Abstract
The role of peptide growth factors in the regulation of fetal metabolism is poorly understood. Since somatomedin-C (SmC) and multiplication-stimulating activity (MSA) have insulin-like actions in postnatal tissues, we have compared the effects of these growth factors on glycogen metabolism in cultured fetal rat hepatocytes with those of insulin and epidermal growth factor (EGF). SmC (25-375 ng/ml) stimulated dose-dependent increases in 14C-glucose incorporation into glycogen (14-73%) and total cellular glycogen content (11-34%) during 4 hours of incubation. MSA and insulin also stimulated glycogenesis but with potencies only 4.5 and 6.7% that of SmC, respectively. The concentrations of SmC, MSA and insulin which caused half-maximal stimulation of 14C-glucose incorporation were 6.7 nM, 150 nM and 100 nM, respectively. The dose-response curves of SmC, MSA and insulin were parallel and their maximal effects were not additive, suggesting a common mechanism of action. In contrast, EGF (2.5-150 ng/ml) stimulated glycogen synthesis but its dose-response curve was not parallel to that of SmC and its maximal effect was only 40% that of SmC or insulin. In addition, EGF and insulin had additive effects at maximal concentrations. These findings suggest that SmC and EGF have direct anabolic effects on fetal carbohydrate metabolism. The glycogenic actions of insulin and MSA in fetal liver may be mediated through binding to a receptor which also binds SmC. Grants HD07447 and HD06301.
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Freemark, M., D'ercole, A. & Handwerger, S. 98 GLYCOGENIC EFFECTS OF SmC, MSA AND EGF IN FETAL RAT HEPATOCYTES. Pediatr Res 19, 619 (1985). https://doi.org/10.1203/00006450-198506000-00118
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DOI: https://doi.org/10.1203/00006450-198506000-00118