MATURATION OF VILLUS AND CRYPT CELL FUNCTIONS IN RAT SMALL-INTESTINE - ROLE OF DIETARY POLYAMINES

To evaluate the role of dietary polyamines in maturation of the rat sm all 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 mumol/dose. Compared to saline treated controls, spermine ( 5 mumol) produced significant increases in mucosal mass parameters (+1 2 to +57%, P < 0.05), induced prematurely an adult pattern of microvil lous enzymes, and enhanced, respectively, by 19- and 3.5-fold (P < 0. 01 vs controls) the concentration of the secretory component of p-immu noglobulins in villous and crypt cells. The response of microvillous e nzymes (lactase, sucrase, maltase, and aminopeptidase) to spermine was dose-dependent and -specific since oral administration of arginine (5 mumol) or ornithine (5 mumol) was without effect. Intestinal changes were found to be significant (P < 0.05) for doses of spermine exceedin g 1 mumol/day, which is in the range of the amount of polyamines provi ded by solid pellets at weaning (0.4 mumol/g). However, intestinal cha nges were undetectable at the physiological amounts of polyamines cons umed by pups from rat milk during the suckling period (less than 0.3 m umol/day). Consistent with a direct effect of spermine on the intestin al cell, the cytosolic activity of ornithine decarboxylase was depress ed by 27-fold (P < 0.005 vs controls) in the jejunum, while inhibition of ornithine decarboxylase by alpha-difluoromethylornithine did marke dly decrease but did not suppress the cell response to spermine. Alter nately, plasma corticosteronemia, which was virtually absent by day 14 in controls, ranged between 1. 4 and 4.6 mug/dl in 60% (N = 9) of the spermine-treated rats. These novel findings indicate that dietary pol yamines exert direct and indirect trophic effects on the rat immature intestine and can trigger at a critical level of intake the adult expr ession of villus and crypt cell functions.