Regulation of the Neuronal Insulin-Like Peptide
Insulin or an insulin-like peptide has been demonstrated within the brains of various animal species1 and more importantly insulin immunoreactivity has been observed within a few neurons.2,3 In an attempt to determine whether this peptide is synthesized locally within the CNS, we have previously employed the technique of in-situ hybridization and a biotinylated rat insulin I cDNA to detect insulin mRNA within isolated and cultured 10 day old rabbit neurons. Neurons were characterized and detected by the neuron-specific enolase staining and glial cells contaminating these cultures were detected by the glial fibrillary acidic protein staining. We observed the presence of insulin transcripts within 3 to 5% of neurons (75% pure cultures) that were maintained in a serum-containing medium (Figure 1a). Interestingly, the same percentage of cells was positive for insulin immunoreactivity. Under similar hybridization conditions utilized for insulin, IGF I and II cDNAs (human) failed to cross-hybridize with these “insulin” transcripts.3
KeywordsExogenous Insulin Insulin Immunoreactivity Rabbit Brain Insulin Synthesis Glial Fibrillary Acidic Protein Staining
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