IGF-I and Brain Growth: Multifarious Effects on Developing Neural Cells and Mechanisms of Action

Abstract

Numerous investigators have provided data supporting an essential role for IGF-I in growth of the brain. IGF-I contributes to multiple processes during brain development, including neural cell survival, proliferation, differentiation and maturation. The IGF type I receptor (IGF-IR) is present on all cell types in the brain, and IGF-I has known actions on neural stem and progenitor cells as well as neurons and glia. IGF-I is highly expressed throughout the brain during development, and its expression is retained in the meninges and in many cell types in the adult brain. While IGF-I has multiple actions on developing neural cells, very few studies have addressed the mechanisms or pathways by which IGF-I mediates these multiple effects. The goal of this chapter is to briefly review data on IGF-I in the developing brain and then to discuss more recent studies that focus on the mechanisms for its varied actions.