Induction of glutamine synthetase by l- α-aminoadipate in developmental stages of cultured astrocytes

Abstract

Effect of l- α-aminoadipate ( l αAA), a gliotoxic l-glutamate analogue, on glutamine synthetase (GS) activity of rat cultured astrocytes was examined. l αAA at sub-toxic concentrations (less than 0.5 mM, for 48 h) increased GS activity of cultured astrocytes. This increase was prevented by 10 μM cycloheximide, an inhibitor of protein synthesis. l αAA increased GS activities of astrocytes cultured in three different conditions, i.e. 12-day-old, 5-week-old and dibutyryl cAMP(DBcAMP)-induced differentiated cultures. Insulin (10 μg/ml) and hydrocortisone (10 μM) increased GS activity of 12-day-old cultured cells, but not that of 5-weeks-old and DBcAMP-treated cells. The increase in GS activity was observed after a transient treatment with l αAA for 4 h. These results show that the induction of GS by l αAA is not related to developmental stages of astrocytes in culture.