Effects of exposure to silver nitrate on the antioxidant defense system and metabolic indices of Vannamei shrimp (Litopenaeus vannamei)

Exposure of aquatic animals to silver, due to production of free radicals, causes oxidative damage and biochemical changes in organisms. Therefore, in present study, changes in the antioxidant defense system and metabolic indices of Litopenaeus vannamei were evaluated during 21 days of exposure to silver nitrate. Shrimps exposed to different concentrations of silver nitrate, including treatment 1: 10% LC50 (0.0084 mg/L), treatment 2: 25% LC50 (0.021 mg/L), treatment 3: 50% LC50 (0.042 mg/L) and treatment 4: 75% LC50 (0.063 mg/L) and one treatment as control treatment. Superoxide dismutase activity in treatments 3 and 4 and total antioxidant capacity in treatment 4 was significantly reduced (P<0.05). But malondialdehyde activity was significantly increased in treatment 4 (P<0.05). Catalase and glutathione activity in all treatments did not show a significant difference (P>0.05). Among metabolic indices, only in treatment 4 protein changes were significantly reduced, and glucose, cholesterol and triglyceride were significantly increased (P<0.05). But the amount of phosphorus and calcium did not show a statistically significant difference (P>0.05). In general, exposure to 75% LC50 of silver nitrate with a significant decrease in the activity of antioxidant enzymes and an increase in malondialdehyde caused oxidative damage and disruption of some metabolic parameters of Litopenaeus vannamei.