Abstract
Age is an important predictor of neuromuscular recovery after peripheral nerve injury. Insulin-like growth factor 1 (IGF-1) is a potent neurotrophic factor that is known to decline with increasing age. The purpose of this study was to determine if locally delivered IGF-1 would improve nerve regeneration and neuromuscular recovery in aged animals. Young and aged rats underwent nerve transection and repair with either saline or IGF-1 continuously delivered to the site of the nerve repair. After 3 months, nerve regeneration and neuromuscular junction morphology were assessed. In both young and aged animals, IGF-1 significantly improved axon number, diameter, and density. IGF-1 also significantly increased myelination and Schwann cell activity and preserved the morphology of the postsynaptic neuromuscular junction (NMJ). These results show that aged regenerating nerve is sensitive to IGF-1 treatment.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Age Factors
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Aging / drug effects*
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Aging / physiology
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Analysis of Variance
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Animals
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Axons / drug effects
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Axons / physiology
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GAP-43 Protein / genetics
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GAP-43 Protein / metabolism
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Insulin-Like Growth Factor I / administration & dosage*
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Muscle, Skeletal / drug effects
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Muscle, Skeletal / metabolism
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Muscle, Skeletal / physiology
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Nerve Fibers, Myelinated / drug effects
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Nerve Fibers, Myelinated / physiology
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Nerve Regeneration / drug effects*
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Nerve Regeneration / physiology
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Neuromuscular Junction / drug effects
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Neuromuscular Junction / physiology
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Rats
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Reverse Transcriptase Polymerase Chain Reaction
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Schwann Cells / drug effects
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Schwann Cells / physiology
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Tibial Nerve / drug effects*
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Tibial Nerve / injuries*
Substances
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GAP-43 Protein
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RNA, Messenger
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Insulin-Like Growth Factor I