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Effect of locally delivered IGF‐1 on nerve regeneration during aging: An experimental study in rats

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. Muscle Nerve, 2009