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. 2021 Aug 7;24(11):907–919. doi: 10.1093/ijnp/pyab055

Figure 1.

Figure 1.

Intracerebroventricular (ICV) injection of AICP facilitates fear extinction. (A) Schematic of experimental design used for fear conditioning and fear extinction. CS, conditioned stimulus; US, unconditioned stimulus. (B) Schematic of injection site and verification of guide cannula targeted at lateral ventricle (LV). (C) Effect of AICP on fear extinction in WT mice. ICV injection of AICP (3.5 µg) immediately after extinction training significantly reduced freezing behavior in post-extinction recall test (vehicle n = 6, AICP n = 7). Two-way ANOVA showed significant effect of treatment (F [1, 11] = 91.16, P < .0001) and interaction (F [1, 11] = 15.14, P = .0025). Post-hoc Bonferroni’s test showed significance effect of AICP on freezing behavior during post-extinction recall test (vehicle 76.387 ± 5.009 vs AICP 34.402 ± 7.227, P < .0001). (D) Effect of DCS (62 µg, ICV) on fear extinction in WT mice. Administration of DCS immediately after extinction training did not show any significant effect in recall test (vehicle 55.355 ± 8.896 vs DCS 59.025 ± 9.826; P > .9999; n = 7 vehicle, 6 DCS; two-way ANOVA with Bonferroni’s post hoc test). (E) AICP (3.5 µg, ICV) treatment in GluN2C KO mice did not show any significant effect on freezing behavior in recall test (vehicle 66.666 ± 8.640 vs AICP 56.248 ± 10.134; P = .6261; n = 5 vehicle, 6 AICP; two-way ANOVA with Bonferroni’s post hoc test). The insets C’, D’, and E’ from respective C, D, and E figures show the injection placement site in the LV from the respective vehicle and AICP or vehicle and DCS treatments. Each circle represents an individual animal. Data from the animals showing injection cites within LV were used for analysis. Data were represented as mean ± SEM.