CEREBELLUM OF THE ADULT REELER MUTANT MOUSE CONTAINS 2 PURKINJE-CELL POPULATIONS WITH RESPECT TO GENE-EXPRESSION FOR THE N-METHYL-D-ASPARTATE RECEPTOR-CHANNEL

Recent studies have identified five NMDA receptor subunits, which exhi bit distinct cellular expressions in the normal rodent brain. The purp ose of this investigation is to clarify the molecular-anatomical organ ization in the cerebellum of the reeler mutant mouse, in which various categories of the Purkinje cells are present as to the cell position and synaptic connectivity. In comparison with the distribution of the inositol 1,4,5-trisphosphate receptor mRNA, a molecular marker specifi c to the Purkinje cells, the epsilon 1 subunit mRNA of the NMDA recept or channel was found in the adjacent sections to be expressed in a sub set of the Purkinje cells. In the rostrocaudal extent, the Purkinje ce lls expressing the epsilon 1 subunit mRNA were distributed preferentia lly in the rostral cerebellum, irrespective of the normal and heteroto pic positions. In the mediolateral extent, they formed segregated cell clusters, interposed by epsilon 1 subunit mRNA-negative clusters. Hyb ridizing signals for the zeta 1 subunit mRNA were found in all the Pur kinje cell population, whereas those for the epsilon 2, epsilon 3, and epsilon 4 subunit mRNAs were not detected in the cells. These finding s suggest that the reeler cerebellum is topographically compartmentali zed by two subpopulations of the Purkinje cells, one expressing the ep silon 1 and zeta 1 subunit mRNAs, and the other expressing the zeta 1 subunit mRNA alone.