Impaired motor coordination and persistent multiple climbing fiber innervation of cerebellar Purkinje cells in mice lacking G alpha q

Mice lacking the alpha-subunit of the heterotrimeric guanine nucleotide binding protein G(q) (G alpha(q)) are viable but suffer from ataxia with typical signs of motor discoordination. The anatomy of the cerebellum Is not overtly disturbed, and excitatory synaptic transmission from parallel fibers to cerebellar Purkinje cells (PCs) and from climbing fibers (CFs) to PCs is functional. However, about 40% of adult G alpha(q) mutant PCs remain multiply innervated by CFs because of a defect in regression of supernumerary CFs in the third postnatal week. Evidence Is provided suggesting that G alpha 7q is part of a signaling pathway that is involved in the elimination of multiple CF innervation during this period.