title: Diet composition affects surgery-associated weight loss in rats with a compromised alimentary tract.
abstract: BACKGROUND
  Esophageal adenocarcinoma (EAC) is the fastest growing cancer in terms of incidence and has a high mortality rate. The animal model to study EAC uses esophagoduodenal anastomosis (EDA) to induce mixed-reflux (bile/acid) causing esophagitis, Barrett's esophagus, and EAC sequence within 6 mo. However, the lack of fully functional stomach in these rats leads to the development of malnutrition.
  
  
  METHODS
  We have assessed the ability of a chemically pure, purified ingredient diet (AIN-93M) to reduce surgery-associated malnutrition in rats that have undergone the EDA-surgery. Animals were either sham- (SH) or EDA-operated and fed either a grain-based rodent diet (RD) (SH-RD, n=3; EDA-RD, n=10) or a purified diet (PD) (SH-PD, n=4; EDA-PD, n=11). The animals were weighed periodically for assessment of weight gain and euthanized at the end of 24 wk to measure esophageal tumor incidence.
  
  
  RESULTS
  Animals that underwent sham surgery continued to gain weight throughout the study period and no tumors were detected. The EDA-operated animals had significantly lower weight gain compared with sham animals. There was no significant difference in weight gain among EDA animals fed two different types of diets until 9 wk after the surgery. After 9 wk, EDA-RD continued to lose weight significantly, whereas the weight loss leveled in EDA-PD (P<0.001). At termination, neither tissue histopathology nor tumor incidence was significantly different between the groups.
  
  
  CONCLUSIONS
  These results show that compared with a natural ingredient diet, a purified ingredient diet can reduce surgery-associated weight loss in rats with a compromised alimentary tract. This reduction in malnutrition has the potential to reduce the confounding effects of weight loss on future animal studies reported.
authors.affiliation: Division of Surgical Oncology, Department of Surgery, University of Louisville School of Medicine, Louisville, Kentucky 40202, USA.
authors.forename: Harini S
authors.initials: HS
authors.lastname: Aiyer
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Robert C G
authors.initials: RC
authors.lastname: Martin
mesh_terms: D000230:Adenocarcinoma / Q000517:prevention & control; D000714:Anastomosis, Surgical / Q000009:adverse effects* / Q000379:methods*; D000818:Animals; D004064:Digestive System / Q000503:physiopathology*; D004386:Duodenum / Q000601:surgery; D004938:Esophageal Neoplasms / Q000517:prevention & control; D004947:Esophagus / Q000601:surgery; D005526:Food, Formulated; D008297:Male; D044342:Malnutrition / Q000209:etiology / Q000503:physiopathology; D023421:Models, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D015431:Weight Loss / Q000502:physiology*