Feed-borne exposure to deoxynivalenol leads to acute and chronic effects on liver enzymes and histology in carp

Deoxynivalenol (DON) is a frequent contaminant of feeds in aquaculture but the consequences of this contamination have rarely been evaluated. Previous studies on carp indicated effects of DON on liver function and histology after four weeks of feeding. The present study aimed to unravel the time course of liver responses of carp to orally applied DON. Therefore liver enzyme activities and histology have been investigated after 7, 14, 26 and 56 days of DON feeding. The acute response comprises down-regulation of biotransformation enzymes, whereas the chronic response to DON is characterized by activation of alanine aminotransferase which indicates damage to liver tissue. Examination of histological sections of liver tissue revealed that changes such as fat aggregation, vacuolization and hyperaemia were present after 14 and 26 days of exposure to DON but not thereafter. Several enzymes involved in glutathione cycling and reduction of oxidative stress were found to be reduced after 26 and 56 days of DON feeding. The results suggest that supporting the antioxidative system e.g. by using glutathione-enriched yeast extracts as a food additive might be successful in preventing the effects of DON in carp. This is the basis of a fundamental hypothesis since DON contamination of fish feed leads to pronounced effects on liver histology and liver enzyme activities which may also cause changes in the normal liver metabolism of endogenous and xenobiotic compounds.