Infantile exposure to lead and late-age cognitive decline: Relevance to AD

Background: Early-life lead (Pb) exposure induces overexpression of the amyloid beta precursor protein and its amyloid beta product in older rats and primates. We exposed rodents to Pb during different life span periods and examined cognitive function in old age and its impact on biomarkers associated with Alzheimer's disease (AD). Methods: Morris, Y, and the elevated plus mazes were used. Western blot, quantitative polymerase chain reaction (qPCR), and enzyme-linked immunosorbent assay were used to study the levels of AD biomarkers. Results: Cognitive impairment was observed in mice exposed as infants but not as adults. Overexpression of AD-related genes (amyloid beta precursor protein and β-site amyloid precursor protein cleaving enzyme 1) and their products, as well as their transcriptional regulator - specificity protein 1 (Sp1) - occurred only in older mice with developmental exposure to Pb. Conclusions: A window of vulnerability to Pb neurotoxicity exists in the developing brain that can influence AD pathogenesis and cognitive decline in old age.