Intravenous or luminal amino acids are insufficient to maintain pancreatic growth and digestive enzyme expression in the absence of intact dietary protein

Megan D. Baumler, Matthew Koopman, Diana D.H. Thomas, Denise M. Ney, Guy E. Groblewski

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

We previously reported that rats receiving total parenteral nutrition (TPN) undergo significant pancreatic atrophy characterized by reduced total protein and digestive enzyme expression due to a lack of intestinal stimulation by nutrients (Baumler MD, Nelson DW, Ney DM, Groblewski GE. Am J Physiol Gastrointest Liver Physiol 292: G857-G866, 2007). Essentially identical results were recently reported in mice fed protein-free diets (Crozier SJ, D'Alecy LG, Ernst SA, Ginsburg LE, Williams JA. Gastroenterology 137: 1093-1101, 2009), provoking the question of whether reductions in pancreatic protein and digestive enzyme expression could be prevented by providing amino acids orally or by intravenous (IV) infusion while maintaining intestinal stimulation with fat and carbohydrate. Controlled studies were conducted in rats with IV catheters including orally fed/saline infusion or TPN-fed control rats compared with rats fed a protein-free diet, oral amino acid, or IV amino acid feeding, all with oral carbohydrate and fat. Interestingly, neither oral nor IV amino acids were sufficient to prevent the pancreatic atrophy seen for TPN controls or protein-free diets. Oral and IV amino acids partially attenuated the 75-90% reductions in pancreatic amylase and trypsinogen expression; however, values remained 50% lower than orally fed control rats. Lipase expression was more modestly reduced by a lack of dietary protein but did respond to IV amino acids. In comparison, chymotrypsinogen expression was induced nearly twofold in TPN animals but was not altered in other experimental groups compared with oral control animals. In contrast to pancreas, protein-free diets had no detectable effects on jejunal mucosal villus height, total mass, protein, DNA, or sucrase activity. These data underscore that, in the rat, intact dietary protein is essential in maintaining pancreatic growth and digestive enzyme adaptation but has surprisingly little effect on small intestinal mucosa.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume299
Issue number2
DOIs
StatePublished - Aug 1 2010
Externally publishedYes

Fingerprint

Dietary Proteins
Protein-Restricted Diet
Total Parenteral Nutrition
Amino Acids
Enzymes
Growth
Atrophy
Fats
Chymotrypsinogen
Carbohydrates
Trypsinogen
Sucrase
Proteins
Gastroenterology
Intestinal Mucosa
Amylases
Lipase
Intravenous Infusions
Pancreas
Catheters

Keywords

  • Acinar cells
  • Pancreatic adaptation
  • Protein malnutrition
  • Total parenteral nutrition

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

Cite this

Intravenous or luminal amino acids are insufficient to maintain pancreatic growth and digestive enzyme expression in the absence of intact dietary protein. / Baumler, Megan D.; Koopman, Matthew; Thomas, Diana D.H.; Ney, Denise M.; Groblewski, Guy E.

In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 299, No. 2, 01.08.2010.

Research output: Contribution to journalArticle

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