Ontogeny of D-mannose transport and metabolism in rat small intestine.
Oral mannose therapy is used to treat congenital disorders of glycosylation caused by a deficiency in phosphomannose isomerase. The segmental distribution and ontogenic regulation of D-mannose transport, phosphomannose isomerase, and phosphomannose mutase is investigated in the small intestine of fetuses, newborn, suckling, 1-month-old, and adult rats. The small intestine transports D-mannose by both Na(+)-dependent and Na(+)-independent transport mechanisms. The activities of both systems normalized to intestinal weight peak at birth and thereafter they decreased. In all the ages tested, the activity of the Na(+)-independent mechanism was higher than that of the Na(+)/mannose transport system. At birth, the Na(+)-independent D-mannose transport in the ileum was significantly higher than that in jejunum. Phosphomannose isomerase activity and mRNA levels increased at 1 month, and the values in the ileum were lower than in jejunum. Phosphomannose mutase activity in jejunum increased during the early stages of life, and it decreased at 1 month old, as does the amount of mannose incorporated into glycoproteins, whereas in the ileum, they were not affected by age. The phosphomannose isomerase/phosphomannose mutase activity ratio decreased at birth and during the suckling period, and increased at 1 month old. In conclusion, intestinal D-mannose transport activity and metabolism were affected by ontogeny and intestinal segment.
Departamento de Fisiología y Zoología, Universidad de Sevilla, Spain.
Mecedes
M
Cano
Anunciación A
AA
Ilundain
D000818:Animals; D001692:Biological Transport / Q000235:genetics / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology; D007421:Intestine, Small / Q000378:metabolism*; D008358:Mannose / Q000378:metabolism*; D008359:Mannose-6-Phosphate Isomerase / Q000235:genetics / Q000378:metabolism; D008954:Models, Biological; D017875:Phosphotransferases (Phosphomutases) / Q000235:genetics / Q000378:metabolism; D016133:Polymerase Chain Reaction; D051381:Rats
D008359:Mannose-6-Phosphate Isomerase; D017875:Phosphotransferases (Phosphomutases); C052799:phosphomannomutase; D008358:Mannose