Fig. 4: Per2 deficiency benefits motor function recovery via inhibiting microglial ferroptosis.

a BMS scores during 42 days of recovery after SCI in Per2^flox/flox and Per2^CKO mice (n = 10 animals per group). b Representative images of footprint analysis at 42 d after SCI. c, d Quantification analysis of stride length and width (n = 10 animals per group). e Immunofluorescence images of Hexb and Acsl4 at the lesion epicenter, showing decreased Acsl4 expression in microglia of the spinal cord in Per2^CKO mice at 3 dpi than in Per2^flox/flox mice. Scale bars, 100 μm or 20 μm. f Quantification of the Hexb⁺/Acsl4⁺ of the total Hexb⁺ microglia (n = 5 animals per group). g Representative TEM images of the microglia of Per2^flox/flox and Per2^CKO mice at 3 dpi. Red arrow: damaged mitochondria. Yellow arrow: relatively mild damaged mitochondria. Scale bars, 5 μm or 1 μm. h Nissl staining to observe the number of neurons in spinal cord tissues of the different groups at 42 dpi. Arrows indicate neurons containing Nissl bodies. Scale bars, 100 μm or 20 μm. i Quantification of the Nissl bodies (n = 6 animals per group). j Representative immunofluorescence images of NeuN in spinal cord tissues of the different groups at 42 dpi. Scale bars, 200 μm. k Quantification of the number of NeuN⁺ neurons (n = 6 animals per group). l The levels of IGF-1 in the serum of mice at 3 dpi (n = 10 animals per group) were detected by ELISA kits. All data are presented as the mean ± SD. P values were determined by two-way ANOVA with Tukey’s test for multiple comparisons (a), two-tailed unpaired Student’s t-test (c, d, f, i, k), and one-way ANOVA with Tukey’s multiple-comparisons test (l). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; ns not significant.