Evock C M, Walton P E, Etherton T D
Pennsylvania State University, University Park 16802.
J Anim Sci. 1990 Jul;68(7):1953-64. doi: 10.2527/1990.6871953x.
The present study was conducted to determine 1) whether porcine growth hormone (pGH) affected insulin-like growth factor (IGF)-II concentrations in growing pigs and 2) the distribution of [125I]IGF-I and [125I]IGF-II binding activity and immunoreactive IGF-I and IGF-II in serum from control, pGH-treated and hypophysectomized (hypox) pigs. Seven weeks of pGH treatment had no effect on serum IGF-II concentrations, but after 11 wk serum IGF-II had increased by up to 50%. In normal pig serum, [125I]IGF-I bound to specific insulin-like growth factor binding proteins (IGF-BP) of 40 kDa (87.5%) and 150 kDa (12.5%). Treatment with pGH increased the proportion of IGF-I bound to the large IGF-BP (approximately 48%). In contrast, [125I]IGF-II partitioned to specific IGF-BP of 450 kDa (30%), 150 kDa (46%) and 40 kDa (23%). After treatment with pGH, binding of IGF-II to the 150-kDa IGF-BP increased to 57% of total specific binding. Binding of IGF-I and IGF-II to the 150-kDa IGF-BP was virtually abolished in hypox pig serum. IGF-I immunoreactivity was predominantly associated with the 150-kDa IGF-BP (67 to 83%), with the remainder bound to the small IGF-BP. There was no detectable free IGF-I in pig serum. Treatment with pGH did not affect the distribution of immunoreactive IGF-I between the two IGF-BP complexes, although there was a marked elevation in total serum IGF-I concentration. Immunoreactive IGF-II was detected in all three IGF-BP complexes. In control serum, the largest quantity (46%) of immunoreactive IGF-II was associated with the 40-kDa IGF-BP. Thirty-four percent was bound to the 150-kDa IGF-BP complex. Administration of pGH led to an increased association with the 150-kDa complex (50%) and a concomitant decrease in IGF-II associated with the 40-kDa species (35%). In summary, IGF-II concentrations in the pig are elevated by prolonged pGH treatment. Furthermore, there is a unique large IGF-BP in postnatal pig serum that specifically binds IGF-II but not IGF-I.
1）猪生长激素（pGH）是否影响生长猪体内胰岛素样生长因子（IGF）-II的浓度；2）在对照猪、接受pGH处理的猪和垂体切除（垂体摘除）猪的血清中，[125I]IGF-I和[125I]IGF-II的结合活性分布以及免疫反应性IGF-I和IGF-II的情况。pGH处理7周对血清IGF-II浓度无影响，但11周后血清IGF-II升高了多达50%。在正常猪血清中，[125I]IGF-I与40 kDa（87.5%）和150 kDa（12.5%）的特异性胰岛素样生长因子结合蛋白（IGF-BP）结合。pGH处理使与大IGF-BP结合的IGF-I比例增加（约48%）。相比之下，[125I]IGF-II分配到450 kDa（30%）、150 kDa（46%）和40 kDa（23%）的特异性IGF-BP。pGH处理后，IGF-II与150-kDa IGF-BP的结合增加到总特异性结合的57%。在垂体摘除猪血清中，IGF-I和IGF-II与150-kDa IGF-BP的结合几乎完全消失。IGF-I免疫反应性主要与150-kDa IGF-BP相关（67%至83%），其余与小IGF-BP结合。猪血清中未检测到游离IGF-I。pGH处理虽使血清总IGF-I浓度显著升高，但不影响免疫反应性IGF-I在两种IGF-BP复合物之间的分布。在所有三种IGF-BP复合物中均检测到免疫反应性IGF-II。在对照血清中，最大量（46%）的免疫反应性IGF-II与40-kDa IGF-BP相关。34%与150-kDa IGF-BP复合物结合。给予pGH导致与150-kDa复合物的结合增加（50%），同时与40-kDa种类相关的IGF-II减少（35%）。总之，长期pGH处理可使猪体内IGF-II浓度升高。此外，出生后猪血清中存在一种独特的大IGF-BP，它特异性结合IGF-II而非IGF-I。
