title: Peripheral endomorphin-1 levels are suppressed in diabetic patients.
abstract: BACKGROUND
  Endomorphins are endogenous ligands selective for mu-opioid receptors, which have been reported to stimulate appetite and regulate glucose homeostasis. But there are no reports about changes in peripheral endomorphin-1 (EM-1) levels in diabetic patients. The aim of this study was to measure plasma EM-1 levels in fasting and postprandial conditions in diabetic patients.
  
  
  METHODS
  After an overnight fast, 38 patients (mean age, 67+/-8 years; 17 males and 21 females) and 22 healthy volunteers (mean age, 64+/-9 years; 9 males and 13 females) received a standard breakfast meal with total energy content of 476.1kcal. Blood samples were drawn from each subject in heparinized tubes before breakfast and 2h postprandially. Plasma concentrations of EM-1 were measured by radioimmunoassay (RIA).
  
  
  RESULTS
  Comparing with healthy volunteers, EM-1 levels were significantly lower in diabetic patients at both time-points (fasting: 48.38+/-14.13pg/ml vs. 72.71+/-19.62pg/ml, p<0.0001; postprandial: 39.80+/-12.28pg/ml vs. 62.93+/-21.95pg/ml, p=0.0001). When compared with fasting levels, the postprandial concentrations of EM-1 decreased in both diabetic patients, as well as healthy controls. The absolute value of decrease was not significantly different between the two groups.
  
  
  CONCLUSIONS
  Peripheral EM-1 levels were suppressed in diabetic patients and the levels decreased postprandially in both diabetic and healthy volunteers. This implies that EM-1 concentration has correlation with the change in glucose level. Thus, EM-1 could play a role in energy metabolism.
authors.affiliation: Institute and Department of Endocrinology and Metabolism, Shanghai Ninth People's Hospital, Affiliated with Shanghai Jiaotong University School of Medicine, China.
authors.forename: Fang-zhen
authors.initials: FZ
authors.lastname: Xia
authors.forename: Ying-li
authors.initials: YL
authors.lastname: Lu
authors.forename: Yi
authors.initials: Y
authors.lastname: Chen
authors.forename: Ting
authors.initials: T
authors.lastname: Gu
authors.forename: Hui-xin
authors.initials: HX
authors.lastname: Zhang
authors.forename: Jiao
authors.initials: J
authors.lastname: Yu
authors.forename: Li-juan
authors.initials: LJ
authors.lastname: Zhao
mesh_terms: D000368:Aged; D001786:Blood Glucose / Q000378:metabolism; D003920:Diabetes Mellitus / Q000097:blood*; D004032:Diet; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009842:Oligopeptides / Q000097:blood*; D018579:Patient Selection; D019518:Postprandial Period; D011863:Radioimmunoassay; D012016:Reference Values
chemical_list: D001786:Blood Glucose; D009842:Oligopeptides; C105293:endomorphin 1