Differential cellular localization of three splice variants of the mglurl metabotropic glutamate receptor in rat cerebellum

Antibodies were raised against C-terminal peptides of the splice variants a, b and c of the rat mGluRl metabo- tropic glutamate receptor. Affinity purified antibodies each specifically reacting with mGluRla, mGluRlb and mGluRlc were used to study the cellular localization of these receptors in rat cerebellum. The mGluRla antibody strongly labelled Purkinje cells at their cells bodies, portions of their dendritic trees and numerous small punctate elements reminiscent of dendritic spines. Also labelled were some stellate, basket, Golgi and Lugaro cells. Granule cells were devoid of staining. The mGluRlb antibody strongly labelled Purkinje cell bodies and their dendrites at levels which varied within the same lobule of the vermis or the hemispheres. No significant labelling was observed at stellate, basket, Golgi and granule cells, while occasionally a fraction of basket cells and cerebellar glomeruli was moderately immunoreactive. The mGluRlc antibody strongly labelled cell bodies and thick principal dendrites of Purkinje cells but not dendritic spines. Immunonegative Purkinje cells were intermingled with strongly labelled ones in lobules 4-10, while in lobules 1, 2 and 3, no stained Purkinje cells were detected. The mGluRlc antibody also labelled stellate, basket, some Golgi and some Lugaro cells as well as granule cells.