Prenatal exposure to EDCs dis-integrates and reconstitutes neuromolecular-behavioral relationships in adult rats

Exposure to endocrine-disrupting chemicals (EDCs) is ubiquitous in all species, including humans. Previous studies have shown behavioral deficits caused by EDCs that have implications for social competence and sexual selection. The neuromolecular mechanisms for these behavioral changes induced by EDCs have not been thoroughly explored. Here, we tested the hypothesis that EDCs administered to rats during a critical period of embryonic brain development would lead to disruption of normal social preference behavior, and that this involves a network of underlying gene pathways in brain regions that regulate these behaviors. Rats were exposed prenatally to human-relevant concentrations of EDCs [polychlorinated biphenyls (PCB), an industrial chemical mixture; vinclozolin (VIN), a fungicide], or vehicle. In adulthood, a sociosexual preference test (choice between hormone-primed and hormone-depleted opposite-sex rats) was administered. We profiled gene expression of in three brain regions involved in these behaviors [preoptic area (POA), medial amygdala (MeA), ventromedial nucleus (VMN)]. Prenatal PCBs impaired sociosexual preference in both sexes, and VIN disrupted this behavior in males. Each brain region (POA, MeA, VMN) had unique sets of genes altered in a sex- and EDC-specific manner. Sexually dimorphic gene expression disruption was particularly prominent for gene modules pertaining to sex steroid hormones and nonapeptides in the MeA. EDC exposure also changed the relationships between gene expression and behavior in the mate preference test, a pattern we refer to as dis-integration and reconstitution. These findings underscore the profound effects that developmental exposure to EDCs can have on adult social behavior, highlight sex-specific and individual variation in responses, and provide a foundation for further work on the disruption of mate preference behavior after prenatal exposure to EDCs.