Antioxidant defence responses to toxic cyanobacterial bloom in the liver of freshwater fish, Perca fluviatilis from the Gruža reservoir

Abstract

We investigated alterations of antioxidant defence system (ADS) in the liver of freshwater fish, European perch (Perea fluviatilis) as response to toxic Apha­ nizomenon flos-aquae bloom in the Gruza Reservoir. Activities of total, manga­ nese, copper zinc containing superoxide dismutase (Tot SOD, Mn SOD, CuZn SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), phase II biotransformation enzyme glutathione S-transferase (GST), con­ centrations of total glutathione (GSH) and sulphydryl (-SH) groups were mea­ sured before and during bloom period. Histopathological examinations were studied using electron microscopy. Activities of CuZn SOD, CAT and GSH-Px and concentration of -SH groups were significantly lower, while Mn SOD activ­ ity was significantly higher during bloom period. No differences were observed for Tot SOD, GR and GST activities, as well as for GSH concentration. Electron microscopy showed alterations in hepatocytes, which results in damage of cells. Our work represents the first study of its kind and suggest on influence of toxic Aphanizomenon flos-aquae bloom in the Gruza Reservoir on ADS and on histo­ pathological changes in the liver of Perea fiuviatilis indicating on necrotic and apopototic damages of hepatocytes.