title: Effects on glucagon-like peptide-1 secretion by distal ileal administration of nutrients.
abstract: BACKGROUND
  The aim of this study was to investigate the effects of nutrients (glucose, fat, and amino acid) on glucagon-like peptide-1 (GLP-1) secretion by the L cell in the distal ileum and insulin level in peripheral blood.
  
  
  METHODS
  Ninety-six Wistar rats were randomly allocated into 12 groups, with 8 rats in each group: glucose-10 cm, glucose-15 cm, glucose-20 cm, fat-10 cm, fat-15 cm, fat-20 cm, amino acid-10 cm, amino acid-15 cm, amino acid-20 cm, control-10 cm, control-15 cm, and control-20 cm. Blood samples were collected at 0, 30, 60, 90, and 120 min after in vivo distal ileal perfusion of nutrients or normal saline (control groups). Blood glucose level was assessed by a handheld glucometer. Plasma GLP-1 and insulin level were evaluated by ELISA. GLP-1 level was also evaluated by immunohistochemistry analysis of GLP-1 expression in ileal mucosa and scanning electron microscope analysis of ultrastructural changes of L cells.
  
  
  RESULTS
  Under administration of nutrients in the distal ileum of equal length, GLP-1 levels were greatest for fat, then glucose, and then amino acid (the peak concentration of GLP-1 in the fat-10 cm group, the glucose-10 cm group, the amino acid-10 cm group, and the control-10 cm group was 29.76 ± 1.32, 28.54 ± 1.29, 26.30 ± 1.26, and 22.52 ± 1.22 pmol/L, respectively, with p < 0.05). Under administration of nutrients in the distal ileum of equal length, insulin levels were also greatest for fat, then glucose, and then amino acid (the peak concentration of insulin in the fat-10 cm group, the glucose-10 cm group, the amino acid-10 cm group, and the control-10 cm group was 30.10 ± 1.33, 27.17 ± 1.27, 22.98 ± 1.31, and 12.40 ± 1.11 mU/L, respectively, with p < 0.05). Under administration of the same nutrients, the longer the distal ileum was stimulated, the greater the GLP-1 and insulin levels.
  
  
  CONCLUSIONS
  Long distal ileal administration of fat more efficiently stimulated GLP-1 secretion, resulting in enhanced insulin secretion.
authors.affiliation: Department of Biliary, Herniary, and Obesity Surgery, Affiliated Shengjing Hospital of China Medical University, 36 Sanhao Street, Shenyang, 110004, China, doodoo.von@sohu.com.
authors.forename: Xiao
authors.initials: X
authors.lastname: Feng
authors.forename: Shuzhe
authors.initials: S
authors.lastname: Zhong
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Jingang
authors.initials: J
authors.lastname: Liu
mesh_terms: D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism / Q000601:surgery*; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism / Q000601:surgery*; D004041:Dietary Fats / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D015390:Gastric Bypass / Q000379:methods; D052216:Glucagon-Like Peptide 1 / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D007082:Ileum / Q000378:metabolism*; D007274:Injections, Intraperitoneal; D007328:Insulin / Q000097:blood / Q000378:metabolism; D000078790:Insulin Secretion; D007413:Intestinal Mucosa / Q000378:metabolism*; D007739:L Cells; D008297:Male; D051379:Mice; D010446:Peptide Fragments; D051381:Rats; D017208:Rats, Wistar
chemical_list: D004041:Dietary Fats; D007328:Insulin; D010446:Peptide Fragments; D052216:Glucagon-Like Peptide 1; D005947:Glucose