VIRGOLINI MIRIAM BEATRIZ
Congresos y reuniones científicas
Título:
Chronic postweaning Pb exposure modulates the response to environmental stress challenge
Autor/es:
VIRGOLINI, M.B.; WESTON, D.D.; CORY-SLECHTA, D.A
Lugar:
San Diego, California, USA
Reunión:
Congreso; Society for Neuroscience. 34 nd Annual Meeting; 2004
Institución organizadora:
Society for Neuroscience
Resumen:
Low socioeconomic status children in the U.S. sustain the highest blood lead (Pb) levels and live in high stress environments thought to be associated with prolonged cortisol elevation. Notably, Pb exposure and elevated corticosterone (CORT) both target mesolimbic dopamine (DA) systems and produce similar behavioral alterations. Therefore, this study examined the hypothesis that Pb and stress could interact at the behavioral, endocrine and neurochemical level. While male rats subjected to chronic postweaning Pb exposure (0, or 100 ppm in drinking water with associated blood Pb levels of about 12 ug/dl) showed no differences in repeated learning or performance (RLP) in a multiple schedule paradigm, a brief exposure to cold stress (40C for 30 min) immediately before an RLP session decreased accuracy of Pb-treated rats selectively in the learning component. Moreover, this effect was prevented by pretreatment with the cortisol synthesis inhibitor metyrapone (METY). Similarly, Pb-exposed rats subjected to cold stress showed the highest CORT levels (measured at the end of the RLP session), levels that were blunted by METY in all groups. Such differential effects were not observed in response to immobilization stress (45 min) prior to an RLP session. Pb exposure increased DOPAC, HVA, 5-HT, 5-HIAA, and DA turnover in nucleus accumbens and 5-HT and 5-HIAA in hypothalamus. Changes in DOPAC, NE, 5-HT and DA turnover in frontal cortex reflected Pb-stress interactions, while alterations in DOPAC and HVA were associated with stress alone. These results indicate that low level Pb exposure can modulate responses to stressful situations and that the nature of the effects is dependent upon the nature of the stressor. They also raise questions about stress-related mechanisms of Pb effects as well as the adequacy of current risk evaluations based on the study of Pb in isolation. Supported by ES05017, ES01247.
