title: Decreased plasma orexin-A levels in obese individuals.
abstract: Orexin-A and -B stimulate appetite and food intake in rats. Orexins and orexin receptors are present in the hypothalamus as well as the enteric nervous system, the pancreas and the gut. The presence of orexins in peripheral blood, however, has not yet been reported. To determine whether orexin-A is present in human plasma and is related to body weight, we measured plasma orexin-A and leptin levels in a population with a body mass index (BMI) range from 19.8 to 59 kg/m(2). Plasma orexin-A levels correlated negatively and plasma leptin levels correlated positively with BMI. In obese and morbidly obese individuals, orexin-A levels were significantly lower and leptin levels were significantly higher when compared to normal. Our results support previous data suggesting that orexin-A acts also in a peripheral manner. The fact that lower levels of plasma orexin-A are present in obese individuals suggests that it is involved in the regulation of human energy metabolism.
authors.affiliation: Nutrition and Toxicology Institute Maastricht (NUTRIM), Department of General Surgery, Maastricht University, Maastricht, The Netherlands.
authors.forename: J A
authors.initials: JA
authors.lastname: Adam
authors.forename: P P C A
authors.initials: PP
authors.lastname: Menheere
authors.forename: F M H
authors.initials: FM
authors.lastname: van Dielen
authors.forename: P B
authors.initials: PB
authors.lastname: Soeters
authors.forename: W A
authors.initials: WA
authors.lastname: Buurman
authors.forename: J W M
authors.initials: JW
authors.lastname: Greve
mesh_terms: D015992:Body Mass Index; D002352:Carrier Proteins / Q000097:blood*; D016022:Case-Control Studies; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D020738:Leptin / Q000097:blood; D009479:Neuropeptides / Q000097:blood*; D009765:Obesity / Q000097:blood / Q000378:metabolism*; D000068797:Orexins
chemical_list: D002352:Carrier Proteins; C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D020738:Leptin; D009479:Neuropeptides; D000068797:Orexins