title: Remarkable preservation of Ca(2+) homeostasis and inhibition of apoptosis contribute to anti-muscle atrophy effect in hibernating Daurian ground squirrels.
abstract: The underlying mechanisms that hibernators deviated from muscle atrophy during prolonged hibernating inactivity remain elusive. This study tested the hypothesis that the maintenance of intracellular Ca(2+) homeostasis and inhibition of apoptosis would be responsible for preventing muscle atrophy in hibernating Daurian ground squirrels. The results showed that intracellular Ca(2+) homeostasis was maintained in soleus and extensor digitorum longus (EDL) in hibernation and post-hibernation, while cytosolic Ca(2+) was overloaded in gastrocnemius (GAS) in hibernation with a recovery in post-hibernation. The Ca(2+) overload was also observed in interbout arousals in all three type muscles. Besides, the Bax/Bcl-2 ratio was unchanged in transcriptional level among pre-hibernation, hibernation and interbout arousals, and reduced to a minimum in post-hibernation. Furthermore, the Bax/Bcl-2 ratio in protein level was reduced in hibernation but recovered in interbout arousals. Although cytochrome C was increased in GAS and EDL in post-hibernation, no apoptosis was observed by TUNEL assay. These findings suggested that the intracellular Ca(2+) homeostasis in hibernation might be regulated by the cytosolic Ca(2+) overload during interbout arousals, which were likely responsible for preventing muscle atrophy via inhibition of apoptosis. Moreover, the muscle-specificity indicated that the different mechanisms against disuse-induced atrophy might be involved in different muscles in hibernation.
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi'an 710069, China.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Fu
authors.affiliation: National Research Center for Veterinary Medicine, Luo Yang 471003, China.
authors.forename: Huanxin
authors.initials: H
authors.lastname: Hu
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi'an 710069, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Dang
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi'an 710069, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Chang
authors.affiliation: Shaanxi Institute of International Trade and Commerce, Xian Yang 712046, China.
authors.forename: Bei
authors.initials: B
authors.lastname: Du
authors.affiliation: Department of Burns and Cutaneous Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Wu
authors.affiliation: Key Laboratory of Resource Biology and Biotechnology in Western China (Northwest University), Ministry of Education, Xi'an 710069, China.
authors.forename: Yunfang
authors.initials: Y
authors.lastname: Gao
mesh_terms: D000818:Animals; D017209:Apoptosis; D000068959:Body Weight Maintenance; D002118:Calcium / Q000378:metabolism*; D045304:Cytochromes c / Q000378:metabolism; D053938:DNA Fragmentation; D005260:Female; D015870:Gene Expression; D006605:Hibernation; D006706:Homeostasis; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D009133:Muscular Atrophy / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism; D012589:Sciuridae / Q000502:physiology*; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c; D018995:Myosin Heavy Chains; D002118:Calcium