulation of mucosal inflammation, oxidative/nitrosative stress, and cell proliferation.

Topics: Animals; Body Weight; Cholesterol; Colonic Neoplasms; DNA, Single-Stranded; Immunohistochemistry; Inflammation; Male; Mice; Molecular Structure; Organ Size; Proliferating Cell Nuclear Antigen; Quinolines; Time Factors; Triglycerides; Tyrosine