-
[show abstract]
[hide abstract]
ABSTRACT: Hepatic ATP-binding cassette transporter A1 (ABCA1) plays a key role in high-density lipoprotein (HDL) production by apolipoprotein A-I (ApoA-I) lipidation. 3-Hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors, statins, increase ABCA1 mRNA levels in hepatoma cell lines, but their mechanism of action is not yet clear. We investigated how statins increase ABCA1 in rat hepatoma McARH7777 cells. Pitavastatin, atorvastatin, and simvastatin increased total ABCA1 mRNA levels, whereas pravastatin had no effect. Pitavastatin also increased ABCA1 protein. Hepatic ABCA1 expression in rats is regulated by both liver X receptor (LXR) and sterol regulatory element-binding protein (SREBP2) pathways. Pitavastatin repressed peripheral type ABCA1 mRNA levels and its LXR-driven promoter, but activated the liver-type SREBP-driven promoter, and eventually increased total ABCA1 mRNA expression. Furthermore, pitavastatin increased peroxisome proliferator-activated receptor α (PPARα) and its downstream gene expression. Knockdown of PPARα attenuated the increase in ABCA1 protein, indicating that pitavastatin increased ABCA1 protein via PPARα activation, although it repressed LXR activation. Furthermore, the degradation of ABCA1 protein was retarded in pitavastatin-treated cells. These data suggest that pitavastatin increases ABCA1 protein expression by dual mechanisms: SREBP2-mediated mRNA transcription and PPARα-mediated ABCA1 protein stabilization, but not by the PPAR-LXR-ABCA1 pathway. [Supplementary Figures: available only at http://dx.doi.org/10.1254/jphs.10241FP].
Journal of Pharmacological Sciences 05/2011; 116(1):107-15. · 2.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Although statins are prescribed as relatively safe and effective drugs for hypercholesterolemic patients, it has been reported that a significant side effect, myopathy, occurs infrequently during medication. Moreover, because statins decrease cardiac ubiquinone levels, the risk of cardiac dysfunction has been suggested. This study sought to evaluate and compare the cytotoxicity of statins (cerivastatin, pitavastatin, fluvastatin, simvastatin, atorvastatin and pravastatin) in cultured human skeletal muscle cells (HSkMCs) and the effects on ubiquinone levels in statin-treated rat skeletal muscle and heart. Cerivastatin, the most potent inhibitor of HMG-CoA reductase, showed the strongest cytotoxicity (over 10-fold) among the statins examined, while the effects of the others were in a similar range. In rat experiments, neither pitavastatin nor cerivastatin decreased ubiquinone levels in skeletal muscle, but both dose-dependently lowered ubiquinone levels in the heart. As the rates of reduction by pitavastatin (9.6% at 30 mg/kg) and cerivastatin (9.7% at 0.3 mg/kg) were almost equal, it was estimated that cerivastatin reduced ubiquinone levels in the rat heart approximately 100-fold more strongly than pitavastatin, based on the effective doses. We found that cerivastatin showed the most potent cytotoxicity in HSkMCs and strongly lowered ubiquinone levels in the rat heart.
Journal of atherosclerosis and thrombosis 01/2007; 13(6):295-307. · 2.69 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) are the most effective drugs for hypercholesteloremia. However, a significant side effect of statin treatment is rhabdomyolysis. In order to study the effect of statins in skeletal muscle cells, we used a DNA microarray analysis to investigate the changes in gene expression profiles brought about by statins in two skeletal muscle cell lines, namely, differentiated rat L6 myotubes and a human skeletal muscle cell line (hSkMC). In both cell lines, the statins (atorvastatin, cerivastatin and pitavastatin) induced the expression of four genes, which relate to cholesterol metabolism, namely, HMG-CoA synthase 1, HMG-CoA reductase, farnesyl diphosphate synthase and isopentenyl-diphosphate delta isomerase. Statin inhibited the synthesis of cholesterol at least five times more effectively in hSkMCs than in the hepatocytes. In addition, unlike in osteoblasts or coronary artery smooth muscle cells, statins upregulated the mRNA expression of cholesterol-associated enzymes in hSkMCs. These results provide basic information on skeletal muscle cells treated with statins and indicate that the cells are sensitive to the inhibition of HMG-CoA reductase, which may be related to the pathogenesis of muscle damage in statin therapy.
Journal of atherosclerosis and thrombosis 02/2005; 12(3):121-31. · 2.69 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Today 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) are the most often prescribed drugs among the therapeutics for hypercholesterolemia. Pitavastatin is a novel statin that has been developed entirely in Japan from the biological screening to clinical studies persuing more efficatious statin than hitherto known. Preclinical studies on drug metabolism revealed that pitavastatin is distributed selectively to the liver, excreted into bile without metabolic modification, and efficiently re-circulates to the liver to show a prolonged plasma half-life. In guinea pigs, pitavastatin enhanced hepatic LDL receptor activity and reduced VLDL secretion in a liver perfusion study, and it lowered plasma total cholesterol (TC) levels at 0.3 mg/kg and triglyceride (TG) levels at 1 mg/kg, respectively, and more. From these results, pitavastatin is assumed to lower LDL cholesterol (LDL-C) by promoting LDL receptor expression and further potentiate the cholesterol-lowering effect and exert TG-lowering effect by reducing VLDL secretion. (14)C-Pitavastatin is metabolized with CYP2C9 to 8-hydroxy derivative, but its Vmax /Km was about 2 micro l/min/mg, about 1/8 to 1/100 in comparison to the reported values of other statins, indicating that pitavastatin is hardly metabolized. Also, other human P450 species were not inhibited by pitavastatin. Therefore, pitavastatin is considered to have little interaction with drugs through P450. In the summarized clinical results with 862 patients, pitavastatin lowered TC and LDL-C by 28% and 40%, respectively. There was no difference in the frequency of side effects and no serious adverse effect was observed for pitavastatin. Pitavastatin possesses superior plasma lipid-improving effects, induces little drug interaction, and is expected to make a good contribution to the medication of hypercholesterolemia.
Folia Pharmacologica Japonica 06/2004; 123(5):349-62.
-
[show abstract]
[hide abstract]
ABSTRACT: The influence of pitavastatin (CAS 147526-32-7), a potent 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, exerted on fecal and biliary excretion of sterols and bile acids was investigated using guinea pigs. The cumulative amount of [3H] bile acid in bile 0 to 6 h after the injection of high density lipoprotein (HDL), which was labeled with [3H] cholesteryl ester (CE), was slightly decreased with atorvastatin (30 mg/kg, CAS 134523-00-5) and simvastatin (30 mg/kg, CAS 79902-63-9), and the same level as the control was maintained with pitavastatin (3 mg/kg). The amount of excretion of [3H] sterol into bile was significantly increased with atorvastatin and simvastatin, and exhibited a tendency to decline with pitavastatin. The [3H] bile acid/[3H] sterol ratios were significantly lowered with atorvastatin and simvastatin by 41% and 29%, respectively, as compared to the control, and exhibited an upward tendency with pitavastatin (22%). The total amounts of fecal [3H] bile acid from 0 to 7 days were significantly decreased with atorvastatin and simvastatin by 30% and 32%, respectively, and slightly increased with pitavastatin by 8% Furthermore, mRNA expression of the hepatic microsomal cytochrome P-450 enzyme, cholesterol-NADPH: oxygen oxidoreductase (cholesterol 7 alpha-hydroxylase; CYP7A), which is a late limiting enzyme with a bile acid composition, was also decreased with atorvastatin and simvastatin by 54% and 38%, respectively, and slightly increased with pitavastatin (14%). The change in CYP7A mRNA expression was well correlated with the amount of the fecal [3H] bile acid. The bile acid excreting efficacy of pitavastatin was relatively high as compared with atorvastatin or simvastatin. It is suggested that this action may contribute to the powerful cholesterol lowering action of pitavastatin.
Arzneimittel-Forschung 02/2003; 53(5):351-6. · 0.72 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The triglyceride (TG)-lowering effect of pitavastatin (CAS 147526-32-7), a potent 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, was investigated in a guinea pig model of post-prandial lipemia. Plasma TG levels started to rise 2 h after the fat load, reached the maximum at 8 h and then gradually decreased. A 14-day dose of pitavastatin at 3 mg/kg decreased the 8 h plasma TG levels by 59%, and the 0-12 h area under the curve (AUC) of TG levels above the initial levels, by 77%. This effect was also shown with 30 mg/kg of atorvastatin (CAS 134523-00-5), and the same dose of simvastatin (CAS 79902-63-9). The intensity of the action was equivalent for pitavastatin and atorvastatin, but weaker with simvastatin. In order to clarify the mechanism of this action, the effect of pitavastatin exerted on the activity of microsomal triglyceride transfer protein (MTP), which participates in the secretion to the lymph vessel of chyromicron (CM)-TG in the small intestine, and the activity of lipoprotein lipase (LPL), which is the hydrolysis enzyme of the very low density lipoprotein (VLDL)-TG and CM-TG, was examined. However, an influence on the activity of MTP or LPL by pitavastatin was not shown. These results suggested that pitavastatin lowered the postprandial TG levels in guinea pigs by accelerating the remnant clearance, probably through the enhancement of the low density lipoprotein (LDL) receptor. This effect is expected to improve postprandial lipemia.
Arzneimittel-Forschung 02/2003; 53(3):154-8. · 0.72 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The triglyceride-lowering effect of pitavastatin, a potent 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor, was investigated in a rat model of postprandial lipemia. Plasma triglyceride levels started to increase 4 h after the fat load, reached the maximum at 6 h and then gradually decreased. A single dose of pitavastatin (1 mg/kg) significantly suppressed chylomicron-triglyceride secretion into the lymph by 40% and delayed the elevation of plasma triglyceride. Pitavastatin at 1 mg/kg decreased the 6-h plasma triglyceride levels by 53% and at 0.5 mg/kg decreased the 0-12 h area under the curve (AUC) of triglyceride levels by 56%. Atorvastatin also caused decreases, but to a lesser extent. Pitavastatin, and atorvastatin to a lesser extent, reduced the activity of the intestinal microsomal triglyceride transfer protein (MTP) at 6 h. These results suggested that a single dose of pitavastatin lowered postprandial triglyceride levels in rats by decreasing chylomicron-triglyceride secretion, probably through a reduction of intestinal MTP activity and triglyceride droplet formation in the endoplasmic reticulum.
European Journal of Pharmacology 06/2002; 444(1-2):107-13. · 2.52 Impact Factor
