Distribution of glutamate receptors of the NMDA subtype in brains of heterozygous and homozygous weaver mutant mice.

In weaver mice, mutation of an G-protein inwardly rectifying K+ channel leads to a cerebellar developmental anomaly characterized by granule and Purkinje cell loss and, in addition, degeneration of dopaminergic neurons. To evaluate other deficits, glutamate receptors sensitive to N-methyl-D-aspartate (NMDA) were examined by autoradiography with [3H]MK-801 in 36 brain regions from heterozygous (wv/+) and homozygous (wv/wv) weaver mutants, and compared to wild type (+/+) mice. In wv/+ and wv/wv mutants labelling decreased in cortical regions, septum, hippocampus, subiculum, neostriatum, nucleus accumbens, superior colliculus and in the cerebellar granular layer. The reductions in [3H]MK-801 binding were particularly specific in the cerebellar granular layer of wv/wv mutants, but an ubiquitous altered NMDA receptor topology was revealed in other brain regions. Abnormal developmental signals, or aberrant cellular responses, may underlie widespread NMDA receptor reductions, while in cerebellar cortex they could be lacking due to the massive loss of cerebellar granule cells.