CYCLOHEXIMIDE INHIBITS KAINIC ACID-INDUCED GAP-43 MESSENGER-RNA IN DENTATE GRANULE CELLS IN RATS

WE have previously shown that kainic acid-induced seizures in adult ra ts caused an up-regulation of GAP-43 mRNA in the granule cells of the hippocampus, suggesting an involvement of this protein in the kainic a cid-induced sprouting of messy fibres. To determine whether this effec t was dependent on the synthesis of proteins activated under these exp erimental conditions we examined the effect of cycloheximide, a protei n synthesis inhibitor, on kainic acid-induced GAP-43 mRNA. Cycloheximi de, injected s.c. 2 h but not 8 h after kainic acid, markedly reduced the increased expression of GAP-43 mRNA in granule cells. These result s suggest that a rapid mechanism involving new protein synthesis is ac tivated by kainic acid to induce GAP-43 in the granule cells and possi bly trigger the structural remodeling of messy fibres.