L-glutamate and L-glutamine uptake in adult rat cerebellum: an autoradiographic study.

The compartmentation of L-glutamate in the central nervous system has been extensively studied and L-glutamine is believed to be the precursor of the neuronal releasable pool of the L-glutamate. In order to localize the sites of uptake of both L-glutamate and L-glutamine, autoradiography was used in tissue slices of adult rat cerebellum, where granule cells are considered to be glutamatergic. Incubation of the tissue with low concentrations of [3H]L-glutamate or [3H]L-glutamine produces in both cases a heavy labelling of the molecular layer. [3H]L-glutamate uptake seems to be essentially glial (Golgi epithelial cells and Bergmann fibres) while [3H]L-glutamine is more diffusely distributed over the molecular layer. Although no conclusions can be drawn on the nature of L-glutamine uptake, these results are in agreement with the model which considers L-glutamate uptake by glial cells to be the inactivating process of glutamatergic synapses.