ORAL-ADMINISTRATION OF DEUTERIUM-LABELED POLYAMINES TO SUCKING RAT PUPS - LUMINAL UPTAKE, METABOLIC-FATE AND EFFECTS ON GASTROINTESTINAL MATURATION

Non-physiological amounts of oral polyamines have been reported to ind uce precocious gut maturation in rat pups. The aim of the present stud y was to investigate organ distribution and metabolic fate of orally a dministered stable-isotopically labelled polyamines in rat pups. Pups received tetradeuterium-labelled putrescine (Pu-d4; 3 mu mol), spermid ine (Sd-d4; 5 mu mol), spermine (Sp-d4; 3 mu mol), or physiological sa line twice daily on postnatal days 7-10 or 12-15. They were killed on days 10 and 15. We determined activities of ileal lactase (EC 3.2.1.23 ), maltase (EC 3.2.1.20), sucrase (EC 3.2.1.48) and diamine oxidase (E C 1.4.3.6) and established villus and crypt lengths. Polyamines and th eir labelling percentages in organs were determined by GC and mass fra gmentography. Treatments did not affect growth rate, but caused lower weights of liver, kidneys and heart. Maltase activity increased, lacta se decreased, whereas sucrase and diamine oxidase did not change. Vill us and crypt Lengths increased. Organ polyamine pools were labelled to different extents. Irrespective of the orally administered polyamine, all organs contained Pu-d4, Sd-d4 and Sp-d4. Administered Pu-d4 and S d-d4 were recovered mainly as Sd-d4, whereas Sp-drl was recovered as S p-d4 and Sd-d4. Total polyamines in a caecum, colon and erythrocytes i ncreased, but increases were only to a minor extent with regard to lab elled polyamines. Our data confirm precocious gut maturation by exogen ous polyamines. Putrescine appears to be the limiting factor. The exog enous polyamines were distributed among all investigated organs. They are not only used for the synthesis of higher polyamines, but also ret roconverted to their precursors. Changes in erythrocyte polyamine cont ents suggest precocious stimulation of erythropoiesis.