Efeito da exposição aguda do inseticida Fipronil e do herbicida 2,4-D e mistura de ambos em curimbatá, Prochilodus lineatus (Teleósteo, Prochilodontidae).
Abstract
The herbicide 2,4-D and the insecticide fipronil are pesticides frequently
detected in aquatic ecosystems, thus threatening wildlife and health security. The
aim of the present study was to investigate the toxicity of 2,4-D (447 µg ia L-1
) and
fipronil (63.49 µg ia L-1
), isolated and mixed in the neotropical fish Prochilodus
lineatus in a time of 96 h exposure under laboratory conditions. After exposure,
bioconcentration in the organism, the activities of catalase (CAT), glutathione stransferase (GST) and the level of lipid peroxidation (LPO), and changes in the
surface of the branchial epithelium were determined. The bioconcentration factor
was calculated at 0.17 kg-1 L for 2.4 D isolated and 12.4 kg-1 L for fipronil alone. In
animals exposed to the mixture of pesticides, only fipronil bioconcentrated and the
bioconcentration factor was 10.8 kg-1L. In fish exposed to 2,4-D alone, there was an
increase in the enzymatic activities of CAT and GST and LPO indicating oxidative
stress. In fish exposed to fipronil alone, only the GST activity increased. No change
occurred in the activity of CAT and GST in animals exposed to the mixture of
pesticides. In the gills, the histopathological changes occurred more intensity in fish
exposed to fipronil and the mixture of pesticides. The most frequent being
hypertrophy, hyperplasia, epithelial detachment, and vascular congestion. Scanning
electron microscopy (SEM) analyzes showed an increase in the density of cellschloride (CC) and in the morphology of the pavement cells and CCs in fish in the
group exposed to fipronil. The results showed that acute exposure to 2,4-D and
fipronil induce biochemical changes in the activity of antioxidant enzymes as well as
in the HAI. The exposure to fipronil increased CC density and the morphology of CC
and pavement cells in the gills. The mixture of the two pesticides had antagonistic
effects.
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