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. Author manuscript; available in PMC: 2022 Nov 6.
Published in final edited form as: Nat Neurosci. 2022 May 6;25(5):630–645. doi: 10.1038/s41593-022-01065-x

Fig. 3. SuM GABA transmission regulates neural progenitors and early-stage immature neurons.

Fig. 3

(a) Diagram and paradigm of optogenetic stimulation of SuM-DG projections expressing shVgat in the SuM of Ascl1-Ai9 mice.

(b) Sample images of tdTomato+ and DCX+ staining of Ascl1-Ai9 mice at 16 dpi. TdTomato+/DCX+ and tdTomato+/DCX- cells were indicated by closed arrowhead and open arrowhead respectively. Scale bar = 50 µm.

(c–e) Density of tdTomato+ (c), DCX+/tdTomato+ (d) and DCX-/tdTomato+ (e) cells after 16-day optogenetic stimulation of SuM-DG projections in Ascl1-Ai9 mice. n = 5 mice for each group. One-way ANOVA, c: F2,12 = 25.25, P < 0.0001; d: F2,12 = 30.2, P < 0.0001; e: F2,12 = 31.70, P < 0.0001 followed by PLSD post hoc test.

(f) Experimental scheme of slice electrophysiological recording of immature neurons (12 dpi) for ex vivo optogenetic stimulation of SuM-DG projections in Ascl1-Ai9 mice.

(g) Confocal images of a biocytin-labeled tdTomato+/DCX+ cell at 12 dpi after whole-cell patch clamp recording. Scale bar = 20 µm.

(h) Representative traces showing that optogenetic activation of SuM-DG projections induces inward currents (top) in a 12 dpi immature neuron (KCl-based pipette solution), which was blocked by GABAAR antagonist BIC (bottom). h1: enlarged traces from the boxed region in ACSF. Individual traces (gray) are shown with the averaged in red.

(i) An immature neuron at 12 dpi received mixed synaptic and tonic GABAergic currents from SuM neurons (top: in ACSF; bottom: in GABAAR antagonist BIC), KCl-based pipette solution.

(j) Diagram of in vivo optogenetic stimulation of SuM neurons for 16 days in Ascl1-Ai9 mice.

(k) Sample images of an immature tdTomato+ neuron at 16 dpi for morphology analysis. Scale bar = 20 µm.

(l) Confocal overview of tdTomato+ cells and ChR2-YFP terminals from SuM neurons in the DG at 16 dpi. Scale bar = 200 µm.

(m) Morphology of individual tdTomato+ cells at 16 dpi following optogenetic stimulation. Scale bar = 10 µm.

(n–p) Sholl analysis (n), dendrite length (o), and total dendrite branches (p) of tdTomato+ cells at 16 dpi. n = 54 cells for YFP group and n = 53 cells for ChR2 group, **P < 0.0001 by two-sided unpaired t-test.