Fig. 2

Satellite glia respond to central branch axotomy (CBA) by relocating their nuclei dorsally toward the injury site. (a) Diagram of trunk dorsal root ganglion (DRG) CBA injury observations over time (hours post-injury [hpi]). Post-CBA (?CBA?), neurons may grow new dorsal neurites in an attempt to regrow a central branch axon. During this period, a subset of satellite glia (SGC) nuclei move dorsally. (b) Representative migration paths over time of SGC nuclei from uninjured (Control, gray circles) and injured (Post-CBA, rose diamonds) DRGs, relative to the neuronal soma (asterisk). Larger, outlined symbols indicate initial (lighter color) and end (darker color) positions for each cell. (c) Graph of SGC nuclear displacement from initial positions at end of in vivo, time-lapse imaging, comparing SGCs from uninjured (mean: 1.00 ± 1.09 a.u.) and sham (mean: 0.83 ± 1.11 a.u.) injury control (?CON?) DRGs (n = 28 cells from 10 DRGs from 5 fish; Wilcoxon test, p > .05). Dashed line indicates mean; measures normalized to uninjured controls. (d?f) Graphs comparing SGC nuclear displacement (mean: control (CON) 1.00 ± 1.09 a.u., CBA 1.43 ± 0.84 a.u.; Wilcoxon test, p = .038), speed (mean: CON 1.00 ± 0.25 a.u., CBA 1.31 ± 0.18 a.u.; Wilcoxon test, p < .001), and velocity (mean: CON 1.00 ± 1.08 a.u., CBA 1.66 ± 0.87 a.u.; Wilcoxon test, p = .019). Dashed line indicates mean (n = 64 cells from 27 DRGs from 19 fish); measures normalized to CON. Triangles indicate SGC nuclei from DRGs with successful regrowth of the central branch post-CBA and circles represent SGC nuclei from DRGs that did not successfully regrow the central branch. (g) Density distribution graphs of SGC nucleus initial and end positions (relative to the neuronal soma) from CON and CBA DRGs. Arrows represent net change in SGC X- (mean: CON 1.64 ± 2.25 ?m, CBA 1.36 ± 3.29 ?m; Wilcoxon test, p = .26) and Y-positions (mean: CON ?0.16 ± 4.22 ?m, CBA 3.10 ± 3.68 ?m; Wilcoxon test, p = .00031) from initial and end timepoints each condition. (h) Circular plots of SGC nucleus angular position relative to the neuronal soma at initial and end timepoints from CON (mean: Initial 156 ± 125°, end 27 ± 108°; Watson's U2 two-sample test, p > .05) and CBA (mean: Initial 204 ± 117°, end 82 ± 78°; Watson's U2 two-sample test, p < .05) conditions. Dashed arrows indicate mean initial angular position, solid arrows indicate mean end angular position, shaded regions indicate ±1 standard deviation, and star bursts indicate mean central axon angular position pre-injury. nsp ?.05, *p < .05, **p ? .01, ***p ? .001.