3.5.2. Freezing

For freezing during the SRs (Figure 6a), a repeated measures ANOVA (shock × virus × drug × SRs; 2 × 2 × 2 × 6) indicated significant main effects of drug [F(1,56) = 57.964, *p* < 0.001], shock [F(1,56) = 628.020, *p* < 0.001], virus [F(1,56) = 50.831, *p* < 0.001], and SR [F(5,280) = 21.893, *p* < 0.001]. The results also indicated the following interactions: shock × virus [F(1,56) = 52.261, *p* < 0.001], shock × drug [F(1,56) = 51.441, *p* < 0.001]; virus × drug [F(1,56) = 32.402, *p* < 0.001]; shock × virus × drug [F(1,56) = 41.557, *p* < 0.001]; shock × SR [F(5,280) = 20.870, *p* < 0.001], drug × SR [F(5,280) = 2.851, *p* < 0.05], shock × virus × SR [F(5,280) = 2.886, *p* < 0.05], and shock × virus × drug × SR [F(5,280) = 2.233, *p* = 0.05]. Post hoc analysis revealed that the Shock/GFP + Veh, Shock/DR + URB, and Shock/DR + Veh groups demonstrated a significant increase in freezing levels compared with their corresponding control groups (SR1–SR5: all *p* < 0.001). Moreover, the Shock/DR + URB group showed decreased freezing levels compared with the Shock/GFP + Veh group and the Shock/DR + URB group (SR1–SR5: all *p* < 0.001), and increased freezing levels compared with the NoShock/GFP + URB group (SR1, SR2, SR4, and SR5: all *p* < 0.05). Hence, downregulation of β-catenin in the NAc had no effect on freezing behavior by itself, but it blocked the preventive effects of URB597 in shocked rats.
