Evidence that regenerating optic axons maintain long-term growth in the lizard Ctenophorus ornatus: Growth-associated protein-43 and gefiltin expression

In the lizard, Ctenophorus ornatus, the optic nerve regenerates but animals remain blind via the experimental eye, presumably as a result of axons fai ling to consolidate a retinotopic map in the optic tectum. Here we have exa mined immunohistochemically the expression of the growth-associated protein GAP-33 and the low-molecular-weight intermediate filament protein gefiltin , up to one year after optic nerve crush. Both proteins were found to be pe rmanently up-regulated, suggesting that regenerating axons are held in a pe rmanent state of re-growth. We speculate that, in the lizard, the continued expression of GAP-43 and th e failure to switch from the expression of low-to high-molecular-weight int ermediate filament proteins are associated with the inability to consolidat e a retinotopic projection. (C) 2001 IBRO. Published by Elsevier Science Lt d. All rights reserved.