Abstract
Insulin excess has been implicated in the greater perinatal morbidity and mortality in IDM. Since insulin acts by binding to cell surface receptors, we studied the receptors on cord blood monocytes of 22 NI and 8 IDM delivered by elective C-section at 36-38 wks. gestation. IDM had more receptor sites per monocyte (105,000) than NI (38,000) and 12 normal adults (25,000) studied similarly. The higher number of receptors in IDM occurred in the face of higher concentrations of insulin in their cord blood than in NI. Monocytes from both NI and IDM showed greater affinity for insulin than those from adults, (4.63 and 4.55 vs. 2.35×108 M−1 p<0.025). In NI of similar gestational age, a significant correlation was found between birthweight and insulin binding. Insulin binding to liver plasma membranes of fetal rats increased progressively from 14 d gestation through birth. At birth the maximum binding capacity was significantly greater per 100ug protein (25ng insulin) than in adult rat membranes, (17ng insulin, p<0.025). Scatchard analysis also showed that binding affinity constants were markedly greater for term fetuses than adults (Ke=3.94×108 vs. 2.85×108 M−1). Thus, in contrast to down-regulation of receptor number reported in adult hyperinsulinemia, IDM have an increase in receptor number which may be an exaggeration of the developmental process observed in normal fetuses. Greater binding of insulin to tissue of IDM may therefore expose these infants to greater hazards from the effects of insulin.
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Neufeld, N., Kaplan, S. & Lippe, B. 204 INSULIN BINDING STUDIES IN NORMAL INFANTS (NI) AND INFANTS OF DIABETIC MOTHERS (IDM). Pediatr Res 12 (Suppl 4), 397 (1978). https://doi.org/10.1203/00006450-197804001-00209
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DOI: https://doi.org/10.1203/00006450-197804001-00209