You are here:
EFFECTS OF PERFLUOROOCTANE SULFONATE (PFOS) ON THYROID HORMONE STATUS IN ADULT AND NEONATAL RATS
Citation:
Logan, M. N., J R. Thibodeaux, R. G. Hanson, AND C S. Lau. EFFECTS OF PERFLUOROOCTANE SULFONATE (PFOS) ON THYROID HORMONE STATUS IN ADULT AND NEONATAL RATS. Presented at Society of Toxicology, Baltimore, MD, March 21-25, 2004.
Description:
EFFECTS OF PERFLUOROOCTANE SULFONATE (PFOS) ON THYROID HORMONE STATUS IN ADULT AND NEONATAL RATS. M.N. Logan1, J.R. Thibodeaux2, R.G. Hanson2, C. Lau2. 1North Carolina Central University, Durham, NC, 2Reprod. Tox. Div. NHEERL, US EPA, Research Triangle Park, NC.
Perfluorooctane sulfonate is an environmentally persistent compound ubiquitously found in humans and wildlife. Previous studies have suggested that PFOS alters thyroid hormone status in laboratory animals. The current study examines whether hormone metabolism is involved in PFOS mediated thyroid deficiency. Adult Sprague-Dawley rats were given (oral gavage) 3 or 5 mg/kg PFOS/K+ for 21 days, while controls received 0.5% Tween-20 vehicle. Serum thyroxine (T4) and triiodothyronine (T3), and liver uridinediphosphate-glucuronosyl transferase (UDP-GT), a microsomal enzyme that metabolizes (T4), were determined at days 3, 7, 14 and 21 after initiation of treatment. Significant reductions in serum total T4 (58%), free T4 (70%), and total T3 (23%) were noted in the PFOS-treated rats in as little as 3 days in both dose groups. Hormonal deficits were sustained throughout the study. However, no significant alterations in T4-UDP-GT activities were detected; at day 21, mean T4-UDP-GT activities were 0.614, 0.571, and 0.654 pmol/mg protein/min for control, 3, and 5 mg/kg PFOS groups, respectively. Previously, we have shown that prenatal exposure to PFOS led to hypothyroxinemia in rat pups, while serum T3 levels were not affected. The current study extended the chemical exposure to the postnatal period. PFOS (10 mg/kg, p.o.) was given to rat pups daily from PD1 to PD48. All pups survived the chemical treatment, but serum tT4, fT4 and tT3 were significantly reduced by 64%, 68% and 29% of controls, respectively. The hormonal deficits persisted into young adulthood. These results suggest that PFOS reduces circulating thyroid hormones effectively in both mature and developing rats, but enhancement of hepatic metabolism of the hormones is not likely involved in altering the hormone economy. Funded by EPA/NCCU Toxicology research program, training agreement CT 829460 with the Department of Biology, NCCU. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.