Figure 2
Effects of PDE4 inhibition on fear memory reinstatement and fear memory extinction. The experimental design is represented above the graphs. The red arrows represent the moment of treatment. (A) No differences were observed among groups during retrieval and Test A1. However, animals treated with ROF presented less freezing behavior, 10 days after Test A1, during early extinction (first 3 min) compared to control in the same session. In late extinction (last 3 min), the control group showed less freezing behavior compared to itself during early extinction. After a reminder shock, in the reinstatement test, both groups showed higher freezing levels than themselves during late extinction. (B) Animals treated with ROF after retrieval presented less freezing behavior than controls in the extinction session, suggesting facilitation of fear extinction. 24 h after extinction, in Test A1, the ROF-treated group presented less freezing than controls. (C) The extinction session separated into 2 min time-bin showed that ROF-treated animals reduced the fear expression faster than controls. The data in (A) and (B) is represented by mean ± S.E.M. and the individual values of the percentage of freezing expressed by animals during each session. The data in (C) is represented by mean ± S.E.M. expressed in extinction divided into 2 min time-bin. The * represents a significant difference (*P < 0.05) compared to VEH in the same session. The # represents a significant difference (#P < 0.05) compared to the same group during early extinction. The + represents a significant difference (+ P < 0.05) compared to the same group during late extinction. n: VEH = 8; ROF = 8.
