Fig. 6: Increased calcium signals in NG2 glia and enhanced anxiety-like behavior in chronic social defeat stress (CSDS) mice.

a Schematic illustrating the experimental approach for calcium imaging and behavioral tests. After 10 consecutive days of CSDS, experimental animals were housed singly to perform the following experiments. b, c Representative images (b) and traces (c) of Ca²⁺ fluctuations measured in hippocampal NG2 glia from a control mouse and CSDS mouse at postnatal 8–12 weeks. Two predominant types of Ca²⁺ events are defined: somatic fluctuations (red), process waves (olive for control and green for CSDS). Approximate territory boundaries are outlined in blue, but these were not used for data analyses and are shown only for illustrative purposes. Scale bars, 20 µm. d Average data for Ca²⁺ fluctuation properties in control and CSDS mice (from 3 mice for each group). The frequency of Ca²⁺ fluctuations per min per cell is shown in upper panel: somata of control, 0.07 ± 0.01 vs. somata of CSDS, 0.08 ± 0.01, P = 0.9845, two-tailed Mann–Whitney test; processes of control, 0.40 ± 0.04 vs. processes of CSDS, 0.86 ± 0.08; P < 0.0001, two-tailed Mann–Whitney test, *** indicates P < 0.001, n.s. indicates not significant, n = 63 and 86 cells for control and CSDS, respectively. The amplitude of Ca²⁺ fluctuations is shown in lower panel: somata of control, 2.99 ± 0.47 vs. somata of CSDS, 2.55 ± 0.30, P = 0.9162, two-tailed Mann–Whitney test; processes of control, 4.63 ± 0.29 vs. processes of CSDS, 4.03 ± 0.15, P = 0.0799, two-tailed Mann–Whitney test, n.s. indicates not significant, the n refers to the number of Ca²⁺ fluctuations for control and CSDS. Bounds of box: 10th and 90th percentile and whisker: SEM. e Representative open-field activity tracks show the effects of optical stimulation in CSDS mice and its control group; Pdgfrα-creER⁺;ChR2⁺ mice group and its Pdgfrα-creER⁺;ChR2⁻ control group in a period of 25 min including blue light stimulations (20 Hz, 20 msec, 10 s ON/OFF). f The summary bar graphs show the time in center zone (upper panel) and the distance (lower panel) traveled by the mice over 25 min in an open-field chamber for the two sets of experimental groups. Time in center zone: 155.59 ± 29.80 sec in Pre-CSDS vs. 43.96 ± 13.29 sec in Post-CSDS, n = 6 mice at postnatal 8–12 weeks, two-tailed paired t test, P = 0.0083; 208.81 ± 32.54 sec in Pdgfrα-creER⁺;ChR2⁻ vs. 111.22 ± 21.06 sec, n = 12 mice at postnatal 8–12 weeks for each group, two-tailed Mann–Whitney test, P = 0.0332. Total distance traveled in 25 min: 53.06 ± 3.69 m in Pre-CSDS vs. 26.21 ± 3.67 m in Post-CSDS, n = 6 mice at postnatal 8–12 weeks, two-tailed paired t test, P = 0.0003; 61.13 ± 5.54 m in Pdgfrα-creER⁺;ChR2⁻ vs. 53.68 ± 4.99 m, n = 12 mice at postnatal 8–12 weeks for each group, two-tailed unpaired t test, P = 0.3282. g Representative elevated plus maze activity tracks show the effects of optical stimulation between CSDS mice and its control group; Pdgfrα-creER⁺;ChR2⁺ mice group and its Pdgfrα-creER⁺;ChR2⁻ control group in a period of 15 min including blue light stimulations (20 Hz, 20 msec, 10 s ON/OFF). h The summary bar graphs show the time spent in the open arms (upper panel) and the time spent in the closed arms (lower panel) traveled by the mice over 15 min in an elevated plus maze for the two sets of experimental groups. Time in open arms: 81.64 ± 25.06 sec in Pre-CSDS vs. 11.83 ± 4.13 sec in Post-CSDS, n = 6 mice at postnatal 8–12 weeks, two-tailed paired t test, P = 0.0458; 76.90 ± 15.56 sec in Pdgfrα-creER⁺;ChR2⁻ vs. 37.18 ± 10.57 sec, n = 12 mice at postnatal 8–12 weeks for each group, two-tailed unpaired t test, P = 0.0463. Time in closed arms: 743.98 ± 27.99 sec in Pre-CSDS vs. 866.59 ± 8.70 sec in Post-CSDS, n = 6 mice at postnatal 8–12 weeks, two-tailed paired t test, P = 0.0112; 732.59 ± 22.73 sec in Pdgfrα-creER⁺;ChR2⁻ vs. 814.55 ± 19.62 sec, n = 12 mice at postnatal 8–12 weeks for each group, two-tailed Mann–Whitney test, P = 0.0173. * indicates P < 0.05, ** indicates P < 0.01, *** indicates P < 0.001, n.s. indicates not significant. Data are presented as mean values ± SEM and the error bar represents SEM.