Decrease in triglyceride accumulation in tissues by restricted diet and improvement of diabetes in Otsuka Long-Evans Tokushima fatty rats, a non-insulin-dependent diabetes model

With respect to the connection between triglyceride (TG) and non-insulin-de pendent diabetes mellitus (NIDDM), previous reports have shown that TG accu mulation in the liver and muscle is one of the causes of insulin resistance , and TG accumulation in pancreatic islets induces impairment of pancreatic beta-cell function. This experiment examined the relationship between an a melioration of hypertriglyceridemia (HTG), a decrease in TG accumulation in tissues, and an improvement of NIDDM by food restriction. In this experime nt using Otsuka Long-Evans Tokushima fatty (OLETF) rats developing NIDDM an d Long-Evans Tokushima Otsuka (LETO) rats as controls, sequential changes i n body weight and TG content in tissue were measured and biochemical blood tests, an insulin euglycemic clamp test, and histopathologic examination of the pancreas and liver were performed. OLETF rats were allocated to a food -satiated group (satiated) or 30% food-restricted group (restricted), As a result, several findings were more evident in the restricted group than in the satiated group: (1) reductions in body weight and intraabdominal fat we ight, decreases in plasma TG, insulin, and glucose levels, a decrease in th e TG secretion rate, and an increase in plasma lipoprotein lipase (LPL) act ivity, (2) decreases in the TG content in the liver, pancreas, and muscle, (3) improvement of the glucose infusion rate (GIR), and (4) a marked reduct ion of TG accumulation in the liver and pancreatic islets on histopathologi c examination. These results indicate that the improved HTG caused a reduct ion in TG accumulation in the liver and muscle, thereby improving insulin r esistance. Moreover, the decrease in TG accumulation in pancreatic islets s uggests an improvement of pancreatic beta-cell function. Copyright (C) 2000 by W.B. Saunders Company.