Fig. 8: Targeting age-related FGFR1 dysregulation promotes AHN and reverses depressive phenotype in aged mice.

a A schematic representation and timeline showing the administration of vehicle and corticosterone in WT young and old mice. V3W, administration of vehicle for 3 weeks; C3W, administration of corticosterone for 3 weeks. b Western blot for FGFR1 and GAPDH in vehicle- or corticosterone-administrated young and old mice. c A quantification of FGFR1 to GAPDH from the young groups in b showing no difference between the C3W and the V3W groups. The data are represented as means ± s.e.m.; n = 6 for V3W and n = 7 for C3W mice. An unpaired two-tailed t-test showed no significant difference in Numb expression between the C3W and V3W in young WT mice (t(11) = 0.1177, P = 0.9085). ns, not significant. d A quantification of FGFR1 to GAPDH from the old group in b showing a significant increase in the C3W group compared with the V3W group. The data are represented as means ± s.e.m.; n = 14 mice were included for each condition. An unpaired two-tailed t-test revealed a significant increase in Numb expression in the C3W compared with the V3W in old WT mice (t(26) = 7.574, P < 0.0001).****P < 0.0001; ns, not significant. e A schematic representation and timeline showing optogenetic induction of adult neurogenesis in mouse depression model. The viral injection in old Fgfr1^flox/flox mice and administration of vehicle for 2 weeks, followed by EdU and 1 week of corticosterone with blue light then behavior tests. D, L and SL represent the AAV-EF1a-DIO-mCherry-shNumb injection kept in dark, AAV-EF1a-DIO-mCherry-shNumb with light stimulation and AAV-EF1a-DIO-mCherry-shScramble injection with light stimulation, respectively. f Representative immunohistochemical staining images showing BDNF expression in the dentate gyrus of mice injected with AAV-EF1a-DIO-mCherry-shNumb and kept in the dark, AAV-EF1a-DIO-mCherry-shNumb with light stimulation and AAV-EF1a-DIO-mCherry-shScramble with light stimulation. Scale bar, 300 μm; 50 μm (inset). g Representative images showing EdU⁺ expression in the dentate gyrus of mice injected with AAV-EF1a-DIO-mCherry-shNumb and kept in the dark, AAV-EF1a-DIO-mCherry-shNumb with light stimulation and AAV-EF1a-DIO-mCherry-shScramble with light stimulation. Scale bar, 100 μm; 50 μm (inset). h A quantification of BDNF H-score according to BDNF expression in the dentate gyrus of mice injected with AAV-EF1a-DIO-mCherry-shNumb and kept in the dark, AAV-EF1a-DIO-mCherry-shNumb with light stimulation and AAV-EF1a-DIO-mCherry-shScramble with light stimulation. D, L, and SL represent the AAV-EF1a-DIO-mCherry-shNumb injection kept in dark, AAV-EF1a-DIO-mCherry-shNumb with light stimulation and AAV-EF1a-DIO-mCherry-shScramble injection with light stimulation, respectively. The data are represented as means ± s.e.m.; n = 6 mouse samples were included for each condition. A one-way ANOVA revealed a significant effect on BDNF expression (F(2, 15) = 13.37, P = 0.0005). Post hoc comparisons using Tukey’s multiple comparisons test showed significant differences between D and L (P = 0.0013) and between L and SL (P = 0.0011) but not between D and SL (P = 0.9972). **P < 0.01. i A quantification of EdU⁺ cells in the subgranular zone of dentate gyrus in g. The data are represented as means ± s.e.m.; n = 6 for D, n = 8 for L and n = 6 for SL. A one-way ANOVA revealed a significant effect on EdU⁺ cell counts (F(2, 17) = 22.98, P < 0.0001). Post hoc comparisons using Tukey’s multiple comparisons test showed significant differences between D and L (P < 0.0001) and between L and SL (P = 0.0004) but not between D and SL (P = 0.4133). ****P < 0.0001. D, L and SL represent the AAV-EF1a-DIO-mCherry-shNumb injection kept in dark, AAV-EF1a-DIO-mCherry-shNumb with light stimulation and AAV-EF1a-DIO-mCherry-shScramble injection with light stimulation, respectively. j Representative images of EdU⁺ cells counterstained for Ki-67 (top) and Tbr2 (bottom). The arrows indicate cells with colocalizing signals. Scale bars, 50 μm. k A quantification of the data shown in j. The data are represented as means ± s.e.m. The sample sizes were as follow: n = 6 for Ki-67 D, n = 4 for Ki-67 L, n = 4 for Ki-67 SL, n = 4 for Tbr2 D, n = 4 for Tbr2 L and n = 4 for Tbr2 SL. A two-way ANOVA revealed significant main effects of light stimulation (F(2,20) = 8.244, P = 0.0024) and marker type (F(1,20) = 6.979, P = 0.0156) but no significant interaction between light stimulation and marker type (F(2,20) = 0.6860, P = 0.5151). Post hoc comparisons using Šídák’s multiple comparisons test showed a significant increase in Tbr2⁺ cells under the L compared with SL (P = 0.0138), while no significant difference was observed between D and L (P = 0.7004) or between D and SL (P = 0.9446) in KI67⁺ cells. ns, not significant; *P < 0.05. D, L and SL represent the AAV-EF1a-DIO-mCherry-shNumb injection kept in dark, AAV-EF1a-DIO-mCherry-shNumb with light stimulation and AAV-EF1a-DIO-mCherry-shScramble injection with light stimulation, respectively. l Anxiety index in optogenetically rescued aged Fgfr1^flox/flox mice with cKO in DG. D, L and SL represent the AAV-EF1a-DIO-mCherry-shNumb injection kept in dark, AAV-EF1a-DIO-mCherry-shNumb with light stimulation and AAV-EF1a-DIO-mCherry-shScramble injection with light stimulation, respectively. The data are presented as means ± s.e.m.; n = 10 mice were included for each condition. A one-way ANOVA revealed no significant effect on anxiety index (F(2,27) = 2.579, P = 0.0944). Post hoc comparisons using Tukey’s multiple comparisons test showed no significant differences between any groups (all P > 0.05). ns, not significant. m Total immobility in optogenetically rescued aged Fgfr1^flox/flox mice with cKO in dentate gyrus. D, L and SL represent the AAV-EF1a-DIO-mCherry-shNumb injection kept in dark, AAV-EF1a-DIO-mCherry-shNumb with light stimulation and AAV-EF1a-DIO-mCherry-shScramble injection with light stimulation, respectively. The data are presented as means ± s.e.m.; n = 10 mice were included for each condition. A one-way ANOVA revealed a significant main effect on immobility time in the tail suspension test (F(2,27) = 15.63, P < 0.0001). Post hoc comparisons using Tukey’s multiple comparisons test showed that immobility time was significantly reduced in L compared with D (P = 0.0008) and L compared with SL (P < 0.0001), while no significant difference was found between D and SL (P = 0.4857). ****P < 0.0001.