scholarly journals AMP-activated protein kinase activation and NADPH oxidase inhibition by inorganic nitrate and nitrite prevent liver steatosis

2018 ◽  
Vol 116 (1) ◽  
pp. 217-226 ◽  
Author(s):  
Isabel Cordero-Herrera ◽  
Mikael Kozyra ◽  
Zhengbing Zhuge ◽  
Sarah McCann Haworth ◽  
Chiara Moretti ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Metabolic Syndrome ◽  
Protein Kinase ◽  
Nadph Oxidase ◽  
Liver Steatosis ◽  
Metabolic Effects ◽  
Dietary Nitrate ◽  
No Signaling ◽  
Nitrate And Nitrite ◽  
Amp Activated Protein Kinase

Advanced age and unhealthy dietary habits contribute to the increasing incidence of obesity and type 2 diabetes. These metabolic disorders, which are often accompanied by oxidative stress and compromised nitric oxide (NO) signaling, increase the risk of adverse cardiovascular complications and development of fatty liver disease. Here, we investigated the therapeutic effects of dietary nitrate, which is found in high levels in green leafy vegetables, on liver steatosis associated with metabolic syndrome. Dietary nitrate fuels a nitrate–nitrite–NO signaling pathway, which prevented many features of metabolic syndrome and liver steatosis that developed in mice fed a high-fat diet, with or without combination with an inhibitor of NOS (l-NAME). These favorable effects of nitrate were absent in germ-free mice, demonstrating the central importance of host microbiota in bioactivation of nitrate. In a human liver cell line (HepG2) and in a validated hepatic 3D model with primary human hepatocyte spheroids, nitrite treatment reduced the degree of metabolically induced steatosis (i.e., high glucose, insulin, and free fatty acids), as well as drug-induced steatosis (i.e., amiodarone). Mechanistically, the salutary metabolic effects of nitrate and nitrite can be ascribed to nitrite-derived formation of NO species and activation of soluble guanylyl cyclase, where xanthine oxidoreductase is proposed to mediate the reduction of nitrite. Boosting this nitrate–nitrite–NO pathway results in attenuation of NADPH oxidase-derived oxidative stress and stimulation of AMP-activated protein kinase and downstream signaling pathways regulating lipogenesis, fatty acid oxidation, and glucose homeostasis. These findings may have implications for novel nutrition-based preventive and therapeutic strategies against liver steatosis associated with metabolic dysfunction.

scholarly journals Nebivolol improves diastolic dysfunction and myocardial remodeling through reductions in oxidative stress in the transgenic (mRen2) rat

2012 ◽  
Vol 302 (11) ◽  
pp. H2341-H2351 ◽  
Author(s):  
Lixin Ma ◽  
Rukhsana Gul ◽  
Javad Habibi ◽  
Ming Yang ◽  
Lakshmi Pulakat ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Protein Kinase ◽  
Nadph Oxidase ◽  
Diastolic Dysfunction ◽  
Diastolic Function ◽  
Interstitial Fibrosis ◽  
Left Ventricular ◽  
No Synthase ◽  
Sprague Dawley ◽  
Amp Activated Protein Kinase

Angiotensin II contributes to myocardial tissue remodeling and interstitial fibrosis through NADPH oxidase-mediated generation of oxidative stress in the progression of heart failure. Recent data have suggested that nebivolol, a third-generation β-blocker, improves diastolic dysfunction by targeting nitric oxide (NO) and metabolic pathways that decrease interstitial fibrosis. We sought to determine if targeting NO would improve diastolic function in a model of tissue renin-angiotensin system overactivation. We used the transgenic (TG) (mRen2)27 rat, which overexpresses the murine renin transgene and manifests insulin resistance and left ventricular dysfunction. We treated 6- to 7-wk-old TG (mRen2)27 rats and age-matched Sprague-Dawley control rats with nebivolol (10 mg·kg−1·day−1) or placebo via osmotic minipumps for a period of 21 days. Compared with Sprague-Dawley control rats, TG (mRen2)27 rats displayed a prolonged diastolic relaxation time and reduced initial filling rate associated with increased interstitial fibrosis and left ventricular hypertrophy. These findings were temporally related to increased NADPH oxidase activity and subunits p47 phox and Rac1 and increased total ROS and peroxynitrite formation in parallel with reductions in the antioxidant heme oxygenase as well as the phosphorylation/activation of endothelial NO synthase and PKB/Akt. Treatment with nebivolol restored diastolic function and interstitial fibrosis through increases in the phosphorylation of 5′-AMP-activated protein kinase, Akt, and endothelial NO synthase and reductions in oxidant stress. These results support that targeting NO with nebivolol treatment improves diastolic dysfunction through reducing myocardial oxidative stress by enhancing 5′-AMP-activated protein kinase and Akt activation of NO biosynthesis.

Abstract 337: Activation of Myocardial AMP-activated Protein Kinase by Metformin Prevents Progression of Heart Failure in Dogs; Involvement of eNOS Activation

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Hideyuki Sasaki ◽  
Hiroshi Asanuma ◽  
Masashi Fujita ◽  
Hiroyuki Takahama ◽  
Masanori Asakura ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Heart Failure ◽  
Cell Death ◽  
Protein Kinase ◽  
Left Ventricular ◽  
Vehicle Group ◽  
Mrna Levels ◽  
Compound C ◽  
Amp Activated Protein Kinase

Background; Several studies have shown that metformin activates AMP-activated protein kinase (AMPK), which mediates potent cardioprotection against ischemia-reperfusion injury. AMPK is also activated in experimental failing myocardium, suggesting that activation of AMPK is beneficial for the pathophysiology of heart failure. We investigated whether metformin prevents oxidative stress-induced cell death in rat cardiomyocytes and attenuates the progression of heart failure in dogs. Methods and Results; The treatment with metformin (10 μmol/L) protected the rat cultured cardiomyocytes against cell death due to H 2 O 2 exposure (50 μmol/L) as indicated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), TUNEL staining, and flow cytometry. These effects were blunted by an AMPK inhibitor, compound-C (20 μmol/L), suggesting that the activation of AMPK decreased the extent of apoptosis-induced cell death due to H 2 O 2 exposure. Continuous rapid ventricular pacing (230/min for 4 weeks) in dogs caused heart failure and the treatment with metformin (100 mg/kg/day PO, n=8) decreased left ventricular (LV) end-diastolic dimension (32.8±0.4 vs. 36.5±1.0 mm, p< 0.01) and pressure (11.8±1.1 vs. 22±0.9 mmHg, p< 0.01), and increased LV fractional shortening (18.6±1.8 vs. 9.6±0.7 %, p< 0.01) along with enhanced phosphorylation of AMPK and the decreased the number of TUNEL-positive cells of the LV myocardium compared with the vehicle group (n=8). Interestingly, metformin increased the protein and mRNA levels of endothelial nitric oxide synthase of the LV myocardium and plasma nitric oxide levels. Metformin improved the plasma insulin resistance without increased myocardial GLUT-4 translocation. Furthermore, the subcutaneous administration of AICAR (50 mg/kg/every other day), another AMPK activator mediated the equivalent effects to metformin, strengthening the pivotal role of AMPK in reduction of apoptosis and prevention of heart failure. Conclusions; Activation of myocardial AMPK attenuated the oxidative stress-induced cardiomyocyte apoptosis and prevented the progression of heart failure in dogs, along with eNOS activation. Thus, metformin or AICAR may be applicable as a novel therapy for heart failure.

scholarly journals mTOR Inhibitor Therapy and Metabolic Consequences: Where Do We Stand?

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Aleksandra Kezic ◽  
Ljiljana Popovic ◽  
Katarina Lalic
Keyword(s):  
Protein Kinase ◽  
Glucose Metabolism ◽  
Calorie Restriction ◽  
Mtor Inhibitor ◽  
Hepatic Glucose Production ◽  
Mtor Inhibitors ◽  
Glucose Production ◽  
Metabolic Effects ◽  
Solid Organ ◽  
Amp Activated Protein Kinase

mTOR (mechanistic target of rapamycin) protein kinase acts as a central integrator of nutrient signaling pathways. Besides the immunosuppressive role after solid organ transplantations or in the treatment of some cancers, another promising role of mTOR inhibitor as an antiaging therapeutic has emerged in the recent years. Acute or intermittent rapamycin treatment has some resemblance to calorie restriction in metabolic effects such as an increased insulin sensitivity. However, the chronic inhibition of mTOR by macrolide rapamycin or other rapalogs has been associated with glucose intolerance and insulin resistance and may even provoke type II diabetes. These metabolic adverse effects limit the use of mTOR inhibitors. Metformin is a widely used drug for the treatment of type 2 diabetes which activates AMP-activated protein kinase (AMPK), acting as calorie restriction mimetic. In addition to the glucose-lowering effect resulting from the decreased hepatic glucose production and increased glucose utilization, metformin induces fatty acid oxidations. Here, we review the recent advances in our understanding of the metabolic consequences regarding glucose metabolism induced by mTOR inhibitors and compare them to the metabolic profile provoked by metformin use. We further suggest metformin use concurrent with rapalogs in order to pharmacologically address the impaired glucose metabolism and prevent the development of new-onset diabetes mellitus after solid organ transplantations induced by the chronic rapalog treatment.

scholarly journals Sex Differences in the Metabolic Effects of Testosterone in Sheep

Endocrinology ◽  
2012 ◽  
Vol 153 (1) ◽  
pp. 123-131 ◽  
Author(s):  
Scott D. Clarke ◽  
Iain J. Clarke ◽  
Alexandra Rao ◽  
Michael A. Cowley ◽  
Belinda A. Henry
Keyword(s):  
Skeletal Muscle ◽  
Protein Kinase ◽  
Uncoupling Protein ◽  
Specific Effect ◽  
Metabolic Effects ◽  
Mrna Levels ◽  
Nonesterified Fatty Acids ◽  
Glucose Levels ◽  
Amp Activated Protein Kinase ◽  
The Brain

Adiposity is regulated in a sexually divergent manner. This is partly due to sex steroids, but the differential effects of androgens in males and females are unclear. We investigated effects of testosterone on energy balance in castrated male (n = 6) and female sheep (n = 4), which received 3 × 200 mg testosterone implants for 2 wk or blank implants (controls). Temperature probes were implanted into retroperitoneal fat and skeletal muscle. Blood samples were taken to measure metabolites and insulin. In males, muscle and fat biopsies were collected to measure uncoupling protein (UCP) mRNA and phosphorylation of AMP-activated protein kinase and Akt. Testosterone did not change food intake in either sex. Temperature in muscle was higher in males than females, and testosterone reduced heat production in males only. In fat, however, temperature was higher in the castrate males compared with females, and there was no effect of testosterone treatment in either sex. Preprandial glucose levels were lower, but nonesterified fatty acids were higher in females compared with males, irrespective of testosterone. In males, the onset of feeding increased UCP1 and UCP3 mRNA levels in skeletal muscle, without an effect of testosterone. During feeding, testosterone reduced glucose levels in males only but did not alter the phosphorylation of AMP-activated protein kinase or Akt in muscle. Thus, testosterone maintains lower muscle and fat temperatures in males but not females. The mechanism underlying this sex-specific effect of testosterone is unknown but may be due to sexual differentiation of the brain centers controlling energy expenditure.

AMP-activated protein kinase inhibits MPP+-induced oxidative stress and apoptotic death of SH-SY5Y cells through sequential stimulation of Akt and autophagy

2019 ◽  
Vol 863 ◽  
pp. 172677 ◽  
Author(s):  
Maja Jovanovic-Tucovic ◽  
Ljubica Harhaji-Trajkovic ◽  
Marija Dulovic ◽  
Gordana Tovilovic-Kovacevic ◽  
Nevena Zogovic ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Protein Kinase ◽  
Apoptotic Death ◽  
Amp Activated Protein Kinase ◽  
Stimulation Of
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