Role of the insulin-like growth factor system in epiphyseal cartilage on the development of Langshan and Arbor Acres chickens, Gallus domesticus

We measured the mRNA transcript expression patterns for members of the insulin-like growth factor (IGF) system during embryonic and postnatal development in epiphyseal cartilage from Langshan (LS) and Arbor Acres (AA) chickens. Insulin-like growth factor binding protein (IGFBP)-2 expression was positively correlated with IGF-I from embryonic day (E) 14 to postnatal d (P) 0 and with IGF-II from E14 to P14 but negatively correlated with IGF-I from P0 to P42 and IGF-II from P14 to P42. Expression of IGFBP-5 correlated positively with IGF-I from E14 to P0 but negatively from P0 to P28. The results suggest that these genes are regulated in a coordinated fashion during development. A negative correlation was found between IGFBP-7 and IGF-II during P0 to P42. A positive correlation was found between IGFBP-3 (E14 to E18, P14 to P42) and IGF-IR and between IGFBP-3 (E14 to P0, P14 to P42) and IGF-I. The endocrine factors can be integrated with nutrition to regulate animal growth. In our study, AA chickens were fed a nutrient-rich AA diet, and LS chickens were fed either an AA diet or a less-rich diet. The LS and AA chickens fed the same AA diet showed no differences in IGF-I, IGF-I receptor, IGFBP-2, IGFBP-5, IGFBP-7, and IGFBP-3 but did still show differences in IGF-II. Our data indicate that these select genes may show linked expression during certain periods of development and that differences in gene expression respond differently to nutrient intake in LS and AA chickens.