Meeting Abstract
P3.89 Saturday, Jan. 5 A Tadpole Tail Assay Reveals Potential Thyroid Hormone-Disrupting Effects of Wastewater Effluent in African Clawed Frog (Xenopus laevis) OWEN, M.C.*; SEARCY, B.T.; SCHWENDIMAN, A.L.; HURLOCK, C.; PROPPER, C.R.; Northern Arizona University; Northern Arizona University; Northern Arizona University; Northern Arizona University; Northern Arizona University MO56@nau.edu
Many individual anthropogenic chemicals released into the environment (endocrine disrupting compounds; EDCs) disrupt thyroid hormone (TH) function in wildlife. However, few studies have evaluated the impact of complex mixes of EDCs on TH function. Amphibian metamorphosis is under regulation of TH and therefore makes an excellent marker for impacts by EDCs. Wastewater effluent (WW) contains a mixture of compounds, many of which have known EDC activity. Previous studies in our lab with X. laevis tadpoles demonstrate that developmental exposure to WW decreases the time to metamorphosis, suggesting that compounds in the water may be mimicking TH activity. However, in the whole animal system it is not clear where along the hypothalamic-pituitary-thyroid axis compounds in the wastewater are acting. The purpose of this study was to determine whether one marker of TH activity, tail fin regression, is responsive to chemicals extracted from WW. Tadpole tails (NF stage 51-54) were exposed for 72 hours to a 0X, 1X or 5X concentrated extract of WW alone or in combination with 10 nM triiodothyronine (T3). Tails exposed to 1X WW showed reduced regression compared to controls or T3-exposed tails (p=0.001). 1X WW exposed tails also exhibited a trend towards inhibiting T3-induced tail regression (P= 0.08). Therefore, environmentally relevant concentrations of chemicals in WW may inhibit TH-dependent metamorphic markers and may be acting as a TH antagonist in the the tadpole tail. The different results between the studies in our laboratory demonstrates the importance of comparing whole animal studies to in vitro analysis when evaluating the endocrine disrupting capacity of complex mixtures.
