The effect of epidermal growth factor on the distribution of SGLT-1 in rabbit jejunum

Abstract

The effect of epidermal growth factor (EGF) on the cellular and villous distribution of the sugar transporter SGLT-1 was examined. New Zealand White rabbits (1 kg) were anesthetized, and two jejunal blind loops were isolated and exposed to either 0.9% saline or EGF (60 ng/mL saline), for 1 h. In separate experiments, tissue was harvested for brush border membrane vesicles (BBMV), microsomal membranes, or fixed for immunohistochemistry. SGLT-1 was measured in membrane fractions by Western immunoblot or localized along the villus–crypt axis by immunofluorescent microscopy. EGF increased BBMV SGLT-1 content compared with paired controls. EGF stimulation also induced a corresponding decrease in microsomal SGLT-1 levels and induced the expression of additional SGLT-1 immunoreactivity further down the villus axis. The findings suggest that EGF upregulates intestinal glucose transport by stimulating the translocation of SGLT-1 from an internal microsomal pool into the brush border, thereby recruiting more villus enterocytes into the glucose transporting population.Key words: EGF, epidermal growth factor, SGLT-1, immunofluorescence.