Gender-Dependent Effects of Endocrine Disrupting Chemicals on Retinoic Acid-Related Orphan Receptor Alpha [RORA] and Aromatase Genes on Human Progenitor Neurons

Abstract

Normally we encounter a myriad of chemicals in our daily lives. Endocrine disrupting chemicals [EDCs] are ubiquitous in our environment and upon bodily entry many be stored in adipose tissue and, in pregnant woman, can reach the developing fetal brain, disrupting normal fetal brain development. EDC-induced aberrant levels of sex hormones can alter sexual dimorphism [i.e. degree of feminization or masculinization; sex differences in brain and behavior] and may contribute to the differential susceptibility of males and females to autism. Fetal development is guarded by the placenta which expresses high levels of aromatase, an enzyme that converts testosterone [T] to estrogen [E], and it appears that this process prevents the transfer of maternal T to the vulnerable developing fetus. Many investigators have shown a clear association between exposure to high levels of T during the prenatal and early postnatal periods, and development of autism spectrum disorder [ASD]. Retinoic acid-related orphan receptor-alpha [RORA] is a transcription factor that regulates aromatase. We analyzed the effects of six commonly encountered EDCs on human progenitor neurons from both genders and evaluated the differential expression of both aromatase and RORA by real-time PCR using an in vitro approach. We also evaluated the effects of the EDCs on neurite formation. Male and female human neuroblastoma cell lines were used to evaluate the effects of EDCs on neurite formation and the expression of RORA and CYP19A1. The morphologic analyses showed significant neuromodifications in neurite formation and a significant differential downregulation of RORA in male, but not in female neurons. Dysregulation in CYP19A1 was not gender-associated but was dependent on the dose of EDCs. Our findings confirm previous reports of differential downregulation of RORA in male neurons while expanding the gene-environment connection where estrogenic or androgenic EDCs can profoundly dysregulate RORA and aromatase gene expression, leading to a cascade of a highly integrated gene-network, associated with ASD.