Fig. 4: Locomotion-induced Ca²⁺ transients in OPCs is mediated by norepinephrine.

a (top) Transgenic strategy to express mGCaMP6s in NA neurons in Dbh-mGC6s mice. (bottom) Cartoon showing the distribution of NA projections from the LC to the cortex. b Maximum intensity projection of mGCaMP6s-expressing (green, eGFP) NA axonal projections (magenta, TH) in the cortex. (inset) Arrowheads highlights varicosities. c, d Average intensity projection of NA fibers in the cortex of Dbh-mGC6s mice, overlaid with region with Ca²⁺ signals c, and color-coded map of detected regions of interest (ROIs) (d). e Example Ca²⁺ traces of the 6 ROIs shown in (d). f Heat map of the intensity and temporal distribution of Ca²⁺ events (top), aligned with the mouse locomotion activity (black trace, bottom). Grey highlights show correlation between locomotion and Ca²⁺ signals. Graphs comparing frequency (g) and amplitude (h) of Ca²⁺ events in NA fibers during resting and active phases. i Frequency distribution of the time-lag between the initiation of locomotion and Ca²⁺ activity in NA neurons (cyan) and OPCs (orange). j Maximum intensity projection of NA fibers (green) and PDGFRα (magenta) in the cortex. k High-magnification image of PDGFRα + OPC and NA fibers in the boxed area in j. Insets (I–III) highlight contact between OPC and NA fibers. I Maximum intensity projection of NA fibers in control (Ctrl) and DSP-4 treated Dbh-mGC6 mice. m Graph showing the mean fluorescence intensity of eGFP in the cortex of control and DSP-4 mice. n, o (left) Average intensity projection of an OPC in a NG2-GC6f;tdT mouse before (n) and after (o) DSP-4 treatment. (right) Raster plots showing Ca²⁺ events (top) and locomotion activity (bottom). A recombined pericyte (highlighted in red) was used to locate the cell (n, o). p, q Graphs showing the frequency of Ca²⁺ events during the resting & active phases before (p) and after (q) treatment with DSP-4. r Graph showing Active/Resting Ca²⁺ activity ratio (A/R ratio) before and after DSP-4. s–u Graph comparing the average frequency of Ca²⁺ event (r), the duration (t) and the amplitude (s) of Ca²⁺ events in the resting phase before DSP-4 (black) and in the active phase after DSP-4 (green). All data are presented as mean ± SEM. g, h n = 19 imaging fields, N = 2 mice; Wilcoxon matched-pairs rank tests: ****P < 0.0001. m n = 9 section, N = 3 mice (Ctrl) and n = 12 section, N = 4 mice (DSP4); Unpaired t-test: ****P < 0.0001. p–s n = 11 cells, N = 3 mice; Paired t-test: ***P = 0.0004, *P = 0.0187 (p, r, s), Wilcoxon matched-pairs rank test (q). t, u n = 19 cells, N = 3 mice; Kolmogorov–Smirnov Test for cumulative frequency distribution: ***P < 0.0004. Ctrl, control. s, seconds. z, z-score. Scale bars: 20 µm and inset 2 µm (b); 15 µm (c, d, n, o); 20 µm (k); 50 µm (j, l). Part of the illustration in (a) was created using BioRender. Source data are provided in the Source Data file.