Ganglioside changes in the regenerating goldfish optic system: comparison with glycoproteins and phospholipids

Axonally transported radioactivity in sialoglycoconjugates, labeled by intraocular injection of [3H]N-acetylmannosamine, increased significantly during regeneration of goldfish optic axons at 30 degrees C. Ganglioside radioactivity showed the largest increase--approximately eightfold--in the optic nerve tract at 8 days after optic nerve crush while sialoglycoprotein radioactivity increased fourfold under the same conditions. As regeneration proceeded the magnitude of the increase in the nerve tract diminished for both glycoconjugates. In the optic tectum, however, transported radioactivities remained approximately twofold higher than controls between 15 and 25 days postcrush. The zwitterionic fraction of glycerophospholipids, labeled by intraocular injection of [14C]glycerol, also showed large increases during regeneration, but the acidic glycerophospholipids showed only modest increases. Thus while membrane components in general were elevated during the early stages of regeneration, the most pronounced increases occurred in gangliosides and certain glycerophospholipids. The significance of these changes in the regeneration process remain to be determined.