Immuno-electron microscopic demonstration of GABA and glutamate synapses in Mongolian gerbils hippocampus after...

The subcellular distribution of glutamate and GABA in synapses of Mongolian gerbils hippocampus was examined using post-embedding immunogold staining method for electron microscopy. Immunolabelling was performed with 10 nm gold-antibody complexes for glutamate and GABA. The gold particle densities gave reliable information about the relative concentrations of these amino acid neurotransmitters. Our results indicate that ischemia leads to the temporal decrease of GABA-like immunoreactivity in symmetric synapses and a slight enhancement of the level of glutamate-like reactivity in asymmetric ones. The striking finding was a redistribution of glutamate-like immunoreactivity from neurons to glia. This suggests the capacity of glia to metabolize the excess of glutamate after ischemia. The disturbances at the level of neurotransmitters and their possible role in hippocampal neuronal injury were stressed.