Figure 2. Noradrenergic signaling is required for locomotion-induced activation of Bergmann glia.

A, Spontaneous (arrowhead) and enforced (green bars) locomotion and corresponding Bergmann glia Ca²⁺ levels (GCaMP3 fluorescence). B, Normalized Bergmann glia Ca²⁺ changes associated with spontaneous (6 of 13 events) and enforced locomotion (6 of 159 events) from experiment in A. C, Individual (gray traces) and average (black traces) Bergmann glia Ca²⁺ transients resulting from enforced locomotion with (lower traces) or without (upper traces) a preceding spontaneous event. D, Consecutive trials of enforced locomotion (green bar) pseudocolored according to magnitude of Ca²⁺ change. Arrow indicates time of trazodone injection (10 mg/kg i.p.). Left, average EMG power during 20 consecutive trials at right. E, Normalized amplitude of Bergmann glia Ca²⁺ elevations elicited by enforced locomotion. Each point is average of 4 consecutive trials normalized to baseline. Regions highlighted by light grey bar used to determine baseline and dark grey bar the maximal response to drug. Black symbols represent mean ± SEM. F, Effect of neuromodulatory receptor antagonists on Bergmann glia Ca²⁺ response to enforced locomotion. Columns represent mean ± SEM. Concentrations from left (mg/kg i.p.): 10, 10, 20, 20, 20, 20, 10. Number of experiments from left: 6, 5, 5, 5, 5, 4, 3. Asterisks indicate significant reduction relative to baseline in one-way ANOVA followed by Bonferroni post-hoc test. G, Bergmann glia Ca²⁺ transients in consecutive trials of enforced locomotion before and after local application of antagonists. Summary graph is mean ± SEM. Concentrations (μM): 100 terazosin, 3 metoprolol, 300/200 NBQX/CPP. Number of experiments from left: 8, 5, 5, 5. Asterisks indicate significant difference in one-way ANOVA followed by Bonferroni post-hoc test.