The Protective Effects of an Adsorbent against Oxidative Stress in Quails Fed Aflatoxin-Contaminated Diet

Abstract

Background: Contamination of crops with aflatoxin is considered a serious global threat to food safety, since potent carcinogenic, teratogenic, mutagenic and immunosuppressive effects of aflatoxins are well recognized. Recently, the use of adsorbents has been linked with protective effects against oxidative stress in several diseases. Thus, the aim of this study was to assess the occurrence of oxidative stress in quails (Coturnix coturnix) fed with aflatoxin-contaminated diet, as well as the protective effect of an adsorbent.

Materials, Methods & Results: Twenty-eight quails were divided into four groups (n = 7): diet without additives (control; the group A), diet and adsorbent containing aluminosilicates (the group B), aflatoxin-contaminated diet (200 ppb) (the group C), and aflatoxin-contaminated diet (200 ppb) and adsorbent containing aluminosilicates (the group D). The composition of the adsorbent containing aluminosilicates was 0.3% based on yeast cell wall, silymarin, and bentonite. The animals received feed and water ad libitum during 20 days. At the end of the experimental period, total blood was collected by cardiac puncture in tubes without anticoagulant to obtain serum (centrifuged at 3500 g during 10 min) for later determination of biochemical parameters. The liver was placed in a solution of Tris–HCl 10 mM, pH 7.4 for TBARS (Thiobarbituric acid reactive substances), ROS (Reactive oxygen species), SOD (Superoxide dismutase) and CAT (Catalase) analysis. The hepatic tissue was gently homogenized in a glass potter in specific buffer, homogenated, and centrifuged at 10.000 g at 4ºC for 10 min to yield a supernatant (S1) used for analyses. Homogenate aliquots were stored at -80°C until utilization. Fragments of liver and intestine (5 cm) were collected for histopathological analyses. Between days 15 to 20 of the experiment, group C quails showed clinical signs, such as apathy, creepy feathers and reduced feed intake. At day 20 of experiment, macroscopically, the liver of quails belonging to the group C showed greenish yellow color differently from the other groups. Microscopically, no alterations were observed in the liver of animals in groups A and B. Severe diffuse microvacuolar degeneration (hydropic) of hepatocytes and small foci of necrosis in the liver were observed in the group C, as observed in the group D, but in a more moderate degree to microvacuolar degeneration. Seric total protein, albumin, globulin and uric acid levels decreased in the group C and D. The levels of alanine aminotransferase (ALT) increased in the group C, and the treatment with adsorbent was able to avoid this increment. Seric and hepatic reactive oxygen species and TBARS increased in the group C, and the treatment with adsorbent reduced theses parameters in the group D. Catalase (CAT) activity decreased, while ALA-D increased in the group C. The treatment with adsorbent was able to prevent CAT activity decrease, but it did not prevent the increase in ALA-D activity.

Discussion: Aflatoxins are considered one of the most important problems in poultry production causing high economic losses to producers. In this study, the use of adsorbent showed a protective effect to hepatic tissue, minimizing histopathological lesions, as well as by preventing lipid peroxidation and exacerbated production of free radicals. Based on this data, aflatoxin intoxication causes hepatic oxidative stress that contributes directly to disease pathogenesis, and the addition of an adsorbent containing 0.3% based on bentonite, yeast cell wall and silymarin may be considered a new approach to prevent cellular and hepatic damage caused by aflatoxins.