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Nonalcoholic fatty liver disease (NAFLD) is one of the most frequent metabolic chronic liver diseases in developed countries and puts the populations at risk of progression to liver necro-inflammation, fibrosis, cirrhosis, and hepatocellular carcinoma. Mitochondrial dysfunction is involved in the onset of NAFLD and contributes to the progression from NAFLD to nonalcoholic steatohepatitis (NASH). Thus, liver mitochondria could become the target for treatments for improving liver function in NAFLD patients. This chapter describes the most important steps used for potential therapeutic interventions in NAFLD patients, discusses current options gathered from both experimental and clinical evidence, and presents some novel options for potentially improving mitochondrial function in NAFLD.

Aim: To investigate in vitro the therapeutic effect and mechanisms of silybin in a cellular model of hepatic steatosis., Methods: Rat hepatoma FaO cells were loaded with lipids by exposure to 0.75 mmol/L oleate/palmitate for 3 h to mimic liver steatosis. Then, the steatotic cells were incubated for 24 h with different concentrations (25 to 100 μmol/L) of silybin as phytosome complex with vitamin E. The effects of silybin on lipid accumulation and metabolism, and on indices of oxidative stress were evaluated by absorption and fluorescence microscopy, quantitative real-time PCR, Western blot, spectrophotometric and fluorimetric assays., Results: Lipid-loading resulted in intracellular triglyceride (TG) accumulation inside lipid droplets, whose number and size increased. TG accumulation was mediated by increased levels of peroxisome proliferator-activated receptors (PPARs) and sterol regulatory element-binding protein-1c (SREBP-1c). The lipid imbalance was associated with higher production of reactive oxygen species (ROS) resulting in increased lipid peroxidation, stimulation of catalase activity and activation of nuclear factor kappa-B (NF-κB). Incubation of steatotic cells with silybin 50 μmol/L significantly reduced TG accumulation likely by promoting lipid catabolism and by inhibiting lipogenic pathways, as suggested by the changes in carnitine palmitoyltransferase 1 (CPT-1), PPAR and SREBP-1c levels. The reduction in fat accumulation exerted by silybin in the steatotic cells was associated with the improvement of the oxidative imbalance caused by lipid excess as demonstrated by the reduction in ROS content, lipid peroxidation, catalase activity and NF-κB activation., Conclusion: We demonstrated the direct anti-steatotic and anti-oxidant effects of silybin in steatotic cells, thus elucidating at a cellular level the encouraging results demonstrated in clinical and animal studies.

Mitochondria play a key role in intracellular energy-generating processes, cell life and death, and are heavily involved in several metabolic pathways by integrating signaling networks; thus, a very large number of conditions are characterized by mitochondrial bioenergetic in humans. Often, mitochondrial changes are directly or indirectly dependent on the activation of intracellular stress cascades or death receptor-mediated pathways. Reactive oxygen species (ROS) formation, glutathione (GSH) depletion, protein alkylation and respiratory complex alterations are major events associated with mitochondrial dysfunction and represent critical initiating events in most forms of chronic liver disease. Through creating an analogy with a disrupted electric circuit gone bad, the present review focuses initially on how hepatic mitochondrial bioenergetics is affected in the context of drug and disease-induced liver failure and how targeting mitochondria with several antioxidant agents can be helpful for preventing the disruption of the mitochondrial electric circuit.

Whereas long-term cholestasis results in intestinal alterations and increased permeability to hepatotoxins, the effect of short-term cholestasis is less known and was investigated in bile duct ligated (BDL) rats. In the intestinal mucosa, at Day 7 BDL, total glutathione and protein sulfhydryl contents had decreased, oxidized glutathione levels increased (P<0.05 vs baseline), and a reduced epithelium thickness with dissolving crypt phenomena was observed in 40% of rats. At Day 10, total protein content, glutathione-related enzyme activities, and the transmural electrophysiological activity had decreased (-50%); by contrast, oxidized proteins doubled (P<0.05), and histological changes were extended to 70% of rats. In vitro exposure to taurodeoxycholate at micellar concentrations determined dysepithelization in normal gut but dissolving crypt phenomena and necrosis in cholestatic bowels. In the liver, ongoing cholestasis was associated with early oxidative changes especially in mitochondria, where protein sulfhydryls were decreased and negatively correlated with glutathione-protein mixed disulfides (r=-0.807, P<0.001). Daily oral administration of tauroursodeoxycholate, a hydrophilic bile salt, and glutathione to BDL rats improved intestinal histology, function, and redox state. In conclusion, short-term cholestasis results in distinctive functional, oxidative, and morphological changes of intestinal mucosa, determined increased vulnerability to toxic injury, and parallel hepatic oxidative damage.

Objective: To review evidence on the diagnosis and management of nonalcoholic fatty liver disease (NAFLD), the most common cause of chronic liver disease in human beings., Sources of Information: The literature was searched for clinical trials and review articles on NAFLD. Levels I and II evidence indicates the benefit of both lifestyle and pharmacologic interventions for NAFLD and nonalcoholic steatohepatitis (NASH)., Main Message: Scientific evidence does not currently support systematic screening for NAFLD. Both NAFLD and NASH are frequently discovered in overweight and obese patients with asymptomatic elevation of serum aminotransferase levels. Ultrasonography detects the presence of a fatty liver, but is unreliable for detecting and quantifying liver fibrosis. Patients with NAFLD should be monitored for possible progression to NASH, particularly if they have diabetes or metabolic syndrome. Although diet and exercise are the mainstays of treatment, medication might be warranted if an appropriate diet and regular physical activity do not improve biochemical markers and liver morphology. Referral for liver biopsy and further evaluation should be considered for those at higher risk of developing NASH., Conclusion: Although most patients with NAFLD have a benign course, some progress to NASH, liver cirrhosis, and hepatocellular carcinoma. These patients should be carefully monitored for progression of disease and treated for associated metabolic disturbances. An integrated approach to care is essential.

Carvedilol, a beta-adrenoreceptor antagonist with strong antioxidant activity, produces a high degree of cardioprotection in a variety of experimental models of ischemic cardiac injury. Although growing evidences suggest specific effects on mitochondrial metabolism, how carvedilol would exert its overall activity has not been completely disclosed. In the present work we have investigated the impact of carvedilol-treatment on mitochondrial bioenergetic functions and ROS metabolism in H9C2 cells. This analysis has revealed a dose-dependent decrease in respiratory fluxes by NAD-dependent substrates associated with a consistent decline of mitochondrial complex I activity. These changes were associated with an increase in mitochondrial H(2)O(2) production, total glutathione and protein thiols content. To evaluate the antioxidant activity of carvedilol, the effect of the exposure of control and carvedilol-pretreated H9C2 cells to H(2)O(2) were investigated. The H(2)O(2)-mediated oxidative insult resulted in a significant decrease of mitochondrial respiration, glutathione and protein thiol content and in an increased level of GSSG. These changes were prevented by carvedilol-pretreatment. A similar protective effect on mitochondrial respiration could be obtained by pre-treatment of the cells with a sub-saturating amount of rotenone, a complex I inhibitor. We therefore suggest that carvedilol exerts its protective antioxidant action both by a direct antioxidant effect and by a preconditioning-like mechanism, via inhibition of mitochondrial complex I.

Nonalcoholic fatty liver disease (NAFLD) is a frequent and potentially progressive chronic liver disease that occurs in subjects who do not abuse alcohol. NAFLD is often associated with obesity, metabolic syndrome and insulin resistance and its more aggressive form, nonalcoholic steatohepatitis (NASH) is a major cause of cryptogenic cirrhosis. NAFLD/NASH are commonly detected because of elevated serum aminotransferase levels, ultrasonographic fatty liver and, at liver histology, steatosis, inflammation, and occasionally fibrosis that may progress to cirrhosis. No established treatment exists for this potentially serious disorder. Current management of NAFLD/NASH is largely conservative and includes diet regimen, aerobic exercise, and interventions towards the associated metabolic abnormalities. The main concern is therefore to decrease liver steatosis and its progression toward steatohepatitis and fibrosis, and the risk of "cryptogenic" cirrhosis. Among the most promising medications, weight reducing drugs, insulin sensitizers and lipid-lowering agents, antioxidants, bile salts, co-factors increasing the mitochondrial transport of fatty acids are being considered. Among them, thiazolidinediones are the most promising drug family that act by activating PPARgamma nuclear receptors and by regulating both microsomal and peroxisomal lipid oxidative pathways. Pharmacological treatment of obesity and probiotics should be considered as potential therapeutic options. In this review, after summarizing the general background on fatty liver, the most current and attractive pharmacological approaches to the problem of NAFLD/NASH are discussed.

Although fatty liver (FL) is considered an innocuous condition, the frequent incidence of graft failure when FL are transplanted has renewed interest in the intracellular disorders causative of or consequent to fatty degeneration. Oxidative stress and nutritional status modulate the tolerance to reperfusion injury in control livers (CL), but very little is known in the case of FL. This study was designed to compare the oxidative balance in CL and FL from fed and food-deprived rats. Serum and liver samples were collected from fed and starved (18 h) rats with CL or FL induced by a choline-deficient diet. Hepatic injury was assessed by transaminase activities and histology. The hepatic concentrations of glutathione (GSH), vitamin C, alpha-tocopherol, thiobarbituric acid-reactive substances (TBARS) and protein carbonyls (PC) were measured. Fed rats with FL had significantly greater TBARS and lower alpha-tocopherol and vitamin C levels than those with CL, whereas GSH and PC concentrations were not affected. Starvation impaired the oxidative balance in both groups. However, compared with the other groups, FL from food-deprived rats generally had the lowest hepatic concentrations of alpha-tocopherol, vitamin C and GSH. Unlike in CL, protein oxidation occurred in FL. These data indicate that fatty liver induced by consumption of a choline-deficient diet is associated with a lower level of antioxidants, which results in lipid peroxidation. Starvation further affects these alterations and extends the damage to proteins. In conclusion, steatosis and starvation may act synergistically on the depletion of antioxidants, predisposing fatty livers to a reduced tolerance to oxidative injury.

Mounting clinical and experimental evidence indicates that free radicals play important roles in many physiological and pathological conditions. The wider application of free radical measurement has increased awareness of functional implications of radical-induced impairment of the oxidative/antioxidative balance. In the following review, the role of oxygen free radicals in some human and experimental pathological conditions is described, with particular emphasis on the mechanisms by which they produce oxidative damage to lipids, proteins, and nucleic bases. The role of free radicals and the activation of the antioxidant systems in arteriosclerosis and ageing, diabetes, ischemia/reperfusion injury, ethanol intoxication, and liver steatosis is discussed. Therapeutic approaches to the use of antioxidants have been described and prospects for clinical use have been considered.

Although it is well known that chronic ethanol abuse produces sexual dysfunction and impaired spermatogenesis, the mechanisms of ethanol-induced testicular alterations are not fully explained. Therefore, the aim of this study was to investigate the mechanisms of testicular oxidative damage in rats given drinking water containing 3% ethanol for 8 weeks. Control rats were pair-fed with saccharose. The mean daily ethanol intake was 4.05 g kg(-1), corresponding to the consumption of 41 of wine (10% alcohol) or 0.71 of whiskey (40% alcohol) by a man of 70 kg body wt. Exposure to ethanol caused a significant depletion in the testicular levels of glutathione (GSH), protein containing sulfhydryl groups, tocopherol and ascorbic acid, and an increase in the concentrations of malondialdehyde (index of lipid peroxidation) and carbonyl proteins (index of protein oxidation). Other effects were decreases in the concentration of adenosine 5'-triphosphate and in the activity of glutathione peroxidase, and an increase in the activity of alcohol dehydrogenase. In summary, this study shows that in the rat, daily consumption of ethanol in the drinking water increases lipid and protein oxidation. In addition to impaired antioxidant defence, an imbalance in energy production may also play a role in the toxic reaction to alcohol.