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Insulin receptors in patients with insulinomas: changes in receptor affinity and concentration
Abstract:
We have measured the specific binding of 125I-insulin to insulin receptors on circulating monocytes from 5 patients with insulinomas. In all patients the concentration of insulin receptors was inversely related to the basal, circulating level of insulin (corrected for proinsulin content). In the four patients with chronically elevated concentrations of plasma insulin, receptor concentrations were decreased. In three of these patients there were also marked alterations in receptor affinity. With insulinomas, correlations with the clinical state appear to be clearer when receptor concentration and especially receptor affinity are considered in addition to circulating insulin and proinsulin levels.
Insights
Patients with insulinomas show decreased insulin receptors inversely related to high insulin levels. Receptor concentration and affinity correlate better with clinical status than insulin levels alone.
Area of Science:
- Endocrinology
- Metabolic Research
- Molecular Biology
Background:
- Insulinomas are tumors producing excess insulin, leading to hyperinsulinemia.
- Insulin resistance is often associated with altered insulin receptor expression and function.
Purpose of the Study:
- To investigate the relationship between insulin levels, insulin receptor concentration, and receptor affinity in patients with insulinomas.
- To determine if receptor characteristics correlate with the clinical presentation of insulinoma.
Main Methods:
- Measured specific binding of radioiodinated insulin (125I-insulin) to monocytes.
- Quantified insulin receptor concentration and affinity.
- Assessed circulating insulin and proinsulin levels.
Main Results:
- Insulin receptor concentration was inversely proportional to basal insulin levels in all patients.
- Four patients with chronically elevated insulin had decreased insulin receptor concentrations.
- Three patients exhibited significant alterations in insulin receptor affinity.
Conclusions:
- Insulinomas lead to changes in insulin receptor dynamics, including decreased concentration and altered affinity.
- Assessing both insulin receptor concentration and affinity provides a clearer correlation with the clinical state in insulinoma patients than insulin levels alone.