Cerebellar degeneration in lurcher mice under confocal laser scanning microscope

Abstract

Lurcher mutant mice represent a natural model of genetically-determined olivocerebellar degeneration caused by a mutation in the δ2 glutamate receptor gene. They suffer from progressive postnatal loss of cerebellar Purkinje cells and a decrease of granule cells and inferior olive neurons. Their wild type littermates serve as healthy controls. A confocal laser scanning microscope was used aiming investigation the dynamics of changes in the cerebellar cortex of Lurcher and wild type mice derived from two strains during the period of 8-21 postnatal days. Fluorescent double-staining was used to visualize mainly the Purkinje cells in cerebellar slices. In wild types, only normal Purkinje cells of round or regular drop-shaped were present, when staining intensity of other individual cell structures differed in dependence on the age of the animal. In Lurcher mutants, there were still some normal-shaped cells. Nevertheless, depending on the animal's age, a wide variety of stages of the cell degeneration were depicted. The main characteristics of Purkinje cell degeneration in the early stage are: disruption of the continuity of the Purkinje cell layer, dark spots in cell nuclei and an irregular coloring of the cytoplasm. Later, the cells and their nuclei were deformed, often with two main dendrites sprouting from the cell body. Finally, the cell and nucleus margins were unclear, dendrites were significantly thickened, showing signs of shrinkage and fragmentation. Cell nucleoli underwent changes in number and appearance. No differences between the Lurcher mice of both strains (C3H and B6CBA) under examination were found.