title: Orexin-A and leptin change inversely in fasting non-obese subjects.
abstract: OBJECTIVE
  Leptin, neuropeptide-Y (NPY) and orexin are peptides regulating energy metabolism and appetite control. NPY and orexin are mainly found in the central nervous system and they have also recently been found in the peripheral nervous system. We investigated how fasting affects changes in circulating concentrations of these peptides and their association with nutritional and metabolic parameters in humans.
  
  
  METHODS
  Ten non-obese female patients with psychosomatic disorders fasted for 7 or 10 days. Blood samples were collected at 0800 h before fasting, on the 3rd and 7th days during the fast (with an additional sample taken on the 10th day when the fasting continued for 10 days) and on the 3rd and 7th days of refeeding. We measured blood concentrations of orexin-A, NPY, leptin, adrenocorticotropin, cortisol, insulin, C-peptide, glucose, and beta-hydroxybutyrate.
  
  
  RESULTS
  Body mass index and plasma leptin concentrations concomitantly and significantly decreased during fasting, whereas serum orexin-A concentrations significantly increased and were negatively correlated with plasma leptin concentrations. Plasma NPY concentrations decreased slightly but were not significantly different from the prefasting values, and no significant relationship with leptin or orexin-A was found. Orexin-A and leptin concentrations showed a significant inverse correlation with serum glucose, insulin, C-peptide, and beta-hydroxybutyrate concentrations. Only changes in plasma leptin concentrations showed a significant negative correlation with serum cortisol concentrations. All the measured indices which changed during fasting returned to the prefasting concentrations by the 7th day of refeeding.
  
  
  CONCLUSIONS
  Peripheral orexin-A and leptin concentrations inversely change during fasting, which is significantly correlated with energy metabolism in humans.
authors.affiliation: Division of Psychosomatic Research, National Institute of Mental Health, National Center of Neurology and Psychiatry, Ichikawa, Japan. komaki@ncnp-k.go.jp
authors.forename: G
authors.initials: G
authors.lastname: Komaki
authors.forename: Y
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: H
authors.initials: H
authors.lastname: Nishikata
authors.forename: K
authors.initials: K
authors.lastname: Kawai
authors.forename: T
authors.initials: T
authors.lastname: Nozaki
authors.forename: M
authors.initials: M
authors.lastname: Takii
authors.forename: H
authors.initials: H
authors.lastname: Sogawa
authors.forename: C
authors.initials: C
authors.lastname: Kubo
mesh_terms: D000293:Adolescent; D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D015992:Body Mass Index; D002352:Carrier Proteins / Q000097:blood*; D005215:Fasting / Q000097:blood*; D005260:Female; D006728:Hormones / Q000097:blood; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D020738:Leptin / Q000097:blood*; D008875:Middle Aged; D009478:Neuropeptide Y / Q000097:blood; D009479:Neuropeptides / Q000097:blood*; D018377:Neurotransmitter Agents / Q000097:blood*; D000068797:Orexins
chemical_list: D001786:Blood Glucose; D002352:Carrier Proteins; C000596229:HCRT protein, human; D006728:Hormones; D047908:Intracellular Signaling Peptides and Proteins; D020738:Leptin; D009478:Neuropeptide Y; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D000068797:Orexins