Planta Med 2007; 73 - P_571
DOI: 10.1055/s-2007-987351

Salvia fruticosa tea drinking reduces the expression of sodium/glucose cotransporter 1 in enterocytes brush-border membrane of streptozotocin-induced diabetic rats

MF Azevedo 1, CF Lima 1, JM Wilson 2, H Koepsell 3, M Fernandes-Ferreira 1, MJ Almeida 1, C Pereira-Wilson 1
  • 1Department/Center of Biology, University of Minho, Campus de Gualtar, 4710–057 Braga, Portugal
  • 2Laboratory of Ecophysiology, CIIMAR – University of Porto, Rua dos Bragas 289, 4050–123 Porto, Portugal
  • 3Institute of Anatomy and Cell Biology, University of Würzburg, Koellikerstrasse 6, 97070 Würzburg, Germany

Considering the increasing prevalence of Type 2 diabetes mellitus and a lack of efficient treatment, there is a growing interest on the research of natural bioactive compounds. Salvia fruticosa (greek sage) is a medicinal plant to which antidiabetic properties have been attributed [1, 2] and previous results confirmed an effect on control of blood glucose in rats. The aim of this work was to study the antidiabetic effects of sage tea drinking at the levels of intestinal epithelium and insulin secretion in normal and streptozotocin (STZ)-induced diabetic rats. Sage tea was given ad libitum, instead of water, for 14 days to the treated animals. SGLT1 (Na+/glucose cotransporter 1) and GLUT2 (facilitative glucose transporter 2) expression in enterocytes were evaluated by Western blotting. Effects on glucagon-like peptide 1 (GLP1) and islet regeneration (β cell insulin expression) were assessed by immunohistochemistry. Glucose and insulin were measured in the plasma. An increase in the expression of SGLT1 in brush-border membrane (BBM) (P<0.001) and GLUT2 in crude homogenates (P=0.027) was observed in diabetic animals. Sage tea only decreased SGLT1 expression by 63% (P=0.008). Fasting plasma glucose levels stabilized in tea STZ-diabetic rats when compared to water controls. A slightly increase in plasma insulin of sage tea drinking diabetic rats was observed (P>0.05), accompanied by an increase in the intensity of insulin signal from β cells compared with diabetic control rats (P=0.012). GLP1 immunoreactive cells were fewer in number in diabetic compared with normal animals (P=0.002), although GLP1 intensity was higher (P=0.035). No effects of tea were detected. Salvia fruticosa tea seems to be beneficial on a diabetic condition, where an increased intestinal transport capacity exacerbates hyperglycaemia, mainly by reducing the SGLT1 expression in BBM.

Acknowledgements: MFA and CFL are supported by FCT grants: SFRH/BD/12527/2003 and SFRH/BPD/26316/2006, respectively. This work was supported by FCT research grant POCI/AGR/62040/2004.

References: [1] Alarcon-Aguilar, F.J. et al. (2002), Phytother. Res., 16: 383–6. [2] Perfumi M, et al. (1991), J Ethnopharmacol., 34: 135–140.