PI3K inhibition reduces normal L-LTP and β-lactone-mediated enhancement of Ep-L-LTP. A, Pretreatment with PI3K inhibitor LY294002 significantly (p < 0.0001) reduces L-LTP. Inset, Representative traces taken at different time points (1 = 30 min; 2 = 180 min) for no treatment “Control” and treatment with LY294002. B, Normal basal synaptic transmission in LY294002-treated hippocampal slices (n = 7) compared with vehicle-treated control (n = 7) slices. The graph shows input–output curves of fEPSP slope (mV/ms) versus stimulus at the Schaffer collateral pathway upon treatment with the vehicle (DMSO) or LY294002. C, Incubation with LY294002 before β-lactone application significantly (p < 0.0001) decreases the enhancement in Ep-L-LTP. Inset, Representative traces taken at different time points (1 = 30 min; 2 = 180 min) for β-lactone alone and LY294002 + β-lactone.