Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: March 6, 2006
Publication Date: March 6, 2006
Citation: Kuo, A., Clover, C.M., Rosebrough, R.W., McMurtry, J.P., Mitchell, A.D., Caperna, T.J., Li, C., Kahl, S., Elsasser, T.H. 2006. The IGF system in chickens: Factors affecting gene expression in muscle and liver [abstract]. Journal of Federation of American Societies for Experimental Biology. 20:A172. Technical Abstract: Age and dietary protein supply control muscle growth directly and indirectly through the influence of regulatory factors. Insulin-like growth factors (IGF1 and 2) and IGF binding proteins (IGFBP) are key regulators of muscle development and metabolism in birds and other vertebrate species. Gene expression of IGF1 and 2, IGF receptor, and IGFBP 1,2,4 and 5 in the liver, pectoralis major (PM), and vastus lateralis muscles (VL) from broiler chickens were determined by Real Time PCR. In an age study, tissue was collected from chickens at 7 (D7) and 35 (D35) days-of-age fed a 24% protein diet. An additional two groups of chickens were fed either 12% (P12) or 30% (P30) dietary protein after 7 days-of-age, and samples were collected at D39. Plasma IGF1 was 2-fold higher on D35 than D7. Hepatic IGF1, IGFBP1, and IGFBP4 gene expressions were significantly higher at D35 than D7. At D7, PM IGFBP4 and VL IGF2 were expressed greater than at D35. In the dietary protein study, chickens fed P30 had higher plasma IGF1. In this group (P30) body, fat, and lean tissue weights, bone mineral density and bone mineral content were 2.5-fold greater than P12. However, hepatic IGF1, IGFBP1 and IGFBP5 mRNA expression levels were higher in P12 than P30. In PM, IGFBP4 gene expression was greater in the chicks fed 30% dietary protein. VL muscle IGF receptor gene expression was greater in the chickens fed P30 than P12. These data demonstrate that IGF and IGFBP gene expression are influenced by age and dietary protein in the chicken.