Meeting Abstract
44.2 Jan. 6 Disruption of the Fish Thyroid Axis by Polybrominated Diphenyl Ether (PBDE) Flame Retardants LEMA, S.C.*; DICKEY, J.T.; SCHULTZ, I.R.; SWANSON, P.; Northwest Fisheries Science Center; Univ. of Washington; Battelle Marine Sciences Laboratory; Northwest Fisheries Science Center sean.lema@noaa.gov
Polybrominated diphenyl ethers (PBDEs) are a class of brominated hydrocarbons used as flame retardant additives in plastics, polyurethane foam, and textiles. While PBDEs have helped reduce the loss of human life from fires, concern about the ecological and health risks of PBDEs has been heightened by recent evidence that levels of these chemicals are increasing in wildlife and humans. Little is known, however, about potential impacts of PBDEs to fish health. PBDEs share a structural similarity with polychlorinated biphenyls (PCBs), and there is evidence that PBDEs may disrupt the thyroid system. The goal of this study was to evaluate the effects of the PBDE congener 2,2′,4,4′-tetrabromodiphenyl ether (PBDE-47) on the thyroid axis of one model fish species, the fathead minnow (Pimephales promelas). Breeding pairs of adult fathead minnows were given oral doses of PBDE-47 bioencapsulated in brine shrimp for 21 days. Effects of PBDE-47 exposure on plasma thyroid hormone levels and on gene expression for thyroid-stimulating hormone &beta subunit (TSH&beta) and thyroid hormone receptors &alpha and &beta were assessed by radioimmunoassay and quantitative real-time RT PCR, respectively. Minnows treated with PBDE-47 had depressed plasma levels of thyroxine (T4) but no change in levels of triiodothyronine (T3). PBDE-47 exposure also altered gene expression for TSH&beta in the pituitary and for thyroid hormone receptors &alpha and &beta in the brain. Together, our results show that PBDE-47 can disrupt the thyroid axis in teleost fish. Since thyroid hormones regulate metabolism and have permissive roles in growth, neural development, and reproduction in fish, future work will examine how PBDE exposure may impact these processes. (Funded by NOAA Oceans and Human Health Initiative)
