Finerenone Reduces Intrinsic Arterial Stiffness in Munich Wistar Frömter Rats, a Genetic Model of Chronic Kidney Disease.

BACKGROUND: Development of albuminuria and arterial stiffness in Munich Wistar Frömter (MWF) rats, a model of chronic kidney disease, is related to alterations in extracellular matrix, increased oxidative stress, and endothelial dysfunction. Finerenone (FIN), a novel, nonsteroidal, potent, and selective mineralocorticoid receptor antagonist, improves endothelial dysfunction through enhancing nitric oxide (NO) bioavailability and decreasing superoxide anion levels due to an upregulation in vascular and renal superoxide dismutase activity. We hypothesize that FIN reduces arterial stiffness in this model associated to the reduction in albuminuria and matrix metalloproteinase (MMP)-2/9 activity. METHODS: Twelve-week-old MWF rats with established albuminuria and age-matched normoalbuminuric Wistar (W) rats were treated with FIN (10 mg/kg/day, once-daily oral gavage) or with vehicle (control, C) for 4 weeks. RESULTS: Arterial stiffness was significantly higher in mesenteric arteries (MA) of MWF-C as compared to W-C. FIN treatment significantly lowered ß-index, a measure of intrinsic stiffness independent of geometry, in MWF (ßMWF-FIN = 7.7 ± 0.4 vs. ßMWF-C = 9.2 ± 0.5, p < 0.05) positively correlating with urinary albumin excretion. Elastin fenestrae area in the internal elastic lamina of MA from MWF-FIN was significantly larger (+377%, p < 0.05). FIN increased plasma pro-MMP-2 and decreased plasma MMP-2 and MMP-9 activities, correlating with reductions in ß-index. MA from MWF-FIN exhibited higher NO bioavailability and reduced superoxide anion levels compared to MWF-C. CONCLUSION: FIN treatment reduces intrinsic arterial stiffness in MA from MWF rats associated with changes in elastin organization, normalization of MMP-2 and MMP-9 activities, and reduction of oxidative stress. Moreover, reduction of arterial stiffness correlates with reduction in albuminuria.

Impact of caloric restriction on AMPK and endoplasmic reticulum stress in peripheral tissues and circulating peripheral blood mononuclear cells from Zucker rats.

The activation of endoplasmic reticulum (ER) stress and a reduction of AMP-dependent protein kinase (AMPK) phosphorylation have been described in obesity. We hypothesize that a moderate caloric restriction (CR) might contribute to reducing ER stress and increasing AMPK phosphorylation in peripheral tissues from genetically obese Zucker fa/fa rats and in peripheral blood mononuclear cells (PBMCs). Zucker Lean and Zucker fa/fa rats were fed with chow diet either ad libitum (AL) (C, as controls) or 80% of AL (CR) for 2 weeks, giving rise to four experimental groups: Lean C, Lean CR, fa/fa C and fa/fa CR. CR significantly increased AMPK phosphorylation in the liver, perirenal adipose tissue (PRAT) and PBMCs from fa/fa rats but not in the subcutaneous AT (SCAT), suggesting a reduced response of SCAT to CR. Liver samples of fa/fa rats exhibited an increased mRNA expression of PERK, EIF-2α, XBP-1(s), Chop and caspase 3, which was significantly reduced by CR. PRAT exhibited an overexpression of Edem and PDIA-4 in fa/fa rats, but only PDIA-4 expression was reduced by CR. eIF-2α phosphorylation was significantly increased in all studied tissues from fa/fa rats and reduced by CR. A negative correlation was detected between p-AMPK and p-eIF-2α in the liver, PRAT and PBMCs from fa/fa rats but not in SCAT. This study shows that a moderate CR reduces ER stress and improves AMPK phosphorylation in several peripheral tissues and in circulating PBMCs, suggesting that alterations observed in PBMCs could reflect metabolic alterations associated with obesity.

Beneficial Effect of Bariatric Surgery on Abnormal MMP-9 and AMPK Activities: Potential Markers of Obesity-Related CV Risk.

Bariatric surgery (BS) results in sustained weight loss and may reverse inflammation, metabolic alterations, extracellular matrix remodeling and arterial stiffness. We hypothesize that increased stiffening in omental arteries from obese patients might be associated with an increase in MMP activity and a decrease in p-AMPK, together with systemic oxidative stress and inflammation. Moreover, BS could contribute to reversing these alterations. This study was conducted with 38 patients of Caucasian origin: 31 adult patients with morbid obesity (9 men and 22 women; mean age 46 years and BMI = 42.7 ± 1.0 kg/m2) and 7 non-obese subjects (7 women; mean age 45 years and BMI = 22.7 ± 0.6 kg/m2). Seventeen obese patients were studied before and 12 months after BS. The stiffness index ß, an index of intrinsic arterial stiffness, was determined in omental arteries and was significantly higher in obese patients. Levels of phosphorylated AMPK (p-AMPKThr-172) and SIRT-1 were significantly lower in peripheral blood mononuclear cells (PBMCs) from obese patients than those from non-obese patients (p < 0.05) and were normalized after BS. Total and active MMP-9 activities, LDH, protein carbonyls and uric acid were higher in obese patients and reduced by BS. Moreover, there was a correlation between plasmatic LDH levels and the stiffness index ß. BS has a beneficial effect on abnormal MMP-9, LDH and AMPK activities that might be associated with the development of arterial stiffness in obese patients. Since these parameters are easily measured in blood samples, they could constitute potential biomarkers of cardiovascular risk in morbid obesity.

Beneficial effects of murtilla extract and madecassic acid on insulin sensitivity and endothelial function in a model of diet-induced obesity.

Infusions of murtilla leaves exhibit antioxidant, analgesic, and anti-inflammatory properties. Several compounds that are structurally similar to madecassic acid (MA), a component of murtilla leaf extract (ethyl acetate extract, EAE), have been shown to inhibit protein tyrosine phosphatase 1B (PTP1P). The aim of this study was to evaluate if EAE and two compounds identified in EAE (MA and myricetin [MYR]) could have a beneficial effect on systemic and vascular insulin sensitivity and endothelial function in a model of diet-induced obesity. Experiments were performed in 5-week-old male C57BL6J mice fed with a standard (LF) or a very high-fat diet (HF) for 4 weeks and treated with EAE, MA, MYR, or the vehicle as control (C). EAE significantly inhibited PTP1B. EAE and MA, but not MYR, significantly improved systemic insulin sensitivity in HF mice and vascular relaxation to Ach in aorta segments, due to a significant increase of eNOS phosphorylation and enhanced nitric oxide availability. EAE, MA, and MYR also accounted for increased relaxant responses to insulin in HF mice, thus evidencing that the treatments significantly improved aortic insulin sensitivity. This study shows for the first time that EAE and MA could constitute interesting candidates for treating insulin resistance and endothelial dysfunction associated with obesity.

Finerenone Attenuates Endothelial Dysfunction and Albuminuria in a Chronic Kidney Disease Model by a Reduction in Oxidative Stress.

Albuminuria is an early marker of renovascular damage associated to an increase in oxidative stress. The Munich Wistar Frömter (MWF) rat is a model of chronic kidney disease (CKD), which exhibits endothelial dysfunction associated to low nitric oxide availability. We hypothesize that the new highly selective, non-steroidal mineralocorticoid receptor (MR) antagonist, finerenone, reverses both endothelial dysfunction and microalbuminuria. Twelve-week-old MWF (MWF-C; MWF-FIN) and aged-matched normoalbuminuric Wistar (W-C; W-FIN) rats were treated with finerenone (FIN, 10 mg/kg/day p.o.) or vehicle (C) for 4-week. Systolic blood pressure (SBP) and albuminuria were determined the last day of treatment. Finerenone lowered albuminuria by >40% and significantly reduced SBP in MWF. Aortic rings of MWF-C showed higher contractions to either noradrenaline (NA) or angiotensin II (Ang II), and lower relaxation to acetylcholine (Ach) than W-C rings. These alterations were reversed by finerenone to W-C control levels due to an upregulation in phosphorylated Akt and eNOS, and an increase in NO availability. Apocynin and 3-amino-1,2,4-triazole significantly reduced contractions to NA or Ang II in MWF-C, but not in MWF-FIN rings. Accordingly, a significant increase of Mn-superoxide dismutase (SOD) and Cu/Zn-SOD protein levels were observed in rings of MWF-FIN, without differences in p22phox, p47phox or catalase levels. Total SOD activity was increased in kidneys from MWF-FIN rats. In conclusion, finerenone improves endothelial dysfunction through an enhancement in NO bioavailability and a decrease in superoxide anion levels due to an upregulation in SOD activity. This is associated with an increase in renal SOD activity and a reduction of albuminuria.

Arterial stiffness is associated with adipokine dysregulation in non-hypertensive obese mice.

The aim of this study was to characterize alterations in vascular structure and mechanics in murine mesenteric arteries from obese non-hypertensive mice, as well as their relationship with adipokines. Four-week old C57BL/6J male mice were assigned either to a control (C, 10% kcal from fat) or a high-fat diet (HFD, 45% kcal from fat) for 32weeks. HFD animals weighed 30% more than controls (p<0.001), exhibited similar blood pressure, increased leptin, insulin and superoxide anion (O2(-)) levels, and reduced adiponectin levels and nitric oxide (NO) bioavailability. Arterial structure showed an outward remodeling with an increase in total number of both adventitial and smooth muscle cells in HFD. Moreover, HFD mice exhibited an increased arterial stiffness assessed by ß-values (C=2.4±0.5 vs HFD=5.3±0.8; p<0.05) and aortic pulse wave velocity (PWV, C=3.4±0.1 vs HFD=3.9±0.1; p<0.05). ß-Values and PWV positively correlated with leptin, insulin or O2(-) levels, whereas they negatively correlated with adiponectin levels and NO bioavailability (p<0.01). A reduction in fenestrae number together with an increase in type-I collagen amount (p<0.05) were observed in HFD. These data demonstrate that HFD accounts for the development of vascular remodeling and arterial stiffness associated with adipokine dysregulation and oxidative stress, independently of hypertension development.

Involvement of the dorsomedial prefrontal cortex in high-fat food conditioning in adolescent mice.

Our hypothesis is that direct targeting of brain areas involved in the perception of food as a rewarding stimulus accounts for initial hyperphagia caused by high-fat food (HFD). Because adolescents are more sensitive than adults to HFD, studies were performed in five-week old male mice. We analyzed the effect of acute exposition to HFD on c-Fos immunolabeling and we observed that this diet selectively increased c-Fos immunolabeling in the dorsomedial prefrontal cortex (PFC). Furthermore HFD triggered strong and long-lasting conditioned place-preference (CPP) behavior. We also found that the strength of conditioning correlated with the up-regulation of the expression of genes involved in dopaminergic transmission together with a decreased expression of the Per2 gene in the CPF. Our data are coherent with the involvement of the dorsomedial PFC in the perception of HFD as a positive reinforcer and suggest that sensory stimuli activate this brain area after HFD intake.

Remodeling of energy metabolism and absence of electrophysiological changes in the heart of obese hyperleptinemic mice. New insights into the pleiotropic role of leptin.

Dietary treatment with high-fat diets (HFD) triggers diabetes and hyperleptinemia, concomitantly with a partial state of leptin resistance that affects hepatic and adipose tissue but not the heart. In this context, characterized by widespread steatosis, cardiac lipid content remains unchanged. As previously reported, HFD-evoked hyperleptinemia could be a pivotal element contributing to increase fatty-acid (FA) metabolism in the heart and to prevent cardiac steatosis. This metabolic adaptation might theoretically reduce energy efficiency in cardiomyocytes and lead to cardiac electrophysiological remodeling. Therefore the aim of the current study has been to investigate the impact of long-term HFD on cardiac metabolism and electrophysiological properties of the principal ionic currents responsible of the action potential duration in mouse cardiomyocytes. Male C57BL/6J mice were fed a control (10 kcal% from fat) or HFD (45 kcal% from fat) during 32 weeks. Quantification of enzymatic activities regulating mitochondrial uptake of pyruvate and FA showed an increase of both carnitine-palmitoyltransferase and citrate synthase activities together with a decrease of lactate dehydrogenase and pyruvate dehydrogenase activities. Increased expression of uncoupling protein-3, Mn-, and Cu/Zn-superoxide dismutases and catalase were also detected. Total glutathione/oxidized glutathione ratios were unaffected by HFD. These data suggest that HFD triggers adaptive mechanisms aimed at (i) facilitating FA catabolism, and (ii) preventing oxidative stress. All these changes did not affect the duration of action potentials in cardiomyocytes and only slightly modified electrocardiographic parameters.