Figure 1.

Protein synthesis is required for inhibitory avoidance long term memory retrieval. (a) Schematic representation of rat brain section at three rostrocaudal planes (AP: −3.6; −3.8 and −4.16 mm from Bregma) showing the extent of area reached by the infusion in the dorsal hippocampus (CA1). The drawings were adapted from Paxinos and Watson⁴⁸. (b) Intrahippocampal rapamycin (Rapa) infusion 15 min before test (TS) session carried out 24 h after training (TR) impairs inhibitory avoidance long term memory (IA-LTM) retrieval. **p < 0.01, vehicle (Veh) vs. Rapa group and Rapa vs. reTS, one-way ANOVA followed by Newman-Keuls Comparison Test, n = 5-6. Data are expressed as mean ± SEM of TR or TS session step-down latency. (c) Intrahippocampal infusion of emetine (Eme) 15 min before TS also affects 24 h IA-LTM retrieval. *p < 0.05, Veh vs. Eme group, unpaired Student’s t Test, n = 6-7. Data are expressed as mean ± SEM of TR or TS session step-down latency. (d) Reversible blockade of an already expressed IA-LTM memory by intrahippocampal Rapa infusion 15 min before TS session 24 h after the first TS without any infusion. **p < 0.01, Veh vs. Rapa, 1°TS Veh vs. Rapa, and Rapa vs. reTS groups; ***p < 0.001, Rapa vs. 1°TS Rapa groups, one-way ANOVA followed by Newman-Keuls Test, n = 9-10. Data are expressed as mean ± SEM of TR or TS session step-down latency.