Intraventricularly applied D-galactosamine inhibits the incorporation of [(3)H]-fucose into rat brain glycoproteins.

In the rat, intraventricularly applied D-galactosamine (GalN) (10 or 20 mumoles) inhibited [(3)H]-fucose incoporation into hippocampal and subcortical glycoproteins by appr. 50% of the controls. The inhibitory effect occurred within 40 min after GalN administration and did not reach normal values even 16 h upon GalN injection. During the first hours upon GalN administration the inhibition of fucose incorporation involved predominanatly water-soluble and Triton-soluble glycoproteins, whereas the Triton-resistant fraction showed a delayed suppression. The results suggest that GalN suppresses the formaton of membrane glycoproteins (because only 15% of fucose radioactivity remained in water-soluble fraction) which are believed to play an essential role in formation of long-term memory. Under these aspects, the amnesic effect of GalN on the retention of a brightness discrimination and the abolishment by uridine treatment, as observed in our laboratory, may be interpreted as a further support to the particular role of glycoproteins in the consolidation of a memory trace.