Assessments of tight junction proteins occludin, claudin 5 and scaffold proteins ZO1 and ZO2 in endothelial cells of the rat blood-brain barrier: Cellular responses to neurotoxicants malathion and lead acetate

The blood-brain barrier (BBB) is essential for central nervous system (CNS) normal function. It is formed by endothelial cells with special characteristics, which confer the BBB with low permeability and high transendothelial electrical resistance (TEER). We previously demonstrated that malathion and lead, two neurotoxicants widely present in the environment, decrease TEER and increase permeability in in vitro models of the BBB. In this study we assessed tight junction disruption at the protein and gene expression levels using a rat brain microvascular endothelial cell line (RBE4) exposed to lead acetate at 10−5 M and 10−6 M, malathion at 10−5 M, malaoxon at 10−6 M, and their combinations. Cells were incubated with treatments for 2 h, 4 h, 8 h, 16 h, and 24 h periods. Immunoblotting assessments demonstrated that protein levels of tight junction proteins occludin and claudin 5, and scaffold proteins ZO1 and ZO2 were decreased after treatments. Gene expression determinations did not correlate with the decreases in protein, indicating that the effects on these proteins were post-translational.