(A) Representative immunofluorescent staining for GFP (AAV infection, green), P0 (myelin, red), NF200 (axon, pink) and merge (with DAPI, blue) in a sciatic nerve longitudinal section at 3 days after lysolecithin injection. (A1) High magnifications of boxed areas shown in A. Scale bar in A, 2 mm; in A1, 50 μm. (B and C) Representative immunofluorescent staining for GFP (green), P0 (blue), NF200 (red) and merge in sciatic nerve cross sections in lysolecithin injected and control groups. Scale bar, 2 mm. (D and E) Compared with the control group, lysolecithin treatment significantly increased GFP expression (D), and decreased myelination (E). (n = 3 mice/group, bilateral sciatic nerve per mice). However, the lysolecithin injection did not affect axons (NF200, red A-C). (F) GFP (green), P0 (red), and merged (with DAPI, blue) images demonstrate long-term expression of GFP (indicative of effective AAV infection), and remyelination of sciatic nerve axons at 5 weeks after lysolecithin injection. Scale bar, 50 μm. (G–H) GFP (green), NT-3 (red), and merged (with DAPI, blue) images demonstrate the presence or absence of lysolecithin injection and corresponding NT-3 expression after AAV-NT-3 administration at 5 weeks after lysolecithin injection. Scale bars, 2 mm. (I and K) Five weeks after lysolecithin injection, there was no difference between the control and lysolecithin injected group in axon density (I, NF200) and myelination (J, P0). However, transient demyelination in the presence of AAV-NT-3 virus injection increased NT-3 expressed in sciatic nerves (K) (n = 3 mice/group, bilateral sciatic nerves per mice). Error bars show mean ±SD. *p < 0.05, **p < 0.01, Student’s t tests. (L) Transient BMS functional deficit was observed only at 1 day after lysolecithin injection, but such deficit was quickly recovered at 7 and 14 days post-injection. **p < 0.01 versus control. (n = 6 mice/group). Abbreviations: AAV, adeno-associated virus (serotype 2); DAPI, DAPI dihydrochloride; GFP, green fluorescent protein; NS, no significance; NT-3, neurotrophin-3; P0, P0 protein.