Effects on Liver Hydrogen Peroxide Metabolism Induced by Dietary Selenium Deficiency or Excess in Chickens

To determine the relationship between dietary selenium (Se) deficiency or excess and liver hydrogen peroxide (H₂O₂) metabolism in chickens, 1-day-old chickens received insufficient Se (0.028 mg Se per kg of diet) or excess Se (3.0 or 5.0 mg Se per kg of diet) in their diets for 8 weeks. Body and liver weight changes, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, H₂O₂ content, and activities and mRNA levels of enzymes associated with H₂O₂ metabolism (catalase (CAT) and superoxide dismutase (SOD) 1–3) were determined in the liver. This study showed that Se deficiency or excess Se intake elicited relative severe changes. Se deficiency decreased growth, while Se excess promoted growth in chickens. Both diets vastly altered the liver function, but no obvious histopathological changes were observed in the liver. Se deficiency significantly lowered SOD and CAT activities, and the H₂O₂ content in the liver and serum increased. Se excess (3.0 mg/kg) decreased SOD and CAT activities with changes in their mRNA levels, and the H₂O₂ content increased. The larger Se excess (5.0 mg/kg) showed more serious effects but was not fatal. These results indicated that the H₂O₂ metabolism played a destructive role in the changes in bird liver function induced by Se deficiency or excess.