• Environmental Agent Exposure during Development and Stress

    We are investigating the effects of lead (Pb2+) in combination with stress and manganese when the exposure occurs during early development. This is an important area of investigation in children’s health since Pb2+ exposure still occurs, mostly in very young children of low social economic status (SES) families, and these exposures result in long-term cognitive and behavioral changes.

    Cofactors implicated in the effects of Pb2+ on development include, but are not limited to, stressors and manganese. Low SES conditions have been associated with stress, and children in these situations tend to have higher levels of circulating cortisol, suggesting increased stress. In regard to manganese, high levels are introduced in the diet with the use of soy-based infant formula as well as air pollution. The combination of these factors may explain why some children are more affected by Pb2+ than others.

    To better control the intervals of exposure to metals and stressors, we are developing a model using rats. We have begun by investigating the effects of Pb2+ and different stressors as models of low SES on the development of the monoamine neurotransmitters in the brain and hormonal responses to stress.

    We have done similar experiments with manganese and with all three together to look at the long-term effects. We showed that manganese and stress produce long-term effects, but we have not yet found an effective dose of Pb2+. Preliminary data suggest that rats may be less sensitive to Pb2+ than humans; therefore we are working to find a dose for rats that produces outcomes similar to those seen in children. We will then test the combined effects of all three factors.