UP-REGULATION OF POLYSIALIC ACID IN PERIPHERAL MYELINATED AXONS OF RAT CHRONICALLY EXPOSED TO 2,5-HEXANEDIONE

Myelinated nerve fibres isolated from Wistar rats chronically exposed to 2,5-hexanedione (0.8 ml/kg/day, intraperitoneally) over a period of 20 days, were stained with lectin-horseradish peroxidase conjugates. The lectins with high affinity for terminal D-galactopyranosyl residue s, Bandeiraea simplicifolia-B4 (BSA I-B4) and peanut agglutinin (PNA), showed glycoconjugates in the control nodes of Ranvier. In the treate d animals, application of PNA-HRP caused weak reactivity to the node o f Ranvier; digestion with sialidase prior to the application of PNA-HR P conjugate enhanced reactivity, thus revealing the presence of a sial oglycoprotein. The results indicate that glycoconjugates of the Ranvie r node undergo a rearrangement during exposure to 2,5-hexanedione. In particular, neutral glycoproteins with terminal galactose are replaced by sialoglycoproteins. These findings are consistent with the propose d role of polysialic acid as a regulator of axonal behaviour during re generation.