Atorvastatin reduces cardiac and adipose tissue inflammation in rats with metabolic syndrome.

BACKGROUND: Statins are strong inhibitors of cholesterol biosynthesis and help to prevent cardiovascular disease. They also exert additional pleiotropic effects that include an anti-inflammatory action and are independent of cholesterol, but the molecular mechanisms underlying these additional effects have remained unclear. We have now examined the effects of atorvastatin on cardiac and adipose tissue inflammation in DahlS.Z-Leprfa/Leprfa (DS/obese) rats, which we previously established as a model of metabolic syndrome (MetS). METHODS AND RESULTS: DS/obese rats were treated with atorvastatin (6 or 20mgkg-1day-1) from 9 to 13weeks of age. Atorvastatin ameliorated cardiac fibrosis, diastolic dysfunction, oxidative stress, and inflammation as well as adipose tissue inflammation in these animals at both doses. The high dose of atorvastatin reduced adipocyte hypertrophy to a greater extent than did the low dose. Atorvastatin inhibited the up-regulation of peroxisome proliferator-activated receptor γ gene expression in adipose tissue as well as decreased the serum adiponectin concentration in DS/obese rats. It also activated AMP-activated protein kinase (AMPK) as well as inactivated nuclear factor-κB (NF-κB) in the heart of these animals. The down-regulation of AMPK and NF-κB activities in adipose tissue of DS/obese rats was attenuated and further enhanced, respectively, by atorvastatin treatment. CONCLUSIONS: The present results suggest that the anti-inflammatory effects of atorvastatin on the heart and adipose tissue are attributable at least partly to increased AMPK activity and decreased NF-κB activity in this rat model of MetS.

Effects of miglitol, sitagliptin, and initial combination therapy with both on plasma incretin responses to a mixed meal and visceral fat in over-weight Japanese patients with type 2 diabetes. "the MASTER randomized, controlled trial".

AIM: To assess changes in circulating incretin levels and body fat compositions with initial combination therapy with α-glucosidase inhibitor and dipeptidyl peptidase-4 inhibitor in patients with type 2 diabetes (T2D). METHODS: In this multicenter open-label 24-week trial, Japanese over-weight (BMI ≥ 25 kg/m(2)) patients with T2D not taking medication or taking metformin and/or sulfonylurea were randomly assigned to receive either 50mg of miglitol three times a day (M, n=14), 50mg of sitagliptin once a day (S, n=14), or a combination of both (M+S, n=13). Changes in plasma incretin levels during a meal tolerance test (MTT) and body fat composition with impedance method were evaluated. RESULTS: During MTT, postprandial plasma glucose levels decreased more after M+S than after M or S, and postprandial serum insulin levels decreased significantly after M and M+S whereas they increased after S. After M, active gastric inhibitory polypeptide (aGIP) decreased significantly at 30 min despite a significant increase at 120 min. After S, aGIP levels increased significantly throughout the MTT. After M+S, aGIP increased significantly at 0 and 120 min despite of significant decrease at 30 min. M+S further enhanced postprandial active glucagon-like peptide-1 levels during MTT than S did. Total body fat mass decreased significantly after M and M+S. Visceral fat mass decreased significantly only after M+S. Serum adiponectin increased significantly only after M+S. CONCLUSIONS: In over-weight patients with T2D, M+S may have a beneficial effect on adiposity with relation to these different effects on two incretins.

Mechanism underlying the efficacy of combination therapy with losartan and hydrochlorothiazide in rats with salt-sensitive hypertension.

Although thiazide diuretics are commonly used to supplement angiotensin receptor blockers for treatment of hypertension, the mechanism underlying the therapeutic effects of this drug combination remains unclear. We investigated the antihypertensive and cardioprotective effects of combination therapy with losartan (LOS) and hydrochlorothiazide (HCTZ), in comparison with those of either drug alone, in Dahl salt-sensitive hypertensive rats. Rats fed a high-salt diet from 6 weeks of age were treated with LOS, HCTZ, both drugs (COMB) and vehicle from 6 to 11 weeks. The salt-induced increase in systolic blood pressure was attenuated moderately by LOS and to a greater extent by HCTZ and COMB. Left ventricular (LV) hypertrophy and fibrosis, diastolic dysfunction, as well as angiotensin-converting enzyme and angiotensin II type 1A (AT(1A)) receptor gene expression were attenuated similarly by LOS and HCTZ and more so by COMB. LOS downregulated expression of the AT(1A) receptor gene, without affecting that of the AT(2) receptor gene, in the aorta. In contrast, neither HCTZ nor COMB affected aortic expression of the AT(1A) receptor gene, but both markedly upregulated that of the AT(2) receptor gene. The salt-induced decrease in the plasma concentration of nitric oxide metabolites was attenuated substantially by LOS and abolished by both HCTZ and COMB. In conclusion, the combination of LOS and HCTZ attenuated hypertension, as well as LV remodeling and diastolic dysfunction, more effectively than did LOS or HCTZ alone in rats with salt-sensitive hypertension. Modulation of the cardiac and vascular renin-angiotensin system may have contributed to these beneficial effects of the drug combination.

Accurate detection of drug-induced delayed ventricular repolarization with a suitable correction formula in Langendorff guinea pig heart.

The aims of this study were to determine a suitable method to correct the ventricular repolarization period against the RR interval in isolated perfused Langendorff guinea pig heart and to clarify the reliability of this model using several drugs. QT and RR intervals from an electrocardiogram and the epicardial monophasic action potential duration (MAP(90)) were measured. Two drugs clinically known to be QT-prolonging (E-4031, moxifloxacin) and two known to be non-QT-prolonging (verapamil, zatebradine) were used for the study. To determine a method of correcting the ventricular repolarization period against RR interval, heart rates were slowed with 0.3 µM zatebradine, a specific bradycardiac agent, and then accelerated with atrial pacing to obtain a wide range of MAP(90)/RR relationships. An exponential rate-correction model elicited the most appropriate algorithm for the relationship among the four models tested. Based on linear regression analysis, the exponential showed superior dissociation of corrected MAP(90)s against RR intervals than generic Bazett's and Fridericia's formulae. E-4031 and moxifloxacin prolonged the corrected QT (QTc) intervals and MAP(90) under atrial pacing at a cycle length of 0.25 sec (MAP(90(pacing))) dose-dependently; verapamil and zatebradine failed to prolong them, indicating that the reliability of this model was excellent. MAP(90(pacing)) prolongation by moxifloxacin, the positive compound in the clinical "Thorough QT/QTc Study", was seen at around QTc-prolonging concentrations in clinic, suggesting that the sensitivity would be appropriate for QT evaluation. We therefore concluded that the isolated guinea pig heart model is sufficiently sensitive and useful for assessing the potential QT prolongation of drugs.

Effect of corosolic acid on gluconeogenesis in rat liver.

Corosolic acid (CRA), an active component of Banaba leaves (Lagerstroemia speciosa L.), decreases blood glucose in diabetic animals and humans. In this study, we investigated the mechanism of action of CRA on gluconeogenesis in rat liver. CRA (20-100 microM) dose-dependently decreased gluconeogenesis in perfused liver and in isolated hepatocytes. Fructose-2,6-bisphosphate (F-2,6-BP), a gluconeogenic intermediate, plays a critical role in hepatic glucose output by regulating gluconeogenesis and glycolysis in the liver. CRA increased the production of F-2,6-BP along with a decrease in intracellular levels of cAMP both in the presence and in the absence of forskolin in isolated hepatocytes. While a cAMP-dependent protein kinase (PKA) inhibitor inhibited hepatic gluconeogenesis, the drug did not intensify the inhibitory effect of CRA on hepatic gluconeogenesis in isolated hepatocytes. These results indicate that CRA inhibits gluconeogenesis by increasing the production of F-2,6-BP by lowering the cAMP level and inhibiting PKA activity in isolated hepatocytes. Furthermore, CRA increased glucokinase activity in isolated hepatocytes without affecting glucose-6-phosphatase activity, suggesting the promotion of glycolysis. These effects on hepatic glucose metabolism may underlie the various anti-diabetic actions of CRA.

14-3-3 and calmodulin control subcellular distribution of Kir/Gem and its regulation of cell shape and calcium channel activity.

Individual members of the RGK family of Ras-related GTPases, which comprise Rad, Gem/Kir, Rem and Rem2, have been implicated in important functions such as the regulation of voltage-gated calcium channel activity and remodeling of cell shape. The GTPase Kir/Gem inhibits the activity of calcium channels by interacting with the beta-subunit and also regulates cytoskeleton dynamics by inhibiting the Rho-Rho kinase pathway. In addition, Kir/Gem interacts with 14-3-3 and calmodulin, but the significance of this interaction on Kir/Gem function is poorly understood. Here, we present a comprehensive analysis of the binding of 14-3-3 and calmodulin to Kir/Gem. We show that 14-3-3, in conjunction with calmodulin, regulates the subcellular distribution of Kir/Gem between the cytoplasm and the nucleus. In addition, 14-3-3 and calmodulin binding modulate Kir/Gem-mediated cell shape remodeling and downregulation of calcium channel activity. Competition experiments show that binding of 14-3-3, calmodulin and calcium channel beta-subunits to Kir/Gem is mutually exclusive, providing a rationale for the observed regulatory effects of 14-3-3 and calmodulin on Kir/Gem localization and function.