Metabolic parameters and oxidative balance in juvenile Rhamdia quelen exposed to rice paddy herbicides: Roundup®, Primoleo®, and Facet®

- Fish showed no mortality when exposed to realistic concentrations of these herbicides.
- Differential changes in biochemical composition were observed in the fish exposed to different herbicides.
- R. quelen specimens appear to be capable of modulating their antioxidant defenses.
- This species sustains no oxidative damage when exposed to the herbicides Roundup® and Primoleo®.
- Facet® caused significant damage to juveniles of this species.

The present study sought to assess the response of Rhamdia quelen juveniles (6-8 cm total body length) to exposure to different concentrations of three herbicides: Roundup® Original (18, 36, 72, and 144 μg/L), Primoleo® (2.5, 5, 10, and 15 μg/L), and Facet® (1.75, 3.5, 7, and 14 μg/L). Total protein (TP), glycogen (GG), total lipids (TL), triacylglycerols (TAG), lipid peroxidation (TBARS), and activity of the antioxidant enzymes superoxide dismutase (SOD) and catalase (CAT) in gills, liver, kidneys, and muscle were measured by spectrophotometry. Roundup® (glyphosate) reduced the TP, GG, and TL in gills and TL in liver and kidney and increased TP in liver and increased GG in muscle. In contrast to Primoleo® (atrazine), all tissues stored TAG and consumed LT, besides the gills also reduced PT. There was still an increase in GG in the kidneys and muscle. Facet® (quinclorac) induced changes mainly in the liver (increased TP, TL, and TAG content) and muscle (increased GG, TL, and TAG depletion). Gill tissue exhibited TP depletion alone, and kidney tissue metabolism was unchanged. This fish species appears capable of modulating its enzymes to the point where it sustains no oxidative damage as a result of exposure to the herbicides glyphosate (possibly due to increased CAT activity), atrazine (despite no changes in SOD or CAT activity), and quinclorac (with increased lipid peroxidation, particularly in gill, kidney, and muscle tissue, despite elevated SOD activity). Although it is not considered a target species, R. quelen suffers harmful effects from interaction with these herbicides.

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