title: Thyroid hormone status of Atlantic croaker exposed to Aroclor 1254 and selected PCB congeners.
abstract: Atlantic croaker (Micropogonias undulatus) were exposed to the polychlorinated biphenyl (PCB) mixture (Aroclor 1254) or one of three individual congeners (planar PCB 77 or ortho-substituted PCB 47 and PCB 153) in the diet for 30 days to investigate the effects of PCBs on circulating thyroid hormones, thyroxine (T4) and triiodothyronine (T3). Aroclor 1254 (0.2 and 1.0 mg/kg body mass/day) decreased plasma T3 levels consistently, but the effects on T4 levels were inconsistent from year to year. Exposure to PCB 153 (0.1 and 1.0 mg/kg body mass/day) significantly lowered both T4 and T3, while PCB 47 at the same doses had no effect on thyroid hormone levels. The lower doses of PCB 77 (0.004, 0.01 and 0.02 mg/kg body mass/day) had no effect on T4 or T3, whereas the highest dose (0.1 mg/kg body mass/day) increased T4 levels significantly. The results of the present study demonstrate that exposure to PCBs at environmentally realistic concentrations can have profound effects on the thyroid status of Atlantic croaker. The ortho-substituted PCB 153 appears to contribute at least partially to the deleterious effects of Aroclor 1254 on thyroid status, whereas the planar PCB 77 at concentrations present in the mixture is unlikely to alter thyroid hormone levels.
authors.affiliation: The University of Texas at Austin, Marine Science Institute, 750 Channel View Drive, Port Aransas, Texas 78373, USA.
authors.forename: Kimberly D
authors.initials: KD
authors.lastname: LeRoy
authors.forename: Peter
authors.initials: P
authors.lastname: Thomas
authors.forename: Izhar A
authors.initials: IA
authors.lastname: Khan
mesh_terms: D000818:Animals; D013956:Antithyroid Agents / Q000633:toxicity*; D020111:Chlorodiphenyl (54% Chlorine) / Q000633:toxicity*; D004785:Environmental Pollutants / Q000633:toxicity*; D005260:Female; D007202:Indicators and Reagents; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010473:Perciformes / Q000378:metabolism*; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D012727:Sex Characteristics; D013963:Thyroid Hormones / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D013956:Antithyroid Agents; D004785:Environmental Pollutants; D007202:Indicators and Reagents; D013963:Thyroid Hormones; D014284:Triiodothyronine; D020111:Chlorodiphenyl (54% Chlorine); D011078:Polychlorinated Biphenyls; D013974:Thyroxine