Impact of intrauterine exposure to PCB on the function of the hypothalamus-pituitary-thyroid axis of the offspring animals

Abstract

PCBs, also known as polychlorinated biphenyls, are organochlorine compounds and flame retardants, used as coolant fluids and lubricants for transformers, capacitors, and other industrial equipment that have been banned for over 25 years in many countries. Due to their permanence in the environment, humans were exposed to PCBs through the consumption of contaminated food, mainly fish of marine origin. Some studies have already demonstrated a negative correlation between serum levels of PCBs and serum concentrations of T3, T4, and TSH in pregnant women. In addition, studies report a relationship between prenatal exposure to PCBs and a cognitive deficit in children. Given the placental transfer of lipophilic endocrine disruptors across the placenta, and the importance of the intrauterine period for programming health and disease in adulthood through epigenetic mechanisms, the main objective of the present study will be to investigate the consequences and molecular mechanisms triggered by exposure to pregnant Wistar rats to PCBs during pregnancy on the function of the hypothalamic-pituitary-thyroid axis of their offspring during adulthood. The hypothalamus, pituitary, and thyroid of young rats will be used in assays to analyze the expression of genes and proteins involved in the function of the hypothalamic-pituitary-thyroid axis. If significant changes in gene expression are observed, additional studies will be performed to assess whether maternal exposure to PCBs programs thyroid gene expression in offspring through epigenetic mechanisms, such as DNA methylation and post-translational histone changes.(AU)