OBJECTIVES: This study investigated the effects of continuous feeding of rats with a palatable high-fat diet on: body weight gain, adiposity, liver and muscle glycogen content, blood glucose and insulin levels, and pancreatic morphology and insulin secretion by in vitro isolated pancreatic beta cells. METHODS: Male Wistar rats (21 days old) were fed with a palatable high-fat diet or a chow diet during 15wk. Body weight and food intake were recorded daily whereas blood glucose and insulin were analyzed weekly. After they were killed, pancreas, liver, gastrocnemius muscle and adipose tissues were removed and weighted. Morphology analysis of pancreatic tissue sections was performed using light microscopy. Serum insulin and the insulin secreted by isolated pancreatic islets, incubated for 90min under different concentrations of glucose, were analyzed by radioimmunoassay. RESULTS: The palatable high-fat diet increased adiposity, body weight gain and liver glycogen content when compared with the animals fed with a chow diet. Blood glucose and insulin levels did not differ between groups. The insulin secretion from isolated islets increased in the high-fat diet group only at physiological concentrations of glucose (G= 8.3mM). The size of the pancreas of rats receiving the high-fat diet decreased, although the number of beta cells increased. In addition, the lumen of pancreatic vessels was narrower compared with control islets. CONCLUSION: The obesity resulting from a high-fat diet did not alter the blood glucose and insulin levels of fasted rats. Despite the morphological alterations of the pancreas, normal blood glucose concentration in rats receiving a high-fat diet remained at physiological range due to a preserved secretory capacity of the pancreatic islets.
diet; Islets of Langerhans; obesity; pancreas
