title: Oxidative stress biomarkers and heart function in bullfrog tadpoles exposed to Roundup Original.
abstract: Oxidative stress biomarkers, in vivo heart rate (f (H)), and contraction dynamics of ventricle strips of bullfrog (Lithobates catesbeiana) tadpoles were evaluated after 48 h of exposure to a sub-lethal concentration (1 ppm) of the herbicide Roundup Original (glyphosate 41%). The activities of the antioxidant enzymes superoxide dismutase and catalase were increased in the liver and decreased in muscle, while oxidative damage to lipids increased above control values in both tissues, showing that the generation of reactive oxygen species and oxidative stress are involved in the toxicity induced by Roundup. Additionally, tadpoles' hyperactivity was associated with tachycardia in vivo, probably due to a stress-induced adrenergic stimulation. Ventricle strips of Roundup-exposed tadpoles (R-group) presented a faster relaxation and also a higher cardiac pumping capacity at the in vivo contraction frequency, indicating that bullfrog tadpoles were able to perform cardiac mechanistic adjustments to face Roundup-exposure. However, the lower maximal in vitro contraction frequency of the R-group could limit its in vivo cardiac performance, when the adrenergic-stimulation is present. The association between the high energetic cost to counteract the harmful effects of this herbicide and the induction of oxidative stress suggest that low and realistic concentrations of Roundup can have an impact on tadpoles' performance and success, jeopardizing their survival and/or population establishment.
authors.affiliation: Campus of Sorocaba, Federal University of São Carlos, Avenida Darci Carvalho Dafferner 200, Sorocaba, SP, 18043-970, Brazil. monica@ufscar.br
authors.forename: Monica J
authors.initials: MJ
authors.lastname: Costa
authors.forename: Diana A
authors.initials: DA
authors.lastname: Monteiro
authors.forename: Abilio L
authors.initials: AL
authors.lastname: Oliveira-Neto
authors.forename: Francisco T
authors.initials: FT
authors.lastname: Rantin
authors.forename: Ana L
authors.initials: AL
authors.lastname: Kalinin
mesh_terms: D000818:Animals; D002374:Catalase / Q000187:drug effects / Q000378:metabolism; D005998:Glycine / Q000031:analogs & derivatives* / Q000633:toxicity; D006540:Herbicides / Q000633:toxicity*; D006948:Hyperkinesis / Q000139:chemically induced; D007814:Larva / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D009200:Myocardial Contraction / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects*; D011892:Rana catesbeiana / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000187:drug effects / Q000378:metabolism; D013610:Tachycardia / Q000139:chemically induced; D000097797:Glyphosate
chemical_list: D002374:Catalase; D005998:Glycine; D006540:Herbicides; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D000097797:Glyphosate