Insulin-like growth factors in the treatment of neurological disease

Although the functional deficits of neurological diseases vary, they are all pathologically marked by neuronal degeneration. The ability of insulin-like growth factor-I (IGF-I) to support both sensory and motor neuron regeneration has suggested its potential in treatment of neurological diseases. IGF-I is pleiotrophic, stimulating survival, neurite outgrowth and motility in neurons, as well as myelination of neurons by glia. Understanding the intracellular signaling pathways that mediate these pleiotrophic responses to IGF-I is important for tailoring IGF-I treatment to the appropriate neurological deficit. This review surveys the current understanding of IGF-I pleiotrophism, the underlying signaling conferring these effects, and the status of IGF-I in treatment of human neurological disorders.