Age-Related Changes in the Rate and Composition of the Slow Axonal Transport

Abstract

In contrast to the fast axonal transport which remains fairly constant throughout the development and aging of the animal, the rate of slow axonal transport has been shown to decrease progressively with age (Komiya, 1980). A parallel decline in the regeneration rate after nerve injury and a significant elongation of the initial delay before the onset of active regeneration has also been observed (Komiya, 1981). From the analysis of transported cytoskeletal proteins in sciatic nerves of young adult rats, we have shown that these proteins existed in the axon as two types of polymers, stable and dynamic, which could be distinguished biochemically (Tashiro & Komiya, 1989). In this study, occurrence of tubulin in these two forms in the aged animal was investigated in relation to its transport in order to elucidate the underlying changes in the organization of the axonal cytoskeleton.