Alanyl-Glutamine Dipeptide-Supplemented Parenteral Nutrition Improves Intestinal Metabolism and Prevents Increased Permeability in Rats

Abstract

ObjectiveThe authors determined the effects of alanyl-glutamine-supplemented total parenteral nutrition (TPN) on niucosal metabolism, integrity, and permeability of the small intestine in rats. MethodsMale Sprague-Dawley rats were randomized to receive TPN supplemented with a conventional amino acids mixture (STD group) or the same solution supplemented with alanyl-glutamine; both solutions were isocaloric and isonitrogenous. On the seventh day of TPN, D-xylose and fluorescein isothiocyanate (FITC)-dextran were administered orally. One hour later, superior mesenteric vein (SMV) D-xylose and plasma FITC-dextran concentration were measured.Intestinal blood flow and calculated intestinal substrates flux were measured with ultrasonic transit time flowmetery. ResultsPlasma FITC-dextran increased significantly in the STD group. Intestinal blood flow and SMV Dxylose concentration did not differ between the groups. Mucosal weight, villus height, mucosal wall thickness, mucosal protein, and DNA and RNA content in jejunal mucosa were significantly increased in the alanyl-glutamine group. Jejunal mucosal glutaminase activity and net intestinal uptake of glutamine (glutamine flux) were significantly higher in the alanyl-glutamine group as compared with the STD group. ConclusionAddition of alanyl-glutamine dipeptide to the TPN solution improves intestinal glutamine metabolism and prevents mucosal atrophy and deterioration of permeability. 334

Protective effects of alanyl-glutamine supplementation against nelfinavir-induced epithelial impairment in IEC-6 cells and in mouse intestinal mucosa

“…Alanyl-glutamine (AQ) is more stable, soluble and well tolerated and has been shown to be at least as effective as glutamine in intestinal injury repair in vitro, in vivo and in patients. [17][18][19][20][21][22][23][24] Our group has demonstrated that AQ or glutamine supplementation given to patients on HAART, decreased diarrhea rates and increased antiretroviral serum concentration, indirectly indicating improvement of the intestinal epithelial function. 21 Similarly, a clinical trial demonstrated that AQ supplementation ameliorated clinical symptoms of gastrointestinal toxicity in patients on chemotherapy.…”

Glutamine and Whey Protein Improve Intestinal Permeability and Morphology in Patients with Crohn’s Disease: A Randomized Controlled Trial

“…Glutamine serves as the principle fuel and nitrogen source for the enterocytes. In a number of experimental studies [17,18,20,23] both enteral and parenteral glutamine have been reported to improve IP, Data are expressed as mean ± standard deviation (SD) or median (range) and number (percentage) prevent bacterial translocation and reduce the endotoxin levels. Likewise, the positive effect of enteral/parenteral glutamine on the gut barrier function has been observed in a multiplicity of clinical conditions [12,[14][15][16]34]; however, the speculative benefits of glutamine on IP and morphology, described in the experimental models of colitis [35][36][37], lack corroboration in case of IBD.…”

“…The human intestine extracts approximately 13% of the circulating glutamine [11], which prevents intestinal hyperpermeability, bacterial translocation and maintains intestinal mucosal integrity in a variety of diseases [12][13][14][15][16]. The benefits of glutamine have been described in a number of experimental and human studies, using either enteral [17][18][19][20] or parenteral [21][22][23] glutamine. Glutamine exerts specific effects on the tight junction (TJ) proteins and influences the intracellular mediators thereby enhancing the TJ resistance [24].…”

Gut Glutamine Metabolism at Different Stages of Sepsis in Rats

“…10,11 In fact, our previous study revealed that glutamine-supplemented parenteral nutrition increased the arterial-SMV concentration difference for glutamine in nonseptic rats, without causing any alterations in gut glutamine extraction. 34 However, only a few reports have documented the effects of glutamine supplementation on the small bowel during sepsis. Ardawi 35 investigated the effects of administering glutamine-supplemented TPN to septic rats and observed increased net uptake of glutamine by the small bowel, compared with septic rats treated with glutamine-free TPN.…”