M4 PM Endocrine Disruption in Fish (Part 2)
Monday, 14 November 2005: 1:50 PM - 5:30 PM in Ballroom 4

(LER-1117-843870) Alterations in thyroid hormone status in Atlantic croaker exposed to Aroclor 1254 and selected PCB congeners.

LeRoy, K¹, Thomas, P¹, Khan, I¹, ¹ University of Texas Marine Science Institute, Port Aransas, TX, USA

ABSTRACT- Many studies in animal and human populations have demonstrated that PCB exposure interferes with the normal function of the thyroid system. In this study, Atlantic croaker (Micropogonias undulatus) were exposed to a polychlorinated biphenyl (PCB) mixture (Aroclor 1254) or one of four individual congeners (two planar, PCB 77 and 126; two non-planar, PCB 47 and 153) in the diet for 30 days during gonadal recrudescence to investigate the effects of PCBs on thyroidal status. Thyroid hormones were extracted from plasma samples, and thyroid hormones triiodothyronine (T₃) and thyroxine (T₄) were measured with an enzyme-linked immunosorbent assay. Both male and female croaker exposed to the mixture Aroclor 1254 or individual congeners PCB 77, 126, or 153, showed decreased levels of T₃, but not T₄. By examining the effects of PCB mixtures and individual congeners on thyroidal status in Atlantic croaker, we can further develop our understanding of the mechanisms of action of these synthetic endocrine-disrupting chemicals and better predict values for both human, fish, and wildlife risk assessment.

Key words: thyroid, Micropogonias undulatus, polychlorinated biphenyls, congener