Juliana Tieppo

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.

N-Acetylcysteine Effects on Genotoxic and Oxidative Stress Parameters in Cirrhotic Rats with Hepatopulmonary Syndrome

The aim of this study was to evaluate the potential antioxidant effects of N-acetylcysteine in hepatopulmonary syndrome, a complication of cirrhosis, using an experimental model of common bile duct ligation in rats. Male Wistar rats were divided into four experimental groups: CBDL (animals submitted to common bile duct ligation); Sham (animals submitted to simulated common bile duct ligation); Sham + N-acetylcysteine, and CBDL + N-acetylcysteine. N-acetylcysteine (10 mg/kg, intraperitoneally) was administered for 2 weeks starting on day 14 after surgery. Some alterations in the liver integrity were investigated by evaluation of serum enzymes aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, and arterial blood gases. Lipoperoxidation by thiobarbituric acid-reactive substances assay, superoxide dismutase activity and total nitrates was measured as parameters of oxidative stress, performed on lung homogenates. Micronucleus assay in bone marrow and comet assay in lung, liver and blood were performed to assess the genotoxic effects by oxidative stress. The results showed an improvement in the enzymatic parameters and arterial blood gases, a reduction of lipoperoxidation and in the total nitrates after treatment with N-acetylcysteine. Histological analysis showed vasodilatation in the lung, which was reversed by N-acetylcysteine. Micronuclei frequency and DNA damage in lung and liver were increased in the CBDL group. N-Acetylcysteine caused no genotoxic effect and did not influence the induction of micronucleus in bone marrow and DNA damage in lung and liver. The results suggest protective effects after treatment with N-acetylcysteine in cirrhotic rats with hepatopulmonary syndrome.

Suppression of Amphiregulin/Epidermal Growth Factor Receptor Signals Contributes to the Protective Effects of Quercetin in Cirrhotic Rats

The hepatic wound-healing response to chronic noxious stimuli may lead to liver fibrosis, a key feature of the preneoplastic cirrhotic liver. Fibrogenic cells activate in response to a variety of cytokines, growth factors, and inflammatory mediators. The involvement of members of the epidermal growth factor family in this process has been suggested. Amphiregulin is an epidermal growth factor receptor (EGFR) ligand specifically induced upon liver injury. We investigated the effects of quercetin on the amphiregulin/EGFR signal and on the activation of downstream pathways leading to cell growth. Rats were divided into 4 groups (8 rats/group): rats subjected to common bile duct ligation (CBDL), Sham (rats subjected to simulated CBDL), quercetin-treated sham, and quercetin-treated CBDL (CBDL-Q). Quercetin (50 mg/kg i.p. injection) was administered daily for 2 wk starting on d 14 after surgery. Overexpression of amphiregulin, EGFR, TNFα, IL-6, TGFβ, platelet-derived growth factor (PDGF), extracellular regulated kinase, protein kinase B (Akt), cycloxygenase (COX)-2, and glioma-associated oncogenes (GLI)-1 and-2 were observed in liver of CBDL rats after 4 wk of bile duct ligation. CBDL-Q rats had a significantly diminished expression of amphiregulin and EGFR compared with untreated CBDL rats. Furthermore, mRNA levels of TNFα, IL-6, TGFβ, and PDGF and the protein content of COX-2, GLI-1, and GLI-2 were significantly lower in CBDL-Q rats than in untreated CBDL rats. The findings indicate that quercetin ameliorated activation of survival pathways and downregulated the expression of genes related to inflammation and precancerous conditions. Suppression of amphiregulin/EGFR signals may contribute to this effect.

Quercetin Treatment Ameliorates Systemic Oxidative Stress in Cirrhotic Rats

Our aim was to investigate whether the antioxidant quercetin protects against liver injury and ameliorates the systemic oxidative stress in rats with common bile duct ligation. Secondary biliary cirrhosis was induced through 28 days of bile duct obstruction. Animals received quercetin (Q) after 14 days of obstruction. Groups of control (CO) and cirrhotic (CBDL) animals received a daily 50 mg/kg body weight i.p. injection of quercetin (CO + Q; CBDL + Q) or vehicle (CO; CBDL). Quercetin corrected the reduction in superoxide dismutase (SOD), catalase CAT, and glutathione peroxidase GPx activities and prevented the increase of thiobarbituric acid reactive substances (TBARS), aminotransferases, and alkaline phosphatase in cirrhotic animals. Quercetin administration also corrected the reduced total nitrate concentration in the liver and prevented liver fibrosis and necrosis. These effects suggest that quercetin might be a useful agent to preserve liver function and prevent systemic oxidative stress.

METHIONINE- AND CHOLINE-DEFICIENT DIET INDUCES HEPATIC CHANGES CHARACTERISTIC OF NON-ALCOHOLIC STEATOHEPATITIS

CONTEXT Non-alcoholic steatohepatitis is a disease with a high incidence, difficult diagnosis, and as yet no effective treatment. So, the use of experimental models for non-alcoholic steatohepatitis induction and the study of its routes of development have been studied. OBJECTIVES This study was designed to develop an experimental model of non-alcoholic steatohepatitis based on a methionine- and choline-deficient diet that is manufactured in Brazil so as to evaluate the liver alterations resulting from the disorder. METHODS Thirty male C57BL6 mice divided in two groups (n = 15) were used: the experimental group fed a methionine- and choline-deficient diet manufactured by Brazilian company PragSoluções®, and the control group fed a normal diet, for a period of 2 weeks. The animals were then killed by exsanguination to sample blood for systemic biochemical analyses, and subsequently submitted to laparotomy with total hepatectomy and preparation of the material for histological analysis. The statistical analysis was done using the Students t-test for independent samples, with significance level of 5%. RESULTS The mice that received the methionine- and choline-deficient diet showed weight loss and significant increase in hepatic damage enzymes, as well as decreased systemic levels of glycemia, triglycerides, total cholesterol, HDL and VLDL. The diagnosis of non-alcoholic steatohepatitis was performed in 100% of the mice that were fed the methionine- and choline-deficient diet. All non-alcoholic steatohepatitis animals showed some degree of macrovesicular steatosis, ballooning, and inflammatory process. None of the animals which were fed the control diet presented histological alterations. All non-alcoholic steatohepatitis animals showed significantly increased lipoperoxidation and antioxidant enzyme GSH activity. CONCLUSION The low cost and easily accessible methionine- and choline-deficient diet explored in this study is highly effective in inducing steatosis and steatohepatitis in animal model, alterations that are similar to those observed in human livers.

Ligadura de ducto biliar como modelo de estudo da síndrome hepatopulmonar e estresse oxidativo

BACKGROUND The hepatopulmonary syndrome is characterized by hepatic dysfunction and presence of dilated pulmonary vessels, with alterations in air diffusion that can be demonstrated in the experimental model of common bile duct ligation. AIM To evaluate the oxidative stress in pulmonary tissue of cirrhotic rats with common bile duct ligation. MATERIAL/METHODS We used 12 male Wistar rats weighing between 200-300 g divided in two groups: control (Co = 6) and cirrhotic (Ci = 6). We evaluated aminotransferases, arterial gasometry, lipoperoxidation and chemoluminescence), and antioxidant enzymatic activity with superoxide dismutase. The tissues analyzed for hepatopulmonary syndrome were cirrhotic liver and lung. RESULTS The animals with common bile duct ligation showed alterations in the following aminotransferases: aspartate aminotransferase, Co = 105.3 +/- 43/Ci = 500.5 +/- 90.3, alanine aminotransferase, Co = 78.75 +/- 37.7/Ci = 162.75 +/- 35.4, and alkaline phosphatase, Co = 160 +/- 20.45/Ci = 373 +/- 45.44. The lipoperoxidation and the antioxidant response had significant differences between the groups when evaluated in lung (lipoperoxidation) Co = 0.87 +/- 0.3/Ci = 2.01 +/- 0.9, chemoluminescence Co = 16008.41 +/- 1171.45/Ci = 20250.36 +/- 827.82 superoxide dismutase Co = 6.66 +/- 1.34/Ci = 16.06 +/- 2.67. CONCLUSIONS Our results suggest that in this experimental model of cirrhosis using common bile duct ligation, there is an increase in lipoperoxidation in pulmonary tissue as well as an increase in superoxide dismutases antioxidant activity, suggesting a pulmonary injury caused by secondary biliary cirrhosis.

Avaliação da força muscular respiratória e da função pulmonar em pacientes com insuficiência cardíaca

BACKGROUND: Heart failure (HF) is the inability of the heart to pump enough blood to supply the necessities of the body. Pulmonary function and respiratory muscles can be affected and typical symptoms presented by the patients include discomfort at a minimal exertion. OBJECTIVE: To verify pulmonary function and respiratory muscle strength in patients with class II and III HF as defined by the New York Heart Association (NYHA). METHODS: The study was descriptive and observational, and comprised 12 class II and III HF patients in follow-up at the out-patient. Pulmonary function assessments [Forced Expiratory Volume in the first second (FEV1) and Forced Vital Capacity (FVC)] were performed using microspirometry and respiratory muscle strength [Maximal Expiratory Pressure (MEPmax) and Maximal Inspiratory Pressure (MIPmax)] were evaluated using a pressure transducer (Globalmed™). RESULTS: Differences were found between the functional classes II and III in relation to pulmonary function: FEV1 (II: 91.17±19.87; III: 68.17±21.78); FVC (II: 68.17±21.78; III: 73.67±22.94); and respiratory muscle strength: MIPmax (II: 71.67±40.70; III: 53.33±29.27) and MEPmax (II: 98.83±34.56; III: 58.33±15.06). The class II were higher for all study parameters, only MEPmax revealed a statistically significant difference. CONCLUSION: The pulmonary function and respiratory muscle strength are impaired in heart failure patients class III patients, particularly in relation to MEPmax.

Modelos experimentais para avaliação das alterações pulmonares na síndrome hepatopulmonar

OBJECTIVE The aim of this study was to identify the best experimental model in which to observe the pulmonary alterations characterizing hepatopulmonary syndrome (HPS). METHODS Male Wistar rats, with mean weight of 250 g, were used in four experimental models: inhaled carbon tetrachloride; intraperitoneal carbon tetrachloride; partial portal vein ligation; and bile duct ligation (BDL). The animals in all groups were divided into control and experimental subgroups. The following variables were measured: transaminase levels; blood gases; lipoperoxidation, using thiobarbituric acid reactive substances (TBARS) and chemiluminescence; and levels of superoxide dismutase (SOD) anti-oxidant activity. Anatomopathological examination of the lung was also performed. RESULTS There were statistically significant differences between the BDL control and BDL experimental groups: aspartate aminotransferase (105.3 +/- 43 vs. 500.5 +/- 90.3 IU/L); alanine aminotransferase (78.75 +/- 37.7 vs. 162.75 +/- 35.4 IU/L); alkaline phosphatase (160 +/- 20.45 vs. 373.25 +/- 45.44 IU/L); arterial oxygen tension (85.25 +/- 8.1 vs. 49.9 +/- 22.5 mmHg); and oxygen saturation (95 +/- 0.7 vs. 73.3 +/- 12.07%). Lipoperoxidation and antioxidant activity also differed significantly between the two BDL groups (control vs. experimental): TBARS (0.87 +/- 0.3 vs. 2.01 +/- 0.9 nmol/mg protein); chemiluminescence (16008.41 +/- 1171.45 vs. 20250.36 +/- 827.82 cps/mg protein); and SOD (6.66 +/- 1.34 vs. 16.06 +/- 2.67 IU/mg protein). The anatomopathological examination confirmed pulmonary vasodilatation in the BDL model. In the other models, there were no alterations that were characteristic of HPS. CONCLUSIONS The data obtained suggest that the BDL model can be used in future studies involving hepatic alterations related to oxidative stress and HPS.

Alterações pulmonares em um modelo de diabetes mellitus em ratos: o efeito da terapia antioxidante

OBJECTIVE To evaluate structural alterations of the lung in rats with diabetes mellitus (DM), by quantifying oxidative stress and DNA damage, as well as to determine the effects that exogenous superoxide dismutase (SOD) has on such alterations. METHODS A controlled experimental study involving 40 male Wistar rats, divided into four groups (10 animals each): control; SOD-only (without DM but treated with SOD); IDM-only (with streptozotocininduced DM but untreated); and IDM+SOD (with streptozotocin-induced DM, treated with SOD). The animals were evaluated over a 60-day period, day 0 being defined as the day on which the streptozotocin-injected animals presented glycemia > 250 mg/dL. The SOD was administered for the last 7 days of that period. At the end of the study period, samples of lung tissue were collected for histopathological analysis, evaluation of tissue oxidative stress, and assessment of DNA damage. RESULTS There were no significant differences among the groups regarding DNA damage. In the IDM-only group, there was a significant increase in the extracellular matrix and significantly greater hyperplasia of the capillary endothelium than in the SOD-only and control groups. In addition, there were significant changes in type II pneumocytes and macrophages, suggesting an inflammatory process, in the IDM-only group. However, in the IDM+SOD group, there was a reduction in the extracellular matrix, as well as normalization of the capillary endothelium and of the type II pneumocytes. CONCLUSIONS Exogenous SOD can reverse changes in the lungs of animals with induced DM.