Fig. 4

DRP1 loss in adult animals causes body weight loss, muscle atrophy and muscle weakness. a DRP1 protein levels are downregulated in different types of skeletal muscles in HSADRP1-null mice. O.D. levels represent the average of at least three independent experiments ± SEM. b Growth curve of control and Drp1^−/− littermates during and after tamoxifen treatment. KO mice start to lose body weight after 7 weeks of tamoxifen treatment and during the following weeks. The data represent average ± SEM (WT, n = 10; KO, n = 11). c Dissected gastrocnemius muscles from the control and DRP1-null mice show an important muscle atrophy after DRP1 deletion in adult animals. d Quantification of the cross-sectional area of myofibers indicates a significant reduction in DRP1-ablated muscles. Values represent average ± SEM (WT, n = 5; KO 70 days, n = 5; KO 180 days, n = 3). e Representative haematoxilin–eosin staining of Tibialis Anterior muscle showing signs of myofiber degeneration/regeneration in Drp1^−/− after 180 days of treatment. f In Drp1^−/− muscles after 180 days of treatment, there are 10 and 25% of myofibers are centrally nucleated, in tibialis anterior muscle and gastrocnemius muscle, respectively (n = 3 mice each condition). g Force measurements performed in vivo on gastrocnemius muscles. Absence of DRP1 leads to a significant decrease in both absolute force and maximal specific force generated during tetanic contraction. The data represent average ± SEM (n = 3). Two-tailed unpaired Student’s t test and two-way analysis of variant (ANOVA) were used. Statistical significance: *p ≤ 0.05; **p ≤ 0.01; ***p ≤ 0.001