Chernausek S D
Division of Endocrinology, Children's Hospital Medical Center, Cincinnati, Ohio 45229.
J Neurosci Res. 1993 Feb 1;34(2):189-97. doi: 10.1002/jnr.490340206.
The insulin-like growth factors are postulated to play a role during brain development. Because they are believed to act in a paracrine/autocrine manner, the production of insulin-like growth factor-I (IGF-I) by cultured astroglial cells was examined. Quantities of IGF-I in conditioned media were determined by RIA after separation of IGFs from IGF-binding proteins by high-pressure liquid chromatography. Astrocytes from 1-day-old rats and the rat glioma cell line (C6) both secreted 7.5-kDa IGF-I. A peak of immunoreactivity with an apparent mol wt of 12,000 was additionally present in media conditioned by C6 cells. Exposure to epidermal growth factor (EGF) increased media content of immunoreactive IGF-I slightly (60%) in C6 cells but more than 2-fold in normal astrocytes. Fibroblast growth factor also increased the amount of IGF-I contained in media conditioned by normal astrocytes. To determine whether the secreted IGF-I was biologically active, media IGFs were immunoneutralized with a monoclonal antibody (Sm 1.25). In the presence of the antibody, EGF-stimulated astrocyte replication was blocked. These data indicate that IGF-I secretion by rodent astrocytes is stimulated by factors thought to be important for brain growth and development and that the IGFs are likely intimate participants in EGF-induced astrocyte growth.
胰岛素样生长因子被认为在脑发育过程中发挥作用。由于它们被认为以旁分泌/自分泌方式起作用，因此研究了培养的星形胶质细胞产生胰岛素样生长因子-I（IGF-I）的情况。通过高压液相色谱将IGF与IGF结合蛋白分离后，用放射免疫分析法测定条件培养基中IGF-I的量。1日龄大鼠的星形胶质细胞和大鼠胶质瘤细胞系（C6）均分泌7.5 kDa的IGF-I。在C6细胞条件培养基中还存在一个表观分子量为12,000的免疫反应性峰值。暴露于表皮生长因子（EGF）使C6细胞中免疫反应性IGF-I的培养基含量略有增加（60%），但在正常星形胶质细胞中增加了2倍以上。成纤维细胞生长因子也增加了正常星形胶质细胞条件培养基中所含IGF-I的量。为了确定分泌的IGF-I是否具有生物活性，用单克隆抗体（Sm 1.25）对培养基中的IGF进行免疫中和。在抗体存在的情况下，EGF刺激的星形胶质细胞复制被阻断。这些数据表明，啮齿动物星形胶质细胞分泌IGF-I受到被认为对脑生长和发育很重要的因子的刺激，并且IGF可能是EGF诱导的星形胶质细胞生长的密切参与者。
