Effects of subchronic exposure to Successor 600 (pethoxamid 600 g L-1) on common carp Cyprinus carpio.

OBJECTIVES: We investigated the effects of the herbicide preparation Successor 600 on biochemical and haematological indices and the histolopathological parameters of common carp after 28 day exposure. Furthermore, the hepatosomatic index and induction of xenobiotic metabolizing enzymes and biomarkers were assessed.

DESIGN: Juvenile fish were exposed to sublethal concentrations of Successor(R) 600 (0.06 mg L-1, 0.22 mg L-1 or 0.60 mg L-1) for 28 days. Haematological indices were assessed using unified methods of haematological examination in fish. Plasma biochemical indices were measured by biochemical analyzer, the vitellogenin concentration in male fish plasma was estimated by direct sandwich ELISA. In hepatopancreas, ethoxyresorufin-O-deethylase (EROD) activity was measured spectrofluorimetrically, concentration of total cytochrome P450 (CYP), glutathion (GSH) content and glutathion-S-transferase (GST) activity were determined spectrophotometrically. Histological changes in samples of hepatopancreas, skin, gills, spleen, head kidney and trunk kidney were examined by light microscopy.

RESULTS: Haemoglobin, MCH and MCHC were significantly (p<0.05) reduced in fish treated with Successor(R) 600 of 0.22 and 0.60 mg L-1. LDH was enhanced (p<0.05), in the highest concentration of the preparation. Vitellogenin was detected in all male fish, with no difference between groups. HSI, GSH and GST were elevated (p<0.05), owing to the exposure, whereas CYP and EROD were not affected. Slight histopathological changes were demonstrated in skin, gills and hepatopancreas, with steroid tissue in head kidney samples of 0.60 mg L-1 treated fish.

CONCLUSION: Successor 600 affected the haematological profile of the treated fish, while the effects on biochemical indices were less expressed. Male plasma vitellogenin concentrations were not indicative of estrogen disruptive effects after 28 days. The importance of GSH and GST for the metabolisation were demonstrated. In contrast, CYP and EROD were not influenced by any concentration tested. HSI was found to reflex pollution with Successor 600. Histopathological indices caused by the treatment were observed in various tissue samples of the treated fish.