Advance Access publication July 16, 2010 Enhanced Learning Deficits in Female Rats Following Lifetime Pb Exposure Combined with Prenatal Stress

Pb (lead) exposure and stress are co-occurring risk factors (particularly in low socioeconomic communities) that also act on common biological substrates and produce common adverse outcomes, including cognitive impairments. This study sought to determine whether lifetime Pb exposure combined with prenatal stress would enhance the cognitive deficits independently associ-ated with each of these risk factors and to explore associated mechanisms of any observed impairments. Learning was evalu-ated using a multiple schedule of repeated learning and performance in female rats subjected to lifetime Pb exposure (0 or 50 ppm Pb in drinking water beginning in dams 2 months prior to breeding; blood Pb levels ~10 mg/dl), to prenatal restraint stress on gestational days 16 and 17, or to both. Blood Pb, corticosterone levels, brain monoamines, and hippocampal nerve growth factor levels were also measured. Sequence-specifi