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Abstract. Moderate caloric restriction prolongs lifespan. Changes in oxidative stress and hormesis may be involved in this process. The aim of this study is to examine the effects of different levels of chronic caloric restriction (CR) and acute fasting on stress response and oxidative stress parameters in rat liver and plasma. Forty-two rats were divided into groups: control group, calorie-restricted groups with intake of 80-90%, 60-70%, 40-50%, 20-30% of daily caloric needs and acute fasting group. To determine alanine aminotransferase (ALT), aspartate aminotransferase (AST) and superoxide dismutase (SOD) activity, concentration of corticosterone, nitrites and nitrates (NO x ), malondialdehyde (MDA) and glutathione (GSH), liver samples and blood were collected. Increase in plasma corticosterone concentration and AST and ALT activity was found in severe CR. Ingestion 40-50% daily caloric needs or less increased liver MDA and NO x concentration and decreased SOD activity. Ingestion 60-70% daily caloric needs increased Mn-SOD activity, GSH and NO x . In acute fasting group and group taking 20-30% daily caloric needs, GSH was significantly lower than in control group. Severe CR and acute fasting increase oxidative damage and decrease antioxidative capacity of hepatocytes. Moderate CR increases antioxidative capacity of hepatocytes due to increase in Mn-SOD activity and GSH concentration, which might have a role in anti-aging and hormetic mechanism of CR.

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Development of nonalcoholic fatty liver disease (NAFLD) occurs through initial steatosis and subsequent oxidative stress. The aim of this study was to examine the effects of α-lipoic acid (LA) on methionine-choline deficient (MCD) diet-induced NAFLD in mice. Male C57BL/6 mice (n=21) were divided into three groups (n=7 per group): (1) control fed with standard chow, (2) MCD2 group--fed with MCD diet for 2 weeks, and (3) MCD2+LA group--2 weeks on MCD receiving LA i.p. 100 mg/kg/day. After the treatment, liver samples were taken for pathohistology, oxidative stress parameters, antioxidative enzymes, and liver free fatty acid (FFA) composition. Mild microvesicular hepatic steatosis was found in MCD2 group, while it was reduced to single fat droplets evident in MCD2+LA group. Lipid peroxidation and nitrosative stress were increased by MCD diet, while LA administration induced a decrease in liver malondialdehyde and nitrates+nitrites level. Similary, LA improved liver antioxidative capacity by increasing total superoxide dismutase (tSOD), manganese SOD (MnSOD), and copper/zinc-SOD (Cu/ZnSOD) activity as well as glutathione (GSH) content. Liver FFA profile has shown a significant decrease in saturated acids, arachidonic, and docosahexaenoic acid (DHA), while LA treatment increased their proportions. It can be concluded that LA ameliorates lipid peroxidation and nitrosative stress in MCD diet-induced hepatic steatosis through an increase in SOD activity and GSH level. In addition, LA increases the proportion of palmitic, stearic, arachidonic, and DHA in the fatty liver. An increase in DHA may be a potential mechanism of anti-inflammatory and antioxidant effects of LA in MCD diet-induced NAFLD.

Insulin resistance, oxidative stress, and proinflammatory cytokines play a key role in pathogenesis of nonalcoholic fatty liver disease (NAFLD). The aim of our study was to investigate the dynamics of oxidative/nitrosative stress in methionine–choline-deficient (MCD) diet -induced NAFLD in mice. Male C57BL/6 mice were divided into following groups: group 1: control group on standard diet; group 2: MCD diet for 2, 4, and 6 weeks (MCD2, MCD4, and MCD6, respectively). After treatment, liver and blood samples were taken for histopathology, alanine- and aspartate aminotransferase, acute phase reactants, and oxidative/nitrosative stress parameters. Liver malondialdehyde level was higher in all MCD-fed groups versus control group ( p < 0.01), while nitrites + nitrates level showed a progressive increase. The activity of total superoxide dismutase and its isoenzymes was significantly lower in all MCD-fed groups ( p < 0.01). Although catalase activity was significantly lower in MCD-fed animals at all intervals ( p < 0.01), the lowest activity of this enzyme was evident in MCD4 group. Liver content of glutathione was lower in MCD4 ( p < 0.05) and MCD6 group ( p < 0.01) versus control.Ferritin and C-reactive protein serum concentration were significantly higher only in MCD6 group. Our study suggests that MCD diet induces a progressive rise in nitrosative stress in the liver. Additionally, the most prominent decrease in liver antioxidative capacity is in the fourth week, which implies that application of antioxidants would be most suitable in this period, in order to prevent nonalcoholic steatohepatitis but not the initial NAFLD phase.

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The aim of our study was to investigate the effects of binge drinking on prooxidant/antioxidant system in rat liver in acute cadmium (Cd) intoxication. In experiment male Wistar rats were used and divided into following groups: 1. control, 2. ethanol-treated group, in five subsequent doses of 2 g/kg administered by orogastric tube, 3. Cd-treated group in a single dose of 2.5 mg/kg intraperitoneally, 4. group that received Cd 12 hours after the last dose of ethanol. Blood and liver samples were collected for determination of oxidative stress parameters, 24 hours after treatment. When administered in combination, ethanol and Cd induced a more pronounced increase in serum and liver malondialdehyde level than either of these substances alone (p<0.01). Liver manganese superoxide dismutase (MnSOD) activity was increased both in ethanol and Cd-treated group (p<0.01), while liver copper/zinc superoxide dismutase (Cu/ZnSOD) activity was elevated in Cd group only. However, when administered in combination, ethanol and Cd induced a more pronounced decrease in liver MnSOD and Cu/ZnSOD activity 24 hours after treatment (p<0.01). Based on our study, it can be concluded that ethanol may act sinergistically with Cd in inducing lipid peroxidation and reduction in liver SOD activity

Caloric restriction (CR) prevents or delays a wide range of aging-related diseases possibly through alleviation of oxidative stress. The aim of our study was to examine the effect of CR on oxidative and nitrosative cardiac damage in rats, induced by acute ethanol intoxication. Male Wistar rats were divided into following groups: control; calorie-restricted groups with intake of 60-70% (CR60-70) and 40-50% of daily energy needs (CR40-50); ethanol-treated group (E); calorie-restricted, ethanol-treated groups (CR60-70 + E, CR40-50 + E). Ethanol was administered in five doses of 2 g/kg every 12 h, while the duration of CR was five weeks before ethanol treatment. Malondialdehyde level was significantly lower in CR60-70 + E and significantly higher in CR40-50 + E vs. control. Nitrite and nitrate level was significantly higher in CR40-50 + E compared to control group. Activity of total superoxide dismutase (SOD) and its isoenzyme, copper/zinc-SOD (Cu/ZnSOD), was significantly higher in CR60-70 + E and lower in CR40-50 + E vs. control. Activity of manganese-SOD (MnSOD), that is also SOD isoenzyme, was significantly lower in  CR40-50 + E compared to control group. Plasma content of sulfhydryl (SH) groups was significantly higher in CR60-70 group vs. control. Plasma concentration of total cholesterol, triacylglycerol, low-density lipoproteins and high-density lipoproteins was significantly lower in CR60-70 group compared to control values. Food restriction to 60-70% of daily energy needs has a protective effect on acute ethanol-induced oxidative and nitrosative cardiac damage, at least partly due to alleviation of ethanol-induced decrease in SOD activity, while restriction to 40-50% of energy needs aggravates lipid peroxidation and nitrosative stress.