Motor and visuospatial abilities in a model of olivocerebellar and retinal degeneration--Lurcher mutant mice of C3H strain.

Lurcher mutant mice represent a natural model of olivocerebellar degeneration. They suffer from loss of Purkinje cells and decreased number of granule cells and inferior olive neurons. The degeneration leads to cerebellar ataxia and deterioration of cognitive functions. Some animals of the C3H strain have also the retinal degeneration. The aim of the study was to analyze the morphology of cerebellar and retinal degeneration and to evaluate the ability of motor coordination and visuospatial orientation in C3H Lurcher mutant mice. Cerebella of Lurcher mutant and wild type mice were examined with several histological, histochemical and immunohistochemical methods. Motor coordination was tested on a bar, ladder and rotarod. Spatial orientation and learning were tested in the Morris water maze with visible or hidden platform. Histological examinations showed decreased numbers of Purkinje cell in Lurchers. Various histological methods brought different information about the course or stage of the cerebellar degeneration. Retinal degeneration was identified with hematoxyline-eosine staining very well. Lurchers performed worse in motor coordination tests and in both the spatial orientation and learning test. Retinal degeneration influenced negatively both the spatial learning and orientation. Motor tests were influenced by retinal degeneration only in the wild type mice. Wild type mice showed some ability of idiothetic navigation, which was not found in Lurchers.