• In vitro assay;
  • Thyroid hormone;
  • Amphibian;
  • Gene expression;
  • Environmental contaminants


There is a need for the development of a rapid method for identifying chemicals that disrupt thyroid hormone (TH) action while maintaining complex tissue structure and biological variation. Moreover, no assay to date allows a simultaneous screen of an individual's response to multiple chemicals. A cultured tail fin biopsy or C-fin assay was developed using Rana catesbeiana tadpoles. Multiple tail fin biopsies were taken per tadpole, cultured in serum-free medium, and then each biopsy was exposed to a different treatment condition. The effects of known disruptors of TH action were evaluated in the C-fin assay. Chemical exposure was performed ± 10 nM 3,3′,5-triiodothyronine and real-time quantitative polymerase chain reaction (QPCR) of two TH-responsive transcripts, TH receptor β (TRβ) and the Rana larval keratin type I (RLKI), was performed. Within 48 h of exposure to Triac (1-100 nM), roscovitine (0.6–60 µM), or genistein (1–100 µM), perturbations in TH signaling were detected. Tetrabromobisphenol A (TBBPA) (10-1,000 nM) showed no effect. Acetochlor (1–100 nM) elicited a modest effect on the TH-dependent induction of TRβ transcript. These data reveal that a direct tissue effect may not be critical for TBBPA and acetochlor to disrupt TH action previously observed in intact tadpoles. Environ. Toxicol. Chem. 2010;29:380–388. © 2009 SETAC