Effect of vanadate administration on blood glucose and insulin levels as well as on the exocrine pancreatic function in streptozotocin-diabetic rats

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Abstract
In the present study, streptozotocin-induced diabetic rats with their corresponding controls, were treated orally with sodium metavanadate. A gradual increase of the vanadate concentration up to 0.8 mg/ml in the drinking water, lowered the blood glucose levels of the diabetic animals to normal values without changing the insulin levels. On the other hand, vanadate did not affect the blood glucose levels of the non-diabetic animals; it did however induce lower levels of circulating insulin in these animals. The lowering of the glycaemic values of the diabetic animals was closely related to the consumption of vanadate. When the treatment was ceased, the blood glucose levels rose rapidly. The diabetic animals responded to the vanadate treatment with two sensitivities; while the large majority of the diabetic animals displayed stable normoglycaemic values, others had fluctuating values. Amylase content in the exocrine pancreas of these two subgroups of animals was studied separately and compared to that from the non-treated control and diabetic animals. The presence of amylase in the pancreatic acinar cells was assessed by the protein A-gold immunocytochemical approach and biochemical determinations. Amylase was found to be very low in the non-treated diabetic animals. Lowering of the blood glucose levels induced by the vanadate treatment restored the amylase to levels similar to those of the controls. However, vanadate-treated diabetic animals with fluctuating levels of blood glucose, demonstrated only a partial recovery of amylase. Thus, vanadate treatment was found to have a normalizing effect on blood glucose levels in diabetic animals as well as restoring amylase content in the pancreas of diabetic animals. This appeared to be closely related to the glycaemic values of the diabetic animals.