The effect of calorie restriction on acute ethanol-induced oxidative and nitrosative liver injury in rats

Mitigating the effects of time in the heart and liver: the variable effects of short- and long-term caloric restriction

Caloric restriction (CR) is known for its anti-aging benefits, partly due to reduced oxidative stress and enhanced antioxidant defense. However, CR outcomes vary based on its intensity, timing, and duration. This study explored CR's effects on antioxidant activity in the heart and liver of male Wistar rats during aging. We investigated two CR paradigms: long-term CR (LTCR), started early in life, and short-term CR (STCR), initiated in middle or old age for 3 months. Contrary to previous findings of short-term CR deleterious effects of on the nervous system, our results revealed increased levels of key antioxidants after STCR. More specifically, we found an increase in GSH-Px and GSH under STCR that was particularly pronounced in the liver, while an increase in CAT and GR activities was observed in the heart of the STCR groups. Catalase was characterized as an enzyme particularly responsive to CR, as its activity was also increased in both the liver and heart after long-term caloric restriction. Our results highlight a significant tissue-specific response to CR and contribute to our understanding of the dynamic effects of CR, which in turn has implications for refining its therapeutic potential in combating age-related decline.

Impact of Intermittent Fasting and Dietary Restriction on Redox State, Energetic Metabolism, and Liver Injury in Common Bile Duct Ligation Model

The aim of this work was to test whether we can treat cholestasis with dietary approaches applied after the onset of the disease. The effects of intermittent fasting and dietary restriction on liver damage caused by common bile duct ligation (BDL) in rats were studied, with particular attention paid to changes in the activity of enzymes of energy metabolism and antioxidant protection. Morphological changes in liver tissue and serum markers of liver damage were assessed in rats with BDL kept for one month on ad libitum diet, intermittent fasting, or 35% dietary restriction. We studied parameters of glucose metabolism (activity of glycolysis and gluconeogenesis enzymes), TCA cycle, and indicators of oxidative stress and redox status of the liver tissue. Dietary restriction resulted in an increase in gluconeogenesis activity, antioxidant capacity, and autophagy activation. When implemented after BDL, none of the dietary restriction protocols reduced the level of oxidative stress, detrimental morphological and biochemical alterations, or the fibrosis progression. Thus, under severe damage and oxidative stress developing in cholestasis, dietary restrictions are not hepatoprotective and can only be used in a pre-treatment mode.

Effects of dietary restriction on hepatic sulfur-containing amino acid metabolism and its significance in acetaminophen-induced liver injury

Dietary restriction (DR) has been revealed to have health benefits as it induces reduction in oxidative stress. Glutathione (GSH), an important cellular antioxidant, is increased in rodent livers owing to DR; however, the exact mechanism and clinical relevance of DR are yet to be fully understood. In this study, male C57BL/6 mice were administered a 50% restricted diet for 7 d, and the hepatic sulfur-containing amino acid (SAA) metabolism was determined to assess the biosynthesis of GSH. The hepatic methionine level was found to decrease, while the homocysteine, cysteine, and GSH levels were increased owing to decreased betaine-homocysteine methyltransferase (BHMT) and increased CβS, CγL, and glutamate cysteine ligase catalytic subunit (GCLC) proteins in the livers of mice subjected to DR. To determine the effects of DR on drug-induced oxidative liver injury, mice subjected to DR were injected with a toxic dose (300 mg/kg) of acetaminophen (APAP). DR significantly alleviated APAP-induced liver damage and oxidative stress, which might be attributed to the higher levels of GSH and related antioxidant enzyme (GPx, GSTα, and GSTµ) in the livers. The decrease in the levels of hepatic CYP1A, 2E1, and 3A, which imply the inhibition of APAP metabolic activation, could contribute to the lower hepatotoxicity in mice subjected to DR. Overall, our findings revealed that DR stimulated the hepatic transsulfuration pathway and GSH synthesis. The consequent elevation of GSH could thus serve as an important mechanism of DR-mediated liver protection against APAP intoxication.

Effect of intermittent fasting on saving zone of stasis in burn wounds in rats

BACKGROUND

Intermittent Fasting (IF) has proved to have various positive effects on life span, diseases, and healing of tissues in rodents. We evaluated the protective effect of fasting in maintaining the ischemic zones in burn wounds.

METHODS

In this study, 20 rats were divided into two groups where the IF rats were deprived of food for three months. Burn wounds were created by burn comb model on the back of all rats. On days 3 and 21 after injury, five rats in each group were euthanized whereby samples were collected for histopathological, immunohistochemical (Bcl2, P53 and VEGF), and biochemical (MDA, TAC, HP) evaluations.

RESULTS

Histopathological analysis revealed epithelial layer and zone of ischemia remained viable in the intermittent fasting group on day 3. On the 21st day, epithelialization, angiogenesis, inflammation, fibrocyte-fibroblast, and collagen density were different in the ischemic and necrotic zones between the control and intermittent fasting groups (p<0.05). We found no statistical differences in Bcl2, P53, VEGF, MDA, TAC, and HP on day 3 between the intermittent fasting and control groups.

CONCLUSIONS

Intermittent fasting before burn wounds reduces tissue damage caused by ischemia and enhanced the viability of cells in zone of stasis. It also accelerated wound healing by increasing epithelialization and collagen production in the skin and regulating inflammatory responses. This intervention appears to be related to better collagen arrangement and angiogenesis.

Effects of food restriction on the expression of genes related to acetaminophen-induced liver toxicity in rats

It is well known that fasting substantially affects the metabolism of drugs and chemicals. Food restriction also affects drug kinetics, such as absorption, metabolism, and excretion, and therefore, it can potentially modulate the onset of chemical toxicity or drug-induced adverse reactions. In the present study, the expression of drug-metabolizing enzyme genes and total glutathione content in the liver, which are related to toxicity induced by overdose of the hepatotoxic drug acetaminophen (N-acetyl-p-aminophenol; APAP), were examined in rats reared under different feeding conditions: ad libitum feeding, 16-h fasting, and food restriction (fed 70% of the average intake of ad libitum feeding for 10 days) conditions. The rats under food restriction conditions as well as fasted rats showed significantly higher expression of Cyp2e1, the gene encoding the enzyme that metabolizes APAP to its toxic metabolite N-acetyl-p-benzoquinone imine (NAPQI). They also had lower levels of liver total glutathione, which detoxifies NAPQI. In contrast, the gene expression of UDP-glucuronosyltransferase 1A6 (Ugt1a6), sulfotransferase 1A1 (Sult1a1), and glutathione S-transferase M1 (Gstm1) was not affected by food restriction or fasting. When APAP was administered (800 mg/kg), histopathological changes were not observed in rats fed ad libitum, while hepatocellular necrosis was observed in most of the rats treated with APAP after fasting or food restriction. Taken together, these results suggest that not only fasting but also food restriction exacerbate APAP-induced acute liver injury, probably by the induction of CYP2E1 and the reduction of liver glutathione contents, in rodents.

Beneficial effects of rosmarinic acid against alcohol-induced hepatotoxicity in rats

Alcohol is a severe hepatotoxicant that causes a variety of liver disorders. Rosmarinic acid (RA), a natural phenol, shows some biological activities, including antioxidant and anti-inflammatory effects. We investigated the effects of RA (10 mg/kg) against ethanol-induced oxidative damage and hepatotoxicity in rats. Animals received ethanol (4 g/kg, i.g.) and (or) RA (10 mg/kg, i.g.) daily for 4 weeks. At the end of the treatment period, rats were weighed and use for biochemical, molecular, and histopathological examinations. Ethanol increased hepatic lipid peroxidation (P < 0.001) and decreased hepatic levels of reduced glutathione (P < 0.01), catalase (P < 0.05), and superoxide dismutase (P < 0.001) compared with control group. RA prevented the prooxidant and antioxidant imbalance induced by ethanol in liver. Furthermore, RA ameliorated the increased liver mass, serum levels of ALT, AST, LDH, TNF-α, and IL-6 in ethanol group. Necrosis and infiltration of inflammatory cells in liver parenchyma were attenuated by RA treatment. Our findings showed that RA prevents ethanol-induced oxidant/antioxidant imbalance and liver injury in an experimental model of ethanol-induced hepatotoxicity. Therefore, RA may be a good candidate to protect against ethanol-induced hepatotoxicity; this deserves consideration and further examination.

Xanthohumol, a prenylated flavonoid from hops (Humulus lupulus L.), protects rat tissues against oxidative damage after acute ethanol administration

Ethanol-mediated free radical generation is directly involved in alcoholic liver disease. In addition, chronic alcohol bingeing also induces pathological changes and dysfunction in multi-organs. In the present study, the protective effect of xanthohumol (XN) on ethanol-induced damage was evaluated by determining antioxidative parameters and stress oxidative markers in liver, kidney, lung, heart and brain of rats. An acute treatment (4 g/kg b.w.) of ethanol resulted in the depletion of superoxide dismutase, catalase and glutathione S-transferase activities and reduced glutathione content. This effect was accompanied by the increased activity of tissue damage marker enzymes (glutamate oxaloacetate transaminase, glutamate pyruvate transaminase and lactate dehydrogenase) and a significant increase in lipid peroxidation and hydrogen peroxide concentrations. Pre-treatment with XN protected rat tissues from ethanol-induced oxidative imbalance and partially mitigated the levels to nearly normal levels in all tissues checked. This effect was dose dependent, suggesting that XN reduces stress oxidative and protects rat tissues from alcohol-induced injury.

The effects of caloric restriction against ethanol-induced oxidative and nitrosative cardiotoxicity and plasma lipids in rats

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.