Adaptation of Sprague Dawley rats to long-term feeding of high fat or highfructose diets

Background Present animal models used to emulate type 2 diabetes may not ac curately reflect the metabolic changes that occur in humans. Aim of the stu dy The purpose of this research was to evaluate diets reported to induce in sulin resistance and impaired glucose metabolism in rats as a potentially u seful model for studying type 2 diabetes. Methods Three groups of male Spra gue Dawley rats (n=7) were fed either a control diet, based on AW recommend ations (53 % cornstarch, 10 % sucrose and 7 % soybean oil), a high fat diet (25 % soybean oil, 35 % cornstarch) or a high fructose diet (53 % fructose , 10 % sucrose) for a 3 month period. Glucose tolerance tests were carried out in week 3 and week 9 of the experiment. At the termination of the exper iment, serum insulin, glucose, cholesterol and triacylglycerols were measur ed. Glucose incorporation into glycogen and glycogen synthase activity were measured in soleus muscles. Results Similar weight gain was observed for a ll three groups of rats. Glucose tolerance curves and fasting glucose level s were not significantly different at any time point in the experiment. Ins ulin levels were unchanged for the controls (171+/-21 pM), high fructose (1 64+/-16 pM) and high fat (181+/-30 pM) diets. Fasting serum triacylglycerol s and cholesterol levels were not significantly elevated by dietary treatme nt. In soleus muscles, rats on all three diets had a significant increase i n glycogen synthesis in response to insulin, but synthesis was similar in a ll three groups. Glycogen synthase activity was also not significantly affe cted by long-term dietary inter vention. Conclusions In this study, healthy Sprague Dawley rats fed high fat or high fructose diets for 3 months adapt ed to the nutritional intervention without developing classical signs of in sulin resistance and impaired glucose tolerance.