Endocrine Abstracts

Environmental endocrine-disrupting chemicals (EDCs) are exogenous chemicals that perturb hormones and their actions. Exposures to EDCs during critical periods of life, especially in the developing fetus and infant, are particularly problematic due to the high sensitivity of the perinatal hypothalamus to endogenous hormones and exogenous compounds. Our lab has been using a rat model of prenatal exposure to two classes of EDCs: a polychlorinated biphenyl (PCB) mixture used previously in industry, the fungicide vinclozolin, in current agricultural use, or the vehicle. These chemicals are administered to the dam during the period of prenatal brain sexual differentiation in the developing offspring. These latter female and male rats are phenotyped for effects on development, hormones and behavior in adulthood, and functional behavioral outcomes. Protein, gene expression, and epigenetic changes to the brains of these animals are also determined. Our results show that sociosexual and anxiety-like behaviors are changed by EDCs in a sexually-dimorphic manner. Gene expression profiling of brains from these animals has identified suites of genes differentially affected by EDCs compared to vehicle rats, with sex-, age-, and brain-region specific differences. Recent results have focused on the implications of these changes induced by EDCs for mate choice behavior and underlying neural pathways involved in conveying information about the attractiveness of a mate and transducing it into a behavioral choice. As a whole, our work indicates that gestational exposure to PCBs has lifelong effects on the developing brain, neuroendocrine systems, and reproductive and social behaviors in exposed individuals. These data are highly relevant to humans and wildlife, as all individuals are exposed to environmental chemicals due to their persistence and ubiquity.