Effects of thyroid hormones, thyroid hormone disruptors, and treated wastewater on bullfrog tadpole chemosensory function and behaviour

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Heerema, Jody L.
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta : University of Lethbridge, Dept. of Biological Sciences
Endocrine disrupting compounds (EDCs) are persistent in wastewater effluent and discharged into receiving waters. Some EDCs can interact with the thyroid system in vertebrates. The present study investigated the effects of TH disruption on olfactory responses in Lithobates (Rana) catesbeiana tadpoles. A neurophysiological and a behavioural technique were developed to study olfactory acuity in tadpoles. To investigate the effects of thyroid hormone (TH) disruption, tadpoles were exposed to either 3,5’,3-triiodothyronine (T3), thyroxine (T4), 17β-estradiol (E2), known EDCs, or wastewater effluent. Olfactory-mediated avoidance responses to a chemosensory stimulus were measured. Exposure to T3 and treated wastewater resulted in impaired avoidance responses. Exposures to T4, E2 and known EDCs had no effect on behavioural responses. These results indicated that EDCs in wastewater effluent may contribute to olfactory impairment through TH disruption. Chemosensory-mediated behaviour may serve as an environmentally relevant endpoint to determine possible effects of TH disruption in wastewater effluent receiving waters.
chemosensory-mediated behaviour , endocrine disrupting compounds , olfactory acuity , premetamorphic tadpoles , thyroid hormone disruption , wastewater effluent