Thyroid Hormones in Fetal Development

Abstract

Normal fetal growth and development depend on several endocrine, metabolic, and nutritional factors [ 1 ]. Among them, an important role is played by thyroid hormones (TH) (T4 thyroxine and T3 triiodothyronine) both of maternal and fetal origin. The supply of maternal TH to the human fetus depends mainly on the mother's thyroid function and on several placental transport mechanisms. Moreover, during pregnancy, double the normal iodine intake of the mother is required to preserve normal TH concentrations [ 2 ]. In fetus hypothalamus-pituitary-thyroid-target tissue axis is activated shortly after the thyroid gland has reached its anatomical site in the fi rst weeks of gestation. A full maturation of the complex system including TH transport, receptor availability, and normal function of postreceptoral mechanisms are however needed to ensure the specifi c biological action at target tissues.

The Role of Endocrine and Dioxin-Like Activity of Extracts of Petroleum Substances in Developmental Toxicity as Detected in a Panel of CALUX Reporter Gene Assays

“…To facilitate comparison of our data to those in the literature, Table 2 presents a summary of endocrine and dioxin-like activity of PAHs and PS, as reported in the literature, also indicating where results were in line with the data from the present study (marked with [+] in the last column). In addition to what has been reported before, and because the thyroid hormone system is strongly involved in developmental processes ( Bernasconi et al , 2015 ), the present study also included the TRβ CALUX assay. However, although disturbance of the thyroid system can be an important mode of action in developmental toxicity ( Haddow et al , 1999 ; Jomaa et al , 2014 ), none of the products showed a meaningful interaction with the respective receptor, which is in concordance with results in vivo as reported by Fowles et al (2016) .…”

Association between pre- and postnatal exposure to endocrine-disrupting chemicals and birth and neurodevelopmental outcomes: an extensive review

“…By mimicking thyroid hormones, PBDEs can disrupt the necessary roles of these hormones in fetal growth and development [ 101 - 103 ]. The thyroid hormones triiodothyronine (T3) and thyroxine (T4) play important roles in fetal growth and development during pregnancy; therefore, PBDE-induced thyroid disruption may have downstream effects on birth outcomes [ 101 , 104 ]. PBDE exposure is associated with placental epigenetic dysregulation, altered messenger ribonucleic acid expression, and metabolomic disruptions [ 105 - 107 ].…”

“…[101][102][103] The thyroid hormones triiodothyronine (T3) and thyroxine (T4) play important roles in fetal growth and development during pregnancy; therefore, PBDE-induced thyroid disruption may have downstream effects on birth outcomes. 101,104) PBDE exposure is associated with placental epigenetic dysregulation, altered messenger ribonucleic acid expression, and metabolomic disruptions. [105][106][107] Birth outcomes are extremely important indicators of future adult health; therefore, adverse birth outcomes are associated with several adult diseases, including obesity, hypertension, heart disease, diabetes, and stroke.…”

Thyroid hormones: Metabolism and transportation in the fetoplacental unit

“…Regulate oxidative phosphorylation basal rate. Bernasconi et al (2015); Forhead and Fowden (2014) Regulate body heat production and oxygen consumption.…”

“…Several animal models have demonstrated that the bioavailability of fetal hormones involved in tissue growth, including growth hormone, leptin, prostaglandins, and insulin‐like growth factors, is affected by TH concentrations during development (Forhead & Fowden, 2014). Interestingly, fT4 maternal concentrations are positively linked to fetal and newborn size and weight in rats (Bernasconi et al, 2015; Forhead & Fowden, 2014). However, in humans, higher maternal concentrations of fT4 are associated with lower birthweight (Derakhshan et al, 2020).…”