Axonal transport of proteoglycans in regenerating goldfish optic nerve

Labeling of goldfish optic nerve and tectum proteoglycans (PGs) was quantified following intraocular injection of 35SO4 and [3H]proline or [3H]glucosamine. Both intact animals and animals which had survived for periods of 10 to 119 days after an optic nerve crush lesion were examined. Regenerating retinal ganglion cell (RGC) axons reached the rostral pole of the tectum by 10 days postcrush and by 21 days had densely innervated the optic synaptic laminae. If the contralateral tectum had been removed, the regenerating RGC axons innervated the remaining ipsilateral tectum with a delay of approximately 14 days. There was a biphasic increase in the synthesis and transport of PGs during optic fiber regeneration which was not affected by the removal of the tectum. More highly sulfated PGs were preferentially off-loaded from the orthograde transport pool proximally in the optic nerve, both in the unoperated animals and during regeneration. These PGs also had longer and/or more glycosaminoglycan (GAG) chains than those off-loaded distally, in the tectum. During early regeneration, the synthesis and transport of chondroitin sulfate PGs (CSPGs) increased more than those of heparan sulfate PGs, and during the period of optic fiber invasion of the synaptic laminae, the PGs retained in the nerve had a higher content of CSPGs than those transported into the tectum. Removal of the contralateral tectum at the time of nerve crush resulted in a decrease in the size and/or numbers of GAGs and overall sulfation of PGs in the nerve by 21 days postoperatively.(ABSTRACT TRUNCATED AT 250 WORDS)