Induction of Alimentary Diabetes and Insulin Responses to Glucose in Microtus arvalis Pallas

Abstract

In Microtus arvalis Pallas, new born voles were fostered to JCR mice and supplied with pellets for mice containing little fiber after weaning. High concentrations of glycosuria accompanied with hyperglycemia were induced in about 50% of voles supplied with pellets for mice. In the glycosuric voles, the fermentation ability and pH of the contents in the forestomach lowered considerably, and large amounts of starch in the diet were considered to be transported to the pyloric stomach without being fermented in the forestomach, and hydrolyzed into glucose to be absorbed in the duodenum. In normal control voles, insulin secretory response to a glucose load was similar to that in mice. In the slight diabetic voles, the plasma insulin levels rose over 200 μU/ml and the insulin secretory response to glucose was remained. But in the serious diabetic voles, the plasma insulin levels lowered under 10 μU/ml and the insulin secretory response was almost absent. According to immunohistochemical studies on pancreatic islet B cells, partial degranulation were observed at the slight diabetic stage. However, at the serious diabetic stage, degranulation and vacuolation of B cells became pronounced. These results clearly indicated that in herbivorous voles, alimentary diabetes were induced by lowering of the fermentation ability in the forestomach and the diabetic voles fell into complete insulin deficiency at the serious stage.