Prenatal Exposures to Multiple Thyroid Hormone Disruptors: Effects on Glucose and Lipid Metabolism

Abstract

Background. Thyroid hormones (THs) are essential for normal human fetal development and play a major role in the regulation of glucose and lipid metabolism. Delivery of TH to target tissues is dependent on processes including TH synthesis, transport, and metabolism. Thyroid hormone endocrine disruptors (TH-EDCs) are chemical substances that interfere with these processes, potentially leading to adverse pregnancy outcomes. Objectives. This review focuses on the effects of prenatal exposures to combinations of TH-EDCs on fetal and neonatal glucose and lipid metabolism and also discusses the various mechanisms by which TH-EDCs interfere with other hormonal pathways. Methods. We conducted a comprehensive narrative review on the effects of TH-EDCs with particular emphasis on exposure during pregnancy. Discussion. TH imbalance has been linked to many metabolic processes and the effects of TH imbalance are particularly pronounced in early fetal development due to fetal dependence on maternal TH for proper growth and development. The pervasive presence of EDCs in the environment results in ubiquitous exposure to either single or mixtures of EDCs with deleterious effects on metabolism. Conclusions. Further evaluation of combined effects of TH-EDCs on fetal metabolic endpoints could improve advice provided to expectant mothers.

Intrauterine exposure to low-dose DBP in the mice induces obesity in offspring via suppression of UCP1 mediated ER stress

“…The specific manifestations are: disruption of major weight control hormones such as catecholamine, thyroid hormone, estrogen, insulin, growth hormone, leptin, testosterone and corticosteroids; altered hormone sensitivity, especially for dopamine, serotonin, and angiotensin; and disruption of metabolic processes. Together, these effects can lead to tissue and organ damage, especially in nerves and muscles 12 – 16 , even at low levels of exposure. In our study, pregnant mice were administered DBP was from the 12th day of gestation to the 7th day after birth, a critical period in the differentiation of adipose tissue, reproductive organs and the immune system.…”

Reproductive and hormone-related outcomes in women whose mothers were exposed in utero to diethylstilbestrol (DES): A report from the US National Cancer Institute DES Third Generation Study

“…Our data suggested a possible increase of thyroid conditions in exposed women who responded to the follow-up questionnaire. Emerging evidence suggests that prenatal exposure to EDC may disrupt thyroid function 42,43 , but data are lacking for EDC effects in the offspring generation. Finally, compared with the unexposed, DES-exposed third generation women were of lower birth weight, a finding that was expected due to pregnancy complications, particularly preterm delivery, experienced by their mothers.…”

An Emerging Role of micro-RNA in the Effect of the Endocrine Disruptors

“…It has been reported that numerous EDCs can directly affect the normal functioning of the thyroid gland. In numerous studies, it has been shown that different EDCs such as PCBs, BPA, or DTT have thyroid-disrupting effects in animals and humans (Patrick, 2009 ; Molehin et al, 2016 ).…”