title: Isosteviol reduces plasma glucose levels in the intravenous glucose tolerance test in Zucker diabetic fatty rats.
abstract: OBJECTIVE
  The aim of this study was to test the effect of isosteviol on blood glucose and insulin levels during the intravenous glucose tolerance test (IVGTT) in Wistar and Zucker diabetic fatty (ZDF) rats.
  
  
  METHODS
  ZDF rats were divided into a control and three isosteviol treatment (1, 5 and 10 mg/kg) groups. Wistar rats were divided into a control group and an isosteviol treatment group (10 mg/kg). The rats were fasted for 12 h prior to infusion of isosteviol and glucose (1.0 g/kg). Blood samples were taken at 0, 5, 15, 30, 60, 90 and 120 min after the injection of glucose. Glucose concentrations were determined by the glucose oxidase method, and plasma insulin was analysed by radioimmunoassay. The area under the curve (AUC) of the net change in plasma glucose concentration was used to compare the isosteviol treatment and control groups.
  
  
  RESULTS
  In ZDF rats, isosteviol at 5 and 10 mg/kg caused a significant (p < 0.05) reduction in the AUC of glucose during the IVGTT. However, isosteviol did not increase plasma insulin concentrations in ZDF rats. In Wistar rats, isosteviol did not significantly affect plasma glucose or insulin levels during the IVGTT.
  
  
  CONCLUSIONS
  Isosteviol exerts an antihyperglycaemic effect during IVGTT in ZDF rats but not in Wistar rats. Isosteviol has no significant effect on plasma insulin concentrations. The glucose-lowering effect of isosteviol may be due to changes in the sensitivity of peripheral tissues to insulin.
authors.affiliation: Sansom Institute, School of Pharmacy and Medical Science, University of South Australia, Adelaide, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Ma
authors.forename: Z
authors.initials: Z
authors.lastname: Ma
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: R W
authors.initials: RW
authors.lastname: Milne
authors.forename: D
authors.initials: D
authors.lastname: Xu
authors.forename: A K
authors.initials: AK
authors.lastname: Davey
authors.forename: A M
authors.initials: AM
authors.lastname: Evans
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism*; D003920:Diabetes Mellitus / Q000097:blood*; D045786:Diterpenes, Kaurane / Q000494:pharmacology*; D005951:Glucose Tolerance Test; D007700:Kinetics; D008297:Male; D009765:Obesity / Q000097:blood*; D051381:Rats; D011924:Rats, Zucker
chemical_list: D001786:Blood Glucose; D045786:Diterpenes, Kaurane; C515747:isosteviol