Pb exposures are highest in low socioeconomic status populations that are also thought to experience the highest levels of environmental stress. Our prior studies confirm permanent alterations in baseline fixed interval (FI) performance and its alteration following stress challenges in response to maternal Pb, maternal stress and their combination. The current study extended these observations to an experimental model that would most closely approximate human parameters of these risk factors. Dams were exposed to 0, 50 or 150 ppm Pb in drinking water, maternal restraint stress, or both. Offspring were continued on the same Pb exposure as the dam, and a subset were also subjected to offspring stress challenges. Mean blood Pb values of offspring ranged from <2, 11-12 and 27-29 ug/dl, respectively with slightly elevated levels for males and for those subjected to offspring stress. Performance on an FI schedule of food reinforcement, a baseline with known sensitivity to Pb exposure, was examined over time, including sessions preceded by one of three different stress challenges (restraint, cold, novelty). Behavioral consequences were more pronounced in females than males, with significant increases in FI response rates across behavioral session in the groups exposed to Pb alone or Pb combined with either maternal or maternal +offspring stress, whereas only marginal increases occurred in the 0 ppm maternal or 0 ppm maternal + offspring stress groups. These changes were largely attributable to increased run rates and decreased inter-response times, with postreinforcement pause times not systematically affected. Similar trends were evident in males, but restricted to the 50 and 150 ppm + maternal stress groups. These findings confirm that stress can enhance the behavioral toxicity of Pb even at very low blood Pb levels and highlight a preferential vulnerability of females to these effects. ES012712
