Glycyl-glutamine-supplemented long-term total parenteral nutrition selectively improves structure and function in heterotopic small-bowel autotransplantation in the pig

Marked atrophy and impaired absorptive and barrier function occur in transplanted small intestinal graft during total parenteral nutrition (TPN), TPN is required by all the patients after small bowel transplantation (SBT). Glutamine (Gln) is a conditional indispensable amino acid that is not included in regimens for parenteral nutrition because of its chemical instability in aqueous solution. Glutamine-containing dipeptide, however, is heat-stable. With this study, we determine whether the glycyl-glutamine-supplemented long-term TPN improves mucosal structure and function in heterotopic transplanted small intestinal graft in the pig. Ten outbred pigs, randomly divided into two groups, underwent heterotopic small bowel autotransplantation. In the STPN group, the animals received standard TPN without glycyl-glutamine (Gly-Gln) and in the GTPN group, the animals received isonitrogenous (0.3g kg day(-1)) and isocalories (nonprotein calories, 30 kcal kg day(-1)) TPN with Gly-Gln (3% Gln) for 28 days. At the end of TPN, there was no significant difference in the body weight loss between two groups (P>0.05). The mucosal contents of Gln and protein were significantly higher in the GTPN group than in the STPN group (P<0.05). The mucosal disaccharidase activities in the homogenate of the graft mucosa of the GTPN group were significantly higher than that of the STPN group (P<0.05). The villous height, surface area, mucosal thickness were significantly higher in the GTPN group than in the STPN group (P<0.05). There was no significant difference in crypt depth between the two groups (P>0.05). These results suggest that glycyl-glutamine-supplemented long-term TPN improves graft mucosal structure in heterotopic autotransplanted small bowel grafts in the pig. Long-term (4 weeks) TPN supplemented with Gln could alleviate small intestinal graft atrophy, but could not completely eliminate atrophy.