EXTRACELLULAR PHOSPHORYLATION OF MEMBRANE-PROTEIN MODIFIES THETA-BURST-INDUCED LONG-TERM POTENTIATION IN CA1 NEURONS OF GUINEA-PIG HIPPOCAMPAL SLICES

The involvement of ecto-protein kinase activity in activity-dependent long-term potentiation (LTP) was studied in CA1 neurons of guinea-pig hippocampal slices. Application of 5 mu M K-252b, an ecto-protein kina se inhibitor, blocked LTP induced by a theta-burst stimulation (3 burs ts composed of 5 pulses at 100 Hz with inter-burst intervals of 200 ms ). On the other hand, under 10 mu M RK682, an ecto-phosphatase inhibit or, a robust LTP was induced by a weak theta-burst stimulation (3 burs ts composed of 3 pulses) which was just at the threshold for the induc tion of LTP in the control perfusate. These findings suggest that ATP released from presynaptic terminals during the burst stimulation plays an important role in the induction of LTP through phosphorylation of extracellular domains of synaptic membrane proteins, as the substrate for ecto-protein kinase.