Developmental effects of perfluoroalkyl acids (PFAS) in chicken

p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; font: 11.5px 'Times New Roman'} Perfluoralkyl acids (PFAS) are anthropogenic substances frequently found in the environment, wildlife and humans worldwide. They are persistent and have previously been seen to disturb thyroid hormones as well as to cause neurobehavioral effects. Filial imprinting in chicken can be used to study effects on behavior, memory and learning after developmental exposure to chemicals. Thyroid hormones control the sensitive period for imprinting and regulates a number of different genes involved in memory and learning. In this study effects of a PFAS mixture on gene expression of the thyroid responsive genes type II iodothyronine 5´-deiodinase (D2) and octamer motif-binding factor 1 (OCT1) were evaluated in left cerebral hemisphere in chicken after exposure to 180 μg PFAS/egg, at embryonic day 4 (E4), as well as histomorphological effects on the thyroid gland after exposure to 30 μg PFAS/egg or 180 μg PFAS/egg at E4. In addition, this work included development of a method for evaluating the effects of developmental exposure to chemicals on imprinting behavior. The genes tested showed no difference in mRNA expression in PFAS exposed groups compared with control. The thyroid gland showed a significant decrease in follicular epithelial cell height in chicks exposed to 180 μg PFAS/egg compared with control. The imprinting method needs further development before it can be used to evaluate the effects of exposure during development on imprinting behavior. Changes in thyroid hormones have been reported in mice, chicken and humans after exposure to PFAS. The results in this study indicate that PFAS can disturb thyroid hormones in chicken and in this case it is seen as decreased epithelial cell height, indicating lowered thyroid hormones synthesis. The mechanism by which this occurs and the implications of this needs further investigation.