Fig. 5: Optogenetic activation of FGFR1-induced AHN in depression model via FGFR1–Notch–BDNF axis in the dentate gyrus.

a A schematic representation and timeline showing the viral injection in CamKIIα-Cre mice and administration of EdU with blue light. b Representation images showing EdU⁺ cell in subgranular zone (SGZ) of dentate gyrus under blue light stimulation for 12 h. Scale bar, 100 μm (inset, 50 μm). c A quantification of the data shown in b. The experimental groups included: CamKIIα-Cre mice injected with optoFGFR1 virus into the hippocampal dentate gyrus, kept in dark, and administered EdU 12 h before sacrifice (dark); CamKIIα-Cre mice injected with optoFGFR1 virus, given EdU and exposed to blue LED stimulation for 12 h (light); CamKIIα-Cre mice injected with EGFP control virus, given EdU and exposed to 12 h of blue LED stimulation (EGFP light). The data are represented as means ± s.e.m.; n = 6 (dark), n = 5 (light) and n = 5 (EGFP light), CamKIIα-Cre mice were included for each condition. A one-way ANOVA revealed a significant effect of optoFGFR1 light stimulation (F(2,13) = 107.8, P < 0.0001). Post hoc comparisons using Tukey’s multiple comparisons test showed that light had significantly more EdU⁺ cells than both the dark (P < 0.0001) and EGFP light (P < 0.0001). ****P < 0.0001. d An experimental timeline for evaluating neural stem cell proliferation following blockade of the BDNF-TrkB pathway in optoFGFR1-transduced mouse hippocampus (left) and quantification of EdU⁺ cells in the SGZ after 12 h of blue light stimulation (right). The data are represented as means ± s.e.m.; n = 4 mice were included for each condition. A two-way ANOVA revealed significant main effects of ANA-12 treatment (F(1,12) = 52.00, P < 0.0001), light stimulation (F(1,12) = 39.20, P < 0.0001) and their interaction (F(1,12) = 35.00, P < 0.0001). Post hoc comparisons using Šídák’s multiple comparisons test showed that light stimulation significantly increased EdU⁺ cell numbers in vehicle-treated mice compared with dark controls (P < 0.0001), while ANA-12 treatment blocked this effect (light vehicle versus light ANA-12, P < 0.0001). No significant differences were found within dark conditions or between ANA-12–treated groups under light exposures. ns, not significant; ****P < 0.0001. e An experimental timeline for evaluating neural stem cell proliferation following blockade of the Notch pathway via gamma-secretase inhibition in optoFGFR1-transduced mouse hippocampus (left) and quantification of EdU⁺ cells in the SGZ after 12 h of blue light stimulation (right). The data are represented as means ± s.e.m.; n = 4 mice were included for each condition. A two-way ANOVA revealed significant main effects of DAPT treatment (F(1,12) = 12.37, P = 0.0043), light stimulation (F(1,12) = 37.26, P < 0.0001), and their interaction (F(1,12) = 52.30, P < 0.0001). Post hoc comparisons using Šídák’s multiple comparisons test showed that light stimulation significantly increased EdU⁺ cell numbers in vehicle-treated mice compared with dark controls (P < 0.0001), while DAPT treatment blocked this effect (Light Vehicle vs Light DAPT, P < 0.0001). No significant differences were found within dark conditions or between DAPT–treated groups under light exposures. ns, not significant; ****P < 0.0001. f Schematic representation and timeline showing optogenetic induction of adult neurogenesis in mouse depression model. The viral injection of Fgfr1^flox/flox mice undergo administration of vehicle for 2 weeks followed by EdU and 1 week of corticosterone with blue light. g Representative images showing EdU⁺ cell in SGZ after administration of vehicle and corticosterone for 3 weeks. Scale bar, 100 μm (inset, 50 μm). h Quantification of the data shown in g. Data are represented as means ± s.e.m.; n = 8 mice were included for each condition. An unpaired two-tailed t-test revealed a significant increase in proliferating cells in the light group(t(14) = 9.182, P < 0.0001). **** P < 0.0001. i Representative images of EdU⁺ cells counterstained for Ki-67 (upper) and Tbr2 (lower). Arrows indicate cells with colocalizing signals. Scale bars, 50 μm. j Quantification of the data shown in i. Data are represented as means ± s.e.m.; n = 8 mice were included for each condition. Two-way ANOVA revealed significant main effects of light stimulation (F(1,28) = 34.39, P < 0.0001), marker type (F(1,28) = 4.337, P = 0.0465), and their interaction (F(1,28) = 10.80, P = 0.0027). Post hoc comparisons using Šídák’s multiple comparisons test showed that light stimulation significantly increased the number of Tbr2+ cells compared with dark controls (P < 0.0001), while no significant difference was observed in KI67⁺ cells between light and dark groups (P = 0.1517). ns, not significant; ****P < 0.0001.