title: Effects and mechanisms of auricular vagus nerve stimulation on high-fat-diet--induced obese rats.
abstract: OBJECTIVE
  Obesity is a major public health problem. Regulating food intake and promoting metabolism of fat are two important options for treating obesity. Auricular vagus nerve stimulation (AVNS) is considered as an alternative approach to vagal nerve stimulation. The aim of this study was to investigate the effects of AVNS and its mechanisms on obesity in obese rats.
  
  
  METHODS
  Male Sprague-Dawley rats were fed either a high-fat diet (HFD) or a normal diet for 8 wk. Qualified HFD rats were randomly divided into three groups: the HFD group, the AVNS group, and the sham group for 6 wk treatment. Body weight and daily energy intake were recorded weekly. The rats were sacrificed for measurement of weight of bilateral perirenal, epididymal white adipose tissue (WAT), dorsal brown adipose tissue (BAT), and gastric emptying. Serum cholecystokinin (CCK), peptide YY3 to 36 (PYY3-36) and norepinephrine (NE) were assayed by enzyme-linked immunosorbent assay. Real-time quantitative polymerase chain reaction was used to assess the mRNA expressions of CCK subtype receptor a (CCKa) in the antrum, PYY3-36 receptor in the distal ileum, β3-adrenoceptor, and uncoupling protein gene 1 (UCP1) in the BAT.
  
  
  RESULTS
  Compared with HFD group, AVNS significantly reduced body weight and epididymal WAT and increased BAT weight, serum NE, mRNA expressions of β3-adrenoceptors, and UCP1 of the BAT, but had no effect on daily energy intake, perirenal WAT weight, gastric emptying, serum levels of CCK and PYY, or mRNA expressions of CCKa receptor and PYY3-36 receptor in the relevant tissues. The sham group, as a comparison group for AVNS, saw less effect in any of the indexes compared with the HFD group. AVNS had more effect on weight loss, reduction of perirenal WAT, and increase of NE, β3-adrenoceptor, and UCP1 than sham.
  
  
  CONCLUSIONS
  AVNS was more effective in reducing body weight and causing visceral fat loss. Biochemical tests found more NE released in the serum and more β3-adrenoceptor and UCP1 expression in the BAT. All of these features suggested that energy expenditure might play an important role in obesity management by AVNS.
authors.affiliation: Department of Acupuncture and Moxibustion, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China; Key Laboratory of Acupuncture and Immunological Effects, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Han
authors.initials: H
authors.lastname: Li
authors.affiliation: Department of Acuology, The Second Clinical College, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: Jian-Bin
authors.initials: JB
authors.lastname: Zhang
authors.affiliation: Department of Urology, The First People's Hospital of Wujiang City, Suzhou, Jiangsu, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Xu
authors.affiliation: Department of Acupuncture and Moxibustion, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.
authors.forename: Qing-Qing
authors.initials: QQ
authors.lastname: Tang
authors.affiliation: First Clinical College, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: Wei-Xing
authors.initials: WX
authors.lastname: Shen
authors.affiliation: Department of Acupuncture and Moxibustion, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.
authors.forename: Jing-Zhu
authors.initials: JZ
authors.lastname: Zhou
authors.affiliation: Division of Gastroenterology, University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Jian-De
authors.initials: JD
authors.lastname: Chen
authors.affiliation: Department of Acupuncture and Moxibustion, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China. Electronic address: karham1987@gmail.com.
authors.forename: Yin-Ping
authors.initials: YP
authors.lastname: Wang
authors.affiliation: Department of Acupuncture and Moxibustion, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China; Key Laboratory of Acupuncture and Immunological Effects, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
authors.forename: Li
authors.initials: L
authors.lastname: Han
authors.affiliation: Department of Acuology, The Second Clinical College, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Jian-Bin
authors.affiliation: Department of Urology, The First People's Hospital of Wujiang City, Suzhou, Jiangsu, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Chen
authors.affiliation: Department of Acupuncture and Moxibustion, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.
authors.forename: Tang
authors.initials: T
authors.lastname: Qing-Qing
authors.affiliation: First Clinical College, Nanjing University of Chinese Medicine, Nanjing, Jiangsu, China.
authors.forename: Shen
authors.initials: S
authors.lastname: Wei-Xing
authors.affiliation: Department of Acupuncture and Moxibustion, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Jing-Zhu
authors.affiliation: Division of Gastroenterology, University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Chen
authors.initials: C
authors.lastname: Jian-De
authors.affiliation: Department of Acupuncture and Moxibustion, The First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu, China. Electronic address: karham1987@gmail.com.
authors.forename: Wang
authors.initials: W
authors.lastname: Yin-Ping
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D002001:Adipose Tissue, Brown / Q000378:metabolism; D052436:Adipose Tissue, White / Q000378:metabolism; D000818:Animals; D059305:Diet, High-Fat; D004041:Dietary Fats / Q000008:administration & dosage; D004423:Ear; D002149:Energy Intake; D004734:Energy Metabolism; D050152:Intra-Abdominal Fat / Q000378:metabolism; D007473:Ion Channels / Q000378:metabolism; D008297:Male; D024101:Mitochondrial Proteins / Q000378:metabolism; D009638:Norepinephrine / Q000097:blood; D009765:Obesity / Q000209:etiology / Q000378:metabolism / Q000628:therapy*; D017207:Rats, Sprague-Dawley; D022702:Receptors, Adrenergic, beta-3 / Q000378:metabolism; D000071256:Uncoupling Protein 1; D055536:Vagus Nerve Stimulation / Q000379:methods*; D015431:Weight Loss
chemical_list: D004041:Dietary Fats; D007473:Ion Channels; D024101:Mitochondrial Proteins; D022702:Receptors, Adrenergic, beta-3; C000604373:Ucp1 protein, rat; D000071256:Uncoupling Protein 1; D009638:Norepinephrine
keywords: Auricular vagus nerve stimulation; Energy expenditure; Food intake; Metabolism; Obesity