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Erythrocyte insulin binding in preterm newborn infants
Insights
Newborn preterm infants show higher erythrocyte insulin receptor binding due to increased receptor concentration and affinity. This binding is linked to gestational and postnatal age, not plasma insulin levels.
Area of Science:
- Endocrinology
- Neonatology
- Cell Biology
Background:
- Insulin resistance is a concern in preterm infants.
- Erythrocyte insulin receptors offer a model for studying insulin binding in neonates.
Purpose of the Study:
- To characterize erythrocyte insulin receptor binding in preterm and term newborn infants.
- To investigate the influence of gestational and postnatal age on insulin receptor characteristics.
Main Methods:
- Studied 125I-insulin binding to erythrocytes from 42 preterm and 32 term infants.
- Analyzed binding at different postnatal ages (birth, 2-7 days, 8-16 days).
- Correlated binding with gestational and postnatal age, and plasma insulin/C-peptide.
Main Results:
- Preterm infants at birth had significantly higher insulin binding than term infants.
- Binding decreased with increasing gestational and postnatal age.
- Enhanced binding in preterm infants was due to increased receptor concentration and affinity.
- Receptor concentration correlated with postnatal age; affinity correlated with gestational age.
Conclusions:
- Erythrocyte insulin receptor characteristics differ between preterm and term newborns.
- Gestational and postnatal age significantly influence insulin receptor binding in infants.
- Findings suggest potential early alterations in insulin sensitivity in preterm infants.
Abstract:
To characterize the erythrocyte insulin receptor in newborn infants we studied the binding of 125I-insulin to the erythrocytes from 42 preterm infants (14 at birth, 14 aged 2-7 days, and 14 aged 8-16 days) with a mean gestational age of 34.1 wk, and from 32 term infants (16 at birth and 16 aged 2-7 days). The insulin binding to cord blood erythrocytes from preterm infants was significantly higher than that of cord blood cells from term infants and to postnatal cells from preterm as well as term infants. The erythrocytes from preterm infants aged 2-7 days bound more insulin than cells from preterm infants aged 8-16 days. The maximum insulin binding (specific insulin binding at tracer concentration of insulin) correlated negatively with the gestational age both at birth and over the 1st postnatal wk. In the preterm infants there was a strong negative correlation between the maximum insulin binding and postnatal age. The enhanced insulin binding to cord blood erythrocytes from preterm infants was due to both an increased receptor concentration and a high affinity for insulin. The increased affinity persisted over the 1st wk of life. In preterm infants older than 1 wk the insulin binding characteristics were basically similar to those in term newborn infants. In all infants studied the receptor concentration seemed to be postnatal age dependent while the receptor affinity was gestational age dependent. No correlation was found between the insulin binding data and the plasma concentrations of immunoreactive insulin or C-peptide.(ABSTRACT TRUNCATED AT 250 WORDS)