ROLE OF INSULIN-LIKE GROWTH-FACTORS IN PERIPHERAL-NERVE REGENERATION

Prolonged denervation results in atrophy of target organs and increase d risk of permanent paralysis. A better understanding of the mechanism responsible for nerve regeneration may one day lead to improved rates of nerve regeneration and diminished risk of loss of function. Neurob iologists have known for decades that soluble neurotrophic activity is present in nerves and nerve targets. Until recently, the soluble mole cules that regulate the rate of nerve regeneration have eluded identif ication. Insulin-like growth factor (IGF) gene expression is correlate d with synapse formation during development and regeneration. IGFs are now identified as the first soluble nerve- and muscle-derived neurotr ophic factors found to regulate the rate of peripheral nerve regenerat ion. The roles of IGFs and other neurotrophic factors in peripheral ne rve regeneration, motor nerve terminal sprouting and synapse formation are reviewed.