BLOCK OF LONG-TERM POTENTIATION BY INTRACELLULAR APPLICATION OF ANTI-PHOSPHATIDYLINOSITOL 4,5-BISPHOSPHATE ANTIBODY IN HIPPOCAMPAL PYRAMIDAL NEURONS

We examined the effects of black widow spider toxin and anti-phosphati dylinositol 4,5-bisphosphate antibody on the changes in excitatory pos tsynaptic currents and spontaneous excitatory postsynaptic currents ac companying long-term potentiation using whole-cell recording from hipp ocampal CA1 pyramidal neurons of rodents. In the presence of black wid ow spider toxin, tetanic stimulation of input fibers produced a short- lived potentiation followed by a gradual decline of the excitatory pos tsynaptic current amplitude. With an anti-phosphatidylinositol 4,5-bis phosphate antibody containing pipette, tetanus elicited only decrement al potentiation of excitatory postsynaptic currents with a reduced fre quency of spontaneous excitatory postsynaptic currents, suggesting inh ibition of retrograde reinforcement from the antibody-injected neuron. With both black widow spider toxin and anti-phosphatidylinositol 4,5- bisphosphate antibody, neurons showed a rapid depression of excitatory postsynaptic currents after tetanus. The results indicate that time-d ependent interactions between presynaptic terminals and the postsynapt ic spines take place during long-term potentiation.