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Does insulin down-regulate its own receptor on erythrocytes in vitro?
Experimental and Clinical Endocrinology
|March 1, 1984
Summary
This study found that in vitro, insulin did not significantly alter insulin receptor binding on erythrocytes in normal or type II diabetic individuals. Short-term regulation of insulin receptor affinity likely involves factors beyond just insulin levels.
Area of Science:
- Endocrinology
- Cell Biology
- Metabolic Research
Background:
- Insulin resistance is a hallmark of type II diabetes.
- Insulin receptor regulation, including downregulation, is crucial for glucose homeostasis.
- Previous in vivo studies suggested insulin affects its own receptor binding.
Purpose of the Study:
- To investigate the in vitro effect of exogenous insulin on insulin receptor binding to erythrocytes.
- To determine if supraphysiologic insulin concentrations can induce insulin receptor downregulation in vitro.
- To compare insulin binding in normal and type II diabetic subjects.
Main Methods:
- Incubation of whole blood from fasting normal and type II diabetic subjects with or without exogenous insulin for 5 hours.
- Evaluation of 125I-insulin binding to erythrocytes.
- Analysis of insulin receptor binding percentages.
Main Results:
- No significant alteration in insulin binding to erythrocytes was observed even with supraphysiologic insulin concentrations in vitro.
- Specific binding percentages were comparable between normal (8.6 +/- 0.59%) and type II diabetic (8.1 +/- 0.41%) subjects at tracer concentration.
- In vitro conditions did not demonstrate a downregulation of insulin receptor binding.
Conclusions:
- Exogenous insulin does not appear to directly downregulate its own receptors on erythrocytes in vitro.
- Short-term regulation of insulin receptor affinity in humans may be influenced by factors other than circulating insulin levels.
- Further research is needed to elucidate the mechanisms of insulin receptor regulation in vivo.