EFFECTS OF HIGH SUCROSE DIET ON INSULIN-LIKE EFFECTS OF VANADATE IN DIABETIC RATS

The insulin-like effects of vanadate were compared in streptozotocin-i nduced diabetic rats fed on high starch control and high sucrose diets for a period of six weeks. Diabetic rats in both diet groups were cha racterized by hypoinsulinemia, hyperglycemia (6.8-7.0 fold increase) a nd significant decreases (p < 0.001) in the activities of glycogen syn thase, phosphorylase and lipogenic enzymes, ATP-citrate lyase, glucose 6-phosphate dehydrogenase and malic enzyme in liver. There were no di et-dependent differences in these abnormalities. However, the insulin- mimetic agent vanadate was more effective in diabetic rats fed sucrose diet as compared to animals fed control starch diet. Vanadate adminis tration resulted in 30% and 64% decreases in plasma glucose levels in diabetic rats fed control and sucrose diets, respectively. The activit ies of glycogen synthase (active) and phosphorylase (active and total) were restored significantly by vanadate in control (p < 0.05-0.01) an d sucrose (p < 0.001) diets fed diabetic rats. This insulin-mimetic ag ent increased the activities of hepatic lipogenic enzymes in control d iet fed rats to 38-47% of normal levels whereas in sucrose fed group i t completely restored the activities. Sucrose diet caused a distinct e ffect on the plasma levels of triacylglycerol (4-fold increase) and ap olipoprotein B (2.8-fold increase) in diabetic rats and vanadate suppl ementation decreased their levels by 65-75%. These data indicate that vanadate exerts insulin-like effects in diabetic rats more effectively in sucrose fed group than the animals fed control diet. In addition, vanadate also prevents sucrose-induced hypertriglyceridemia.