Effects of protein deprivation on growth and small intestine morphology are not improved by glutamine or glutamate in gastrostomy-fed rat pups.
OBJECTIVE
Critically ill neonates often have their enteral intake severely limited shortly after birth. Whether glutamine (Gln) or glutamate (Glu) can preserve intestinal structure and function in the neonate undergoing limited enteral feeding is not clear. We hypothesize that Gln and Glu can similarly preserve intestinal structure in the developing small intestine of infant rats fed a low protein diet.


METHODS
Using a gastrostomy-fed "pup-in-a-cup" rat model, the effects of Gln and Glu on the developing rat small intestine were examined. Four groups of 6- to 7-day-old pups were fed rat milk substitute (RMS) via gastrostomy tube. One group was provided 100% and three were provided 25% of the protein normally received from their mothers. Two of the groups fed 25% protein received additional Gln or Glu for 6 days.


RESULTS
Pups receiving the 100% protein RMS were larger than pups receiving the 25% protein RMS with or without Gln/Glu supplementation (P < 0.001). Average villus height (P < 0.01) and area (P < 0.01) were greater in pups receiving 100% protein RMS than in pups given 25% protein RMS formula. There was no significant difference among the groups in mucosal maltase or alkaline phosphatase activities. Tight junction protein claudin-1 was significantly higher in the group fed 100% protein RMS diet, while occludin did not differ among the 4 groups. Neither Gln nor Glu increased claudin-1 or occludin in rats fed 25% protein.


CONCLUSIONS
These results suggest that neither Gln nor Glu supplementation can substitute effectively for whole protein in the developing rat small intestine for the outcomes that were evaluated.
Li
Nan
N
Department of Pediatrics, University of Florida, College of Medicine, Gainesville, Florida, USA.
Lassman
Beth J
BJ
Liu
Zhiwei
Z
Liboni
Kellym
K
Neu
Josef
J
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development; D062445:Claudin-1; D004044:Dietary Proteins / Q000008:administration & dosage*; D004195:Disease Models, Animal; D005774:Gastrostomy; D018698:Glutamic Acid / Q000494:pharmacology*; D005973:Glutamine / Q000494:pharmacology*; D015151:Immunoblotting; D007413:Intestinal Mucosa / Q000187:drug effects / Q000254:growth & development / Q000473:pathology; D007421:Intestine, Small / Q000187:drug effects* / Q000254:growth & development* / Q000473:pathology; D008565:Membrane Proteins / Q000032:analysis; D062793:Occludin; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D019108:Tight Junctions; D015430:Weight Gain; D000520:alpha-Glucosidases / Q000378:metabolism
D062445:Claudin-1; C568114:Cldn1 protein, rat; D004044:Dietary Proteins; D008565:Membrane Proteins; D062793:Occludin; C568987:Ocln protein, rat; D005973:Glutamine; D018698:Glutamic Acid; D000469:Alkaline Phosphatase; D000520:alpha-Glucosidases