Endocrine-Disrupting Chemicals and Hippocampal Development: The Role of Estrogen and Androgen Signaling

Transcriptomic characterization of 2D and 3D human induced pluripotent stem cell-based in vitro models as New Approach Methodologies for developmental neurotoxicity testing

The safety and developmental neurotoxicity (DNT) potential of chemicals remain critically understudied due to limitations of current in vivo testing guidelines, which are low throughput, resource-intensive, and hindered by species differences that limit their relevance to human health. To address these issues, robust New Approach Methodologies (NAMs) using deeply characterized cell models are essential. This study presents the comprehensive transcriptomic characterization of two advanced human-induced pluripotent stem cell (hiPSC)-derived models: a 2D adherent and a 3D neurosphere model of human neural progenitor cells (hiNPCs) differentiated up to 21 days. Using high-throughput RNA sequencing, we compared gene expression profiles of 2D and 3D models at three developmental stages (3, 14, and 21 days of differentiation). Both models exhibit maturation towards post-mitotic neurons, with the 3D model maturing faster and showing a higher prevalence of GABAergic neurons, while the 2D model is enriched with glutamatergic neurons. Both models demonstrate broad applicability domains, including excitatory and inhibitory neurons, astrocytes, and key endocrine and especially the understudied cholinergic receptors. Comparison with human fetal brain samples confirms their physiological relevance. This study provides novel in-depth applicability insights into the temporal and dimensional aspects of hiPSC-derived neural models for DNT testing. The complementary use of these two models is highlighted: the 2D model excels in synaptogenesis assessment, while the 3D model is particularly suited for neural network formation as observed as well in previous functional studies with these models. This research marks a significant advancement in developing human-relevant, high-throughput DNT assays for regulatory purposes.

Prenatal exposure to neonicotinoid insecticides, fetal endocrine hormones and birth size: Findings from SMBCS

BACKGROUND

Neonicotinoid insecticides (NNIs) were reported to be endocrine disruptors and cause adverse health effects in human. However, epidemiological evidence about the effect of prenatal NNIs exposure on birth outcome and hormones remains limited.

OBJECTIVES

This study aimed to explore the effects of prenatal NNIs exposure on neonatal birth size and endocrine hormones, and assess the potential mediating role of hormones.

METHODS

The study included 860 mother-child pairs from the Sheyang Mini Birth Cohort Study. 12 parent NNIs (p-NNIs) and 6 metabolites of NNIs (m-NNIs) were measured in maternal urine samples collected on their delivery days, and 5 thyroid hormones and 2 sex hormones were analyzed in cord serum. The concentrations of p-NNIs and its specific metabolite(s) were summed to characterize the role of each class of NNIs. Generalized linear model and weighted quantile sum regression were used to examine the impact of prenatal NNIs exposure on birth size and endocrine hormones, and potential mediating roles of hormones were further explored using mediation analysis.

RESULTS

Higher detection frequencies of m-NNIs were observed than those in p-NNIs. A decrease in neonatal head circumference for gestation age z-score was associated with a 10-fold increase in 5-OH-IMI (β = -0.15, 95 %CI: -0.26, -0.03), ∑DIN (β = -0.22, 95 %CI: -0.40, -0.03), ∑IMI (β = -0.20, 95 %CI: -0.35, -0.06) and ∑NNIs (β = -0.23, 95 %CI: -0.42, -0.04). ∑IMI and ∑DIN were the major contributors to the significantly negative mixture effect and no sex-specific effect was observed. Negative associations were observed between ∑DIN and TT3 (β = -0.013, 95 %CI: -0.025, -0.002), ∑IMI and T (β = -0.035, 95 %CI: -0.065, -0.004), respectively. Furthermore, TT3 and T demonstrated 6.7 % and 6.1 % mediating effects on the negative association of prenatal ∑DIN and ∑IMI exposure with head circumference.

CONCLUSIONS

Our findings suggested the potential endocrine disruptive properties of NNIs and their impacts on head circumference. Endocrine hormones may partly mediate these associations.

Associations of prenatal exposure to per- and polyfluoroalkyl substances and fetal sex hormones in the Guangxi Zhuang Birth Cohort Study: Greater effect of long-chain PFAS

Fetal sex hormone homeostasis disruption could lead to reproductive and developmental abnormalities. However, previous studies have reported inconsistent findings regarding the association of maternal per- and polyfluoroalkyl substances (PFAS) exposure with fetal sex hormone levels. A total of 277 mother-infant pairs from the Guangxi Zhuang Birth Cohort Study between 2015 and 2019 were selected. We quantified nine PFAS in maternal serum in early pregnancy, and detected three sex hormones, namely, estradiol (E2), progesterone (P4) and testosterone (TT), in cord blood. The generalized linear model (GLM) and Bayesian kernel machine regression (BKMR) model were used for single- and multiple-exposure analyses, respectively. In the GLM, there was no significant association between an individual PFAS and any hormone level or the E2/TT ratio, but a negative association between perfluorododecanoic acid (PFDoA) exposure and P4 levels in female infants was observed after stratification by sex. In the BKMR, a mixture of nine PFAS was positively associated with E2 levels and the E2/TT ratio, with the same main contributors, i.e., perfluoroundecanoic acid (PFUnA). And PFAS mixtures were not associated with P4 or TT levels. After stratification by infant sex, positive associations of PFAS mixtures with E2 levels and the E2/TT ratio were observed only in male infants, with the same main contributors, i.e., PFUnA. There was a positive association between PFAS mixtures and P4 levels in male infants, in which PFUnA was the main contributor; but a reverse association between PFAS mixtures and P4 levels in female infants, in which PFDoA was the main contributor. This study suggested that prenatal exposure to PFAS mixtures is associated with fetal sex hormones, and long-chain PFAS may play an important role in this association. Furthermore, sex differences in the association of maternal PFAS exposure with E2 and P4 levels need additional attention.