[Alterations in collagen synthesis after transection of peripheral nerves]

In order to elucidate the mechanisms of fibrosis during Wallerian degeneration after peripheral nerve injuries, the biochemical and immunohistochemical changes in collagen from posterior tibial nerves of albino rabbits have been analyzed after transection of the sciatic nerves. The total amount of collagens in the posterior tibial nerve was found to increase progressively after 2 weeks post-neurectomy. The amount of total soluble collagen and the reducible cross-links were also increased as time advanced after surgery. There was no significant change in the synthesis of genetically distinct types of collagens after neurectomy. The immunohistological study showed that Type I and Type III collagens were increased remarkably in epi- and endoneurium. These findings indicate that the fibrosis of peripheral nerve during Wallerian degeneration is most likely due to the progressive formation of immature collagen fibers in the tissues, rather than the decrease in the amount of nerve proteins as previously discussed.