Christen, Verena

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Christen
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Verena
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Christen, Verena

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2016 - 20172
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Typ: 01A - Beitrag in wissenschaftlicher Zeitschrift × Thema: Neonicotinoids ×

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Gerade angezeigt 1 - 2 von 2
  • Vorschaubild nicht verfügbar
    Publikation
    Developmental neurotoxicity of different pesticides in PC-12 cells in vitro
    (Elsevier, 2017) Christen, Verena; Fent, Karl; Rusconi, Manuel; Crettaz, Pierre [in: Toxicology and Applied Pharmacology]
    The detection of developmental neurotoxicity (DNT) of chemicals has high relevance for protection of human health. However, DNT of many pesticides is only little known. Furthermore, validated in vitro systems for assessment of DNT are not well established. Here we employed the rat phaeochromocytoma cell line PC-12 to evaluate DNT of 18 frequently used pesticides of different classes, including neonicotinoids, pyrethroids, organophosphates, organochlorines, as well as quaternary ammonium compounds, the organic compound used in pesticides, piperonyl butoxide, as well as the insect repellent diethyltoluamide (DEET). We determined the outgrowth of neurites in PC-12 cells co-treated with nerve growth factor and different concentrations of biocides for 5 days. Furthermore, we determined transcriptional alterations of selected genes that may be associated with DNT, such as camk2α and camk2β, gap-43, neurofilament-h, tubulin-α and tubulin-β. Strong and dose- dependent inhibition of neurite outgrowth was induced by azamethiphos and chlorpyrifos, and dieldrin and heptachlor, which was correlated with up-regulation of gap-43. No or only weak effects on neurite outgrowth and transcriptional alterations occurred for neonicotinoids acetamiprid, clothianidin, imidacloprid and thiamethoxam, the pyrethroids λ-cyhalothrin, cyfluthrin, deltamethrin, and permethrin, the biocidal disinfectants C12-C14-alkyl(ethylbenzyl)dimethylammonium (BAC), benzalkonium chloride and barquat (dimethyl benzyl ammonium chloride), and piperonyl butoxide and DEET. Our study confirms potential developmental neurotoxicity of some pesticides and provides first evidence that azamethiphos has the potential to act as a developmental neurotoxic compound. We also demonstrate that inhibition of neurite outgrowth and transcriptional alterations of gap-43 expression correlate, which suggests the employment of gap-43 expression as a biomarker for detection and initial evaluation of potential DNT of chemicals.
    01A - Beitrag in wissenschaftlicher Zeitschrift
  • Vorschaubild nicht verfügbar
    Publikation
    Binary mixtures of neonicotinoids show different transcriptional changes than single neonicotinoids in honeybees (Apis mellifera)
    (Elsevier, 11.11.2016) Christen, Verena; Bachofer, Sara; Fent, Karl; [in: Environmental Pollution]
    Among the many factors responsible for the decline of bee populations are plant protection products such as neonicotinoids. In general, bees are exposed to not only one but mixtures of such chemicals. At environmental realistic concentrations neonicotinoids may display negative effects on the immune system, foraging activity, learning and memory formation of bees. Neonicotinoids induce alterations of gene transcripts such as nicotinic acetylcholine receptor (nAChR) subunits, vitellogenin, genes of the immune system and genes linked to memory formation. While previous studies focused on individual compounds, the effect of neonicotinoid mixtures in bees is poorly known. Here we investigated the effects of neonicotinoids acetamiprid, clothianidin, imidacloprid and thiamethoxam as single compounds, and binary mixtures thereof in honeybees. We determined transcriptional changes of nAChR subunits and vitellogenin in the brain of experimentally exposed honeybees after exposure up to 72 h. Exposure concentrations were selected on the basis of lowest effect concentrations of the single compounds. Transcriptional induction of nAChRs and vitellogenin was strongest for thiamethoxam, and weakest for acetamiprid. To a large extent, binary mixtures did not show additive transcriptional inductions but they were less than additive. Our data suggest that the joint transcriptional activity of neonicotinoids cannot be explained by concentration addition. The in vivo effects are not only governed by agonistic interaction with nAChRs alone, but are more complex as a result of interactions with other pathways as well. Further studies are needed to investigate the physiological joint effects of mixtures of neonicotinoids and other plant protection products on bees to better understand their joint effects.
    01A - Beitrag in wissenschaftlicher Zeitschrift