Regional and cellular differences in fucosylation of glycomacromolecules in the mouse brain. A biochemical and autoradiographic study of early postnatal and adolescent animals.

ABSTRACT

Mice of CBA strain of both sex were injected with [3H]fucose at age 2, 6, 12 or 30 days and the incorporation was determined biochemically 45, 90 and 180 min later. Biochemical measurements of the whole brain (at 90 min postinjection interval) revealed a stepwise age decrease in the amount of incorporated isotope (per mg protein). The amount of [3H]fucose available in the brain has however been found to decrease with age while the degree of its utilization increases. Thus, after correction of the data on [3H]fucose incorporation for the pool of the free isotope, a transient increase in fucosylation rate appeared at postnatal day 12 while the differences among 2-, 6- and 30-day-old animals became negligible. Further, the synthesis of fucosylated soluble glycomacromolecules appeared relatively higher at postnatal day 2 than in older age groups. Examination of different brain regions revealed that the rate of fucosylation is relatively highest in the olfactory bulbs; this prevalence starts appearing with age and becomes most evident in 30-day-old mice. Autoradiography carried out with 6- and 12-day-old animals revealed that the incorporation of [3H]fucose into meningovascular apparatus and the choroid plexus is a few times higher than into brain parenchyma. The regional differences appeared to be similar to those indicated by the biochemical data. Cellular analysis has shown that the incorporation is relatively higher in the cytoplasm of large projecting neurons of the cerebellum, hippocampus and the olfactory bulbs; in the latter region high amounts of macromolecule-bound [3H]fucose also appeared in the synaptic glomeruli.(ABSTRACT TRUNCATED AT 250 WORDS)