Nutritional regulation of IGF-I and IGFBPs.
IGF-I concentrations in serum are decreased in states of chronic undernutrition or when food intake is restricted. A variety of mechanisms including decreased GH receptor binding, post-receptor resistance to GH, and reduced steady-state mRNA for IGF-I contribute to this decrease. In addition, dietary manipulation causes profound alterations in the IGF binding proteins, including reduced IGFBP-3, the principal serum carrier of IGF-I. Under some adverse nutritional conditions IGFBP-1 and IGFBP-2 are increased. Concomitant with changes in IGFBPs, IGF-I volume of distribution is increased and clearance is hastened. It seems likely that nutrition related changes in IGFBPs contribute significantly to alterations in IGF-I concentration and actions.
Underwood
L E
LE
Department of Pediatrics, University of North Carolina at Chapel Hill 27599-7220, USA.
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D009747:Nutritional Physiological Phenomena / Q000502:physiology*
D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I