title: Leucine supplementation improves leptin sensitivity in high-fat diet fed rats.
abstract: BACKGROUND
  Several studies have reported the favorable effect of leucine supplementation on insulin resistance or insulin sensitivity. However, whether or not leucine supplementation improves leptin sensitivity remains unclear.
  
  
  METHODS
  Forty-eight male Sprague-Dawley rats were fed with either a high-fat diet (HFD) or HFD supplemented with 1.5, 3.0, and 4.5% leucine for 16 weeks. At the end of the experiment, serum leptin level was measured by ELISA, and leptin receptor (ObR) in the hypothalamus was examined by immunohistochemistry. The protein expressions of ObR and leptin-signaling pathway in adipose tissues were detected by western blot.
  
  
  RESULTS
  No significant differences in body weight and food/energy intake existed among the four groups. Serum leptin levels were significantly lower, and ObR expression in the hypothalamus and adipose tissues was significantly higher in the three leucine groups than in the control group. These phenomena suggested that leptin sensitivity was improved in the leucine groups. Furthermore, the expressions of JAK2 and STAT3 (activated by ObR) were significantly higher, and that of SOCS3 (inhibits leptin signaling) was significantly lower in the three leucine groups than in the control group.
  
  
  CONCLUSIONS
  Leucine supplementation improves leptin sensitivity in rats on HFD likely by promoting leptin signaling.
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, China.|Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Disease, Soochow University, Suzhou, China.
authors.forename: Xue-Wei
authors.initials: XW
authors.lastname: Yuan
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, China.|Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Disease, Soochow University, Suzhou, China.
authors.forename: Shu-Fen
authors.initials: SF
authors.lastname: Han
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, China.|Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Disease, Soochow University, Suzhou, China.
authors.forename: Jian-Wei
authors.initials: JW
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Radiation Biology, School of Radiation Medicine and Protection, Soochow University, Suzhou, China.
authors.forename: Jia-Ying
authors.initials: JY
authors.lastname: Xu
authors.affiliation: Department of Nutrition and Food Hygiene, School of Public Health, Soochow University, Suzhou, China.|Jiangsu Key Laboratory of Preventive and Translational Medicine for Geriatric Disease, Soochow University, Suzhou, China; qinliqiang@suda.edu.cn.
authors.forename: Li-Qiang
authors.initials: LQ
authors.lastname: Qin
keywords: high-fat diet; leptin sensitivity; leptin signaling; leucine