Effect of Leucine Intake on Body Weight Reduction in Rats Fed High Fat Diet

The principal objective of this study was to determine the effects of leucine on body weight reduction in high fat diet-induced overweight rats. To induce overweight, six-month-old male Sprague-Dawley rats (n = 80) were divided into 8 groups; one group of 10 rats was fed on a normal fat diet and the remaining 70 rats were fed on a high-fat diet (40% of energy as fat) for 14 weeks. Then, 10 rats fed on the normal fat diet and another 10 rats fed on the high fat diet were sacrificed to identify overweight induction. The remaining 60 rats were divided randomly into 6 groups according to body weight and fed on one of the diets with different dietary fat levels (9.6% or 40% of energy as fat) and leucine levels (0, 0.6 or 1.2 g/kg BW) for the following 5 weeks of experiments. The body weight loss in the Leu-administered groups (0.6 g, 1.2 g/kg BW) was significantly higher than those of Leu non-administered groups. The perirenal fat pad weights in the Leu-administered groups were significantly lower than those of the Leu non-administered groups. Of the hepatic enzymes, glucose-6-phosphate dehydrogenase (G6PDH) activities were reduced significantly in the Leu-administered groups than in the Leu non-administered groups. With the oral glucose tolerance test (OGTT), the incremental areas under the curve of the glucose response (IAUC) of the Leu-administered groups were significantly lower than those of the Leu non-administered groups. The fasting glucose concentration and HOMA-IR of the Leu-administered groups were significantly lower than those of the Leu non-administered groups. In conclusion, the results of this study suggest that one of the possible mechanisms of leucine in the observed body weight reduction might involve the inhibition of lipogenic enzyme activities such as glucose-6-phosphate dehydrogenase, rather than the activation of lipolysis enzymes. Additionally, leucine adminstration resulted in improved glucose metabolism.

Effect of dietary soluble fiber on neurohormonal profiles in serum and brain of rats

This study was conducted to investigate the effect of dietary soluble fiber administration and /or high fat diet on serum and brain neurohormonal profiles, adipose tissue mass and body weight gain in Sprague-Dawley rats. Four groups of rats were respectively fed 10% fat diet (C), 10% fat plus pectin diet (P), 20% fat diet (HFC) and 20% fat plus pectin diet (HFP) for 4 weeks. In HFP group, the food and energy intake, body weight gain, FER including fecal excretion were the smallest (p<0.05). Serum HDL-cholesterol, triglyceride and glucose level were also the lowest in HFP group (p<0.05). The weight of brain, epididymal fat pad and adrenal gland except liver didn't show any significant differences among groups. Interestingly serum norepinephrine concentration of HFP group tended to be higher, but dopamine concentration tended to be lower than those of HFC group. However serum catecholamine concentration didn't show any significant differences among all groups. Norepinephrine and epinephrine contents of right portion of midbrain of P and HFP groups were remarkably lower than those of the C group. These results suggested that soluble fiber pectin consumption might affect neurohormonal profiles in serum and brain according to dietary fat level.