Effects of parenteral nutrition supplemented with alanyl-glutamine on nutrition status in rats

Glutamine, a nonessential amino acid, has received increasing attention because it becomes essential during stress and catabolic conditions. Many investigations have shown that during severe stress, the consumption of glutamine exceeds glutamine synthesis, resulting in depletion of glutamine stores. The aim of this study was to evaluate the effects of supplementing parenteral diets with a glutamine-containing dipeptide, L-alanyl-L-glutamine, on rat nutrition status.

Male Wistar rats were used. Animals (n = 36) were centrally catheterized and randomly assigned to 1 of the following groups based on method of parenteral nutrition (PN): control group with oral nutrition and IV infusion of a saline solution; standard parenteral nutrition (SPN) group; or alanyl-glutamine-supplemented PN (ALA-GLN PN) group (20 g/L). Parenteral nutrition was isocaloric and isonitrogenous. Infusions were administered at a rate of 2.0 mL/h over 5 days. Nutrition status was assessed by body weight change, plasma proteins, accumulated urinary creatinine, and nitrogen balance.

Accumulated urinary creatinine increased significantly after day 4 in the ALA-GLN PN group, compared with the SPN group and the controls. Body weight change significantly differed on day 5 between the ALA-GLN PN and SPN groups. After 3 days, nitrogen balance was significantly lower and nitrogen retention higher in the ALA-GLN PN group when compared with the SPN group. Albumin and transferrin concentrations decreased significantly in the SPN group, but did not differ from the controls in the ALA-GLN PN group.

Weight, plasma proteins, urinary accumulated creatinine, and nitrogen retention showed a better evolution in the group supplemented with the glutamine dipeptide when compared with the SPN group. Our results suggest a more suitable nutrition support in animals receiving L-alanyl-L-glutamine.