Effects of chloramine-T exposure on oxidative stress biomarkers and liver biochemistry of rainbow trout, Oncorhynchus mykiss (Walbaum), brown trout, Salmo trutta (L.), and grayling, Thymallus thymallus (L.)

Abstract

Oxidative stress, biochemical and enzymological biomarkers were compared among rainbow trout, Oncorhynchus mykiss (Walbaum), brown trout, Salmo trutta (L.), and grayling, Thymallus thymallus (L.) to determine the mechanisms of hepatotoxicity caused by chloramine-T bath treatment. The fish were exposed to chloramine-T at a concentration of 9 g m -3 for 20 min three times daily every three days. The control groups of fish, which were not exposed, were handled in the same way as the chloramine-T treatment groups. Chloramine-T treatment varies among fish species; for example, such treatment baths markedly decrease the carbonyl derivate levels of oxidative protein and aminotransferase activities, the elevation of which is a compensatory mechanism for impaired metabolism, but only in rainbow trout livers. No significant changes were noted in oxidative stress biomarkers between the control and chloramine-treated brown trout groups. Grayling chloramine-T exposure resulted in significant elevation in severe oxidative stress biomarker levels. Increased carbonyl derivates of oxidative protein can modify aminotransferase and lactate dehydrogenase activity and lactate and pyruvate levels, all of which cause primarily increased enzyme activity because of oxidative stress in the livers of the chloramine-exposed fish. The present study indicates that chloramine-T at a dose of 9 g m -3 can partially attenuate oxidative stress, and can be used for the prophylactic treatment of rainbow and brown trout.