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Effect of age and sex on insulin binding to human erythrocytes
Insights
Insulin binding to red blood cells changes with age, increasing in adults and showing differences between males and females. This study investigated age and sex effects on insulin receptor binding in erythrocytes.
Area of Science:
- Endocrinology
- Physiology
- Cell Biology
Background:
- Insulin's interaction with cells is crucial for glucose metabolism.
- Erythrocytes (red blood cells) serve as a model for studying insulin binding.
- Age and sex are known factors influencing physiological processes.
Purpose of the Study:
- To evaluate the effect of age on insulin binding to erythrocytes.
- To assess the influence of sex on insulin binding.
- To correlate insulin binding with reticulocyte count and receptor characteristics.
Main Methods:
- Insulin binding to erythrocytes was measured using a modified Gambhir's method.
- Subjects were categorized into five age groups, from cord blood to over 60 years.
- Insulin receptor concentration (R0) and affinity (Ke) were determined.
Main Results:
- Highest insulin binding was observed in cord blood erythrocytes, correlated with reticulocyte count.
- Adults (20-59 years) showed significantly higher binding than younger groups.
- Insulin receptor affinity increased with age, potentially as an adaptive response; females exhibited slightly lower binding than males post-puberty due to decreased affinity.
Conclusions:
- Insulin binding to erythrocytes is significantly influenced by age, with distinct patterns in infants and adults.
- Receptor affinity increases with age, suggesting an adaptive mechanism.
- Sex influences insulin binding in adults, with females showing reduced binding primarily due to lower receptor affinity.
Abstract:
Insulin binding to erythrocytes from normal subjects over a wide range of ages (group I, cord blood; group II, Age 6M to 6 yrs; group III, 7 to 19 yrs; group IV, 20 to 59 yrs, group V, over 60 yrs of age) was determined using modified Gambhir's method and the effect of age and sex on the binding was evaluated. The highest insulin binding to cord blood erythrocytes was accounted for by the increased number of reticulocytes since there was a highly significant correlation between insulin binding and the reticulocyte count (r = 0.928, p less than 0.001). Group IV showed significantly higher binding than younger are groups II and III. The mean binding in group V was the highest among all age groups except for group I, although the differences failed to reach statistical significance. The receptor concentrations (R0) were comparable among groups except group I which had a slightly increased R0. The affinity of insulin receptors was the lowest in group I and II, and gradually increased with the age and a positive correlation (p less than 0.01) was obtained between age and Ke. This increase in affinity with age is considered an adaptive response to the intracellular metabolic derangement often seen in the aged. No effect of sex on insulin binding was seen before puberty. However, in normal adults insulin binding of the female tended to be lower than that of the male with slightly increased R0 and decreased affinity in the female. Thus, the slightly decreased binding of the female group was mainly accounted for by the decreased affinity although the difference in the affinity was not significant.