Promotion of healing by orally administered glutamine in elemental diet after small intestinal injury by X-ray radiation.

Glutamine was administered orally to rats with damaged small intestinal mucosa as the result of injury by X-ray radiation at 10 Gy to the abdomen. The healing effects of glutamine on the injured mucosa were studied serially from the day of radiation (Day 0) to Day 4. The rats received two types of isocaloric elemental diet, Gln( + ) containing 2% glutamine and Gln( - ) containing no glutamine, by paired feeding. From Day 2 to Day 4, the wet weight, protein content, and DNA content of the jejunal mucosa were significantly greater in the Gln(+) than in the Gln(-) group. On Day 3, when the damage of the intestinal mucosa was the severest, the crypt cell production rate in the jejunum was significantly higher in the Gln(+) than in the Gln(-) group. The permeability of the intestinal mucosa to 51CrEDTA, administered to the rat stomach through an oro-gastric tube, remained significantly lower in the Gln( + ) group . Light microscopic findings showed that oedema in the lamina propria mucosae of jejunum and fusion of jejunal villi were milder in the Gln(+) group on Day 4. when the mucosal mass began to recover. The arterial and portal blood glutamine concentration, and glutamine extraction by the gut from arterial blood and phosphate-dependent glutaminase activity in the jejunal mucosa, were higher in the Gln(+) than in the Gln(--) group. Ornithine decarboxylase activity was increased in both the jejunum and the ileum from Day 3, but no difference was observed between the two groups. These findings suggest that, after X-ray radiation injury of the intestinal mucosa, the oral administration of the elemental diet containing 2% glutamine improved glutamine metabolism of the body, promoted the proliferation of jejunal epithelium, accelerated the recovery of the mucosal mass and the morphology of villi, and then contributed to maintaining the barrier function of the intestine from an early stage after the injury.