Mild iodine deficiency: molecular and functional repercussions on the maternal hypothalamic-pituitary-thyroid axis, the placenta, and fetal thyroid development

• Grant number: 25/13852-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2025
• End date: July 31, 2026
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Caroline Serrano Do Nascimento
• Grantee: Thacila de Oliveira Marques
• Host Institution: Instituto de Ciências Ambientais, Químicas e Farmacêuticas (ICAQF). Universidade Federal de São Paulo (UNIFESP). Campus Diadema. Diadema , SP, Brazil
• Associated research grant: 24/09333-7 - Impact of mild iodine deficiency during gestation and/or lactation on embryonic thyroid development and the programming of thyroid dysfunctions throughout adulthood: an omics approach, AP.R

Abstract

Iodine is essential for the synthesis of thyroid hormones (TH), whose adequate availability is particularly critical during key developmental periods, such as pregnancy. Severe iodine deficiency during pregnancy results in drastic consequences for the function of the maternal hypothalamic-pituitary-thyroid (HPT) axis, as well as for embryonic development. However, the consequences of mild iodine deficiency on the functioning of the maternal and fetal HPT axis, as well as its impact on the placental transfer of iodide and TH, are not yet fully elucidated. It is worth noting that pregnancy is a period of increased risk for the development of mild iodine deficiency, and many studies have reported a high prevalence of this nutritional deficiency among pregnant women worldwide, including in Brazil. Therefore, the present study aims to investigate the impact of mild iodine deficiency on the molecular and functional aspects of the maternal and fetal HPT axis, in addition to evaluating the consequences of this condition on placental tissue. To this end, pregnant female mice will be maintained on an iodine-deficient diet and will receive drinking water supplemented with either adequate (0.2 mg NaI/L) or mildly deficient (0.08 mg NaI/L) concentrations of sodium iodide throughout the entire gestational period. On gestational day 20 (GD20), pregnant females will be euthanized, and the following tissues will be collected: hypothalamus, pituitary, thyroid, and mammary gland. Furthermore, fetuses will be removed, weighed, and their respective placentas and thyroids will be collected. The samples will be analyzed for gene and protein expression, histological evaluation, and hormone quantification.This study aims to contribute to the understanding of the impacts of a common nutritional imbalance among pregnant women on maternal HPT axis activity, placental function, and thyroid development in the offspring. Based on the data obtained, it will be possible to propose new strategies and/or public health policies focused on the prevention of iodine deficiency in populations particularly susceptible to the development of thyroid dysfunctions, such as pregnant women and fetuses. (AU)