Radecki S V, Capdevielle M C, Buonomo F C, Scanes C G
Department of Animal Science, Rutgers- State University of New Jersey, New Brunswick 08903, USA.
Gen Comp Endocrinol. 1997 Jul;107(1):109-17. doi: 10.1006/gcen.1997.6898.
The present study examined plasma concentrations of insulin-like growth factor (IGF)-I, IGF-II and IGF-binding proteins (IGFBPs) during posthatch growth and development in chickens. Three distinct proteins which bound 125I-IGF-I were observed irrespective of age or sex, these having apparent molecular weights of 22, 28, and 36 kDa. The major IGFBP present during much of the growth and development period was the 28-kDa form followed by the 36-kDa form. Plasma concentrations of IGF-II and of the 22-kDa IGFBP showed little ontogenic variation with the exception of elevated levels of the 22 kDa IGFBP in 1-day-old chicks. The circulating concentrations of IGF-I and of the 28-kDa IGFBP increased progressively between the time of hatching to reach a maximum at 6 weeks of age and subsequently declined to lower levels in adults. Somewhat similarly, the 36-kDa IGFBP increased during early pre- and posthatching growth to a maximum at 6 weeks of age. There were marked sex differences in circulating concentrations of IGF-I in young (4 week) and adult chickens and in the 36-kDa IGFBP in the adult, both being lower in females. Estrogen treatment of adult male chickens decreased the circulating concentrations of IGF-I together with the level of both the 28- and 36-kDa IGFBPs. Testosterone treatment had no effect on the circulating concentrations of either IGF-I or IGFBPs in adult female chickens. We conclude that the relative levels of IGF-I, IGF-II, and the IGFBPs change with age. In addition, circulating concentrations of estrogen may play a role in the regulation of IGF-I and IGFBPs.
本研究检测了雏鸡孵化后生长发育过程中胰岛素样生长因子（IGF）-I、IGF-II和IGF结合蛋白（IGFBP）的血浆浓度。无论年龄或性别，均观察到三种与125I-IGF-I结合的不同蛋白质，其表观分子量分别为22、28和36 kDa。在生长发育的大部分时期，主要的IGFBP是28 kDa形式，其次是36 kDa形式。IGF-II和22 kDa IGFBP的血浆浓度在个体发育过程中变化不大，1日龄雏鸡的22 kDa IGFBP水平升高是个例外。从孵化到6周龄，IGF-I和28 kDa IGFBP的循环浓度逐渐升高，在6周龄时达到最高，随后在成年鸡中降至较低水平。类似地，36 kDa IGFBP在孵化前和孵化后的早期生长过程中增加，在6周龄时达到最高。幼龄（4周）和成年鸡的IGF-I循环浓度以及成年鸡的36 kDa IGFBP存在明显的性别差异，两者在雌性中均较低。对成年雄性鸡进行雌激素处理可降低IGF-I的循环浓度以及28 kDa和36 kDa IGFBP的水平。对成年雌性鸡进行睾酮处理对IGF-I或IGFBPs的循环浓度均无影响。我们得出结论，IGF-I、IGF-II和IGFBPs的相对水平随年龄变化。此外，雌激素的循环浓度可能在IGF-I和IGFBPs的调节中起作用。
