β-Amyloid Increases Enzyme Activity and Protein Levels of Glutamine Synthetase in Cultured Astrocytes

Previous studies have reported that β-amyloid peptides induce properties of reactivity in cultured astrocytes. We report here that aggregated Aβ peptides increase expression of the enzyme glutamine synthetase in cultured astrocytes, as assessed by enzyme assay, Western blot analysis, and immunocytochemistry. The enhanced enzyme levels occur gradually over a period of 4 days after Aβ exposure and maintain peak values for at least several days thereafter. These data suggest that Aβ-related reactive astrocytosis in Alzheimer's disease brain may benefit local neurons by enhancing glial capacity to regulate levels of the excitotoxin glutamate.