Induced growth and maturation of the gastrointestinal tract after Phaseolus vulgaris lectin exposure in suckling rats.

OBJECTIVES In mammals, the postnatal development of the gastrointestinal tract is characterized by vast structural and functional changes. Using a suckling rat model, we investigated whether red kidney bean lectin, phytohemagglutinin (PHA), a potent gut mitogen in adult rats, can accelerate the growth and maturation of the gastrointestinal tract. METHODS At either 10 or 14 days of age, suckling rats were daily gavage fed with PHA (0.05 mg/g body weight) or saline for 3 days. At 1 or 3 days after this treatment, gastrointestinal organ growth, intestinal morphology, disaccharidase pattern, macromolecular absorption capacity, and pancreatic enzyme contents were studied. RESULTS After PHA exposure, increased small intestinal growth and number of crypt cells were observed, whereas the proportion of enterocytes with supranuclear vacuoles in the distal intestine was decreased. The macromolecular absorption of the markers bovine immunoglobulin (Ig)G and bovine serum albumin and plasma levels of maternal IgG decreased, and intestinal disaccharidases switched toward an adult-like pattern. The pancreas weight and pancreatic protein and trypsin contents increased. These changes were partly reversible when the PHA treatment began at 10 days of age, but they persisted when the treatment began at 14 days of age. CONCLUSIONS PHA induced enhanced growth and precocious functional maturation of the gastrointestinal tract in suckling rats. The effects persisted if the PHA treatment started at 14 days of age, but not before, suggesting an age dependent mechanism. These findings may lead to a better understanding of gastrointestinal maturation and constitute a basis for the treatment of mammals having an immature gut.