Shamay A, Cohen N, Niwa M, Gertler A
Department of Biochemistry and Human Nutrition, Faculty of Agriculture, Hebrew University of Jerusalem, Rehovot, Israel.
Endocrinology. 1988 Aug;123(2):804-9. doi: 10.1210/endo-123-2-804.
We have demonstrated that insulin-like growth factor I (IGF-I), at physiological concentrations, is a potent mitogen of bovine undifferentiated mammary epithelial cells cultured in collagen in serum-free medium. Its activity is independent of insulin, although at pharmacological concentrations insulin may substitute for IGF-I. The maximal [3H]thymidine incorporation stimulated by either IGF-I or insulin was only 25-40% of that in medium supplemented with 10% fetal calf serum (FCS) only. Epidermal growth factor (EGF) exhibited low mitogenic activity which was not synergistic with IGF-I in serum-free medium. IGF-I and EGF had low synergistic activity when added separately to 10% FCS-supplemented medium. Strong synergism (100% or more) was observed, however, when both factors were added simultaneously, indicating that their maximum mitogenic effect is dependent on a simultaneous presence of other factors existing in FCS. The galactopoietic effect of IGF-I was tested in organ culture of bovine lactating mammary gland. Neither fatty acid synthesis nor alpha-lactalbumin secretion was stimulated by IGF-I, even at 2000 ng/ml. These results indicate that, at least in our in vitro system, galactopoiesis is not affected by IGF-I.
我们已经证明，胰岛素样生长因子I（IGF-I）在生理浓度下，是在无血清培养基中胶原上培养的牛未分化乳腺上皮细胞的一种强效促有丝分裂原。其活性独立于胰岛素，不过在药理浓度下胰岛素可替代IGF-I。由IGF-I或胰岛素刺激的最大[3H]胸腺嘧啶核苷掺入量仅为仅添加10%胎牛血清（FCS）的培养基中的25%-40%。表皮生长因子（EGF）表现出低促有丝分裂活性，在无血清培养基中与IGF-I无协同作用。当分别添加到补充有10%FCS的培养基中时，IGF-I和EGF具有低协同活性。然而，当同时添加这两种因子时，观察到强协同作用（100%或更高），这表明它们的最大促有丝分裂作用取决于FCS中同时存在的其他因子。在牛泌乳乳腺的器官培养中测试了IGF-I的泌乳效应。即使在2000 ng/ml时，IGF-I也未刺激脂肪酸合成或α-乳白蛋白分泌。这些结果表明，至少在我们的体外系统中，泌乳不受IGF-I影响。
