Analysis of Insulin and Insulin-Like Growth Factor-I Receptors in Neural Tissues

A variety of biochemical and physiological studies in recent years have made it clear that the brain possesses specific receptors and puta- tive signal transduction pathways for insulin and the insulin-like growth factors (IGF-I and IGF-II). These observations have challenged tradi- tional ideas concerning the physiological role of these peptides in the CNS, and have compelled us and others to consider that they are important regulators of metabolism and growth and development in the CNS (reviewed in 1 ). A combination of the techniques used for culturing neuralderived cells and those involved in studying insulin and IGF-I receptors on peripheral nonneural tissue has provided a major stimulus for these studies, the results of which define insulin and the IGFs as neuropeptides. The purpose of this chapter is to present these techniques together in a comprehensive manner so as to pro- vide the reader with an overview of how it is possible to study insulin and the IGF-I receptors in nervous tissue.