Figure 1

Disuse muscle atrophy induced by 2 weeks of cast immobilization. (A) Illustration of a chronic post-cast pain rat model during cast immobilization. Schematic diagram of the experimental protocol for B-D and H-J. Top row (B–G): gastrocnemius muscle (GM). Bottom row (H–M): soleus muscle (SM). The first (B,H), second (C,U), and third (D,J) columns, which present the results of haematoxylin and eosin staining of muscle tissue specimens of untreated rats (baseline), chronic post-cast pain (CPCP) rats at the end of 2 weeks after cast application (c2w), and CPCP rats at 3 weeks after cast removal (r3w), reveal the differences in size of individual muscle fibres between baseline, c2w, and r3w. The histological findings were confirmed by quantitative analysis (E–G,K–M) by comparison between untreated rats (n = 6), CPCP rats at c2w (n = 6), and r3w (n = 5). (E,K) Size distribution of individual GM and SM fibres, respectively, baseline, c2w, and r3w. (F,L) Results of comparison of average size of individual GM and SM fibres, respectively, between baseline, c2w, and r3w. (G,M) Results of comparison of GM and SM wet weight, respectively, between baseline, c2w, and r3w. Data are presented as mean values ± standard error of the mean. Scale bar, 50 µm. ^**P < 0.01, and ^***P < 0.001 relative to the untreated group (one-way ANOVA with Dunnett’s multiple comparison test).