Reduced Serum Insulin-Like Growth Factor (IGF) I Is Associated with Reduced Liver IGF-I mRNA and Liver Growth Hormone Receptor mRNA in Food-Deprived Cattle

• Published in: The Journal of nutrition Vol. 133; no. 8; pp. 2555 - 2560
• Main Authors: Wang, Ying, Eleswarapu, Satyanarayana, Beal, William E., Jiang, Honglin, Swecker, William S., Akers, R. Michael
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 01.08.2003; American Society for Nutritional Sciences
• Subjects: Animals; Biological and medical sciences; blood; Cattle; Feeding. Feeding behavior; food deprivation; Food Deprivation - physiology; foods; Fundamental and applied biological sciences. Psychology; growth hormone receptor; insulin-like growth factor I; Insulin-Like Growth Factor I - genetics; Insulin-Like Growth Factor I - metabolism; liver; Liver - metabolism; Male; messenger RNA; mRNA; Receptors, Somatotropin - genetics; RNA, Messenger - metabolism; somatotropin; steers; Vertebrates: anatomy and physiology, studies on body, several organs or systems; GHR; GH; IGF-I; RPA; insulin-like growth factor I; liver; growth hormone receptor; RACE; cattle; mRNA; GAPDH; Feeding behavior; Digestive system; Liver; Somatotropin hormone; Ox; Insulin like growth factor 1; Feeding; Vertebrata; Insulin like growth factor; Mammalia; Messenger RNA; Adenohypophyseal hormone; Serum; Artiodactyla; Restricted diet; Ungulata; Hormonal receptor
• ISSN: 0022-3166; 1541-6100
• DOI: 10.1093/jn/133.8.2555

Nutritional deprivation decreases blood insulin-like growth factor I (IGF-I) concentrations in a variety of species. In this study, we explored the underlying mechanism by determining the effects of food deprivation on the levels of total IGF-I mRNA and total growth hormone receptor (GHR) mRNA, as well as the levels of individual IGF-I mRNA variants and GHR mRNA variants in the liver of steers. Food deprivation for nearly 3 d decreased the levels of serum IGF-I by 63% (P < 0.01), and this decrease was associated with a 75% decrease (P < 0.01) in total IGF-I mRNA in the liver. The food deprivation–induced decrease in liver total IGF-I mRNA was associated with an equivalent decrease in the levels of both class 1 and class 2 IGF-I mRNA. In addition to IGF-I mRNA, food deprivation also decreased the levels of total GHR mRNA in the liver (P < 0.05), and this decrease was associated with a decrease in the liver expression of GHR mRNA variants 1C3 (P < 0.05) and 1A (P = 0.08). Food deprivation did not affect the levels of two other major GHR mRNA variants, 1B and 1C2, in the liver. These results demonstrate that the food deprivation–induced decrease in circulating IGF-I in steers is associated with a coordinate decrease in the expression of different IGF-I mRNA variants and a specific decrease in the expression of GHR mRNA variants 1C3 and 1A in the liver.