The Antidiabetic and Antihypercholesterolemic Effects of an Aqueous Extract from Pecan Shells in Wistar Rats.

Pecan shell decoction has been used to treat diabetes and obesity-related diseases. In this study, the effects of a pecan shell aqueous extract (PSAE) were evaluated in diabetic and hypercholesterolemic Wistar rats, analyzing clinical signs and biochemical as well as genotoxic and mutagenic parameters, to assess its safe use and efficacy. Diabetes mellitus and hypercholesterolemia were induced with streptozotocin (STZ) and tyloxapol, respectively. Animals were orally administered PSAE (100 mg/kg body weight, b.w.) for 28 days. Biochemical analyses and genotoxicity were evaluated in blood samples and mutagenicity was evaluated in bone marrow. PSAE treatment decreased the blood glucose level and stabilized clinical signs of diabetes in diabetic rats. PSAE diminished the increase in total cholesterol and triglyceride levels in hypercholesterolemic rats. The urea levels were higher in diabetic rats than in treated ones; however, creatinine values were the same in all groups. Elevated transaminase levels were suggestive of liver injuries in diabetic rats, and were not altered by PSAE treatment. PSAE did not show genotoxic or mutagenic activities in diabetic and hypercholesterolemic rats, indicating its safe use at 100 mg/kg b.w. not only in healthy rats but also in rats with induced metabolic alterations. The findings on PSAE's efficacy may indicate that its successful and popular use is in accordance with our results. Thus, PSAE might be a potential candidate for medical purposes as a complementary treatment of diabetes and hypercholesterolemia.

Antioxidant effect of N-acetylcysteine on prehepatic portal hypertensive gastropathy in rats.

BACKGROUND: Portal hypertension is a clinical syndrome associated with the development of a hyperdynamic circulation and gastroesophageal varices. Aim. To evaluate the antioxidant effect of N-acetylcysteine on portal hypertensive rats. MATERIAL AND METHODS: Portal hypertension was induced by partial portal vein ligation (PPVL). Oxidative damage in the stomach was measured by lipoperoxidation trough thiobarbituric acid reactive substances (TBARS) and antioxidant enzyme activity; we also evaluated nitrates and nitrites level and histology stained by hematoxylin-eosin. We performed evaluation of portal pressure and measurement of vessels diameter. Liver damage was evaluated by measuring hepatic enzymes. The animals were divided in four experimental groups (n = 6): Sham-operated (SO), SO + NAC, Partial portal vein ligation (PPVL) and PPVL + NAC. N-acetylcysteine (10 mg/kg ip) was administered daily for 7 days and started 8 days after surgery. RESULTS: The portal hypertensive group showed an increase in portal pressure, vessels diameter, levels of TBARS and nitrates and nitrites when compared to SO group. These values were accompanied by a decrease in superoxide dismutase (SOD) and glutathione peroxidase (GPx) antioxidant enzyme activity. Histology showed dilated vessels in the gastric mucosa in the PPVL group. NAC was able to decrease portal pressure values, vessels diameter, TBARS and also nitrates and nitrites levels when compared to PPVL group. Furthermore, PPVL+NAC group presented an increase in SOD and GPx activity. N-acetylcysteine attenuated damage in gastric mucosa. CONCLUSION: Oxidative stress is associated with portal hypertension and that antioxidant NAC is able to minimize damages of PPVL in rats.

Melatonin restores zinc levels, activates the Keap1/Nrf2 pathway, and modulates endoplasmic reticular stress and HSP in rats with chronic hepatotoxicity.

BACKGROUND: Melatonin (MLT) is a potent antioxidant molecule that is shown to have a beneficial effect in various pathological situations, due to its action against free radicals. AIM: To evaluate the effect of MLT on carbon tetrachloride (CCl4) induced liver injury in rats in terms of oxidative stress, reticular stress, and cell damage. METHODS: Twenty male Wistar rats (230-250 g) were divided into four groups: Control rats, rats treated with MLT alone, rats treated with CCl4 alone, and rats treated with CCl4 plus MLT. CCl4 was administered as follows: Ten doses every 5 d, ten every 4 d, and seven every 3 d. MLT was administered intraperitoneally at a dose of 20 mg/kg from the 10th wk to the end of the experiment (16th wk). RESULTS: MLT was able to reduce the release of liver enzymes in the bloodstream and to decrease oxidative stress in CCl4 treated rats by decreasing the level of thiobarbituric acid reactive substances and increasing superoxide dismutase activity, with a lower reduction in serum zinc levels, guaranteeing a reduction in liver damage; additionally, it increased the expression of nuclear factor (erythroid-derived 2)-like 2 and decreased the expression of Kelch-like ECH-associated protein 1. MLT also decreased the expression of the proteins associated with endoplasmic reticulum stress, i.e., glucose-regulated protein 78 and activating transcription factor 6, as well as of heat shock factor 1 and heat shock protein 70. CONCLUSION: MLT has a hepatoprotective effect in an experimental model of CCl4-induced liver injury, since it reduces oxidative stress, restores zinc levels, and modulates endoplasmic reticulum stress.

Melatonin prevents oxidative stress, inflammatory activity, and DNA damage in cirrhotic rats.

BACKGROUND: Cirrhosis is an important health problem characterized by a significant change in liver parenchyma. In animals, this can be reproduced by an experimental model of bile duct ligation (BDL). Melatonin (MLT) is a physiological hormone synthesized from serotonin that has been studied for its beneficial properties, including its antioxidant potential. AIM: To evaluate MLT's effects on oxidative stress, the inflammatory process, and DNA damage in an experimental model of secondary biliary cirrhosis. METHODS: Male Wistar rats were divided into 4 groups: Control (CO), CO + MLT, BDL, and BDL + MLT. MLT was administered (20 mg/kg) daily beginning on day 15 after biliary obstruction. On day 29 the animals were killed. Blood samples, liver tissue, and bone marrow were collected for further analysis. RESULTS: BDL caused changes in biochemical and histological parameters and markers of inflammatory process. Thiobarbituric acid (0.46 ± 0.01) reactive substance levels, superoxide dismutase activity (2.30 ± 0.07) and nitric oxide levels (2.48 ± 0.36) were significantly lower (P < 0.001) n the groups that received MLT. DNA damage was also lower (P < 0.001) in MLT-treated groups (171.6 ± 32.9) than the BDL-only group (295.5 ± 34.8). Tissue damage and the expression of nuclear factor kappa B, interleukin-1ß, Nrf2, NQO1 and Hsp70 were significantly lower in animals treated with MLT (P < 0.001). CONCLUSION: When administered to rats with BDL-induced secondary biliary cirrhosis, MLT effectively restored the evaluated parameters.

Hepatic oxidative stress in an animal model of sleep apnoea: effects of different duration of exposure.

BACKGROUND: Repeated apnoea events cause intermittent hypoxia (IH), which alters the function of various systems and produces free radicals and oxidative stress. METHODS: We investigated hepatic oxidative stress in adult mice subjected to intermittent hypoxia, simulating sleep apnoea. Three groups were submitted to 21 days of IH (IH-21), 35 days of IH (IH-35), or 35 days of sham IH. We assessed the oxidative damage to lipids by TBARS and to DNA by comet assay; hepatic tissue inflammation was assessed in HE-stained slides. Antioxidants were gauged by catalase, superoxide dismutase, glutathione peroxidase activity and by total glutathione. RESULTS: After IH-21, no significant change was observed in hepatic oxidative stress. After IH-35, significant oxidative stress, lipid peroxidation, DNA damage and reduction of endogenous antioxidants were detected. CONCLUSIONS: In an animal model of sleep apnoea, intermittent hypoxia causes liver damage due to oxidative stress after 35 days, but not after 21 days.

Combination of Trans-Resveratrol and ε-Viniferin Induces a Hepatoprotective Effect in Rats with Severe Acute Liver Failure via Reduction of Oxidative Stress and MMP-9 Expression.

Stilbenes are a major grapevine class of phenolic compounds, known for their biological activities, including anti-inflammatory and antioxidant, but never studied in combination. We aimed to evaluate the effect of trans-resveratrol + ε-viniferin as an antioxidant mixture and its role in inflammatory development an in vivo model of severe acute liver failure induced with TAA. Trans-resveratrol + trans-ε-viniferin (5 mg/kg each) was administered to Wistar rats. Resveratrol + ε-viniferin significantly decreased TBARS and SOD activity and restored CAT and GST activities in the treated group. This stilbene combination reduced the expression of TNFα, iNOS, and COX-2, and inhibited MMP-9. The combination of resveratrol + ε-viniferin had a hepatoprotective effect, reducing DNA damage, exhibiting a protective role on the antioxidant pathway by altering SOD, CAT, and GST activities; by downregulating TNFα, COX-2, and iNOS; and upregulating IL-10. Our results suggested that adding viniferin to resveratrol may be more effective in hepatoprotection than resveratrol alone, opening a new perspective on using this stilbene combination in functional diets.

Quercetin administration ameliorates pulmonary complications of cirrhosis in rats.

In the hepatopulmonary syndrome (HPS), a common complication of liver cirrhosis, pulmonary endothelial endothelin B (ETB) receptor overexpression, enhanced endothelial nitric oxide (NO) synthase (eNOS)-derived NO production, and increases in pulmonary inducible NO synthase (iNOS) and heme oxygenase (HO-1) are important factors in the development of vasodilatation. These changes may be influenced by redox-sensitive signaling pathways, including nuclear factor-kappaB (NF-kappaB). In this study, our aim was to evaluate the effects of the flavonoid antioxidant quercetin on the development of HPS in rats with common bile duct ligation (CBDL). Rats were divided into the following 4 groups: rats subjected to CBDL, Sham (rats subjected to simulated CBDL), quercetin-treated sham, and quercetin-treated CBDL. Quercetin (50 mg/kg) was administered for 2 wk starting on d 14 after surgery. Increased NO production, overexpression of iNOS, eNOS, HO-1, and ETB-receptor and activation of NF-kappaB were observed in lung of CBDL rats. Quercetin inhibited oxidative stress, NF-kappaB activation, and the expression of different pulmonary mediators involved in HPS. Quercetin also ameliorated liver injury and reduced the expression of hepatic endothelin-1 and HO-1 in untreated cirrhotic rats. Our findings suggest that quercetin administered after the onset of hepatic injury significantly ameliorates pulmonary complications in CBDL rats and that limitation of cirrhotic evolution contributes to this effect.

Protective action of glutamine in rats with severe acute liver failure.

BACKGROUND: Severe acute liver failure (SALF) is a rare, but high-mortality, rapidly evolving syndrome that leads to hepatocyte degeneration with impaired liver function. Thioacetamide (TAA) is a known xenobiotic, which promotes the increase of the formation of reactive oxygen species. Erythroid 2-related factor 2 (Nrf2) activates the antioxidant protection of cells. Studies have evidenced the involvement of inflammatory mediators in conditions of oxidative stress. AIM: To evaluate the antioxidant effects of glutamine on Nrf2 activation and NFκB-mediated inflammation in rats with TAA-induced IHAG. METHODS: Male Wistar rats (n = 28) were divided into four groups: control, control+glutamine, TAA, and TAA + glutamine. Two TAA doses (400 mg/kg) were administered intraperitoneally, 8 h apart. Glutamine (25 mg/kg) was administered at 30 min, 24 h, and 36 h. At 48 h, blood was collected for liver integrity analysis [aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP)]. The liver was harvested for histology and assessment of oxidative stress [thiobarbituric acid-reactive substances (TBARS), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione (GSH), Nrf2, Kelch-like ECH-associated protein 1 (Keap1), NADPH quinone oxidoreductase1 (NQO1), superoxide dismutase (SOD)] and inflammatory process. RESULTS: TAA caused disruption of the hepatic parenchyma, with inflammatory infiltration, massive necrosis, and ballooning degeneration. Glutamine mitigated this tissue damage, with visible regeneration of hepatic parenchyma; decreased TBARS (P < 0.001), GSH (P < 0.01), IL-1ß, IL6, and TNFα levels (P <0.01) in hepatic tissue; and decreased blood levels of AST, ALT, and ALP (P <0.05). In addition, CAT, GPx, and GST activities were restored in the glutamine group (P <0.01, P <0.01, and P <0.001, respectively vs TAA alone). Glutamine increased expression of Nrf2 (P < 0.05), NQO1, and SOD (P < 0.01), as well as levels of IL-10 (P <0.001), while decreasing expression of Keap1, TLR4, NFκB (P < 0.001), COX-2 and iNOS, (P < 0.01), and reducing NO2 and NO3 levels (P < 0.05). CONCLUSION: In the TAA experimental model of IHAG, glutamine activated the Nrf2 pathway, thus promoting antioxidant protection, and blunted the NFκB-mediated pathway, reducing inflammation.

Antifibrogenic effect of melatonin in rats with experimental liver cirrhosis induced by carbon tetrachloride.

BACKGROUND AND AIM: Liver diseases are a major public health problem, accounting for a significant number of hospital visits and admissions and an increasing mortality rate. Melatonin (MLT) is a powerful antioxidant molecule that has been shown to be beneficial under various conditions. The objective was to evaluate the effect of MLT on experimental liver cirrhosis induced by carbon tetrachloride (CCl4) in rats. METHODS: Twenty male Wistar rats (230-250 g) were divided into four groups. I: control group (CO); II: CO + MLT; III: CCl4; and IV: CCl4 + MLT. CCl4 was administered intraperitoneally (i.p.) as follows: 10 doses every 5 days, 10 doses every 4 days, and 7 doses every 3 days. MLT was administered i.p. at a dose of 20 mg/kg from the 10th week to the end of the experiment (16th week). RESULTS: In the CCl4 + MLT group, we found that MLT caused a decrease in the level of F2-isoprostanes and NQO1 expression. We also found that MLT reduced the inflammatory process as shown by decreased expressions of NF-KB/p65 and inducible nitric oxide synthase (iNOS) and a smaller amount of inflammatory infiltrate. MLT reduced the expression of transforming growth factor beta1 (TGF-ß1), alpha-smooth muscle actin (α-SMA), and vascular endothelial growth factor (VEGF). Picrosirius staining showed that MLT decreases fibrosis. CONCLUSION: MLT has a potent antifibrogenic effect, modulating the parameters of oxidative stress, angiogenesis, and inflammation.

Oxidative stress and cell damage in a model of precancerous lesions and advanced hepatocellular carcinoma in rats.

Hepatocellular carcinoma (HCC) is the third most frequent cause of cancer deaths throughout the world. This study was aimed to analyze oxidative stress and cell damage in a multistage model of liver carcinogenesis induced by diethylnitrosamine (DEN) in rats. Male Wistar rats weighing 145-150 g were divided into three groups: control, precancerous lesions (PL) (which received 100 mg DEN once a week every 6 weeks up to 28 weeks), and advanced HCC (50 mg DEN once/twice per week up to 19 weeks). Lipid peroxidation (TBARS), superoxide dismutase (SOD) activity, and expression of transforming growth factor-1 beta (TGF)-1ß, endothelial and inducible nitric oxide syntahese (eNOS, iNOS), NADPH quinone oxireductase (NQO)-1, nuclear factor erythroid 2-related factor (NrF)2, kelch-like ECH-associated protein (Keap)1 and heat shock protein (HSP)70 were measured. TBARS concentration was augmented in the PL and advanced HCC groups. SOD activity, TGF-1ß and Nrf2 expression were higher in animals with precancerous lesions. In advanced HCC, expression of NQO1 and iNOS increased while there was a decrease in HPS70 expression. Data obtained provide evidence for the differential activation of proteins involved in oxidative stress and cell damage during progression of carcinogenesis in an animal model of HCC.

Fish oil has beneficial effects on behavior impairment and oxidative stress in rats subjected to a hepatic encephalopathy model.

Hepatic encephalopathy (HE) is a severe neuropsychiatric complication of liver failure, in which there is injury to brain cells, particularly neurons and glia. Brain cells and their function are greatly influenced by omega-3 polyunsaturated fatty acids, essential components of cell membrane phospholipids in the brain that are crucial to normal function. This study assessed the effect of chronic fish oil (FO) supplementation (rich in omega-3 polyunsaturated fatty acids) on behavior and oxidative stress of Wistar rats subjected to HE due to a liver failure caused by thioacetamide (TAA) intoxication. The FO supplementation started in an early phase of brain development, that is, at the 21st day of life, and extended to the 122th day of life. The results indicated that cognitive function, specifically spatial memory, was markedly affected in the group that received TAA. Most notably, the ill effects caused by TAA administration were counteracted by FO supplementation. In addition to behavioral improvements, FO also promoted reduction in levels of thiobarbituric acid-reactive substances and superoxide dismutase activity in hippocampus and cerebral cortex. In summary, FO protected against spatial memory deficits and oxidative stress caused by HE in rats subjected to liver lesion due to TAA intoxication. Further studies are necessary to understand the mechanism underlying FO behaviors in rats subjected to encephalopathy.

Rosmarinic acid as a protective agent against genotoxicity of ethanol in mice.

The aim of the present work was to study the protective effects of rosmarinic acid against ethanol-induced DNA damage in mice. The antigenotoxic capacity of rosmarinic acid (100 mg/kg) was tested using pre-, co- and post-treatment with ethanol (5 g/kg). Peripheral blood (1 and 24 h) and brain cells (24 h) were evaluated using the comet assay and bone marrow was analyzed using the micronucleus assay (24 h). The results were compared to data of TBARS, enzymes with antioxidant activity, and DCFH-DA test. Peripheral blood and brain cells show that mean damage index (DI) and damage frequency (DF) values of ethanol with pre-treatment with rosmarinic acid group were significantly lower than in the ethanol group. In brain cells all different treatments with ethanol and rosmarinic acid showed significant decrease in DI and DF mean values when compared to ethanol group and negative control. No significant differences were observed in micronucleus frequency, activity of antioxidant enzymes and TBARS between groups. The DCFH-DA test show a reduction of 18% of fluorescence intensity when compare with ethanol group. The results show that rosmarinic acid could decrease the levels of DNA damage induced by ethanol, for both tissues and treatment periods.

Uso de quercetina a longo prazo em ratos cirróticos / Long term use of quercetin in cirrhotic rats

OBJETIVO: Avaliar o uso a longo prazo do flavonóide quercetina em ratos cirróticos por ligadura de ducto biliar comum (LDB). MÉTODOS: Foram utilizados 32 ratos machos Wistar, sendo submetidos à LDB ou simulação, e distribuídos em 4 grupos: 1) controle, 2) cirróticos, 3) cirróticos tratados com quercetina 50mg/kg, intraperitonealmente, desde o segundo dia após o procedimento cirúrgico; e 4) cirróticos tratados após o décimo quarto dia do procedimento cirúrgico. Analisou-se a função hepática por meio de testes bioquímicos (BT e BD) e atividade enzimática (ALT, AST, FA e GGT). Na análise anatomopatológica, utilizou-se a coloração de Hematoxilina & Eosina (H&E) e de Picrosírius para fibrose. A análise estatística para avaliação de sobrevivência foi realizada pelo teste Kaplan-Meier. RESULTADOS: Os resultados de sobrevivência dos oito animais de cada grupo foram: Grupo 1 = 200 dias de sobrevivência; Grupo 2 = 46 dias; Grupo 3 = 71 dias; e o Grupo 4 = 90 dias. Nos animais com ligadura de ducto biliar comum houve aumento das provas de função hepática e enzimáticas que se reduziu hipoteticamente com o tratamento com quercetina. Foram identificadas cirrose, congestão vascular porta e centrolobular na análise histopatológica por H&E e Picrosírius. CONCLUSÃO: O uso da quercetina diminuiu de maneira significante as alterações bioquímicas provocadas pela cirrose, aumentando o tempo de sobrevivência dos animais com cirrose biliar secundária à LDB, como verificado pelo teste de análise de sobrevivência.