Effects of different hypoxic training on the mitophagy and angiogenesis in skeletal muscle of mice
Objective To explore the effect of exercise training,hypoxic exposure,and different hy-poxic trainings on the mitophagy and angiogenesis in skeletal muscles of mice.Methods C57BL/6J male mice were randomly divided into a control(C),hypoxic exposure(H),exercise training(E),live high training low(LHTL),and live low training high(LLTH)groups,each of 8.Group H and E were exposed to hypoxia(14.8%～12.5%O2 concentration)for 8 h and normoxic exercise in treadmill per day respectively,while group LHTL undertook the both and group LLTH exercised ever day in the hy-poxic room for 6 weeks(5 days/week).Skeletal muscle samples were harvested after intervention and then frozen or histologically fixed.Western blotting was used to assess gastrocnemius protein,and im-munohistochemistry was employed to evaluate quadriceps angiogenesis.Moreover,the gastrocnemius mi-tochondria were observed using the transmission electron microscope(TEM).Results Compared with group C,the autophagy maker microtubule-associated protein light chain 3Ⅱ/Ⅰ protein ratio(LC3Ⅱ/LC3Ⅰ)of group LHTL and unc51-like autophagy-activating kinase 1 phosphorylation(p-Ulk1)of group E and LHTL increased significantly increased significantly(P<0.01 and P<0.05).Compared with group C,Parkin protein of group LHTL and LLTH,and PTEN induced putative kinase 1(Pink1)pro-tein levels of group H,LHTL and LLTH increased significantly(P<0.05).Moreover,BCL2/adenovirus E1B19Kda protein-interacting protein 3L(Nix)protein levels in group E,LHTL and LLTH increased significantly(P<0.05).In addition,Pink1 protein and LC3Ⅱ/LC3Ⅰ levels of group LHTL were high-er than group E(P<0.05).Compared with group C,the skeletal muscle vascular endothelial growth fac-tor(VEGF)levels of group H,E,LHTL and LLTH and cluster of differentiation 31(CD31)level of group LHTL and LLTH also increased significantly(P<0.05).TEM found the mitochondrial volume ex-pansion in group E and LHTL,and the non-injured myofibril in all groups.Conclusion Hypoxic train-ing,especially LHTL,upregulating mitophagy and angiogenesis in skeletal muscles,is superior to exer-cise training or hypoxic exposure in promoting mitophagy.
exerciseskeletal musclemitophagyangiogenesishypoxic training
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