Induction of precocious intestinal maturation in T-cell deficient athymic neonatal rats

AIM To investigate whether gut maturation could be induced precociously in an athymic T-cell deficient neonatal rat model.METHODS Fourteen day-old athymic(nude) rats(NIH-Foxn 1 rnu) were gavaged with either phytohaemagglutinin-a lectin from red kidney beans(PHA); trypsin-a protease(Prot); or water-vehicle(control) as a single dose on one day or once a day for 3-day. The nude rats were either nurtured by their mothers or cross-fostered by conventional foster dams of the Sprague-Dawley strain from days 3-5 after birth. At 17 d of age, 72 h after administration of the first treatment, intestinal macromolecular permeability was tested in vivo, prior to euthanasia, after which blood and gut organs were sampled.RESULTS Provocation with both, PHA and protease, resulted in increased gut growth and maturation in nude rat pupsindependent of nursing. Foetal-type enterocytes were replaced by non-vacuolated adult-type enterocytes in the distal small intestine epithelium. Decreased intestinal macromolecular permeability(gut closure) was observed, with reduced permeability markers(BIg G and BSA, P < 0.001) in circulation. Increased pancreatic function, with an increased trypsin to protein ratio in pancreas homogenates, was observed independent of nursing in the nude pups. Immunostaining showed the presence of a few CD3^+-cells in the intestinal mucosa of the nude pups. The number of CD3+-cells remained unaltered by provocation and no differences were observed between the nursing sets. Growth and vitality of the nude pups were dependent on nurturing, since cross-fostering by conventional dams increased their macromolecular absorptive capacity(BSA, P < 0.05), as well as their passive immunity(RIg G, P < 0.05).CONCLUSION Precocious gut maturation can be induced by enteral provocation in athymic rat pups, similarly to in euthymic pups, thus showing an independence from thymusderived T-cells.