Rapid axonal transport velocity is reduced in experimental ethylene oxide neuropathy

Chronic exposure of rats to ethylene oxide (EO) causes distal axonal neuropathy of lumbosacral primary sensory neurons. To study the pathogenesis of this neuropathy, we measured rapid axonal transport in peripheral nerves. Rats were exposed for 6 h to 500 ppm EO in a chamber three times a wk for 15 wk. Rapid axonal transport and quantitative histological alterations of peripheral nerves were studied. After [35S]methionine injection into the dorsal root ganglion, the velocity of rapid anterograde axonal transport of radioisotope-labeled protein was measured. The velocity in the rats exposed to EO was 33% less than that in control rats exposed to filtered room air. However, histological differences were slight. Morphometric studies showed that in EO-exposed rats, only the distal portions of the sural nerve had significantly greater incidental degeneration of myelinated fibers than did controls. There were significantly fewer large myelinated fibers only in the distals peroneal nerve. Therefore, a decrease in the velocity of anterograde axonal transport, related to these slight histological abnormalities of the peripheral nerve, may play a causative role in the development of the distal axonal neuropathy owing to chronic EO exposure.