Enhanced axonal transport of glycosaminoglycans in regenerating goldfish optic nerve

Glycosaminoglycans (GAGs) derived from axonally transported proteoglycans were evaluated in regenerating goldfish optic tracts. Fish were administered unilateral optic nerve crushes and stored for 21 days at 21 degrees C. Retinas were labeled by bilateral injection of 35SO4 and sulfated macromolecules axonally transported to the optic tracts were analyzed 8 h postinjection. Results show regenerating tracts contain 6.7-fold more transported 35SO4 in GAGs than their contralateral intact counterparts. Further analysis revealed that regenerating tract GAGs were comprised of 60% chondroitin (4 or 6) sulfate (CS) and 40% heparan sulfate (HS), while unoperated tract GAGs contained 26% CS and 74% HS. These results indicate that there is a large regeneration related increase in the axonal transport of proteoglycans and particular enrichment of transported molecules containing CS chains. The findings can be viewed in the context of recent implication of axonal proteoglycans in processes of fiber outgrowth, adhesion and induction of glial mitosis.