Leucine improves protein nutritional status and regulates hepatic lipid metabolism in calorie‐restricted rats

Abstract

Several studies have highlighted the potential of leucine supplementation for the treatment of metabolic diseases including type 2 diabetes and obesity. Caloric restriction is a common approach to improve the health in diabetic and obese subjects. However, very few studies assessed the effects of leucine supplementation in calorie-restricted animals. Rats were subjected to a 30% calorie-restricted diet for 6 weeks to study the effects of leucine supplementation on protein status markers and lipid metabolism. Caloric restriction reduced the body weight. However, increased leucine intake preserved body lean mass and protein mass and improved protein anabolism as indicated by the increased circulating levels of albumin and insulin-like growth factor-1 (IGF-1), and the liver expression of albumin and IGF-1 messenger RNA. Leucine supplementation also increased the circulating levels of interleukin-6 and leptin but did not affect the tumour necrosis factor-α and monocyte chemotactic protein-1 concentrations. Ketone bodies were increased in rats consuming a leucine-rich diet, but we observed no changes in cholesterol or triglycerides concentrations. Caloric restriction reduced the liver expression of peroxisome proliferator activated receptor-α and glucose-6-phosphatase, whereas leucine supplementation increased the liver expression of 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG-CoA) reductase and sterol regulatory element-binding transcription factor 1. A leucine-rich diet during caloric restriction preserved whole body protein mass and improved markers of protein anabolism. In addition, leucine modulated the hepatic lipid metabolism. These results indicate that increased leucine intake may be useful in preventing excessive protein waste in conditions of large weight loss.

A suplementação de leucina pode atenuar a atrofia muscular? Uma revisão da literatura

“…Although without statistically significant difference, the contents of muscle proteins in this group of animals was 71% greater than the group submitted to dietary restriction and only 15% higher than the group with ad libitum diet, showing that leucine supplementation proved to be an effective strategy to increase muscle mass and muscle protein content in older rats submitted to dietary restriction. These results are consistent with a recent study published by Pedroso et al 25 , who found a decline of 16.5% in lean mass of young rats deprived of 50% of their daily dietary intake for 6 weeks. However, when rats were submitted to the same procedure but added of leucine supplementation (71.43 g / kg / day), lean mass loss of only 8.3% in relation to the initial weight was observed 25 .…”

“…These results are consistent with a recent study published by Pedroso et al 25 , who found a decline of 16.5% in lean mass of young rats deprived of 50% of their daily dietary intake for 6 weeks. However, when rats were submitted to the same procedure but added of leucine supplementation (71.43 g / kg / day), lean mass loss of only 8.3% in relation to the initial weight was observed 25 .…”

The effect of protease on growth performance, nutrient digestibility, and expression of growth-related genes and amino acid transporters in broilers

“…In the current study, protease treatment increased the expression levels of IGF1, IGF2, GH, and LEP in the liver; however, the direct relationship between protease supplementation and increased IGF1, IGF2, GH, and LEP expression in the liver remains unclear. In a large number of previous reports, the dietary supplementation of essential amino acids, like methionine and leucine, increases the expression of IGF-1 in the liver by stimulating the synthesis and release of GH [37][38][39]. In addition, Takenaka et al [40] have demonstrated that the dietary restriction of a single essential amino acid (leucine, lysine, methionine, and tryptophan), or amino acid-free diet, lowers the production of IGF-I within the blood of rats.…”

Resistance training and caloric restriction prevent systolic blood pressure rise by improving the nitric oxide effect on smooth muscle and morphological changes in the aorta of ovariectomized rats

“…The CR diet was adjusted to avoid nutritional deficiencies, increasing the nutrients in proportion to food restriction [ 19 , 20 ]. The diet composition used in the experiment was in accordance with the AIN-93M [ 21 ].…”