Assessing sensitivity of Atlantic salmon post-smolt to dietary endosulfan using histology and markers of endocrine disruption, oxidative stress, and biotransformation

Summary

Seawater adapted Atlantic salmon post-smolts were fed graded levels of technical endosulfan (0.005, 0.05, and I mg kg(-1)) for 16 weeks. Markers of endocrine disruption (plasma vitellogenin, and plasma sex steroid-binding proteins) and oxidative stress (hepatic glutathione peroxidase activity, and a-tocopherol level) were not affected by dietary concentrations used in this study. Adaptive responses such as biotransformation (hepatic 7-ethoxyresorufin-O-deethylase EROD activity) was significantly induced at the lowest and second lowest exposure levels (0.005 and 0.05 mg kg(-1)), but not at the highest exposure levels. Adverse effects such as significantly increased hepatic somatic index was observed in the 1 mg kg(-1) exposure group, however, apparent markers of liver damage (plasma aspartate aminotransferase and alanine aminotransferase level, or liver histopathological necrosis) were absent. The relative amount (%) of red pulp in spleen significantly increased in fish fed 0.005 and 0.05 mg kg(-1) whereas haematology (e.g. blood erythrocyte count and haemoglobin) remained similar to that of the control group. Levels of 0.005 and 0.05 mg kg(-1) did not cause overall adverse effects, whereas levels of 1 mg kg(-1) caused adverse effects as seen from a lacking hepatic biotransformation (EROD) activity and increased hepatic somatic index. Histological changes such as areas of vacuolization and fusion of villi in the intestine at lowest exposure levels warrant further investigation on the effects of dietary endosulfan exposure on nutritional performance and growth. (C) 2010 Elsevier B.V. All rights reserved.