Dietary spermidine and spermine participate in the maturation of galactosyltransferase activity and glycoprotein galactosylation in rat small intestine

This study considered the role of dietary polyamines in the maturation of i ntestinal glycoprotein galactosylation during postnatal development. In the rat small intestine, O-glycan: beta -1,3-galactosyltransferase and N-glyca n: beta -1,4-galactosyltransferase are, respectively, involved in the glyca n chain biosynthesis of mucins and of glycoproteins in the brush border mem branes. Their activities increase significantly at weaning, in parallel wit h a rise-in the intestinal content of spermidine and spermine (as determine d by high performance liquid chromatography) and in proportion to the polya mine increase in food intake. The oral ingestion of spermidine or spermine (at 0.4 mu mol/g body) by immature suckling rats for 4 d reproduced the lev els of spermine and spermidine in their intestines at the time of weaning a nd induced precocious and significant rises in O-glycan: and N-glycan: gala ctosyltransferase activities to those normally found after weaning. In para llel, more galactose residues (detected in the complex oligosaccharide chai ns of glycoproteins by specific lectins after electrophoresis and transfer to nitrocellulose membranes) were observed in the brush border membranes of spermidine- and spermine-treated rats. In contrast, the ingestion of putre scine or ornithine had no effect. Diets with different levels of polyamines (milks and commercial diet), when given at weaning, induced variable evolu tions of the galactosylation process, partly in relation to the amounts of polyamines ingested. These results indicate that spermidine and spermine ar e maturation factors that can reproduce, in immature rats, the same increas e in intestinal glycoprotein galactosylation that is normally observed duri ng weaning. They also suggest that the maturation of glycoprotein galactosy lation may be a multifactorial event in which spermidine and spermine are b oth involved.