Bidirectional transport of gangliosides, glycoproteins and neutral glycosphingolipids in the sensory neurons of rat sciatic nerve.

Bidirectional axonal transport of glycoconjugates was studied in the sensory axons of rat sciatic nerve following injection of radiolabelled precursors into L4 and L5 dorsal root ganglia. After varying time intervals, gangliosides and neutral glycosphingolipids were isolated from anterograde and retrograde accumulation segments and radioactivity determined. Radiolabelled glycoproteins were measured in delipidated residues. These glycoconjugates were shown to undergo both anterograde and retrograde transport, accumulation occurring in roughly parallel manner for the three classes. The velocity of anterograde transport was collectively estimated at approximately 360 mm/day. Neutral glycosphingolipids, previously unknown to be axonally transported, were present in sensory axons and transported in roughly equivalent amounts as gangliosides--as judged by levels of transported radioactivity. TLC-radioautography revealed a number of molecular species in the general region of tetra- and larger glycosylceramides. Fractionation of gangliosides according to sialic acid content demonstrated the presence of mono-, di- and polysialo species at the anterograde site.