Delayed Nerve Stimulation Promotes Axon-Protective Neurofilament Phosphorylation, Accelerates Immune Cell Clearance and Enhances Remyelination In Vivo in Focally Demyelinated Nerves
Figure 2
Increased myelin basic protein (MBP) expression following 1hr ES delivered 5 d post-LPC.
Representative photomicrographs from FG-positive areas on longitudinal sciatic nerve sections processed for MBP immunofluorescence (IF) reveal extensive demyelination 5d post lysophosphatidyl choline (LPC)/FG demyelinating injection (B) as compared to contralateral normal control nerves (A). Temporal analysis of LPC) focal demyelination +/- electrical stimulation (ES) as indicated in days post-LPC: 6d (D), 6d+ES (E), 8d (G), 8d+ES (H), 10d (J) 10d+ES (K) and 12d (M) 12d+ES (N) post-LPC. Note: In the LPC only group, MBP IF was localized in distinct patches consistent with uptake by phagocytosing cells (D, G, J) with faint linear regions similar to periaxonal MBP localization observed by 12 days post-LPC only injection (M). In contrast, in the LPC + ES group faint regions of MBP peri-axonal-like IF were already apparent 8d post-LPC (3d post-ES; H) and consistently stronger in the 10d post-LPC (5d post-ES; K) and 12d post-LPC (7d post-ES; N). Summary bar graphs of relative changes in immunofluorescence signal for MBP in regions of demyelination (C, F, I, L, O). Note: values obtained from individual slides at each time point were normalized to the mean value of the Average Gray per micron2 readings for the nerves ipsilateral to LPC treatment for the LPC only animal on that slide and for that time point. N = 4-6 animals analyzed per condition; regions quantified per condition: 49 ipsi and 38 contra (5d, LPC only); 128 ipsi and 76 contra (6d, LPC only); 81 ipsi and 54 contra (6d LPC+Stim); 83 ipsi and 49 contra (8d, LPC only); 60 ipsi and 58 contra (8d, LPC+Stim); 62 ipsi and 52 contra (10d, LPC only); 54 ipsi and 48 contra (10d, LPC+Stim); 155 ipsi and 73 contra (12d, LPC only); 119 ipsi and 104 contra (12d LPC+Stim). Asterisks indicate significant differences between experimental groups; *P<0.05, **P<0.01, ***P<0.001. Scale bar = 100 µm.