Fig. 6: Suppression of NE transmission by microglia Gi signaling is partly mediated by elevated adenosine level.
From: Microglia regulate sleep through calcium-dependent modulation of norepinephrine transmission
a, Example images of Iba1-labeled microglia (green; left) and TH-labeled axons (red; middle left) in the prefrontal cortex. Middle right, three-dimensional (3D) rendering image of a 50-μm-thick slice (scale bar, 20 μm); top right, high-magnification view of the boxed region (scale bar, 5 μm); bottom right, further enlarged view of the region in the dashed box and automatically detected axon boutons (magenta) (scale bar, 2 μm). b, Distance of boutons to the nearest microglia (n = 140,884 boutons from the prefrontal cortex of 3 mice). c, Schematic of GRABADO imaging in the prefrontal cortex. d, Example imaging session with chemogenetic Gi activation in microglia. Left, field of view (scale bar, 50 μm); five ROIs are outlined, whose adenosine traces are shown on the right. Dashed line, time of CNO or saline injection. e, Effect of chemogenetic Gi activation in microglia on adenosine signals averaged across 20 (saline) or 19 (CNO) sessions from 6 mice. A total of 8–12 ROIs were assessed for each session. The dashed line indicates the time of injection. f, Difference in adenosine before and after saline or CNO injection. Each circle represents data from one session (saline, n = 20 sessions; CNO, n = 19 sessions; from 6 mice). Data are presented as the mean ± s.e.m.; ***P < 0.001 (unpaired two-tailed t-test, ***P = 0.0005). g,h, Extracellular NE levels before and after application of 2-CADO (a metabolically stable analog of adenosine). The dashed line indicates the time of application. Each circle indicates data from one session. 2-CADO, n = 11 sessions; ACSF, n = 11 sessions; from 4 mice. Data are presented as the mean ± s.e.m.; ***P < 0.001 (unpaired two-tailed t-test, ***P = 0.0001; the Δz-score was computed as the difference between the periods [−20, 0] and [40, 60] min). i, Diagram summarizing microglia regulation of sleep through reciprocal interactions between microglia Ca2+ signaling and NE transmission. Data are presented as the mean ± s.e.m.
