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Lipofuscin pigment in neurons of young mice with a hereditary central nervous system defect.

Mutant mice are described which have an early developing locomotor difficulty accompanied by definite neuronal changes in the central nervous system. They develop head tremors during the second postnatal week and later action tremors while walking. Seizures occur spontaneously and can be induced by stimulation. By the third or fourth week, they lose the righting reflex. The most apparent neuropathologic sign is the progressive development of nuclear hyperchromasia, especially in the largest neurons of the spinal cord and brain stem. Purkinje cells of the cerebellum are similarly affected. Hyperchromasia occurs in single, isolated neurons scattered throughout the central nervous system, as well as in groups of cells which comprise a brain stem nucelus. Lipofuscin pigment in quantities comparable to that in neurons of 12 months old mice was found in neurons with hyperchromatic nuclei as early as five weeks of age, an observation which suggests that premature aging might be occurring in the mutant's central nervous system.