The adverse effects of selenomethionine on skeletal muscle, liver, and brain in the steelhead trout (Oncorhynchus mykiss).

Juvenile Oncorhynchus mykiss (average weight: 22.3 g) were fed one of five selenomethionine diets (1.09, 8.79, 15.37, 30.79, or 61.58 mg Se/kg diet). After 4 weeks, hepatic catalase activity over 15.37 mg Se/kg diets was significantly decreased, and the glutathione peroxidase activity over 30.79 mg Se/kg diets was elevated compared to the controls. In the brain, the dopamine levels at 61.58 mg Se/kg diet and the serotonin levels over 15.37 mg Se/kg diets were significantly increased, whereas the 3,4-dihydroxyphenylacetic acid, homovanillic acid, and dopamine turnover, and the 5-hydroxyindoleacetic acid and serotonin turnover over 30.79 mg Se/kg diets were decreased. In muscle, the 3-nitrotyrosine level over 15.37 mg Se/kg diets, acetylcholine esterase activity over 30.79 mg Se/kg diets, and histological alterations over 8.79 mg Se/kg diets were increased. Our current results showed that selenomethionine disrupted dopamine and serotonin metabolism in the brain and damaged the neuromuscular system in skeletal muscle.