Polar bears experience skeletal muscle atrophy in response to food deprivation and reduced activity in winter and summer

作者: John P. Whiteman , Henry J. Harlow , George M. Durner , Eric V. Regehr , Bryan C. Rourke

DOI: 10.1093/CONPHYS/COX049

关键词: Sea iceAnnual cycleMuscle atrophyAnimal scienceForagingBiologyEndocrinologyMyosinInternal medicinePredationHabitatAtrophy

摘要: When reducing activity and using stored energy during seasonal food shortages, animals risk degradation of skeletal muscles, although some species avoid or minimize the resulting atrophy while experiencing these conditions hibernation. Polar bears may be deprived relatively inactive winter (when pregnant females hibernate hunting success declines for other demographic groups) as well summer sea ice retreats from key foraging habitats). We investigated muscle in samples biceps femoris collected free-ranging polar Southern Beaufort Sea (SBS) throughout their annual cycle. Atrophy was most pronounced April-May a result deprivation previous winter, with muscles exhibiting reduced protein concentration, increased water content, lower creatine kinase mRNA. These feeding spring seal prey becomes more available), initiating period recovery. During following melt late summer, ~30% SBS abandon retreating land; August, 'shore' exhibited no atrophy, indicating that they had fully recovered deprivation. individuals subsequently scavenged whale carcasses deposited by humans October, retained good condition. In contrast, ~70% follow north into deep less prey. 'ice' fast; loss rapid changes myosin heavy-chain isoforms response to activity. findings indicate that, unlike hibernation, without cannot mitigate atrophy. Consequently, prolonged fasting climate change-induced creates greater abilities travel hunt.

参考文章(97)
McGill Db, Wahner Hw, Code Cf, Nelson Ra, Jones Jd, Nitrogen metabolism in bears: urea metabolism in summer starvation and in winter sleep and role of urinary bladder in water and nitrogen conservation. Mayo Clinic proceedings. ,vol. 50, pp. 141- ,(1975)
Bruce C. Thompson, Joseph A. Chapman, George A. Feldhamer, Wild mammals of North America : biology, management, and conservation Johns Hopkins University Press. ,(2003)
MICHELLE WEHLING, BAIYUAN CAI, JAMES G. TIDBALL, Modulation of myostatin expression during modified muscle use The FASEB Journal. ,vol. 14, pp. 103- 110 ,(2000) , 10.1096/FASEBJ.14.1.103
Anastassios Philippou, Maria Maridaki, Spiros Pneumaticos, Michael Koutsilieris, The Complexity of the IGF1 Gene Splicing, Posttranslational Modification and Bioactivity Molecular Medicine. ,vol. 20, pp. 202- 214 ,(2014) , 10.2119/MOLMED.2014.00011
S. S. Wing, A. L. Goldberg, Glucocorticoids activate the ATP-ubiquitin-dependent proteolytic system in skeletal muscle during fasting American Journal of Physiology-endocrinology and Metabolism. ,vol. 264, ,(1993) , 10.1152/AJPENDO.1993.264.4.E668
J B Jaynes, J S Chamberlain, J N Buskin, J E Johnson, S D Hauschka, Transcriptional regulation of the muscle creatine kinase gene and regulated expression in transfected mouse myoblasts. Molecular and Cellular Biology. ,vol. 6, pp. 2855- 2864 ,(1986) , 10.1128/MCB.6.8.2855
Andrea M. Hanson, Brooke C. Harrison, Mary H. Young, Louis S. Stodieck, Virginia L. Ferguson, Longitudinal characterization of functional, morphologic, and biochemical adaptations in mouse skeletal muscle with hindlimb suspension Muscle & Nerve. ,vol. 48, pp. 393- 402 ,(2013) , 10.1002/MUS.23753