Protein F1/GAP-43 and PKC gene expression patterns in hippocampus are altered 1-2 h after LTP.

Three days after long-term potentiation (LTP) there is a decrease in the gene expression of protein F1 (GAP-43) and gamma-PKC in CA3 pyramidal cells that is correlated with the magnitude of LTP. We predicted these decreases would be preceded by an increment in gene expression. At 1 h, but not at 2 h after LTP, F1/GAP-43 and gamma-PKC mRNA hybridization were increased, but increases were also observed after control stimulation. At both 1 and 2 h after LTP, changes in F1/GAP-43 hybridization were positively correlated with gamma-PKC hybridization and negatively correlated with LTP magnitude. These data indicate that correlated alterations in F1/GAP-43 gene expression and synaptic efficacy can occur as early as 1 h after LTP and persist for days.