低脂肪食およびトレッドミル訓練が食餌性肥満ラットのダイエットに及ぼす影響

我々は、低脂防食およびトレッドミル訓練がヒトの肥満に類似した高脂肪飼料誘発肥満ラットの体脂肪率、摂食効率及びインスリン作用に及ぼす影響について研究した。高脂肪飼料誘発肥満ラットにおいて、摂食効率(体重増加量/摂取エネルギー)の上昇、高インスリン血症、肝細胞膜インスリン受容体結合能の低下が認められた。トレッドミル訓練および低脂防食+トレッドミル訓練は肥満ラットの肝細胞膜インスリン受容体の結合能を高め、高インスリン血症を抑制する働きがあった。とりわけ、低脂防食+トレッドミル訓練は肥満ラットの体重増加を抑制し体脂肪率を減少させた。これらの代謝変化が高脂肪飼料誘発肥満ラットにおいてダイエット効果を発揮していると考えられる。
Diet-induced obesity (DIO) was produced in 1-month-old male Sprague-Dawley rats during a 10-week period who were fed a high-fat (20%), high-calorie (7.6 kcal/g) DIO diet. Effects of three weight-reducing methods (treadmill training, low-fat diet, treadmill training plus low-fat diet) on body weight, body fat rate, feed efficiency, total cholesterol and triglyceride, plasma insulin and insulin receptor binding capacity on the hepatic cell membrane in the obese rats were investigated. The results indicated that feed efficiency increased, the insulin receptor binding capacity on the hepatic cell membrane decreased and hyperinsulinemia developed in the obese rats. A low-fat diet did not affect body fat rate, feed efficiency, insulin receptor binding capacity on the hepatic cell membrane or hyperinsulinemia. With unrestricted food intake, treadmill training in DIO rats depressed hyperinsulinemia significantly and reduced body fat. Furthermore, treadmill training plus low-fat diet was most effective in inhibiting the body weight gain in the obese rats; it also reduced body fat and feed efficiency to the non-obese control levels. The results indicate that DIO is related to the increase in feed efficiency, the decrease in insulin receptor binding capacity on the hepatic cell membrane and hyperinsulinemia.