Comparison of the effects of sciatic nerve crush or resection on the proteins of fast axonal transport in rat dorsal root ganglion cell axons.

Proteins of fast axonal transport in rat sciatic nerve axons were separated and characterized by SDS-polyacrylamide gel electrophoresis and fluorography, after injection of L-[35S]methionine into the dorsal root ganglion. The effects of crushing or resecting the sciatic nerve on the relative labeling of specific polypeptide bands were compared. Initially, both types of axon injury produced the same response, but after 3 weeks there was a partial return to normal composition in crushed nerves. In resected nerves, the changes characteristic of axon injury persisted beyond 7 weeks. Behavioral testing showed that crushed nerves reinnervated foot skin, whereas no reinnervation was detected after resection. We conclude that in sensory neurons, as in several other neuronal types, the restoration in normal composition of fast-transported protein after axon injury depends on reinnervation of target tissues. This aspect of the cell body reaction to injury seems to be regulated by a retrograde trophic interaction with the target.