Suppression of postsynaptic density protein 95 expression attenuates increased tyrosine phosphorylation of NR2A subunits of N-methyl-D-aspartate receptors and interactions of Src and Fyn with NR2A after transient brain ischemia in rat hippocampus.

The effects of suppression of postsynaptic density protein 95 (PSD-95) expression on the increased tyrosine phosphorylation of N-methyl-D-aspartate receptor subunit NR2A and interactions of Src and Fyn with NR2A after brain ischemia were investigated by immunoprecipitation and immunoblotting. Transient (15 min) brain ischemia was induced by the four-vessel occlusion method in Sprague-Dawley rats. Intracerebroventricular infusion of PSD-95 antisense oligonucleotides (every 24 h for 3 days before ischemia), but not missense oligonucleotides or vehicle, not only markedly decreased the protein level of PSD-95 but also attenuated the elevated tyrosine phosphorylation of NR2A and interactions of Src and Fyn with NR2A induced by 6 h of reperfusion following ischemia in the hippocampus. The protein levels of NR2A, Src and Fyn had no differences under the above conditions. These data suggested that PSD-95 is critical for facilitating NR2A tyrosine phosphorylation by Src family kinases in postischemic brain.