The Trajectory of Brain Monoamines Across Time Following Maternal Lead (Pb) Exposure and /or Prenatal Stress is Altered by Behavioral History

D. A. CORY-SLECHTA; M. B. VIRGOLINI; A. ROSSI-GEORGE; M. THIRUCHELVAM

Baltimore, Maryland, USA

Congreso; Society of Toxicology. 48th Annual Meeting; 2009

Society of Toxicology

 
The Trajectory of Brain Monoamines Across Time Following Maternal Lead (Pb) Exposure and /or Prenatal Stress is Altered by Behavioral History
D. A. Cory-Slechta1; M. B. Virgolini2; A. Rossi-George2; M. Thiruchelvam2
1. Environmental Medicine, University of Rochester Medical School, Rochester, NY, USA.
2. , EOHSI, Piscataway, NJ, USA.        
        
We previously found marked differences in the corticosterone response to stress challenges as a function of behavioral history (BH) in male and female offspring of rat dams treated with lead (Pb) +/- prenatal stress (PS). For example, delayed habituation and even sensitization of corticosterone levels were observed in females with no BH, as compared to habituation of stress-induced corticosterone increases in BH counterparts. This study examined whether BH also modified the neurochemical consequences of maternal Pb +/- PS. Offspring of dams exposed to 0, 50 or 150 ppm Pb drinking water from 2 mos prior to breeding through lactation +/- PS (prenatal restraint stress) either underwent behavioral testing on a fixed interval (FI) schedule of food reward, or were minimally handled and underwent no behavioral testing (NFI). Monoamines in midbrain, striatum and frontal cortex were compared in FI and NFI groups at the end of behavioral testing (6 mos of age), as well as to values derived from their mutual 2 mos old littermates. Comparisons of 6 mos FI vs. NFI values confirmed that BH differentially changed monoamines in all brain regions examined in both males and females. Changes in monoamine trajectories between 2 and 6 mos occurred even in FI and NFI control groups, confirming their normal dynamic nature. Pb +/- PS, however, interacted with BH, further modifying neurochemical changes across time, targeting striatal DA, frontal cortex and nucleus accumbens NE, and 5-HT in all regions in females, and striatal and nucleus accumbens DA in males. These findings underscore the significance of BH in defining the ultimate outcomes of Pb +/- PS and caution against generalizing neurochemical findings from non-behavioral to behavioral conditions. Understanding the impact of BH on monoamine systems may permit a better understanding of Pb +/- stress mechanisms, and guide the development of more precise behavioral therapeutic strategies to reverse such effects. ES012712