Hormonal and nutritional regulation of IGF-I and its binding proteins.

The influence of nutrition on growth seems likely to be mediated in part through IGF-I. Restriction of dietary nutrients adversely effects IGF-I synthesis and action at multiple steps, including decreased GH receptors, postreceptor defects in GH action, decreased steady state levels of IGF-I mRNA, and attenuation of IGF-I action. In addition, undernutrition affects the IGF binding proteins in ways that vary from one tissue to another. Understanding the alterations in IGFBPs that are caused by nutritional insufficiency may provide insight into the actions of the IGFBPs.