Synaptosomal localization and release of glucagon-like materials in the rat brain.

The subcellular localization of glucagon-like materials in the thalamus-hypothalamus and brain stem of the rat was investigated. Both glucagon immunoreactivity (GI) determined by C-terminal specific antibody and glucagon-like immunoreactivity (GLI) determined by non-specific antibody were enriched in the microsomal and synaptosomal fractions relative to the nuclear, myelin and mitochondrial fractions. Furthermore, the synaptosomal fraction of both the thalamus-hypothalamus and brain stem incubated in Krebs-Ringer bicarbonate buffer with 55 mM K+ at 37 degrees C released GI and GLI in the presence of Ca++. These findings suggested that glucagon-like substances detected in the brain have a role in the synaptic function.