Genetic and age related models of neurodegeneration in mice: dystrophic axons.

Dystrophic axons (DA) are non-specific lesions that occur in a wide variety of human and animal diseases. In this paper we describe the distribution of these lesions in three newly discovered mouse neurological mutants. The distribution of DA in these mutants is defined by their names, lumbosacral neuroaxonal dystrophy (lnd), located on Chromosome 7, generalized neuroaxonal dystrophy (gnd) and vestibulomotor degeneration (vmd). The last mutant, which has degeneration as well as DA in lateral vestibular nucleus and vestibulo-spinal tracts, dies in the first weeks of life; the first two live for approximately one year. A previously described mutation, dystonia musculorum (dt), was found to produce generalized DA like gnd, but dt/dt mutants die at an early age. DA were also found to occur in the nuclei gracilis and cuneatus, in the area of Clark's column and in lumbo-sacral spinal cord in aging normal mice either fed ad libitum or at a level of 40% dietary restriction. The dietary regimen had little effect on the numbers of DA observed in susceptible areas of the neuroaxis. The mutant models of neuroaxonal dystrophy may prove useful in studies of the pathophysiology of DA in general and of specific inherited diseases of man, such as infantile neuroaxonal dystrophy and Hallervordin-Spatz disease.