title: Peptide absorption after massive proximal small bowel resection: mechanisms of ileal adaptation.
abstract: BACKGROUND
  Protein absorption occurs as di- and tri-peptides via H(+)/peptide co-transporter-1 (PepT1).
  
  
  OBJECTIVE
  The aim of this study is to identify mechanisms of ileal adaptation after massive proximal enterectomy.
  
  
  OBJECTIVE
  Ileal adaptation in uptake of peptides is mediated through upregulation of PepT1 gene expression.
  
  
  METHODS
  Rats underwent 70% jejunoileal resection. Total mucosal cellular levels of messenger RNA (mRNA) and protein and transporter-mediated uptake per centimeter of the di-peptide glycyl-sarcosine (Gly-Sar) were compared in remnant ileum 1 and 4 weeks postoperatively to control and to 1-week sham laparotomy rats. Histomorphology, food consumption, and weights of rats were monitored.
  
  
  RESULTS
  After 70% resection, although mRNA per cell for PepT1 decreased at 1 week (p = 0.002), expression of mRNA at 4 weeks and protein at 1 and 4 weeks in remnant ileum were unchanged (p > 0.1). Ileal Gly-Sar uptake (V (max)-nanomoles per centimeter per minute, i.e., number of transporters per centimeter) increased at 1 and 4 weeks compared to control and 1-week sham (p < 0.05 each); K (m) (i.e., transporter function) was unchanged. Villous heights (millimeters) in remnant ileum increased at 1- and 4-week time points over controls (0.45 and 0.57 vs 0.21, resp; p < 0.001).
  
  
  CONCLUSIONS
  Ileal adaptation to proximal resection for peptide absorption occurs through cellular proliferation (hyperplasia) and not through cellular upregulation of PepT1 mRNA or protein per enterocyte.
authors.affiliation: Gastroenterology Research Unit and Department of Surgery, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
authors.forename: Hisham G
authors.initials: HG
authors.lastname: Qandeel
authors.forename: Fernando
authors.initials: F
authors.lastname: Alonso
authors.forename: David J
authors.initials: DJ
authors.lastname: Hernandez
authors.forename: Srivats
authors.initials: S
authors.lastname: Madhavan
authors.forename: Judith A
authors.initials: JA
authors.lastname: Duenes
authors.forename: Ye
authors.initials: Y
authors.lastname: Zheng
authors.forename: Michael G
authors.initials: MG
authors.lastname: Sarr
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D049109:Cell Proliferation; D003106:Colon / Q000378:metabolism; D004151:Dipeptides / Q000493:pharmacokinetics; D004386:Duodenum / Q000601:surgery; D020895:Enterocytes / Q000378:metabolism*; D007082:Ileum / Q000033:anatomy & histology / Q000378:metabolism* / Q000601:surgery; D007408:Intestinal Absorption; D007583:Jejunum / Q000601:surgery; D008297:Male; D000074011:Peptide Transporter 1; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D018709:Statistics, Nonparametric; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D013997:Time Factors; D015430:Weight Gain
chemical_list: D004151:Dipeptides; D000074011:Peptide Transporter 1; D012333:RNA, Messenger; C489940:Slc15a1 protein, rat; D027981:Symporters; C004194:glycylsarcosine