Submitted to: Domestic Animal Endocrinology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 3, 1997
Publication Date: N/A
Interpretive Summary: The insulin-like growth factors, IGF-I and IGF-II, comprise a conserved pair of secreted proteins with diverse effects on growth, development and metabolism. This review focuses on our knowledge of the role of these peptide hormones in avaian species. More is known about the importance of these substances in mammals than in any other species. Much of what is known about their action in birds has been derived from studies conducted either on cell types or tissues derived from avian species or from in vivo experiments. Biochemically and physiologically, significant differences in the composition and action of growth factors in birds is different than in other species studied.
Recent research on the function of the insulin-like growth factors in birds as shown that in some aspects the action of these peptide hormones is different compared to mammals. Comparatively, when infused into broiler chickens and turkeys, the hypoglycemic response to insulin-like growth factor-I is similar that of insulin. Insulin-like growth factors (I and II) both evoke other metabolic changes, suggesting that these growth factors may be more closely linked to regulating intermediary metabolism in birds, rather than being a major promoter of somatic growth. Specifically, changes in glucagon and free fatty acid blood concentrations, strongly suggests that the growth factors are important regulators of fat metabolism in birds.