Premature onset of fast axonal transport in bromophenylacetylurea neuropathy: an electrophoretic analysis of proteins exported into motor nerve

To test whether abnormal processing of proteins for fast axonal transport is involved in the neuropathy induced by BPAU (p-bromophenylacetylurea) we examined transport onset. [³⁵S]Methionine was injected into the lumbar ventral horn of rats 2 weeks after BPAU, 400 mg/kg (i.p.) or vehicle. At intervals of 30-90 min consecutive 3-mm segments of the L₄ and L₅ ventral roots were digested for polyacrylamide gel electrophoresis and fluorography. Fast transported proteins were identified by comparison with samples from mid-thigh sciatic nerve ligated for 16 h after radiolabeling. A prominent 26 kDa band represented the earliest exported protein. It was usually absent at 30 min, but it entered the roots by 45 min. This band was consistently displaced further in BPAU nerve (n = 11) than in controls (n = 11). The mean difference was 5 ± 0.6 mm (P < 0.001). However, there was no difference in the apparent velocity of transport. These results imply premature onset of transport in BPAU neuropathy.