Figure 6. CCK interneuron stimulation promotes proliferation of rNSCs via MAPK/ERK signaling and increases neurogenesis.

(A) Experimental paradigm for in vivo stimulation of CCK interneurons and c-Fos analysis.

(B) DG c-Fos expression after CCK chemogenetic activation. Arrows indicate hilar mCherry⁺ c-Fos⁺ cells. Scale bars 100 μm, 20 μm.

(C) Density of c-Fos labeled hilar mCherry⁺ cells. p=0.034 for (3,4) animals by Student’s t-test.

(D) Experimental paradigm for quantification of phospho-ERK, phospho-RB, or EdU uptake in response to chemogenetic stimulation of CCK interneurons.

(E) Phospho-ERK⁺ rNSCs in the DG 80 minutes after IP CNO. Scale bar 10 μm. Arrows highlight pERK⁺ Nestin⁺ adult rNSCs.

(F) Density of pERK⁺ rNSCs for (4,5) animals. Bars indicate means ± SD. p=0.013 by Student’s t-test.

(G) Phospho-RB⁺ rNSCs in the DG 5 hours after IP CNO. Scale bar 10 μm. Arrow highlights a pRB⁺ Nestin⁺ rNSC.

(H) Density of pRB⁺ rNSCs for (5,4) animals. Bars indicate means ± SD. p=0.008 by Student’s t-test.

(I) EdU uptake in rNSCs after 4 days of CNO drinking water. Scale bars 100 μm, 20 μm. Arrow highlights an EdU⁺ Nestin⁺ adult rNSC.

(J-M) Proportion (J) and density (K) of proliferating adult neural stem cells in the DG, density of all proliferating cells (L), and total rNSC pool (M). Bars indicate means ± SD. p=(0.03,0.05,0.80,0.005) for (6,5) animals by Student’s t-test.

(N) Experimental paradigm for quantification of neurogenic proliferation in response to in vivo chemogenetic activation of CCK interneurons.

(O) DCX⁺ adult-born immature neurons after 3 weeks of CNO drinking water. Scale bars 100 μm, 20 μm. Arrows indicate DCX⁺ EdU⁺ cells.

(P-Q) Density (P) of DCX⁺ EdU⁺ immature neurons and rNSC pool (Q) after in vivo chemogenic stimulation of CCK interneurons. Bars indicate means ± SD; p=(0.047,0.29) for (4,6) animals by Student’s t-test. See also Figure S5.