| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Department of Animal Sciences, University of Illinois, Urbana 61801
The insulin-like growth factors (IGF) and insulin perform seemingly unique roles by causing the same metabolic effect: cellular hypertrophy. Although overlapping, there are different consequences to cellular hypertrophy induced by IGF and that induced by insulin. The IGF enhance the cell hypertrophy that is requisite for cell survival, hyperplasia, and differentiation, and insulin enhances cell hypertrophy primarily as a means to increase nutrient stores. The effects of IGF and insulin are controlled by the segregation of their receptors between different cell types. A model is discussed that describes the need for three hormones (IGF-I, IGF-II, and insulin) to control nutrient partitioning. Insulin receptor localization, as well as an episodic mode of secretion, evolved to perform the short-term action of clearing excess nutrients from the circulation. In contrast, a complex and interactive set of factors ensure that maximal IGF activity occurs only when conditions are optimal for growth. A relatively invariant rate of secretion and the IGF binding proteins serve to maintain a large mutable pool of IGF. This pool exists to ensure a constant supply of IGF to maintain the basal metabolic rate and to ensure that, once a cell begins to proliferate or differentiate, adequate exposure is available to complete the process even after severe short-term physiological insults. The IGF concentrations only change in response to prolonged differences in protein and energy availabilities, environmental and body temperatures, and external stress. Also, evidence is now emerging that describes a discrete role for trace nutrients in the regulation of IGF activity. In this latter regard, zinc has the notable role of targeting IGF binding proteins to the cell surface. New data are presented showing that zinc also changes the affinity of the type 1 IGF receptor and cell-associated IGF binding proteins to optimize IGF activity.
Key Words: insulin-like growth factor • binding protein • receptor • zinc
Submitted on May 22, 1997
Accepted on January 20, 1998
This article has been cited by other articles:
|
|
 |
|
  M A Velazquez, J Zaraza, A Oropeza, R Webb, and H Niemann The role of IGF1 in the in vivo production of bovine embryos from superovulated donors Reproduction, February 1, 2009; 137(2): 161 - 180. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. M. Brandt, D. H. Keisler, D. L. Meyer, T. B. Schmidt, and E. P. Berg Serum hormone concentrations relative to carcass composition of a random allotment of commercial-fed beef cattle J Anim Sci, January 1, 2007; 85(1): 267 - 275. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. P. Radcliff, M. J. VandeHaar, Y. Kobayashi, B. K. Sharma, H. A. Tucker, and M. C. Lucy Effect of Dietary Energy and Somatotropin on Components of the Somatotropic Axis in Holstein Heifers J Dairy Sci, May 1, 2004; 87(5): 1229 - 1235. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. N. Sauter, E. Ontsouka, B. Roffler, Y. Zbinden, C. Philipona, M. Pfaffl, B. H. Breier, J. W. Blum, and H. M. Hammon Effects of dexamethasone and colostrum intake on the somatotropic axis in neonatal calves Am J Physiol Endocrinol Metab, August 1, 2003; 285(2): E252 - E261. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Rosendal, H. Langberg, A. Flyvbjerg, J. Frystyk, H. Orskov, and M. Kjar Physical capacity influences the response of insulin-like growth factor and its binding proteins to training J Appl Physiol, November 1, 2002; 93(5): 1669 - 1675. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 V. Gauduchon, S. Werner, G. Prevost, H. Monteil, and D. A. Colin Flow Cytometric Determination of Panton-Valentine Leucocidin S Component Binding Infect. Immun., April 1, 2001; 69(4): 2390 - 2395. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
