Changes on detoxication enzymes in Australoheros facetus (Pisces) experimentally exposed to endosulfan

CRUPKIN, A; GERPE, M.; MORENO,V; MENONE, ML

Sydney- Australia

Congreso; V SETAC World Congress; 2008

SETAC (USA)

A wide range of early warning signals –biomarkers– and particularly enzymatic activities has been developed and proposed for application in monitoring. To be useful in practical monitoring biomarkers selected should be sensitive and responsive to environmentally realistic concentrations and preferably exhibit a good dose response relationship to levels of pollution. Some detoxication enzymes have these characteristics, for example glutathione- S- transferase (GST) which is induced by different synthetic compounds such as organochlorine pesticides and PCBs, among others. In this study the cichlid Australoheros facetus was exposed to environmentally relevant concentrations of the insecticide endosulfan (ug/L) for a short time, simulating exposures that might occur after run-off from agricultural areas. The main goal was to evaluate changes in GST and glutathione reductase (GR) activities in A. facetus upon exposure to endosulfan. Four different concentrations of endosulfan (0.02, 0.5, 5 and 10 ug/L) and  a negative control were assayed. Six specimens were used per treatment. Enzymatic activities were determined by spectrophotometry. A background activity of GST (measured in controls) was 1 order of magnitude higher in liver than in gills. The activity of GST was not different to the control in the gills at any endosulfan concentration tested (p>0.05) while induction in liver was observed at all concentrations tested (p<0.05). These results denotes the well known rol of liver as the major site of xenobiotic biotransformation. The concentration- response relationship of GR showed an inhibition of activity at 0.02 and 0.5 ug/L of endosulfan in the gills. In liver, inhibition was only observed at 0.5 ug/L of endosulfan and no significant differences among controls and the other treatments (p>0.05) were observed. Discussion of results includes the potential use of A. facetus–GST system to assess freshwater pollution and the effects of endosulfan in brain on this species, another target organ of endosulfan.