Aβ-induced attenuation of LTP.

<p>(A) LTP was induced 1 h after injection of saline (control, n = 7) and Aβ (2.5 (n = 4), 12.5 (n = 4), 25 pmol (n = 9)) in saline (1 µl) via an injection cannula. An inserted picture (coronal section) shows the position of an injection cannula attached to a recording electrode in the hippocampus (HIP). (B) Averaged PS amplitudes for the last 10 min were represented as the magnitude of LTP. *, p<0.05, vs. saline (Dunnett's test). (C) Representative fEPSP recordings at the time −70 min (before injection; light grey line), −20 min (after injection; dark grey line) and 50 min (after tetanic stimulation; black line) are shown. Note that fEPSPs after Aβ injection (dark grey line) were almost the same as those before Aβ injection (light grey line). Scale bar, vertical axis (5 mV), cross axis (10 ms). (D, E and F) LTP was induced 1 h after injection of Aβ (25 pmol, n = 9), Aβ + ZnCl₂ (50 pmol, n = 9), and ZnCl₂ (n = 4) in saline. *, p<0.05, ***, p<0.001, vs. saline (n = 7), ^#, p<0.05, ^##, p<0.001 (Tukey's test).