Effects of Glutamine-Enriched Parenteral Nutrition on the Exocrine Pancreas

Total parenteral nutrition (TPN) is associated with intestinal and pancreatic atrophy and pancreatic exocrine insufficiency. Recent investigations have demonstrated that the addition of glutamine to intravenous feedings attenuates TPN-associated intestinal atrophy. However, the effect of glutamine-supplemented intravenous feedings on the pancreas of intact animals is unknown. This study compared the effects of an intravenous infusion of a 2% glutamine-enriched diet (GLN) with an isonitrogenous, isocaloric diet without glutamine (CONT) on the composition and structure of the exocrine pancreas in laboratory rats with and without a 60% small bowel resection. In nonresected, TPN-fed animals, pancreatic weight was significantly increased in the GLN group when compared to CONT (645 ± 33 g us 554 ± 20 g, p < 0.05). Nonresected GLN animals also had increased pancreatic DNA (3.82 ± 0.19 mg us 2.91 ± 0.49 mg, p < 0.005) and protein contents (93.0 ± 5.9 mg us 76.6 ± 7.0 mg, p = 0.08) compared to control. Similar significant increases in pancreatic weight, DNA, and protein were observed in intestinally resected animals fed the glutamine diet. When data from CONT and GLN animals were pooled and analyzed together, glutamine significantly increased total pancreatic trypsinogen and lipase contents (p < 0.05). The increase in trysinogen in resected GLN animals was significantly greater than in CONT animals (283 ± 22 us 139 ± 23, p < 0.005). Biochemical and morphometric observations demonstrated that the trophic effects of glutamine on the exocrine pancreas were manifest by acinar hyperplasia and not hypertrophy. Glutamine appears to be an important nutrient for pancreatic exocrine tissue during TPN. The trophic effect of glutamine on the pancreas may have important clinical relevance in reversing or attenuating pancreatic atrophy and insufficiency during intravenous feeding.