Insulin secretion to glucose stimulus in pancreatic islets isolated from rats fed unbalanced diets

To verify the effect of different energetic sources on insulin secretion, just-weaned male Wistar rats were divided into four groups fed as follows: high carbohydrate (HC), high protein (HP), high lipid (HL) and balanced (C) diets during five weeks. Body weight gain and daily food intake were similar among the four groups. Insulin content of the isolated islets was not different; however, insulin release to a high glucose concentration (16.7 mM) stimulus was clearly higher in islets isolated from rats fed a balanced diet as compared to the other groups (HC, HP and HL). The rates of insulin secretion in islet perfusates from rats fed unbalanced diets were also decreased, although 45Ca2+ outflow rate (FOR) was similar in all groups. Since the rate of U-14C-glucose oxidation was decreased in islets isolated from rats fed unbalanced diets, this could be one of the mechanisms for the reduced rates of insulin release observed. Therefore, the increased supply of specific fuels provoke metabolic alterations in B-cell leading to changes in insulin secretion.