Immunohistochemical analyses of the effects of treatment on functional remodeling of spinal circuits and synaptic connectivity at the lumbar enlargement. (A) Representative Camera Lucida drawings of c-Fos + nuclei in transverse sections at the L2 and L4 levels from control rats, SM-345431 treatment rats, combined treatment rats and intact rats. (B) Average total numbers of c-Fos + nuclei at each level of the lumbar spinal segment. (C) Average total number of c-Fos + nuclei in rostral (L1 + L2) and caudal (L4 + L5) lumbar enlargement segments. (D) Correlation analysis between the total number of c-Fos + nuclei in all segments of the lumbar enlargement and step ability on the treadmill. SM-345431 treatment produced a trend toward decreases in the average number of c-Fos + nuclei, although this trend was not statistically significant compared to the control and SM-345431 treatment groups. However, the combined treatment produced a statistically significant decrease in the number of c-Fos + nuclei, suggesting that specific spinal locomotor circuitry was reinforced by combining SM-345431 treatment with extensive treadmill training. *P < 0.05, **P < 0.01. Statistical analyses were performed using one-way ANOVA and Bonferroni post hoc analyses. Data are presented as the mean ± S.E.M. (E-M) Representative reconstructed confocal images of double staining (transverse section) for synapsin-1 and Tuj-1 in the ventricolumnar area of the spinal cord (E-G: low-magnification images, H-M: high-magnification images). H-J and K-M show the upper and lower boxed areas in E-G, respectively. Scale bars = 50 μm. (N) Quantitative analysis of synapsin-1 expression in the ventricolumnar motor neuron area 3 months after SCT. *P < 0.05, **P < 0.01. Statistical analyses were performed using one-way ANOVA and Bonferroni post hoc analyses. Data are presented as the mean ± S.E.M.