Thyroid embryonic explants as a model to study the effects of BPA and DDE on thyroid embryogenesis

• Grant number: 23/06924-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2023
• End date: February 29, 2024
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Caroline Serrano Do Nascimento
• Grantee: Victor Silva Luzia
• Host Institution: Instituto de Ciências Ambientais, Químicas e Farmacêuticas (ICAQF). Universidade Federal de São Paulo (UNIFESP). Campus Diadema. Diadema , SP, Brazil
• Associated research grant: 16/18517-8 - Endocrine disruptors vs. thyroid: an epigenetic analysis of the development, differentiation and function of thyrocytes and their repercussions on the organism, AP.JP

Abstract

Endocrine disruptors are chemical substances that interfere with endocrine function, producing adverse effects on growth, development, reproduction, and metabolism, with systemic repercussions to varying degrees depending on the time of exposure and the developmental stage at which the individual is exposed. In recent years, different experimental models have been used to better understand the mechanisms of action of endocrine disruptors in different tissues. The thyroid is a target of the disruptive action of a series of compounds used by industry in the manufacture of different products. Thyroid embryonic development is complex. The gland derives from the endoderm, and our previous studies have shown that various endocrine disruptors interfere negatively with the development of this embryonic tissue. However, it is still unclear how these contaminants act during thyroid development at more advanced stages. It is known that after caudal migration and fixation below the cricoid cartilage of the trachea, the thyroid begins to acquire its characteristic bilobed shape, due to intense cell proliferation. Upon reaching its final position, the thyroid precursor begins to express thyroid differentiation genes until completing folliculogenesis and becoming functional. In mice, thyroid development ends on gestational day 16.5. Embryonic thyroid explants have proven to be interesting models for studying thyroid tissue organogenesis and allow a more physiological model of gland development, as they do not involve overexpression of thyroid transcription factors in embryonic stem cells, as described in available protocols in the literature. The main objective of this study is to investigate the molecular mechanisms triggered by exposure to BPA and DDE on embryonic thyroid development. To do so, embryonic thyroid explants will be used at two distinct gestational periods, according to the experiment's objective. To evaluate the effects of maternal exposure to BPA and DDE on embryonic thyroid development, pregnant female mouse embryos (control or treated) will be removed from the uterus on GD16.5 and dissected with a stereoscopic microscope. The thyroid lobes will be removed and processed. To evaluate the direct effects of DE exposure on embryonic thyroid differentiation, explants will be collected from control female mice on GD14.5 and incubated with or without BPA or DDE for 48 hours. The explants obtained in both experiments will be processed to obtain RNA, DNA, or protein. If significant changes in gene expression are observed, additional studies will be conducted to evaluate whether exposure to BPA and DDE programs thyroid gene expression through epigenetic mechanisms such as DNA methylation and post-translational histone modifications.