Stimulation of immunoreactive insulin release by glucose in rat brain synaptosomes

The effect of glucose on the release of immunoreactive insulin (IRI) In syn aptosomes isolated from rat brain was studied. In the absence of glucose sy naptosomes release about 4% (0.77 mu IU/mg protein) of total content. Gluco se increases significantly the IRI released by synaptosomes. Addition of th e glycolytic inhibitor iodoacetic acid (IAA), decreased the glucose-induced release of IRI by about 50%, suggesting that glucose metabolism is involve d. The observation that glucose provides a concentration related signal for IRI release indicates that this synaptosomal preparation may be useful as a model for research on the mechanism of insulin release in brain.