Maturation of villus and crypt cell functions in rat small intestine

Abstract

To evaluate the role of dietary polyamines in maturation of the rat small intestine, spermine was given orally twice daily to suckling pups from day 10 to day 14 postpartum at different doses: 0, 0.2, 0.5, 1, 2.5, and 5 μmol/dose. Compared, to saline treated controls, spermine (5 μmol) produced significant increases in mucosal mass parameters (+12 to +57%,P<0.05), induced prematurely, an adult pattern of microvillous enzymes, and enhanced respectively, by 19- and 3.5-fikd (P<0.01 vs controls) the concentration of the secretory component ofp-immunoglobulins in villous and crypt cells. The response of microvillous enzymes (lactase, sucrase, maltase, and aminopeptidase) to spermine was dose-dependent and-specific since oral administration of arginine (5 μmol) or ornithine (5 μmol) was without effect. Intestinal changes were found to be significant (P<0.05) for doses of spermine exceeding 1 μmol/day, which is in the range of the amount of polyamines provided by solid pellets at weaning (0.4 μmol/g). However, intestinal changes were undetectable at the physiological amounts of polyamines consumed by pups from rat milk during the suckling period (less than 0.3 μmol/day). Consistent with a direct effect of spermine on the intestinal cell, the cytosolic activity of ornithine decarboxylase was depressed by 27-fold (P<0.005 vs controls) in the jejunum, while inhibition of ornithine decarboxylase by α-difluoromethylornithine did markedly decrease but did not suppress the cell response to spermine. Alternately, plasma corticosteronemia, which was virtually, absent by day 14 in controls, ranged between 1.4 and 4.6 μg/dl in 60% (N=9) of the spermine-treated rats. These novel findings indicate that dietary polyamines exert direct and indirect trophic effects on the rat immature intestine and can trigger at a critical level of intake the adult expression of villus and crypt cell functions.