Morphological and Functional Abnormalities in the Ileum of Rats with Spontaneous Hypertension: Studies on SGLT1 Protein

Abstract

Background: Na⁺-dependent _D-glucose and _D-galactose transport was studied in the ileal brush-border membrane vesicles from both spontaneously hypertensive rats (SHR) and their normotensive genetic control Wistar-Kyoto (WKY) rats. Initial rates and accumulation ratios of the transport of both monosaccharides were significantly lower in the hypertensive rats compared to the WKY rats. Methods: In order to determine whether such modifications are related to morphological abnormalities, ileal epithelium of SHR and WKY rats was examined by light and electron microscopy. In addition, immunohistochemical and immunocytochemical localization of Na⁺-glucose cotransporter (SGLT1) was performed. Results: Light microscopy studies showed hypertrophy in the ileal villi of hypertensive rats, with an increase in the villus width when compared to those from normotensive rats. Immunohistochemical studies of SGLT1 showed the protein localized in the apical membrane of the absorptive epithelial cells, along the entire villus. No changes between SHR and WKY rats were noted in the intensity and distribution of the SGLT1 protein along the villus-crypt axis. Electron microscopy studies showed a patchy loss of microvilli in the ileal enterocytes of SHR, compared to those from WKY rats. Immunocytochemical studies of SGLT1 were carried out by the immunogold method. Colloidal gold particles were localized at the ileal microvilli of normotensive rats. No significant presence of SGLT1 was found in the smooth apical surface of ileum from hypertensive rats, although most adjacent microvilli were marked. Conclusion: Morphological changes were accompanied by modifications in the sugar transport and in the immunolocalization of SGLT1 in the ileal epithelium of SHR.

• Hypertension Intestine Sglt1 Sodium-GLUCOSE Transporter