PAF-stimulated protein tyrosine phosphorylation in hippocampus:: Involvement of NO synthase

The effect of platelet-activating factor (PAF) on protein tyrosine phosphorylation was studied in rat hippocampal slices. PAF caused an increase in the tyrosine phosphorylation of two phosphoproteins, which we identified by immunoprecipitation assays as the focal adhesion kinase p125(FAK) and crk-associated substrate p130(Cas). The PAF effect was time- and dose-dependent. In addition, the involvement of PAF receptor was demonstrated by using PCA-4248, a specific receptor antagonist. When NO synthase was inhibited by N-G-monomethyl-L-arginine (L-NMA), PAF-stimulated protein tyrosine phosphorylation was inhibited. In conclusion, our results indicate that PAF increased the tyrosine phosphorylation of both p125(FAK) and p130(Cas) proteins by the production of NO in hippocampus, suggesting that PAF may play a role in the functioning of this cerebral area.