Effects of Carbofuran, Diuron, and Nicosulfuron on Acetylcholinesterase Activity in Goldfish (Carassius auratus)

Juvenile goldfish (Carassius auratus) were exposed to three widely used pesticides; carbofuran, diuron, and nicosulfuron. Acetylcholinesterase (AChE) activity and molecular forms of AChE were first characterized in brain and skeletal muscle of unexposed fish. Skeletal muscle had higher AChE activity than brain (306 and 215 nmol/min/mg protein, respectively). In brain, four molecular forms of AChE were found: A12, G4, G2, and G1. In the muscle, three molecular forms were found A12, A8, and G2. AChE activity was then evaluated in both tissues of fish exposed to different concentration of pesticides (5, 50, and 500 μg/L) for 6, 12, 24, and 48 h. In brain, AChE activity was significantly inhibited during all the periods of exposure in response to 50 μg/L (19–28%) and 500 μg/L (85–87%) carbofuran. Such effect was observed in the muscle only at 500 μg/L (86–92%). Carbofuran had no effect on the distribution of molecular forms. Significant inhibitions (9–12%) of brain AChE activity were also observed in response to diuron and nicosulfuron at 500 μg/L during all periods of exposure and for 50 μg/L nicosulfuron after 24 and 48 h. This study pointed out short-term effects of exposure to sublethal concentrations of the three pesticides, ranging among different chemical families, on brain and muscle AChE in goldfish.