Long term improvement of glucose homeostasis by vanadate in obese hyperinsulinemic fa/fa rats.
The trace element vanadium (V) exerts insulin-like effects in vitro and lowers blood glucose in streptozotocin-diabetic rats. The present study examined whether V can also improve glucose homeostasis in genetically obese, insulin-resistant rats. Na3VO4 was administered for 3 months in water and food to Zucker fa/fa rats. Since these V rats reduced their food intake by about 30% compared to controls (C), one group of untreated rats was pair-fed (P-F) with V rats. In the fed state, the insulin/glucose ratio was lower in V rats than in P-F or C rats, merely because of a decrease (approximately 50%) in plasma insulin levels. Tolerance to oral glucose was improved in V rats only; the integrated glucose response was 30% lower than that in P-F or C rats. Insulin levels were also lower in V rats, but the integrated response was not consistently decreased. During an iv glucose tolerance test, the glucose disappearance rate was 50% higher in V rats than in the other two groups. An iv arginine test clearly showed that B-cell responsiveness was not increased in V rats. Insulin sensitivity, assessed by insulin-induced hypoglycemia, was similar in V and P-F rats and slightly better than that in C rats. In conclusion, oral vanadate produces a sustained improvement of glucose homeostasis by an insulin-like, largely body weight-independent mechanism in genetically insulin-resistant rats.
Brichard
S M
SM
Unité de Diabétologie et Nutrition, University of Louvain, Faculty of Medicine, Brussels, Belgium.
Pottier
A M
AM
Henquin
J C
JC
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001835:Body Weight / Q000187:drug effects; D005215:Fasting; D005260:Female; D005947:Glucose / Q000378:metabolism*; D005951:Glucose Tolerance Test; D006706:Homeostasis / Q000187:drug effects; D006946:Hyperinsulinism / Q000150:complications / Q000378:metabolism*; D007328:Insulin / Q000097:blood / Q000378:metabolism; D009765:Obesity / Q000150:complications / Q000378:metabolism*; D010179:Pancreas / Q000033:anatomy & histology / Q000187:drug effects; D051381:Rats; D011924:Rats, Zucker; D013997:Time Factors; D014638:Vanadates / Q000494:pharmacology*
D001786:Blood Glucose; D007328:Insulin; D014638:Vanadates; D005947:Glucose