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Insulin in the central nervous system.
Advances in Metabolic Disorders
|January 1, 1983
Summary
Accurate insulin measurement in non-pancreatic tissues is crucial. Lower reported insulin levels suggest extrapancreatic synthesis is unlikely, with brain insulin levels influenced by peripheral transfer.
Area of Science:
- Endocrinology
- Neuroscience
- Biochemistry
Background:
- Previous studies reported significant insulin concentrations in non-pancreatic tissues, suggesting local synthesis.
- Discrepancies exist regarding the true insulin levels in extrapancreatic tissues and the methods used for their determination.
Purpose of the Study:
- To accurately determine insulin concentrations in non-pancreatic tissues, such as the brain.
- To re-evaluate the evidence for extrapancreatic insulin synthesis.
Main Methods:
- Measurement of insulin concentrations in various species' brain tissues and IM-9 lymphocytes.
- Comparison of reported insulin levels with newly obtained data.
- Analysis of insulin precursor processing mechanisms in non-endocrine cells.
Main Results:
- Reported insulin concentrations in non-pancreatic tissues were significantly lower than previously suggested.
- Peripheral insulin transfer can influence brain insulin levels, particularly in small-brained animals.
- Absence of insulin precursors and processing mechanisms in non-endocrine cells was observed.
Conclusions:
- The insulin found in non-pancreatic tissues is likely derived from pancreatic insulin, not synthesized locally.
- Previous high concentration reports may be erroneous.
- Extrapancreatic insulin synthesis is unlikely given the low concentrations and lack of precursor machinery.