IGF-2 STIMULATES GROWTH AND METABOLISM OF EARLY MOUSE EMBRYOS

Recent reports indicate that the insulin gene family plays a significant role in early development. Both insulin an IGF-1 stimulate growth and metabolism in preimplantation mouse embryos, however, little is known of the physiological effects of IGF-2. In this study, addition of IGF-2 to defined culture medium for the culture of 2-cell embryos stimulated blastocyst formation by 15%, ICM mitogenesis by 37%, and protein synthesis by 35%. EC50s of 12-63 pM IGF-2 for these responses were in the range for mediation by IGF-2 receptors. These results coupled with the previously demonstrated presence and expression of the IGF-2 receptor from the 2-cell stage supports a role for this third member of the insulin gene family in early development.