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An In Vivo Multiwell-Based Fluorescent Screen for Monitoring Vertebrate Thyroid Hormone Disruption
journal contribution
posted on 2007-08-15, 00:00 authored by Jean-Baptiste Fini, Sébastien Le Mével, Nathalie Turque, Karima Palmier, Daniel Zalko, Jean-Pierre Cravedi, Barbara A. DemeneixThere is a pressing need for high throughput methods to
assess potential effects of endocrine disrupting chemicals
(EDCs) released into the environment. Currently our
ability to identify effects in vitro exceeds that for in vivo
monitoring. However, only in vivo analysis provides the full
spectrum of physiological impacts exerted by a given
chemical. With the aim of finding a physiological system
compatible with automatic plate reading we tested the
capacity of early embryonic stage Xenopus laevis tadpoles
to monitor thyroid hormone (TH) disruption. Fluorescent
transgenic X. laevis embryos bearing a TH/bZIP-eGFP
construct, placed in 96 well plates, were used for a
physiological-based screen for potential TH signaling
disruptors. Using stage NF-45 embryos (time of thyroid
gland formation) allowed rapid detection of chemical
interference with both peripheral TR signaling and production
of endogenous TH. Nanomolar concentrations of TH
receptor agonists could be detected within 72 h. Moreover,
when testing against a 5nM T3 challenge, the effects of
inhibitors of TH production were revealed, including inhibitors
of TH synthesis, (methimazole: 1 mM or sodium perchlorate: 3.56 μM), as well as antagonists acting at the receptor
level (NH3: 2 μM) and a deiodinase inhibitor (iopanoic
acid: 10 μM). Finally, we show that the thyroid disrupting
activities of BPA (10 μM) and TBBPA (1 μM) can also
be detected in this rapid screening protocol. Finally, this
noninvasive technology using an automatic reading system
shows low variability (around 5%) and permits detection
of subtle changes in signaling by EDCs that either inhibit or
activate TH signaling in vivo.
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Nanomolar concentrationsscreening protocolvivo monitoringstage Xenopus laevis tadpolesTH receptor agonistsTBBPATH productionMonitoring Vertebrate Thyroid Hormone DisruptionTherevivo analysisreading systemreceptor levelthyroid gland formation72 hNHNFthyroid hormonedeiodinase inhibitorEDCplate readingnoninvasive technologyBPAlaevis embryos5 nM T 3 challengeTRchemical interferencethroughput methodsTH synthesis
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