title: Insulin but not phlorizin treatment induces a transient increase in GLUT2 gene expression in the kidney of diabetic rats.
abstract: OBJECTIVE
  Increases in the renal glucose transporter gene expression are involved in renal tubule-glomerular diseases. Here we investigate the GLUT2 gene expression changes in the kidney of diabetic rats, by using insulin or phlorizin treatment.
  
  
  METHODS
  Rats were rendered diabetic and studied 20 days later: 4-12 h after one single injection of insulin or phlorizin, and 1-6 days after insulin or phlorizin injection twice a day, comparing with diabetic rats injected with placebo. GLUT2 was investigated by Northern and Western analysis.
  
  
  RESULTS
  In 20-day diabetic rats, acute treatment with insulin lowered the plasma glucose and increased the GLUT2 mRNA ( approximately 100%, p < 0.001) without changes in the protein content, while phlorizin lowered the plasma glucose, but changed neither the GLUT2 mRNA nor the protein expression. Twenty-four hours of insulin treatment increased both GLUT2 mRNA ( approximately 100%, p < 0.001) and protein ( approximately 50%, p < 0.01), but no effects of phlorizin were observed. After 6 days, insulin and phlorizin similarly reduced glycemia, with opposite effects upon plasma insulin and urinary glucose, and both treatments decreased GLUT2 mRNA and protein (p < 0.05).
  
  
  CONCLUSIONS
  In kidney of diabetic rats, an initial and transient upregulation of GLUT2 was induced specifically by insulin only. The 6-day normalization of GLUT2, however, was induced by both insulin and phlorizin treatment, which seems to be related to the plasma glucose lowering.
authors.affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
authors.forename: Helayne Soares
authors.initials: HS
authors.lastname: Freitas
authors.forename: Beatriz
authors.initials: B
authors.lastname: D'Agord Schaan
authors.forename: Robinson Sabino
authors.initials: RS
authors.lastname: da Silva
authors.forename: Maristela Mitiko
authors.initials: MM
authors.lastname: Okamoto
authors.forename: Maria
authors.initials: M
authors.lastname: Oliveira-Souza
authors.forename: Ubiratan Fabres
authors.initials: UF
authors.lastname: Machado
mesh_terms: D000818:Animals; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects*; D051273:Glucose Transporter Type 2 / Q000378:metabolism*; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D007328:Insulin / Q000008:administration & dosage*; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010695:Phlorhizin / Q000008:administration & dosage*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D051273:Glucose Transporter Type 2; D007004:Hypoglycemic Agents; D007328:Insulin; C495683:Slc2a2 protein, rat; D010695:Phlorhizin