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Insulin II gene expression in rat central nervous system
S U Devaskar1, B S Singh, L R Carnaghi
1Department of Pediatrics, St. Louis University School of Medicine, MO.
Regulatory Peptides
|October 20, 1993
Summary
Researchers investigated the origin of insulin in the brain, finding that insulin II mRNA is present in rat brains across all developmental stages. The insulin I gene, however, shows no expression in the brain.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- The presence and origin of insulin within the central nervous system (CNS) remain a subject of debate.
- In vitro studies suggest neuronal insulin mRNA expression, but conventional assays have not detected it in whole brain samples.
Purpose of the Study:
- To investigate the expression of insulin I and insulin II messenger RNAs (mRNAs) in rat brains during different developmental stages.
- To clarify the origin of insulin in the brain by examining gene expression patterns.
Main Methods:
- Utilized RNAse-protection assays and sensitive reverse transcription-polymerase chain reaction (RT-PCR) techniques.
- Analyzed rat brain tissues from various gestational and postnatal periods.
Main Results:
- RNAse-protection assays failed to detect insulin I or insulin II transcripts in fetal and adult rat brains.
- RT-PCR detected insulin II mRNA in fetal, neonatal, and adult rat brains, as well as in extrapancreatic tissues like the yolk sac and liver.
- Insulin I mRNA was not detected in the brain at any developmental stage examined, though it was found in other tissues.
Conclusions:
- The ancestral insulin II gene is expressed in rat brains throughout development (fetal, neonatal, adult).
- The duplicated insulin I gene is not expressed in the brain.
- These findings support the hypothesis of de novo synthesis of insulin II within the brain after early embryonic development.