In vitro effects of bis(1,2-dimethyl-3-hydroxy-4-pyridinonato)oxidovanadium(IV), or VO(dmpp)2, on insulin secretion in pancreatic islets of type 2 diabetic Goto-Kakizaki rats

• Vanadium compounds have been suggested for treatment of type 2 diabetes.
• Oxidovanadium(IV) complex of 1,2-dimethyl-3-hydroxy-4-pyridinonato(dmpp) has been studied.
• VO(dmpp)2, has shown antidiabetic properties by in vitro and in vivo studies.
• Here we show it also improves glucose-induced insulin secretion in GK pancreatic islets.
• This promising result corroborates the use of VO(dmpp)2 for treatment of type 2 diabetes.

Vanadium compounds have been explored as therapy of diabetes, and most studies have focussed on insulin mimetic effects, i.e. reducing hyperglycemia by improving glucose sensitivity and thus glucose uptake in sensitive tissues. We have recently shown that bis(1,2-dimethyl-3-hydroxy-4-pyridinonato)oxidovanadium(IV), VO(dmpp)2, has promising effects when compared to another vanadium compound, bis(maltolato)oxidovanadium(IV), BMOV, and insulin itself, in isolated adipocytes and in vivo in Goto-Kakizaki (GK) rats, an animal model of hereditary type 2 diabetes (T2D). We now have investigated in GK rats whether VO(dmpp)2 also modulates another important defect in T2D, impaired insulin secretion. VO(dmpp)2, but not BMOV, stimulated insulin secretion from isolated GK rat pancreatic islets at high, 16.7 mM, but not at low–normal, 3.3 mM, glucose concentration. Mechanistic studies demonstrate that the insulin releasing effect of VO(dmpp)2 is due to its interaction with several steps in the stimulus-secretion coupling for glucose, including islet glucose metabolism and K-ATP channels, L-type Ca2 + channels, modulation by protein kinases A and C, as well as the exocytotic machinery. In conclusion, VO(dmpp)2 exhibits properties of interest for treatment of the insulin secretory defect in T2D, in addition to its well-described insulin mimetic activity.

VO(dmpp)2 improves insulin secretion only in hyperglycemic condition, from pancreatic islets of spontaneously diabetic GK rats. As this compound ameliorates the defective glucose-induced insulin secretion in an animal model of type 2 diabetes, it seems to exhibit properties of interest for the treatment of this disease.Figure optionsDownload as PowerPoint slide