Obesity and diabetes - a possible experimental model of maturity-onset-type diabetes

This study aimed to acquire a possible experimental model of obese non-insulin-dependent diabetes. Around 230 g Sprague-Dawley female rats were divided into 4 gp: (1) sham ventromedial hypothalamic (VMH) lesioned rats fed low-fat diet (control rats); (2) VMH lesioned rats fed low-fat diet; (3) sham VMH lesioned rats fed high-fat diet and (4) VMH lesioned rats fed high fat diet, and they were observed for 10 weeks (Exp. 1). This experiment was repeated using rats treated by small doses of streptozotocin (5 mg/kg) (Exp. 2). Body weight was measured weekly, blood glucose, every other week and serum insulin, at the end of the experiments. VMH obese rats fed low-fat diet showed normal levels of fasting blood glucose with hyperinsulinemia. VMH obese rats fed high-fat diet showed mildly elevated levels of fasting blood glucose (155 +/- 8 mg/dl as compared to 125 +/- 3 mg/dl of controls) with hyperinsulinemia (5.92 +/- 0.61 ng/ml). Streptozotocin treated VMH obese rats fed low-fat diet did not show increasing levels of fasting blood glucose, while streptozotocin treated VMH obese rats fed high-fat diet showed marked elevation of fasting blood glucose (229 +/- 23 mg/dl). The latter group of rats also had hyperinsulinemia (3.82 +/- 0.45 ng/ml compared to 1.36 +/- 0.14 ng/ml of controls), although concentrations of serum insulin were decreased by streptozotocin treatment compared to levels of VMH obese rats fed high-fat diet. These results demonstrated that VMH obese rats fed high-fat diet showed milk hyperglycemia with hyperinsulinemia. Following treatment of small doses of streptozotocin, VMH obese rats fed high fat diet showed marked hyperglycemia with hyperinsulinemia. The profile of these rats resembles that of maturity onset-type diabetes which accompanies with obesity and hyperinsulinemia.