Axonal transport of cytoskeletal proteins in aluminum toxicity. Aluminum toxicity and axonal transport.

Aluminum administration in certain species results in the accumulation of neurofilament bundles within the neuronal perikaryon and the proximal neuronal processes. The study presented here was designed to investigate how aluminum exerts its effects on the neuronal cytoskeleton. Microinjections of AlCl3 were administered directly to the rabbit lumbar spinal cord; the injections resulted in the accumulation of neurofilament bundles in upwards of 80% of the anterior horn cells. Approximately 7 d later, [35S]methionine was administered to the same region, and exactly 14 d after the radioactive pulse the animals were sacrificed. Sequential 3-mm segments of the sciatic nerves beginning at the root exit zone were processed for gel electrophoresis and fluorography. The counts incorporated into gel bands representing actin, tubulin, and the neurofilament (NF) subunits were determined for each segment, and a distribution curve for the pooled control and pooled aluminum-treated rabbits was constructed. The distribution curves for the two groups, separately analyzed for each cytoskeletal protein, did not significantly differ using an analysis of variance. We conclude that an interruption of slow axonal transport does not occur in this model of aluminum-induced lumbar myelopathy.