Short-term exposure to low doses of rotenone induces developmental, biochemical, behavioral, and histological changes in fish

Abstract

Rotenone, a natural compound derived from plants of the genera Derris and Lonchocarpus, is used worldwide as a pesticide and piscicide. This study aims to assess short-term toxicity of rotenone to early-life stages of the fish Danio rerio and Poecilia reticulata using a wide and integrative range of biomarkers (developmental, biochemical, behavioral, and histopathological). Moreover, the species sensitivity distribution (SSD) approach was used to compare rotenone acute toxicity to fish species. Toxicity tests were based on the OECD protocols, fish embryo toxicity test (for D. rerio embryos), and fish acute toxicity test (for P. reticulata juveniles). D. rerio embryos were used to estimate lethal concentrations and analyze embryonic and enzymatic alterations (activity of catalase, glutathione-S-transferase, and cholinesterase), while P. reticulata juveniles were used for the assessment of histological damage in the gills and liver. Rotenone induced significant mortality in zebrafish embryos with a 96-h lethal concentration 50% (LC50) = 12.2 μg/L. Rotenone was embryotoxic, affecting the development of D. rerio embryos, which showed cardiac edema; tail deformities; loss of equilibrium; and a general delay characterized by lack of tail detachment, delayed somite formation, yolk sac absorption, and lack of pigmentation. Biochemical biomarker inhibition was observed for concentrations ≥1 μg/L for CAT and glutathione-S-transferase (GST) and for cholinesterase (ChE) in concentration from 10 μg/L. Behavioral changes were observed for P. reticulata juveniles exposed to concentrations equal to or above 25 μg/L of rotenone; moreover, histological damage in the liver and gills of fish exposed to concentrations equal to or above 2.5 μg/L could be observed. A hazard concentration 5% (HC5) of 3.2 μg/L was estimated considering the acute toxicity data for different fish species (n = 49). Lethal and sublethal effects of rotenone raise a concern about its effects on nontarget fish species, especially because rotenone and its metabolite rotenolone are frequently reported in the microgram range in natural environments for several days after field applications. Rotenone should be used with caution. Given the high toxicity and wide range of sublethal effects here reported, further studies in a chronic exposure scenario are recommended.

Rotenone exerts developmental neurotoxicity in a human brain spheroid model

“…Rotenone is a natural pesticide widely used, besides to have a relatively short environmental half-life and limited bioavailability, there are evidences that even temporary limited exposure of rotenone could lead the effects in human health (Hatcher et al, 2008; Li et al, 2005; Tanner et al, 2011). Moreover, in vivo and in vitro studies have shown rotenone possible developmental neurotoxicity potential (Khera et al, 1982; Spencer and Sing, 1982; Melo et al, 2015; Krug et al, 2013). For this study, we used a range of concentrations based on published in vitro literature.…”

“…Studies with rotenone has previously shown indications that exposure to this pesticide produce effects on rat, chick and fish development (Khera et al, 1982; Spencer and Sing, 1982; Melo et al, 2015; Rao and Chauhan, 2004) as well as in vitro neurogenesis of iPSC-derived dopaminergic neurons (Fang et al, 2016) and neurite outgrowth (Krug et al, 2013). For example, D. rerio embryos exposed to rotenone showed embryotoxic effects, showing cardiac edema; tail deformities; loss of equilibrium; and a general delay characterized by lack of tail detachment, delayed somite formation, yolk sac absorption, and lack of pigmentation (Melo et al, 2015).…”

“…Rotenone has been suggested as one of the most important environmental risk factor for Parkinson’s Disease (PD) (Betarbet et al, 2000; Perier et al, 2003; Spivey, 2011; Tanner et al, 2011; Nandipati and Litvan, 2016). The major effect of rotenone is related to dopaminergic dysfunction, however, animal studies have found that rotenone may cause diffuse mitochondrial dysfunction in central non-dopaminergic and peripheral cells outside of the CNS (Fleming et al, 2004; Richter et al, 2007) and affect fish, chick and rat development (Khera et al, 1982; Spencer and Sing, 1982; Melo et al, 2015; Rao and Chauhan, 2004). In addition, in vitro studies on human iPSC-derived mixed neuronal and glial cultures have shown activation of the Keap1-Nrf2-ARE pathway after acute and chronical rotenone exposure, at non-cytotoxic concentrations (Pistollato et al, 2017; Zagoura et al, 2017).…”

Toxicidade do inseticida Tiametoxam para o Pacamã(Lophisiolurus alexandri)

“…Segundo Wolf et al (2015) a avaliação de congestão e dilatação de sinusóides pode estar relacionada a forma como o peixe foi eutanasiado. Quanto a necrose hepática, esta foi uma alteração encontrada por outros autores em experimentos com exposição de peixes a agrotóxicos, como em tilápias do Nilo alimentadas com 1.45g/L de deltametrina (Kan et al 2012), Heterobranchus bidorsalis expostos a cipermetrina (Olufayo & Alade 2012) e Poecilia reticulata expostos a 250μg/L de rotenona (Melo et al 2015). Segundo Wolf & Wolfe (2005), a necrose é uma resposta claramente patológica do fígado de peixes relacionada às toxinas.…”

“…Segundo Wolf & Wolfe (2005), a necrose é uma resposta claramente patológica do fígado de peixes relacionada às toxinas. Necrose focal pode estar isolada entre o tecido hepático normal ou infiltrado por células inflamató-rias e é uma alteração que pode estar associada a várias condições tóxicas, incluindo pesticidas (Roberts 2012).O fígado geralmente demonstra os efeitos tóxicos após exposição prolongada (Melo et al 2015), o que foi observado nesse experimento, com o aumento da ocorrência de necrose nos animais expostos cronicamente ao tiametoxam.…”