INFLUENCE OF THE POLYAMINE, SPERMIDINE, ON INTESTINAL MATURATION AND DIETARY ANTIGEN UPTAKE IN THE NEONATAL RAT

Polyamines appear to have an important role in postnatal growth of the rat intestine. In the present study, we examined the effect of spermi dine on the maturation of the intestine and on its ability to exclude macromolecules. Two litters of Sprague-Dawley rat pups were assigned t o one of four experimental groups. These groups received, on Days 7, 8 , and 9, either (a) saline by gavage; (b) spermidine, 0.9 mg (6 mumol) by gavage; (c) cortisone acetate, 3.5 mg i.p.; or (d) saline i.p. On Day 10, animals were fed by gavage with a mixture of bovine serum albu min (BSA; 2 mg/g) and the gamma-globulin fraction of mouse antiovalbum in (anti-OVA) antiserum (1 mg/g) and were bled 4 h later. Intestinal t issues were processed for histologic examination, sucrase determinatio n, and identification of neonatal intestinal Fc receptor (FcRn) by Wes tern blot. Serum immunoreactive BSA (iBSA) and mouse IgG1 and IgG2a an ti-OVA antibodies were estimated by enzyme-linked immunosorbent assay. Sucrase activity was elevated in cortisone- and spermidine-treated co mpared to control rats. iBSA and anti-OVA were significantly reduced i n cortisone-treated compared to control rats but were not diminished s ignificantly in the spermidine-treated animals. A decrease in the neon atal intestinal Fc receptor was apparent in the spermidine-fed group; cortisone produced a large reduction in FcRn. Spermidine-fed animals s howed morphologic evidence of maturation, with loss of giant vacuoles in the distal intestine; cortisone did not produce significant changes in morphology. Thus, while spermidine, like cortisone, enhanced the a ppearance of the disaccharidase sucrase, it did not significantly redu ce the uptake of BSA or IgG, which is usually observed in mature compa red to immature animals. The reason for this dichotomy is not known.