Application of a Novel Social Choice Paradigm to Assess Effects of Prenatal Endocrine-Disrupting Chemical Exposure in Rats (Rattus norvegicus)

Endocrine-disrupting chemical (EDC) exposures during critical periods of gestation cause long-lasting behavioral effects, presumably by disturbing hormonal organization of the brain. Among such EDCs are polychlorinated biphenyls (PCBs), a class of industrial chemicals. PCB exposure in utero leads to alterations in mating behaviors and other sexually dimorphic social interactions in rats. Many of the previous studies on social behavior gave the experimental animal a single or binary choice. This study applied a more complex behavioral apparatus, an X-shaped Plexiglas apparatus (FourPlex), that enabled an experimental animal exposed to PCBs or a vehicle to distinguish and choose among 4 stimulus animals of the same or opposite sex, and of different hormonal status. We found that rats were able to differentiate among the stimuli in the FourPlex and showed the expected preference for an opposite sex, hormone-treated rat, particularly for behaviors conducted in proximity. Prenatal treatment caused subtle shifts in behavior toward stimulus rats in the FourPlex; more robust effects were seen for the sexual dimorphisms in behavior. Importantly, the results differ from our previous results of a simple binary choice model, showing that how an animal behaves in a more complex social paradigm does not predict the outcome in a simple choice model, and vice versa.