The aim of this study was to estimate the effect of carnitine supplementation on lipid disorders and peripheral tissue insulin sensitivity in a non-obese animal model of insulin resistance, the hereditary hypertriglyceridemic (HHTg) rat. Male HHTg rats were fed a standard diet, and half of them received daily doses of carnitine (500 mg·kg(-1) body weight) for 8 weeks. Rats of the original Wistar strain were used for comparison. HHTg rats exhibited increased urinary excretion of free carnitine and reduced carnitine content in the liver and blood. Carnitine supplementation compensated for this shortage and promoted urinary excretion of acetylcarnitine without any signs of (acyl)carnitine accumulation in skeletal muscle. Compared with their untreated littermates, carnitine-treated HHTg rats exhibited lower weight gain, reduced liver steatosis, lower fasting triglyceridemia, and greater reduction of serum free fatty acid content after glucose load. Carnitine treatment was associated with increased mitochondrial biogenesis and oxidative capacity for fatty acids, amelioration of oxidative stress, and restored substrate switching in the liver. In skeletal muscle (diaphragm), carnitine supplementation was associated with significantly higher palmitate oxidation and a more favorable complete to incomplete oxidation products ratio. Carnitine supplementation further enhanced insulin sensitivity ex vivo. No effects on whole-body glucose tolerance were observed. Our data suggest that some metabolic syndrome-related disorders, particularly fatty acid oxidation, steatosis, and oxidative stress in the liver, could be attenuated by carnitine supplementation. The effect of carnitine could be explained, at least partly, by enhanced substrate oxidation and increased fatty acid transport from tissues in the form of short-chain acylcarnitines.
- MeSH
- genetická predispozice k nemoci MeSH
- homeostáza MeSH
- hypertriglyceridemie genetika metabolismus MeSH
- inzulinová rezistence MeSH
- játra metabolismus MeSH
- karnitin aplikace a dávkování analogy a deriváty krev metabolismus farmakologie moč MeSH
- kosterní svaly metabolismus MeSH
- krysa rodu rattus MeSH
- ledviny účinky léků metabolismus MeSH
- metabolismus lipidů účinky léků MeSH
- mitochondriální DNA genetika MeSH
- oxidační stres účinky léků MeSH
- potravní doplňky MeSH
- regulace genové exprese účinky léků fyziologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Nonalcoholic fatty liver disease is associated with chronic oxidative stress. In our study, we explored the antioxidant effect of antidiabetic metformin on chronic [high-fat diet (HFD)-induced] and acute oxidative stress induced by short-term warm partial ischemia-reperfusion (I/R) or on a combination of both in the liver. Wistar rats were fed a standard diet (SD) or HFD for 10 wk, half of them being administered metformin (150 mg·kg body wt(-1)·day(-1)). Metformin treatment prevented acute stress-induced necroinflammatory reaction, reduced alanine aminotransferase and aspartate aminotransferase serum activity, and diminished lipoperoxidation. The effect was more pronounced in the HFD than in the SD group. The metformin-treated groups exhibited less severe mitochondrial damage (markers: cytochrome c release, citrate synthase activity, mtDNA copy number, mitochondrial respiration) and apoptosis (caspase 9 and caspase 3 activation). Metformin-treated HFD-fed rats subjected to I/R exhibited increased antioxidant enzyme activity as well as attenuated mitochondrial respiratory capacity and ATP resynthesis. The exposure to I/R significantly increased NADH- and succinate-related reactive oxygen species (ROS) mitochondrial production in vitro. The effect of I/R was significantly alleviated by previous metformin treatment. Metformin downregulated the I/R-induced expression of proinflammatory (TNF-α, TLR4, IL-1β, Ccr2) and infiltrating monocyte (Ly6c) and macrophage (CD11b) markers. Our data indicate that metformin reduces mitochondrial performance but concomitantly protects the liver from I/R-induced injury. We propose that the beneficial effect of metformin action is based on a combination of three contributory mechanisms: increased antioxidant enzyme activity, lower mitochondrial ROS production, and reduction of postischemic inflammation.
- MeSH
- adenosintrifosfát metabolismus MeSH
- antiflogistika farmakologie MeSH
- antioxidancia farmakologie MeSH
- apoptóza účinky léků MeSH
- časové faktory MeSH
- cytoprotekce MeSH
- dieta s vysokým obsahem tuků MeSH
- energetický metabolismus účinky léků MeSH
- jaterní mitochondrie účinky léků metabolismus patologie MeSH
- játra účinky léků metabolismus patologie MeSH
- mediátory zánětu metabolismus MeSH
- metformin farmakologie MeSH
- modely nemocí na zvířatech MeSH
- nealkoholová steatóza jater farmakoterapie etiologie metabolismus patologie MeSH
- oxidační stres účinky léků MeSH
- peroxidace lipidů účinky léků MeSH
- potkani Wistar MeSH
- reaktivní formy kyslíku metabolismus MeSH
- reperfuzní poškození etiologie metabolismus patologie prevence a kontrola MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Publikační typ
- abstrakt z konference MeSH
- MeSH
- bilirubin * MeSH
- biologické markery * analýza MeSH
- C-reaktivní protein * MeSH
- klinické zkoušky jako téma MeSH
- kyseliny mastné omega-3 * aplikace a dávkování farmakologie imunologie terapeutické užití MeSH
- lidé MeSH
- malabsorpční syndromy * MeSH
- nemoci jater * metabolismus terapie MeSH
- nenasycené mastné kyseliny * aplikace a dávkování farmakologie terapeutické užití MeSH
- parenterální výživa * MeSH
- pilotní projekty * MeSH
- zánět * diagnóza patologie terapie MeSH
- žlučové kyseliny a soli * metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
Autophagy is essential for successful white adipocyte differentiation but the data regarding the timing and relevance of autophagy action during different phases of adipogenesis are limited. We subjected 3T3-L1 preadipocytes to a standard differentiation protocol and inhibited the autophagy within time-limited periods (days 0-2; 2-4; 4-6; 6-8) by asparagine or 3-methyladenine. In the normal course of events, both autophagy flux and the mRNA expression of autophagy related genes (Atg5, Atg12, Atg16, beclin 1) is most intensive at the beginning of differentiation (days 0-4) and then declines. The initiation of differentiation is associated with a 50% reduction of the mitochondrial copy number on day 2 followed by rapid mitochondrial biogenesis. Preadipocytes and differentiated adipocytes differ in the mRNA expression of genes involved in electron transport (Nufsd1, Sdhb, Uqcrc1); ATP synthesis (ATP5b); fatty acid metabolism (CPT1b, Acadl); mitochondrial transporters (Hspa9, Slc25A1) and the TCA cycle (Pcx, Mdh2) as well as citrate synthase activity. Autophagy inhibition during the first two days of differentiation blocked both phenotype changes (lipid accumulation) and the gene expression pattern, while having no or only a marginal effect over any other time period. Similarly, autophagy inhibition between days 0-2 inhibited mitotic clonal expansion as well as mitochondrial network remodeling. In conclusion, we found that autophagy is essential and most active during an initial stage of adipocyte differentiation but it is dispensable during its later stages. We propose that the degradation of preadipocyte cytoplasmic structures, predominantly mitochondria, is an important function of autophagy during this phase and its absence prevents remodeling of the mitochondrial gene expression pattern and mitochondrial network organization.
- MeSH
- adipogeneze účinky léků genetika MeSH
- asparagin farmakologie MeSH
- autofagie účinky léků genetika MeSH
- buněčná diferenciace účinky léků genetika MeSH
- buňky 3T3-L1 MeSH
- mitochondrie účinky léků metabolismus MeSH
- myši MeSH
- tukové buňky cytologie účinky léků MeSH
- vývojová regulace genové exprese účinky léků genetika MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Publikační typ
- abstrakt z konference MeSH
- Publikační typ
- abstrakt z konference MeSH
- Publikační typ
- abstrakt z konference MeSH
In this study, we focused on an analysis of biguanides effects on mitochondrial enzyme activities, mitochondrial membrane potential and membrane permeability transition pore function. We used phenformin, which is more efficient than metformin, and evaluated its effect on rat liver mitochondria and isolated hepatocytes. In contrast to previously published data, we found that phenformin, after a 5 min pre-incubation, dose-dependently inhibits not only mitochondrial complex I but also complex II and IV activity in isolated mitochondria. The enzymes complexes inhibition is paralleled by the decreased respiratory control index and mitochondrial membrane potential. Direct measurements of mitochondrial swelling revealed that phenformin increases the resistance of the permeability transition pore to Ca(2+) ions. Our data might be in agreement with the hypothesis of Schäfer (1976) that binding of biguanides to membrane phospholipids alters membrane properties in a non-specific manner and, subsequently, different enzyme activities are modified via lipid phase. However, our measurements of anisotropy of fluorescence of hydrophobic membrane probe diphenylhexatriene have not shown a measurable effect of membrane fluidity with the 1 mM concentration of phenformin that strongly inhibited complex I activity. Our data therefore suggest that biguanides could be considered as agents with high efficacy but low specifity.
- MeSH
- biguanidy farmakologie MeSH
- fenformin farmakologie MeSH
- inhibitory enzymů farmakologie MeSH
- jaterní mitochondrie účinky léků enzymologie MeSH
- krysa rodu rattus MeSH
- metformin farmakologie MeSH
- potkani Wistar MeSH
- respirační komplex I antagonisté a inhibitory fyziologie MeSH
- respirační komplex II antagonisté a inhibitory fyziologie MeSH
- respirační komplex IV antagonisté a inhibitory fyziologie MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Publikační typ
- abstrakt z konference MeSH
