DIFFERENTIAL LOCALIZATION OF THE METABOTROPIC GLUTAMATE-RECEPTOR MGLUR1A AND THE IONOTROPIC GLUTAMATE-RECEPTOR GLUR2 3 IN NEURONS OF THE HUMAN CEREBRAL-CORTEX/

Specimens of human cerebral cortex were obtained during neurosurgical operations and studied by immunocytochemistry and electron microscopy, using antibodies to the metabotropic glutamate receptor subunit mGluR 1a and the ionotropic glutamate receptor GluR2/3. A small number of no n-pyramidal neuronal cell bodies were labelled for mGluR1a. Double imm unolabelling with mGluR1a and GluR2/3 showed that most pyramidal cell bodies were labelled for GluR2/3 but not for mGluR1a. Despite the non- colocalisation of these two receptor subtypes in cell bodies, however, many dendrites and dendritic spines were double-labelled for mGluR1a and GluR2/3 at electron microscopy. As there is evidence that most neu rons positive for GluR2/3 are pyramidal cells, this suggests that mGlu R1a is present in dendrites of pyramidal neurons, despite absent or lo w levels of immunoreactivity in their cell bodies.