Luminal factors stimulate intestinal repair during the refeeding of malnourished infant rabbits

We examined the role of luminal versus systemic factors in promoting intestinal recovery during the refeeding of previously malnourished infant rabbits. Malnutrition was induced by litter expansion at 7 days of age. A 20-cm Thirty-Vella (T-V) loop was created in the intestine of each malnourished and dietary control animal at 21 days of age. Beginning on day 28, controls and one half of the malnourished group (malnourished-refed) were fed chow ad libitum, whereas the remainder of the malnourished group received half the amount of chow given to the malnourished-refed group. On day 35, proximal and distal segments from the intact intestine that remained in continuity as well as segments from the excluded T-V loops were examined. Malnutrition severely reduced mucosal mass and disaccharidase activities in the intact distal intestine. A brief period of refeeding led to a rapid recovery of these parameters. In contrast, the excluded T-V loop segments of the control, malnourished, and malnourished-refed groups all displayed decreased mucosal mass and impaired function to a degree similar to that observed in the intact distal segment from the malnourished group. These results indicate that luminal factors are essential for (i) the maintenance of normal intestinal structure and function in infant rabbits and (ii) the promotion of mucosal repair following nutritional rehabilitation of malnourished animals.