Distribution of the SGLT1 Na+/glucose cotransporter and mRNA along the crypt-villus axis of rabbit small intestine.

The expression of the Na+/glucose cotransporter (SGLT1) mRNA and protein along the crypt-villus axis of the rabbit small intestine was examined using in situ hybridization and immunocytochemical techniques. We detected mRNA in the cells on the villus, but not in the crypts, and the mRNA abundance increased 6-fold from the base to the tip of the villus. SGLT1 protein was restricted to the brush borders of mature enterocytes. We suggest that the high rate of sugar transport across the tips of the villus is due to the transcription of the SGLT1 gene in mature enterocytes, the subsequent translation of SGLT mRNA, and the insertion direct of the functional SGLT1 transporter into the brush border membrane of these cells lining the villus tip.