Signals that regulate astroglial gene expression: induction of GFAP mRNA following seizures or injury is blocked by protein synthesis inhibitors.

Previous studies have revealed that a single electroconvulsive seizure (ECS) strongly induces glial fibrillary acidic protein (GFAP) expression in astrocytes in the hippocampal dentate gyrus. The signals that trigger this induction are not known, but circumstantial evidence suggests the hypothesis that GFAP expression may be induced as a result of the induction of growth factor expression by dentate granule cells that also occurs as a result of the ECS and other types of seizures. The present study tests one prediction of this hypothesis by evaluating whether increases in GFAP mRNA levels after ECS are blocked by inhibiting protein synthesis at various times after the ECS. We report that the upregulation of GFAP expression following ECS is blocked by protein synthesis inhibitors given 5 min before or up to 12 h after a single ECS. This temporal gradient suggests an intermediate step involving the increased expression of a protein growth factor.