Hepatic glutathione S-transferase activity in mosquitofish (Gambusia affinis) and topmouth gudgeon (Pseudorasobora parva) exposed to fenitrothion

Two common fish species, mosquitofish (Gambusia affinis) and topmouth gudgeon (Pseudorasobora para) were exposed to different concentrations of fenitrothion in static system for 96 h. Hepatic glutathione S-transferase activity was evaluated after 48 and 96 h pesticide exposure, and was also examined in fish pretreated with pepironyl butoxide and triphenyl phosphate and then exposed to fenitrothion. Results indicated presence of intense glutathione S-transferase activity in both species, mosquitofish exhibiting the higher activity. In both species the activity decreased as the concentration of fenitrothion increased, topmouth gudgeon being more susceptible than mosquitofish. In mosquitofish pretreated with pepironyl butoxide, glutathione S-transferase activity was increased (11.8%) compared with the control but in topmouth gudgeon it was decreased (21.6%) at the end of 96 h. Glutathione S-transferase activity was significantly reduced in both species pretreated with triphenyl phosphate at the end of 96 h exposure, topmouth gudgeon being highly susceptible. Ph. D. student, from Southern Ethiopia Health Bureau, Center for Health Research, P. O. Box 317, Awassa, F. R. Ethiopia.