The Pollutant Perfluorohexane Sulfonate (PFHxS) Reduces Serum Thyroxine but Does Not Alter Thyroid Hormone Action in the Postnatal Rat Brain
Examination of PFHxS exposure and Developmental Neurotoxicity (DNT), and of the potential role of thyroid hormone
Abstract:
Per- and polyfluoroalkyl substances (PFAS) are surfactants utilized in an array of commercial products including nonstick cookware, stain resistant textiles, personal care products, and firefighting foam. Despite their widespread use, concerns regarding the safety of these compounds have been raised. One of the most reproducible effects of some PFAS is their ability to reduce serum thyroid hormones (THs) such as thyroxine (T4) and triiodothyronine (T3) in animal models. As THs are required for normal brain development, PFAS may also be developmental neurotoxicants. Here, we examine the endocrine and neurodevelopmental consequences of perfluorohexane sulfonate (PFHxS) exposure in pregnant, lactating, and developing rats, and compare its effects to the goitrogen propylthiouracil (PTU). We show that PFHxS dramatically reduces maternal serum T4, nearly equivalently to PTU (-55 and -51%, respectively). However, only PTU increases thyroid stimulating hormone (TSH). The lactational transfer of PFHxS is significant, and reduces pup serum T4 across the postnatal period. However, only PTU drastically reduces brain THs. Evaluation of brain TH action by phenotyping, RNA-Sequencing, and quantification of radial glia cell morphology supports that PTU interrupts brain TH signaling while PFHxS has limited to no effect. Overall, these data show that PFHxS induces abnormal serum TH profiles in dams and pups; however, there were no indications of hypothyroidism in the postnatal brain. We suggest the stark differences between the neurodevelopmental effects of PFHxS and a typical goitrogen may be due, in part, to the ability of PFHxS to interact with thyroid hormone distributing proteins like transthyretin