Pitavastatin Upregulates Nitric Oxide Synthases in the Kidney of Spontaneously Hypertensive Rats and Wistar-Kyoto Rats

Impacts of High Fructose Diet and Chronic Exercise on Nitric Oxide Synthase and Oxidative Stress in Rat Kidney

Chronic exercise (Ex) exerts antihypertensive and renoprotective effects in rats fed a high fructose diet (HFr). To elucidate the mechanisms, the impacts of an HFr and Ex on the nitric oxide (NO) system and oxidative stress in the kidney were examined. Rats were fed a control diet or an HFr, and a part of the HFr-fed rats underwent treadmill running for 12 weeks. The HFr did not affect nitrate/nitrite (NO_x) levels in plasma and urine, and Ex increased the NO_x levels. The HFr increased thiobarbituric acid reactive substance (TBARS) levels in plasma and urine, and Ex decreased the HFr-increased TBARS levels in plasma. The HFr increased the neuronal and endothelial NO synthase (nNOS and eNOS) expressions, and Ex enhanced the HFr-increased eNOS expression. The HFr inhibited the eNOS phosphorylation at serine 1177, and Ex restored the HFr-inhibited eNOS phosphorylation. The HFr increased xanthine oxidase and NADPH oxidase activities, and Ex restored the HFr-increased xanthine oxidase activity but enhanced the HFr-increased NADPH oxidase activity. The HFr increased the nitrotyrosine levels, and Ex attenuated the HFr-increased levels. These results indicate that although Ex enhances the HFr-increased eNOS expression and NADPH oxidase activity, an HFr inhibits renal eNOS phosphorylation and NO bioavailability, whereas Ex ameliorates them.

A comprehensive review on the lipid and pleiotropic effects of pitavastatin

The 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors, or statins, are administered as first line therapy for hypercholesterolemia, both in primary and secondary prevention. There is a growing body of evidence showing that beyond their lipid-lowering effect, statins have a number of additional beneficial properties. Pitavastatin is a unique lipophilic statin with a strong effect on lowering plasma total cholesterol and triacylglycerol. It has been reported to have pleiotropic effects such as decreasing inflammation and oxidative stress, regulating angiogenesis and osteogenesis, improving endothelial function and arterial stiffness, and reducing tumor progression. Based on the available studies considering the risk of statin-associated muscle symptoms it seems to be also the safest statin. The unique lipid and non-lipid effects of pitavastatin make this molecule a particularly interesting option for the management of different human diseases. In this review, we first summarized the lipid effects of pitavastatin and then strive to unravel the diverse pleiotropic effects of this molecule.

The Impact of Antarctic Ice Microalgae Polysaccharides on D-Galactose-Induced Oxidative Damage in Mice

Antarctic ice microalgae (Chlamydomonas sp.) are a polysaccharide-rich natural marine resource. In this study, we evaluated the impact of Antarctic ice microalgae polysaccharides (AIMP) on D-galactose-induced oxidation in mice. We conducted biological and biochemical tests on tissue and serum samples from mice treated with AIMP. We found that AIMP administration was associated with improved thymus, brain, heart, liver, spleen, and kidney index values. We also found that AIMP treatment inhibited the reduced aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, superoxide dismutase, glutathione peroxidase, and glutathione levels as well as the increased serum, splenic, and hepatic nitric oxide and malondialdehyde levels arising from oxidation in these animals. Pathological examination revealed that AIMP also inhibited D-galactose-induced oxidative damage to the spleen, liver, and skin of these animals. AIMP was additionally found to promote the upregulation of neuronal nitric oxide synthase, endothelial nitric oxide synthase, cuprozinc-superoxide dismutase, manganese superoxide dismutase, catalase, heme oxygenase-1, nuclear factor erythroid 2-related factor 2, γ-glutamylcysteine synthetase, and NAD(P)H dehydrogenase [quinone] 1 as well as the downregulation of inducible nitric oxide synthase in these animals. High-performance liquid chromatography analysis revealed AIMP to be composed of five monosaccharides (mannitol, ribose, anhydrous glucose, xylose, and fucose). Together, these results suggest that AIMP can effectively inhibit oxidative damage more readily than vitamin C in mice with D-galactose-induced oxidative damage, which underscores the value of developing AIMP derivatives for food purposes.

Gasotransmitter signaling in energy homeostasis and metabolic disorders

Gasotransmitters are small molecules of gases, including nitric oxide (NO), hydrogen sulfide (H₂S), and carbon monoxide (CO). These three gasotransmitters can be endogenously produced and regulate a wide range of pathophysiological processes by interacting with specific targets upon diffusion in the biological media. By redox and epigenetic regulation of various physiological functions, NO, H₂S, and CO are critical for the maintenance of intracellular energy homeostasis. Accumulated evidence has shown that these three gasotransmitters control ATP generation, mitochondrial biogenesis, glucose metabolism, insulin sensitivity, lipid metabolism, and thermogenesis, etc. Abnormal generation and metabolism of NO, H₂S, and/or CO are involved in various abnormal metabolic diseases, including obesity, diabetes, and dyslipidemia. In this review, we summarized the roles of NO, H₂S, and CO in the regulation of energy homeostasis as well as their involvements in the metabolism of dysfunction-related diseases. Understanding the interaction among these gasotransmitters and their specific molecular targets are very important for therapeutic applications.

Central Glucagon-like Peptide-1 Receptor Signaling via Brainstem Catecholamine Neurons Counteracts Hypertension in Spontaneously Hypertensive Rats

Glucagon-like peptide-1 receptor (GLP-1R) agonists, widely used to treat type 2 diabetes, reduce blood pressure (BP) in hypertensive patients. Whether this action involves central mechanisms is unknown. We here report that repeated lateral ventricular (LV) injection of GLP-1R agonist, liraglutide, once daily for 15 days counteracted the development of hypertension in spontaneously hypertensive rats (SHR). In parallel, it suppressed urinary norepinephrine excretion, and induced c-Fos expressions in the area postrema (AP) and nucleus tractus solitarius (NTS) of brainstem including the NTS neurons immunoreactive to dopamine beta-hydroxylase (DBH). Acute administration of liraglutide into fourth ventricle, the area with easy access to the AP and NTS, transiently decreased BP in SHR and this effect was attenuated after lesion of NTS DBH neurons with anti-DBH conjugated to saporin (anti-DBH-SAP). In anti-DBH-SAP injected SHR, the antihypertensive effect of repeated LV injection of liraglutide for 14 days was also attenuated. These findings demonstrate that the central GLP-1R signaling via NTS DBH neurons counteracts the development of hypertension in SHR, accompanied by attenuated sympathetic nerve activity.