Nicotine rescues mfLTP in BACE1 KOs without effects in WTs. A, KO slices treated with 10 μm nicotine (black circles) showed significant mfLTP compared to control slices without nicotine (open circles). B, The magnitude of mfLTP in WT slices treated with 10 μm nicotine (black squares) was similar to that of control WT slices (open squares). C, Transient application of nicotine (10 μm, 10 min; gray bar) before and during HFS rescued mfLTP in KOs (black circles). D, The same transient nicotine (10 μm, 10 min; gray bar) application did not influence mfLTP in WT (black squares). Insets: A, B, Changes in PPF ratio with HFS [ΔPPF ratio = (PPF ratio at time b) − (PPF ratio at time a)] for control (Ctl) and Nic; C, D, ΔPPF ratio with nicotine application [(PPF ratio at time b) − (PPF ratio at time a)] and with HFS [(PPF ratio at time c) − (PPF ratio at time a)]. Bars, Average ± SEM. Open circles, Individual data points. *Paired t test, p < 0.001. Arrow, HFS (100 Hz, 1 s × 3). Right panels, Superimposed FP traces taken at times indicated in the left panels. Calibration: 0.5 mV, 5 ms.