PRESYNAPTIC LOCALIZATION OF A METABOTROPIC GLUTAMATE-RECEPTOR, MGLUR4A, IN THE CEREBELLAR CORTEX - A LIGHT AND ELECTRON-MICROSCOPE STUDY INTHE RAT

Localization of a metabotropic glutamate receptor, mGluR4a, was immuno histochemically examined in the rat cerebellum with an antibody, which was produced by using a synthetic peptide corresponding to a C-termin al sequence of rat mGluR4a. Marked mGluR4a-like immunoreactivity (mGlu R4a-LI) was seen in neuropil of the molecular layer of the cerebellar cortex. Electron microscopically, mGluR4a-LI was observed in many axon terminals in the molecular layer. These axon terminals showing mGluRL Fa-LI were filled with round synaptic vesicles and were in asymmetric synaptic contacts most frequently with dendritic spines. The results i ndicate that mGluR4a are located presynaptically in the parallel fiber s arising from the granule cells in the cerebellar cortex.