Electron microscopic autoradiography of D-[3H]aspartate uptake sites in mouse cerebellar slices shows poor labelling of mossy fibre terminals.

Recent evidence indicates that mossy fibres in the cerebellum may use glutamate as their transmitter. To determine if mossy fibre terminals accordingly express a high-affinity uptake mechanism for excitatory amino acids, mouse cerebellar slices were incubated for 3 h with 1 microM D-[3H]aspartate and examined by electron microscopic autoradiography. In the granule cell layer, granule cell bodies were clearly labelled but the majority of mossy fibre terminals were without silver grains.