Elevated lead (Pb) body burden along with high levels of
environmental stress with potentially enhanced cortisol levels is a particular
problem for low socioeconomic status children in the US. Since Pb and stress
target the same brain regions and behavioral functions, their long-term
consequences for offspring were examined here following maternal Pb and stress.
Dams exposed to 150 ppm Pb in drinking water beginning 2 months prior to
gestation and lactation were subjected to restraint stress 3 times per day on gestational
days 16-17 yielding 4 groups: control no-stress (C-NS), control stress (C-S),
Pb no-stress (Pb-NS) and Pb stress (Pb-S). Fourteen-month old male offspring of
dams from the Pb-S group demonstrated significant changes in accuracy in the
learning component of a repeated learning and performance (RLP). Brief exposure
to cold stress (4oC, 30 min), imposed to evaluate the stress
response of offspring, did not differentiate the groups behaviorally, but the
Pb-NS and Pb-S groups exhibited decreased basal corticosterone (CORT) levels
and an impaired CORT response to cold stress. Catecholamine levels were
determined to evaluate long-lasting effects of the combined Pb/stress exposure
in mesolimbic and nigrostriatal dopamine systems. In striatum, Pb exposure alone
and in combination with stress modified DOPAC levels and DA turnover; while in
nucleus accumbens, DA turnover was affected by Pb alone. No major changes were
obtained in frontal cortex although a decrease in NE and 5-HIAA was observed in
the hypothalamus as result of Pb exposure. These results demonstrate that even
prenatal Pb only can permanently modulate the stress response, a critical
physiological mechanism for adaptation. ES05017 and ES01247.