Figure 3.

Persistent PKMζ phosphorylation maintains the late phase of LTP at 3 and 5 h after tetanization. A, A 5 μm concentration of ZIP applied 3 h after tetanization reversed the potentiated pathway but had no effect on the control pathway (n = 6). The level of potentiation before drug exposure was significantly reduced by 1 h after the inhibitor was applied (p < 0.01), and, by 2 h, the tetanized pathway had returned to baseline. B, Infusion of 2.5 μm partially reversed potentiation after 2 h of drug perfusion (p < 0.05; n = 5). C, D, A 1 μm concentration of ZIP (C; n = 6) or a 5 μm concentration of the scrambled inactive peptide (D; n = 6) had no effect on either tetanized or nontetanized pathways. E, A 5 μm concentration of ZIP applied 5 h after tetanization reversed the potentiated pathway but had no effect on the control pathway (n = 4). F, A 5 μm concentration of scrambled inactive peptide had no effect (n = 4).