Figure 4

Improved locomotor recovery and increased white matter sparing (WMS) in Bmal1^−/− mice with SCI. (a) WT and Bmal1^−/− mice (M:F = 1:4 in each group) underwent SCI and were killed on dpi 3. Clock pathway transcripts were analyzed in the injury epicenter/penumbra region by qPCR. In Bmal1^−/− mice, Bmal1 mRNA was undetectable while Nr1d1 and Dbp1 mRNAs were reduced and Cry1 upregulated. (b) WT (M:F = 7:7, including 3 KO littermates) and Bmal1^−/− (M:F = 3:7) mice underwent SCI. BMS analysis of hindlimb function revealed improved chronic recovery in the Bmal1^−/− group. (c, d) WMS analysis was performed on spinal cord tissue collected after completion of the last BMS assessment on dpi 42 (WT M:F = 5:4, Bmal1^−/− M:F = 2:4). (c) Representative images of eriochrome cyanine (EC)-stained transverse sections through the injury epicenter. Note the destruction of EC-stained myelin in the dorsal column area and its relative sparing in the ventral white matter. (d) In the injury epicenter, quantification of EC⁺ myelin signal revealed increased white matter sparing in Bmal1^−/− mice. Data are the mean ± SD; *p < 0.05, **p < 0.01, ***p < 0.001—u-test in (a, d), RM ANOVA with Tukey post-hoc tests in (b) (factor 1, genotype: F_1,148 = 83.0, p < 0.001; factor 2, time of recovery: F_6,38 = 27.5, p < 0.001; factor 1 × factor 2: F_6,38 = 0.59, p > 0.05). No significant gender effects were observed when sex was included as an additional factor in BMS data analysis (gender: F_1,133 = 0.02, p > 0.05, gender x genotype: F_1,133 = 0.77, p > 0.05, gender x genotype x time of recovery: F_6,35 = 0.64, p > 0.05).