Insulin-like growth factor I slows the rate of denervation induced skeletal muscle atrophy.
Loss of the nerve supply to skeletal muscle results in a relentless loss of muscle mass (atrophy) over time. The ability of insulin-like growth factor-1 to reduce atrophy resulting from denervation was examined after transection of the sciatic nerve in transgenic MLC/mIGF-1 mice that over-express mIGF-1 specifically in differentiated myofibres. The cross sectional area (CSA) of all types of myofibres and specifically type IIB myofibres was measured in tibialis anterior muscles from transgenic and wild-type mice at 28 days after denervation. There was a marked myofibre atrophy ( approximately 60%) in the muscles of wild-type mice over this time with increased numbers of myofibres with small CSA. In the muscles of MLC/mIGF-1 mice, over-expression of mIGF-1 reduced the rate of denervation induced myofibre atrophy by approximately 30% and preserved myofibres with larger CSA, compared to wild-type muscles. It is proposed that the protective effect of mIGF-1 on denervated myofibres might be due to reduced protein breakdown.
Shavlakadze
Thea
T
School of Anatomy & Human Biology, The University of Western Australia, 35, Stirling Highway, Crawley, Perth, WA 6009, Australia. sthea@anhb.uwa.edu.au
White
Jason D
JD
Davies
Marilyn
M
Hoh
Joseph F Y
JF
Grounds
Miranda D
MD
D000818:Animals; D001835:Body Weight / Q000502:physiology; D048429:Cell Size; D003714:Denervation; D004195:Disease Models, Animal; D018450:Disease Progression; D015536:Down-Regulation / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D051379:Mice; D008822:Mice, Transgenic; D018485:Muscle Fibers, Skeletal / Q000378:metabolism* / Q000473:pathology; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D009133:Muscular Atrophy / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D020426:Sciatic Neuropathy / Q000150:complications / Q000473:pathology / Q000503:physiopathology; D013997:Time Factors; D015854:Up-Regulation / Q000502:physiology*
D009124:Muscle Proteins; D007334:Insulin-Like Growth Factor I