The Journal of Nutrition Vol. 128 No. 2 February 1998, pp. 300S-301S

Nutritional and Developmental Roles of Insulin-Like Growth Factors between Species: A Brief History and Introduction¹

Douglas C. McFarland

Muscle Biology Laboratories, Department of Animal and Range Sciences, South Dakota State University, Brookings, SD 57007 

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Article References

The 62nd Annual Poultry Nutrition Conference focused on the nutritional and developmental roles of insulin-like growth factors (IGF) in poultry, swine and fish. Historically, the IGF have been known by a number of different names, some of which are listed in Table 1. The term insulin-like growth factor stems from the "insulin-like" actions of the polypeptides and the amino acid sequence homology with insulin. In 1987, Daughaday et al. reviewed the genesis of the nomenclature of these growth factors and proposed that they be called IGF-I and IGF-II. The previously described growth factors of this family seemed to be variants of either IGF-I or IGF-II, the former group being growth hormone dependent and the latter group much less growth hormone dependent. Much of the early work with IGF was a result of efforts to determine the mode of action of pituitary growth hormone. Work in several laboratories (Denko and Bergenstal 1955, Ellis et al. 1953, Murphy et al. 1956) reported that incorporation of sulfate into cartilage was reduced in vivo in hypophysectomized rats and restored by the administration of growth hormone. In 1957, Salmon and Daughaday demonstrated that a serum-borne factor present in both normal rats and hypophysectomized rats treated with growth hormone increased rates of incorporation of ³⁵S-sulfate into cartilage explants compared with hypophysectomized control serum. The factor seemed to be induced by growth hormone, but was not, itself, growth hormone. These findings and others demonstrating various growth-stimulating characteristics of the serum factor were the basis of the "somatomedin hypothesis" (Daughaday et al. 1972). Somatomedin was so named because it mediated the effects of somatotropin (growth hormone). It was later named IGF-I. Using a perfused rat liver system, Schwander et al. (1983) demonstrated that synthesis and secretion of liver IGF was reduced in hypophysectomized rats and could be largely restored by administration of growth hormone. Furthermore, calculated rates of IGF synthesis by the rat liver alone seemed to be sufficient to account for serum IGF concentrations.

Following these observations, reports of the presence of IGF within various tissues at levels that could not be accounted for by contamination by blood (D'Ercole et al. 1984, Underwood et al. 1986) and detection of IGF synthesis by cultured non-hepatic cells (Clemmons et al. 1981) led to the idea that IGF may additionally act through non-endocrine modes of action. Later work using specific mRNA probes confirmed that IGF were indeed produced by numerous tissues in the body and likely act through local or paracrine and autocrine mechanisms (see Holly and Wass 1989 for review). Intense research activity followed and still continues, which has resulted in great advancement in our knowledge of the mechanism of IGF actions as well as its regulation.

The goal of these symposium proceedings is to provide the most recent developments on the role of IGF in nutrition, growth and development of poultry, swine and fish. We are honored this year to have three internationally recognized researchers in IGF participating in this symposium.

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	LITERATURE CITED

Article References

• Clemmons D. R., Underwood L. E., Van Wyk J. J. Hormonal control of immunoreactive somatomedin production by cultured human fibroblasts. J. Clin. Invest. 1981; 67:10-19 [Medline]
• Daughaday, W. D., Hall, K., Raben, M. S., Salmon, W. D., Jr., Van den Brande, J. L. & Van Wyk, J. J. (1972) Somatomedin: proposed designation for sulphation factor. Nature (Lond.) 235: 107.
• Daughaday W. H., Hall K., Salmon W. D. Jr., Van den Brande J. L., Van Wyk J. J. On the nomenclature of the somatomedins and insulin-like growth factors. J. Clin. Endocrinol. & Metab. 1987; 65:1075-1076 [Medline] [Medline]
• Denko C. W., Bergenstal D. M. The effect of hypophysectomy and growth hormone on S³⁵ fixation in cartilage. Endocrinology 1955; 57:76-86
• D'Ercole A. J., Stiles A. D., Underwood L. E. Tissue concentrations of somatomedin C: further evidence for multiple sites of synthesis and paracrine or autocrine mechanisms of action. Proc. Natl. Acad. Sci. USA 1984; 81:935-939 [Abstract/Free Full Text]
• Ellis S., Huble J., Simpson M. E. Influence of hypophysectomy and growth hormone on cartilage sulfate metabolism. Proc. Soc. Exp. Biol. Med. 1953; 84:603-605
• Holly J.M.P., Wass J.A.H. Insulin-like growth factors: autocrine, paracrine or endocrine? New perspectives of the somatomedin hypothesis in the light of recent developments. J. Endocrinol. 1989; 122:611-618 [Medline]
• Murphy W. R., Daughaday W. H., Hartnett C. The effect of hypophysectomy and growth hormone on the incorporation of labeled sulfate into tibial epiphyseal and nasal cartilage of the rat. J. Lab. Clin. Med. 1956; 47:715-722
• Salmon W. D. Jr., Daughaday W. H. A hormonally controlled serum factor which stimulates sulfate incorporation by cartilage in vitro. J. Lab. Clin. Med. 1957; 49:825-836 [Medline]
• Schwander J. C., Hauri C., Zapf J., Froesch E. R. Synthesis and secretion of insulin-like growth factor and its binding protein by the perfused rat liver: dependence on growth hormone status. Endocrinology 1983; 113:297-305 [Medline] [Abstract]
• Underwood L. E., D'Ercole A. J., Clemmons D. R., Van Wyk J. J. Paracrine functions of somatomedins. Clinics Endocrinol. Metab. 1986; 15:59-77 [Medline]

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