Antioxidant and anti-inflammatory action of melatonin in an experimental model of secondary biliary cirrhosis induced by bile duct ligation.

AIM: To evaluate the effects of melatonin (Mel) on oxidative stress in an experimental model of bile duct ligation (BDL). METHODS: Male Wistar rats (n = 32, weight ± 300 g) were allocated across four groups: CO (sham BDL), BDL (BDL surgery), CO + Mel (sham BDL and Mel administration) and BDL + Mel (BDL surgery and Mel administration). Mel was administered intraperitoneally for 2 wk, starting on postoperative day 15, at a dose of 20 mg/kg. RESULTS: Mel was effective at the different standards, reestablishing normal liver enzyme levels, reducing the hepatosomatic and splenosomatic indices, restoring lipoperoxidation and antioxidant enzyme concentrations, reducing fibrosis and inflammation, and thereby reducing liver tissue injury in the treated animals. CONCLUSION: The results of this study suggest a protective effect of Mel when administered to rats with secondary biliary cirrhosis induced by BDL.

N-acetylcysteine modulates angiogenesis and vasodilation in stomach such as DNA damage in blood of portal hypertensive rats.

AIM: To evaluate the antioxidant effect of N-acetylcysteine (NAC) on the stomach of rats with portal hypertension. METHODS: Twenty-four male Wistar rats weighing ± 250 g were divided into four experimental groups (n = 6 each): Sham-operated (SO), SO + NAC, partial portal vein ligation (PPVL), and PPVL + NAC. Treatment with NAC in a dose of 10 mg/kg (i.p.) diluted in 0.6 mL of saline solution was administered daily for 7 d starting 8 d after the surgery. Animals from the PPVL and SO group received saline solution (0.6 mL) for the same period of time as the PPVL + NAC and SO + NAC group. On the 15(th) day the animals were anesthetized and we evaluated portal pressure by cannulating mesenteric artery. After, we removed the stomach for further analysis. We performed immunohistochemical analysis for endothelial nitric oxide synthase (eNOS), vascular endothelial growth factor (VEGF), and nitrotirosine (NTT) proteins in stomach. We also evaluated eNOS and VEGF by Western blot analysis and assessed DNA damage in blood samples by the comet assay. RESULTS: The portal hypertension group exhibited increases in portal pressure when compared to SO group (29.8 ± 1.8 vs 12.0 ± 0.3 mmHg) (P < 0.001). The same was observed when we compared the eNOS (56.8 ± 3.7 vs 13.46 ± 2.8 pixels) (P < 0.001), VEGF (34.9 ± 4.7 vs 17.46 ± 2.6 pixels) (P < 0.05), and NTT (39.01 ± 4.0 vs 12.77 ± 2.3 pixels) (P < 0.05) expression by immunohistochemistry of the PPVL animals with the SO group. The expression of eNOS (0.39 ± 0.03 vs 0.25 ± 0.03 a.µ) (P < 0.01) and VEGF (0.38 ± 0.04 vs 0.26 ± 0.04 a.µ) (P < 0.01) were also evaluated by Western blot analysis, and we observed an increase of both proteins on PPVL animals. We also evaluated the DNA damage by comet assay, and observed an increase on damage index and damage frequency on those animals. NAC decreased portal pressure values in PPVL + NAC animals (16.46 ± 2 vs 29.8 ± 1.8 mmHg) (P < 0.001) when compared to PPVL. The expression of eNOS (14.60 ± 4.1 vs 56.8 ± 3.7 pixels) (P < 0.001), VEGF (19.53 ± 3.2 vs 34.9 ± 4.7 pixels) (P < 0.05) and NTT (21.84 ± 0.7 vs 39.01 ± 4.0 pixels) (P < 0.05) evaluated by immunohistochemistry were also reduced in PPVL + NAC animals. Also, when evaluated by Western blot eNOS expression (0.32 ± 0.03 vs 0.39 ± 0.03 a.µ) (P < 0.05) and VEGF expression (0.31 ± 0.09 vs 0.38 ± 0.04 a.µ) (P < 0.01). Furthermore, NAC modulated DNA damage in PPVL + NAC animals. CONCLUSION: In view of these results, we believe NAC is able to protect the stomach from the alterations induced by the PPVL procedure.

Evaluation of the genotoxic potential of soil contaminated with mineral coal tailings on snail Helix aspersa.

Coal remains an important source of energy, although the fuel is a greater environmental pollutant. Coal is a mixture of several chemicals, especially inorganic elements and polycyclic aromatic hydrocarbons (PAH). Many of these compounds have mutagenic and carcinogenic effects on organisms exposed to this mineral. In the town of Charqueadas (Brazil), the tailings from mining were used for landfill in the lower areas of the town, and the consequence is the formation of large deposits of this material. The purpose of this study was to evaluate the genotoxic potential of soil samples contaminated by coal waste in different sites at Charqueadas, using the land snail Helix aspersa as a biomonitor organism. Thirty terrestrial snails were exposed to different treatments: 20 were exposed to the soil from two different sites in Charqueadas (site 1 and 2; 10 in each group) and 10 non-exposed (control group). Hemolymph cells were collected after 24h, 5days and 7days of exposure and comet assay, micronucleus test, oxidative stress tests were performed. Furthermore, this study quantified the inorganic elements present in soil samples by the PIXE technique and polycyclic aromatic hydrocarbons (PAH) by HPLC. This evaluation shows that, in general, soils from sites in Charqueadas, demonstrated a genotoxic effect associated with increased oxidative stress, inorganic and PAH content. These results demonstrate that the coal pyrite tailings from Charqueadas are potentially genotoxic and that H. aspersa is confirmed to be a sensitive instrument for risk assessment of environmental pollution.