Fig. 2: cKO of FGFR1 in the dentate gyrus accelerates depressive-like behaviors in mouse depression models.

a A schematic representation of chemically induced mouse depression model with WT and Fgfr1^flox/flox mice. b Anxiety index, total immobility time in tail suspension test and sucrose preference in WT mice and Fgfr1^flox/flox mice. The experimental groups included: administration of vehicle for 3 weeks (V3W); administration of vehicle for 2 weeks, followed by corticosterone for 1 week (C1W); and administration of corticosterone for 3 weeks (C3W). WT mice (black) and FGFR1-cKO mice, in which a Cre-virus was injected into the hippocampal dentate gyrus of Fgfr1^flox/flox mice (red), were used. The data are presented as means ± s.e.m.; n = 14 WT mice, n = 5 FGFR1-cKO(V3W), n = 6 FGFR1-cKO (C1W) and n = 5 FGFR1-cKO (C3W) mice were included for each condition. For anxiety index, a two-way ANOVA revealed no significant main effects or interaction between genotype and corticosterone treatment (interaction: F(2, 52) = 0.3102, P = 0.7346; genotype: F(1, 52) = 0.0856, P = 0.7709; corticosterone treatment: F(2, 52) = 0.7861, P = 0.7861). Post hoc comparisons using Tukey’s multiple comparisons showed no pairwise comparisons reached statistical significance. For total immobility, a two-way ANOVA revealed significant main effects of genotype (F(1, 52) = 23.76, P < 0.0001), corticosterone treatment (F(2, 52) = 31.51, P < 0.0001) and a significant interaction between genotype and corticosterone treatment (F(2, 52) = 3.603, P = 0.0343). Post hoc comparisons using Šídák’s multiple comparisons test showed significant differences between several group pairs. (WT V3W versus WT C3W, P < 0.0001; FGFR1-cKO V3W versus FGFR1-cKO C1W, P = 0.0213; FGFR1-cKO V3W versus FGFR1-cKO C3W, P < 0.0001). For sucrose preference, a two-way ANOVA revealed significant main effects of corticosterone treatment (F(2, 53) = 26.89, P < 0.0001) and a significant interaction between genotype and corticosterone treatment (F(2, 53) = 8.859, P = 0.0005) but no significant main effect of genotype (F(1, 53) = 2.309, P = 0.1346). Post hoc comparisons using Šídák’s multiple comparisons test showed significant differences between several group pairs (WT V3W versus WT C3W, P < 0.0001; FGFR1-cKO V3W versus FGFR1-cKO C1W, P = 0.0115; FGFR1-cKO V3W versus FGFR1-cKO C3W, P = 0.0041). ns, not significant; *P < 0.05; **P < 0.01; ****P < 0.0001. c FGFR1 qRT–PCR results after behavior tests of a. The data are represented as means ± s.e.m.; n = 12 for V3W, n = 12 for C1W and n = 13 for C3W WT mice were included for each condition. A one-way ANOVA revealed a significant effects of corticosterone treatment (F(2, 34) = 28.31, P < 0.0001). Post hoc comparisons using Tukey’s multiple comparisons test showed significant differences between several group pairs (V3W versus C1W, P = 0.019; V3W versus C3W, P < 0.0001). *P < 0.05; ****P < 0.0001. d Western blot quantification for FGFR1 in WT mice after behavior tests. The data are represented as means ± s.e.m.; n = 18 for V3W, n = 14 for C1W and n = 17 for C3W WT mice were included for each condition. One-way ANOVA revealed a significant effect of corticosterone treatment (F(2, 46) = 47.44, P < 0.0001). Post hoc comparisons using Tukey’s multiple comparisons test showed significant differences between several group pairs (V3W versus C1W, P = 0.0003; V3W versus C3W, P < 0.0001.) ***P < 0.001; ****P < 0.0001. e A schematic representation and timeline and administration V3W and C1W and behavior tests in the region-specific FGFR1 knockout model. f Representative images showing Cre⁺ cells in different hippocampal regions in Fgfr1^flox/flox mouse indicating cKO of Fgfr1 gene. Scale bar, 100 μm g Anxiety index, total immobility time in tail suspension test, and sucrose preference in WT mice and Fgfr1^flox/flox mice. The experimental groups included: WT; FGFR1-cKO mice, in which a Cre-virus was injected into the hippocampal CA1 of Fgfr1^flox/flox mice (FGFR1-cKO-CA1); FGFR1-cKO mice, in which a Cre-virus was injected into the hippocampal CA3 of Fgfr1^flox/flox mice (FGFR1-cKO-CA3); FGFR1-cKO mice, in which a Cre-virus was injected into the hippocampal dentate gyrus of Fgfr1^flox/flox mice (FGFR1-cKO-DG). Data are presented as means ± s.e.m.; n = 14 WT mice, n = 4 (FGFR1-cKO-CA1;V3W), n = 6 (FGFR1-cKO-CA1;C1W), n = 5 (FGFR1-cKO-CA3;V3W), n = 7 (FGFR1-cKO-CA3;C1W), n = 5 (FGFR1-cKO-DG;V3W), and n = 5 (FGFR1-cKO-DG;C1W) Fgfr1^flox/flox mice were included for each condition. For anxiety index, two-way ANOVA revealed a significant main effect of corticosterone treatment but no significant main effect of hippocampal subregion or interaction between treatment and subregion (interaction: F(2, 52) = 2.083, P = 0.1338; subregion: F(2, 52) = 0.3329, P = 0.7184; corticosterone treatment: F(1, 52) = 7.837, P= 0.0070). Post hoc comparisons using Tukey’s multiple comparisons showed no pairwise comparisons reached statistical significance. For immobility time, two-way ANOVA revealed a significant main effect of corticosterone treatment (F(3, 58) = 12.86, P < 0.0001) and a significant interaction between corticosterone treatment and hippocampal subregion (F(3, 58) = 9.256, P < 0.0001), but no significant main effect of hippocampal subregion alone (F(1, 58) = 3.979, P = 0.0508). Post hoc comparisons using Tukey’s multiple comparisons showed significant differences between a pair (FGFR1-cKO-DG V3W vs FGFR1-cKO-DG C1W, P < 0.0001). For sucrose preference, two-way ANOVA revealed a significant interaction between hippocampal subregion and corticosterone treatment (interaction: F(3, 53) = 15.31, P < 0.0001), as well as a significant main effect of corticosterone treatment (F(1, 53) = 13.44, P = 0.0006), but not of hippocampal subregion (F(3, 53) = 0.3939, P = 0.7579). Post hoc comparisons using Šídák’s multiple comparisons showed significant differences between several pairs (FGFR1-cKO-DG V3W vs FGFR1-cKO-DG C1W, P < 0.0001). ns, not significant; **** p < 0.0001. h Schematic representation of CUMS model of WT and Fgfr1^flox/flox mice. i FGFR1 qRT–PCR results after behavior tests of h. Data are represented as means ± s.e.m.; n = 6 WT mice were included for each condition. An unpaired two-tailed t-test revealed a significant increase in the CUMS group compared with controls (t(10) = 2.409, P = 0.0367). *P < 0.05. j Western blot quantification for FGFR1 in WT mice after behavior tests. Data are represented as means ± s.e.m.; n = 6 WT mice were included for each condition. An unpaired two-tailed t-test revealed a significant increase in the CUMS group compared with controls (t(10) = 3.246, P = 0.0088). **P < 0.01. k Body weight, anxiety index, total immobility time in tail suspension test, and sucrose preference of mouse subjected to CUMS. The experimental groups included: CUMS, a control group with no induced stress (control (Ctrl)) and FGFR1-cKO mice, in which a Cre-virus was injected into the hippocampal dentate gyrus of Fgfr1^flox/flox mice. The data are presented as means ± s.e.m.; n = 6 WT mice, n = 3 FGFR1-cKO Ctrl mice and n = 4 FGFR1-cKO-CUMS mice were included for each condition. For body weight, a two-way ANOVA revealed significant main effects of CUMS weeks (F(4, 75) = 11.33, P < 0.0001) and genotype (F(3, 75) = 52.80, P < 0.0001), as well as a significant interaction between CUMS weeks and genotype (F(12, 75) = 2.748, P = 0.0038). Post hoc comparisons using Tukey’s multiple comparisons test showed that FGFR1-cKO CUMS mice exhibited significantly reduced body weight compared with WT CTRL, WT CUMS and FGFR1-cKO Ctrl mice from week 1 onward (P < 0.01 to P < 0.0001). WT CUMS mice also showed significantly lower body weight than WT CTRL mice at week 3 (P = 0.0358) and week 4 (P = 0.0003). For anxiety index, a two-way ANOVA revealed no significant effects of CUMS weeks (F(4, 75) = 0.983, P = 0.4222), genotype (F(3, 75) = 1.992, P = 0.1225) or their interaction (F(12, 75) = 1.407, P = 0.1819). Post hoc comparisons using Tukey’s multiple comparisons test showed no pairwise comparisons reached statistical significance. For total immobility, two-way ANOVA revealed significant main effects of CUMS weeks (F(4, 75) = 22.80, P < 0.0001) and genotype (F(3, 75) = 37.59, P < 0.0001), as well as a significant interaction between CUMS weeks and genotype (F(12, 75) = 5.737, P < 0.0001). Post hoc comparisons using Tukey’s multiple comparisons test showed that FGFR1-cKO-CUMS mice displayed significant behavioral changes compared with FGFR1-cKO Ctrl mice, with significant differences from week 0 to weeks 1, 2, 3 and 4 (P < 0.05 to P < 0.0001). WT CUMS mice exhibited significant behavioral changes compared with WT CTRL, with significant differences observed at weeks 3 and 4 (P < 0.0001). WT CTRL and FGFR1-cKO Ctrl mice showed no significant differences across the time points (P > 0.05). For sucrose preference, a two-way ANOVA revealed significant main effects of CUMS weeks (F(4, 75) = 7.290, P < 0.0001) and genotype (F(3, 75) = 19.46, P < 0.0001), as well as a significant interaction between CUMS weeks and genotype (F(12, 75) = 3.394, P = 0.0005). Post hoc comparisons using Tukey’s multiple comparisons test showed that FGFR1-cKO-CUMS mice displayed significant behavioral changes compared with FGFR1-cKO Ctrl mice, with significant differences from week 0 to weeks 1, 2, 3 and 4 (P = 0.0146 to P = 0.0028). WT CUMS mice exhibited significant behavioral changes compared with WT CTRL, with significant differences observed at weeks 3 and 4 (P = 0.0002 to P < 0.0001). WT CTRL and FGFR1-cKO Ctrl mice showed no significant differences across the time points (P > 0.05). ns, not significant; *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.