VIRGOLINI MIRIAM BEATRIZ
Congresos y reuniones científicas
Título:
Interactive effects of chronic postweaning Pb exposure and environmental stress
Autor/es:
CORY-SLECHTA, D.A.; WESTON, D.D.; VIRGOLINI, M.B.
Lugar:
Baltimore, Maryland, USA
Reunión:
Congreso; . Society of Toxicology. 43rd Annual Meeting; 2004
Institución organizadora:
Society of Toxicology
Resumen:
Lower socioeconomic status (SES) children in the U.S. also sustain the highest blood lead (Pb) levels. Low SES itself is a known risk factor for adverse health outcomes and behavioral dysfunctions, a phenomenon attributed to higher levels of stress and prolonged cortisol elevation. Pb exposure and elevated cortisol are associated with similar behavioral alterations and target mesolimbic dopamine (DA) systems. The hypothesis that Pb interacts with environmental stress was examined here in male rats subjected to chronic postweaning Pb exposure (0, 50 or 150 ppm in drinking water) with or without environmental stress (groups: control no-stress (C-NS), control stress (C-S), Pb50 no-stress (50-NS), Pb50 stress (50-S), Pb150 no-stress (150-NS) & Pb150 stress (150-S)). As in our past studies, Pb increased response rates on a fixed interval (FI) schedule of food reward by 38% and 58% at 50 and 150 ppm, respectively. Functionality of the HPA axis was measured via blood corticosterone (CORT) levels. Pb itself decreased basal CORT levels at 50 ppm (31%) with less pronounced effects (18%) at 150 ppm. Introduction into a novel environment increased ambulatory and horizontal activity only in the 150-S group and suppressed FI response rates only in the Pb groups, even though equivalent increases in CORT were observed across all groups. Brief exposure to a cold environment increased CORT levels only in the 50-S and 150-S groups but did not differentially influence FI performance. Interactions of Pb and stress cannot be easily ascribed to changes in brain monoamine alterations since changes in levels of DA and serotonin and metabolites in striatum and frontal cortex were primarily due to Pb alone, and no changes were found in nucleus accumbens. These results indicate that Pb exposure can modulate responses to stress situations and stress can unmask effects of Pb. These findings raise questions about stress-related mechanisms of Pb effects as well as the adequacy of risk assessments based on the study of Pb in isolation. Supported by ES05017, ES01247.
