NMDA RECEPTOR EXPRESSION IN THE MOUSE CEREBELLAR CORTEX

A detailed, light microscopic study on the distribution of the N-methy l-D-aspartate receptor subunit 1 (NMDAR1) was carried out with immunoh istochemistry and in situ hybridization on the cerebellar cortex of th e mouse. With a monoclonal antibody, labeling of Purkinje cell bodies varied from intense to negative, while heavy dendritic staining was li mited to the proximal dendrites (unlike the rat, which also had heavil y stained distal dendrites). In the granular layer, the cell bodies an d the dendritic shafts of Golgi II cells were only moderately stained, but very intense labeling was associated with granule cell bodies, an d with their dendrites and dendritic endings in the glomeruli. The mes sy and climbing fibers were negative. In situ hybridization with a cRN A probe showed levels and spatial distributions of NMDAR1 mRNA consist ent with the immunolabeling pattern, in that signals were strongest in the granular and Purkinje cell layers and relatively low or absent in the molecular layer and white matter. The findings are consistent wit h the hypothesis that NMDAR1 may be especially well concentrated at th e synaptic target sites of the messy and climbing fibers. In the mouse , NMDAR1 at the parallel fiber sites associated with Purkinje cell spi ny branchlets may differ from the rat in its level of expression or in its molecular configuration. (C) 1995 Wiley-Liss, Inc.