Parallel effects of insulin-like growth factor-II and insulin on glucose metabolism of developing mouse embryonic limb buds in culture.
The present study was undertaken to evaluate the functional significance of the previously observed increase in the level of IGF-II receptors despite the loss of growth promoting activity of IGF-II in differentiated limb buds in organ culture. In the present study IGF-II and insulin at similar concentration (0.1-1 microgram/ml) stimulated the glucose uptake by the tissue and incorporation into glycogen (approximately 2 and 4 times control) and stimulated the activity of glycogen synthase (approximately 2 times control) of the limb buds irrespective of the differentiation stage of the tissues. IGF-I had little or no effect. None of the hormones (IGF-I, II or insulin) had any effect on the CO2 production by the limb buds. These results suggest a regulatory role of IGF-II, complementary or overlapping with insulin, in glucose metabolism of the developing limb buds. The absence of the effects of both IGF-II and insulin on CO2 production by the tissue, however, indicate that the IGF-II and insulin regulation of glucose metabolism of the limb buds is predominantly on glycogen synthesis.
D000818:Animals; D004622:Embryo, Mammalian / Q000187:drug effects / Q000378:metabolism*; D005121:Extremities / Q000196:embryology; D005947:Glucose / Q000378:metabolism*; D006006:Glycogen Synthase / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology*; D007700:Kinetics; D051379:Mice; D009924:Organ Culture Techniques; D013002:Somatomedins / Q000494:pharmacology*
D007328:Insulin; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D006006:Glycogen Synthase; D005947:Glucose