Proapoptotic Nitric Oxide Production in Amyloid β Protein-Treated Cerebral Microvascular Endothelial Cells

Objective: The objective of this study was to investigate the effects of amyloid β protein (Aβ) on cerebral microvascular endothelium, and their possible involvement in Aβ-induced apoptosis in the neighboring cells.Methods: Cultured bovine brain microvascular endothelial cells (BBECs) were incubated with Aβ for 24 h. Production of nitric oxide (NO) was assessed by nitric oxide-sensitive fluorescent dye, DAF-2, and the expression of NO synthase (NOS) proteins was examined by Western blotting. Effects of Aβ-treated microvascular endothelium on the DNA damage of the neighboring cells were assessed by single-cell gel electrophoresis.Results: Aβ increased the expression of iNOS protein, but did not affect eNOS and nNOS expressions in BBECs. Aβ-treated BBECs showed spontaneous NO production in the presence of L-arginine. The neural cell line PC12 showed marked apoptosis after being co-cultured with Aβ-treated BBECs for 48 h, and the apoptosis was as potent as that induced by the inflammatory stimuli lipopolysac...