Suppression of GIRK channel activity impairs extinction of CFC in male mice. (A) Depiction of CFC. Mice were introduced to a footshock chamber (Med Associates) for 5 min (pre-shock) before delivery of a footshock (0.5 mA/2 sec). Mice remained in the chamber for 1.5 min after the shock (post-shock), at which point they were returned to their home cages and housing room. Mice were reintroduced to the chamber 24 h (context test I) and 96 h (context test II) later for 5 min test sessions. The percentage of time spent freezing (freezing %) during acquisition (pre-shock and post-shock), as and during context tests I and II, were determined and compared across groups. (B) Freezing % during preshock, post-shock, test I, and test II. Symbols (Tukey's multiple comparisons): (***) P < 0.001. (C) Freezing % across the 5 min pre-shock, test I, and test II sessions in male (Tukey's multiple comparisons: [*] P < 0.05, [**] P < 0.01, [***] P < 0.001, [****] P < 0.0001) and female (Tukey's multiple comparisons: [*] P < 0.05, [**] P < 0.01, [***] P < 0.001) mice. (D) Freezing % of male and female mice by minute during test I. (E) Freezing % of male and female mice by minute during test II. Symbols (Dunnett's multiple comparisons: [*] P < 0.05 vs. GFP).
