THE METABOTROPIC GLUTAMATE-RECEPTOR (MGLUR1-ALPHA) IS CONCENTRATED ATPERISYNAPTIC MEMBRANE OF NEURONAL SUBPOPULATIONS AS DETECTED BY IMMUNOGOLD REACTION

An antiserum to mGluR1alpha labeled a 160 kd protein in immunoblots of membranes derived from rat brain or cells transfected with mGluR1alph a. Immunoreactivity for mGluR1alpha was present in discrete subpopulat ions of neurons. The GABAergic neurons of the cerebellar cortex were s trongly immunoreactive; only some Golgi cells were immunonegative. Som atostatin/GABA-immunopositive cells in the neocortex and hippocampus w ere enriched in mGluR1alpha. The hippocampal cells had spiny dendrites that were precisely codistributed with the local axon collaterals of pyramidal and granule cells. Electron microscopic immunometal detectio n of mGluR1alpha showed a preferential localization at the periphery o f the extensive postsynaptic densities of type 1 synapses in both the cerebellum and the hippocampus. The receptor was also present at sites in the dendritic and somatic membrane where synapses were not located .