Expression of glucose transporters in lactating human mammary gland epithelial cells

Summary Background. Human milk contains 60–80 g/l lactose and and oligosaccharides. To synthesize this large amount of carbohydrates, the lacting mammary gland has a high demand for precursor molecules. such as glucose and galactose. Aim of the study. In the present study we investigated the molecular basis for the uptake of glucose and galactose into the human mammary gland. Methods. Using RT-PCR, Southern and Western blotting we analyzed the expression of SGLT1 (sodium glocose cotransporter 1) and GLUT1 (sodium independent glucose transporter) in epithelial cells isolated from fresh human milk. Results. Southern blot analysis of the amplications revealed the expression of SGLT1 mRNA but not of GLUT1 mRNA in milk epithelial cells. Using Western blotting, SGLT1 protein was identified in human milk cells. Conclusions. Our findings indicate that 1) the cell fraction isolated from fresh human milk is a suitable model for investigating gene expression in the human mammary gland and 2) lactating human mammary gland epithelial cells are supplied with monosaccharides mainly via SGLT1. Received: 11 January 2000, Accepted: 5 July 2000