Figure 3. Effects of mGluR5 antagonist and protein synthesis inhibitor on prolonged extinction training-induced inhibition of spontaneous recovery in mice.

(A) On day 1, mice were placed in a context for 3 min and received a footshock every 60 sec for 5 times. On day 2, mice received intraperitoneal injection of saline, 2.5 mg/kg or 5 mg/kg of MTEP and 60 min later they were placed in the same context for 10 min without receiving footshock (extinction training). The extinction training was repeated 3 times with an interval of 30 min. Contextual freezing responses were measured as an index for memory retention on day 3 and day 8. *p<0.05 vs. saline or MTEP 2.5 mg. (B) CPCCOEt (10 mg/kg) injected intraperitoneally 60 min before extinction training failed to affect 90 CS-induced extinction of fear memory. (C) Same experimental procedure as (A) except anisomycin (62.5 µg/side, n = 10) or vehicle (n = 10) was infused into the hippocampus bilaterally 30 min before extinction training. *p<0.05 vs. vehicle. (D) Distribution of cannula tips in the hippocampus from mice infused with Anisomycin (62.5 µg/side, n = 10) or vehicle (n = 10).