Acute toxicity of paraquat and no‐inhibitory chronic effect on brain acetylcholinesterase activity of freshwater fish bryconamericus iheringii (pisces, characidae)

Abstract

Acute toxicity of paraquat (PQ) and its effects on brain acetylcholinesterase (AChE) activity of a freshwater fish males and females Bryconamericus iheringii was evaluated. The LC50 values at 24, 48, 72 and 96 hs were: 40, 47; 24, 17; 22, 15 and 20, 21 mg of PQ/L respectively.

Chronic effect was recorded on AChE activity for all assayed concentrations during 60 days of exposure to PQ with no significant change. A significant increase, time dependent, of AChE activity was observed both in the controls and in the experimental groups. The AChE activity stabilized at 60 days of the test. The increase recorded could be due to the lack of acclimatization of the individuals or to stresses under laboratory conditions. This fact should be considered in AChE activity inhibition studies by plaguicides.

Key words:

• freshwater fish
• paraquat
• survival
• AChE
• brain