Prenatal exposure of mice to an environmental estrogen alters sex differences in brain and behavior

56. PRENATAL EXPOSURE OF MICE TO A LOW-DOSE ENVIRONMENTAL ESTROGEN ALTERS SEX DIFFERENCES IN BRAIN AND BEHAVIOR. Palanza; P:; Ponzi, D., Gioiosa, L., Flugge, G., Parmigiani, S., and Fuchs, E. Dipartimento di Biologia Evolutiva, Universita` di Parma. Laboratory of Neurobiology, German Primate Center, Goettingen. The presence in the environment to a large number of environmental and industrial compounds that have estrogenic activity (Environmental Estrogens, EE) raises major health concerns. Sexually dimorphic behaviors are particularly useful to study the effects of low concentrations of EE, similar to environmental contamination, because they are highly sensitive to alterations of the endocrine mileu. Behavior is the endpoint of complex, integrated systems and therefore is a good biomarker of neuroendocrine and neurobiological alterations. We investigated the effects of prenatal exposure (via maternal treatment) to an environmental-like, low dose of bisphenol A (BPA, an estrogenic compound used in food industry) on mice behavioral response to novelty and on the noradrenergic system in the brain. Mice were tested in a free-choice novelty preference test at adolescence, in a freeexploratory open field and elevated plus-maze (EPM) as adults. Both adolescent and adult mice exposed to BPAshowed either a decrease or a reversion in sexual differences in response to novelty. Contrary to the control profile, BPA-exposed males and females did not differ in exploration, an effect due mainly to changes in BPA-exposed females relative to controls. As adults, mice were sacrificed and their brain were analyzed for alpha2 adrenergic receptor system in locus coeruleus (LC) and preoptic area (PO). Control mice showed a sexually dimorphic profile of receptor density in the PO, while prenatal BPA-exposure lowered such sex differences; BPA-exposed males showed increased receptors number, thus resulting more similar to the control females’ profile. In both the PO and LC of exposed animals, a decreased affinity of alpha2-adrenergic receptors was observed.