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MUCOSAL BIOLOGY

Oral polyamine administration modifies the ontogeny of hexose transporter gene expression in the postnatal rat intestine

¹Division of Gastroenterology, Department of Medicine, and Department of Anatomy and Cell Biology, McGill University Health Center, and ²School of Dietetics and Human Nutrition, McGill University, Montreal, Quebec; ³Division of Gastroenterology, Department of Medicine, University of Alberta, Edmonton, Alberta; and ⁴Department of Paediatrics, Paediatric Endocrinolgy, Hotel Dieu Hospital and Queen's University, Kingston, Ontario, Canada

Submitted 21 February 2006 ; accepted in final form 11 June 2007

Gastrointestinal mucosal polyamines influence enterocyte proliferation and differentiation during small intestinal maturation in the rat. Studies in postnatal rats have shown that ornithine decarboxylase (ODC) protein and mRNA peak before the maximal expression of brush-border membrane (BBM) sucrase-isomaltase (SI) and the sugar transporters sodium-dependent glucose transporter 1 (SGLT1) and glucose transporter 2 (GLUT2). This study was undertaken to test the hypothesis that the oral administration of spermidine in postnatal rats upregulates the expression of ODC, thereby enhancing the expression of SI and SGLT1 in the brush-border membrane as well as basolateral membrane-facilitative GLUT2 and Na⁺-K⁺-ATPase. Northern and Western blot analyses were performed with antibodies and cDNA probes specific for SI, SGLT1, GLUT2, ₁- and ₁-subunits of Na⁺-K⁺-ATPase, and ODC. Postnatal rats fed 6 µmol spermidine daily for 3 days from days 7 to 9 were killed either on postnatal day 10 (Sp10) or day 13 following a 3-day washout period (Sp13). Sp10 rats showed a precocious increase in the abundance of mRNAs for SI, SGLT1, and GLUT2 and Na⁺-K⁺-ATPase activity and ₁- and ₁-isoform gene expression compared with controls. ODC activity and protein and mRNA abundance were also increased in Sp10 animals. The increased expression of these genes was not sustained in Sp13 rats, suggesting that these effects were transient. Thus, 3 days of oral polyamine administration induces the precocious maturation of glucose transporters in the postnatal rat small intestine, which may be mediated by alterations in ODC expression.¹

ontogeny; sodium-dependent glucose transporter-1; glucose transporter-2; sucrase-isomaltase; orthinine decarboxylase