Co-Authors:
Shamay, A., Department of Biochemistry and Human Nutrition, Faculty of Agriculture, Rehovot, Israel, Central Research Laboratory, Fujisawa Pharmaceutical Company, Osaka 532, Japan
Cohen, N., Department of Biochemistry and Human Nutrition, Faculty of Agriculture, Rehovot, Israel, Central Research Laboratory, Fujisawa Pharmaceutical Company, Osaka 532, Japan
Niwa, M., Department of Biochemistry and Human Nutrition, Faculty of Agriculture, Rehovot, Israel, Central Research Laboratory, Fujisawa Pharmaceutical Company, Osaka 532, Japan
Gertler, A., Department of Biochemistry and Human Nutrition, Faculty of Agriculture, Rehovot, Israel, Central Research Laboratory, Fujisawa Pharmaceutical Company, Osaka 532, Japan
Abstract:
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 serumfree 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 α-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. © 1988 by The Endocrine Society.