VIMENTIN IMMUNOREACTIVE GLIAL-CELLS IN THE FISH OPTIC-NERVE - IMPLICATIONS FOR REGENERATION

The poor regenerative ability of neurons of the central nervous system in mammals, as compared with their counterpart in fish or amphibians, is thought to stem from differences in their immediate nonneuronal en vironment and its response to axonal injury. We describe one aspect of the environmental response to axonal injury in a spontaneously regene rating system-the fish optic nerve. The aspect under investigation was the reaction of glial cells at the injury site. This was examined by the use of antibodies that specifically recognize vimentin in fish gli al cells. In the present study, affinity-purified vimentin antibodies were raised against a nonconserved N-terminal 14-amino acid peptide, w hich was predicted from the nucleotide sequence of vimentin. These ant ibodies were found to react specifically with glial cells in vitro. Mo reover, the antivimentin antibodies stained both the optic nerve and t he optic tract, but with different patterns. Specificity of the antibo dies was verified by protein immunoblotting, tissue distribution, and labeling patterns. After injury, vimentin immunoreactivity initially d isappeared from the site of the lesion due to cell death. Early signs of glial cell migration toward the injury site were evident a few days later. It is suggested that the reappearance of vimentin-positive gli al cells at the site of injury is associated with axonal elongation ac ross it, and that they contribute to the regenerative ability of the f ish optic nerve. (C) 1994 Wiley-Liss, Inc.