[Abnormalities of axonal transport as pathogenesis of axonal degeneration in peripheral neuropathy]

Axonal transport is a universal property of nerve cells. Role of axonal transport abnormalities in the pathogenesis of peripheral neuropathies was discussed. Applications of isotope-labeling technique to the study of axonal transport in experimental neuropathy have provided insights into the pathogenesis of axonal degeneration. As a model of dying-back neuropathy, axonal transport has been studied in sciatic motor neurons of rats with neuropathy induced by p-bromophenylacetylurea (BPAU) using this technique. The velocity of rapid anterograde transport was unaffected in this neuropathy and amount of retrograde axonal transport was reduced. The lag time between precursor injection and the onset of transport was shorter in BPAU-treated rats than controls. Whereas, in experimental ethylene oxide (EO) neuropathy rats, rapid transport velocity was markedly reduced in spite of very mild results of morphometric study. Those rapid axonal transport abnormalities may explain some aspects of the pathogenesis of peripheral neuropathies. In BPAU neuropathy model, disturbance of assembly of membrane-limited vesicles in Golgi processing may play a role in turnaround defect which causes dying-back neuropathy. EO neuropathy model suggests the possibility of oxygen utilization disturbance may causes energy dependent rapid transport velocity. Moreover, environments surrounding axon are also important for function of axonal transport. Present information leads to the conclusion that abnormalities in the supply and deposition of transported materials occur in early course of peripheral neuropathy and may contribute to development of the neuropathy.