PROLONGED ZINC-DEFICIENT DIET ALTERS ALKALINE-PHOSPHATASE AND DISACCHARIDASE ACTIVITIES AND INDUCES MORPHOLOGICAL-CHANGES IN THE INTESTINE OF RATS

Effects of zinc deficiency on intestinal disaccharidase remain controv ersial. This study investigated the effects of a prolonged zinc-defici ent diet on selected intestinal enzyme activities and morphology. Twen ty-four Sprague-Dawley rats were randomly divided into zinc-deficient, pair-fed, and ad libitum control group and fed respective diet for 7 weeks. Alkaline phosphatase and disaccharidase (maltase, sucrase, lact ase) activities in jejunal and ileal mucosa as well as in feces were m easured. Morphological changes were examined under the microscope at t he end of the experiment. The activity of intestinal alkaline phosphat ase was lower in zinc-deficient and pair-fed groups than that in ad li bitum control group. Time-dependent decrease in activity of alkaline p hosphatase in feces was more apparent in zinc-deficient group than tha t in the other two groups. The maltase and sucrase activities decrease d in jejunal but not in ileal mucosa in zinc-deficient group. The malt ase activity in feces decreased during the final 2 weeks of the experi ment, but the sucrase and lactase activities did not in zinc-deficient group. The activity of disaccharidase in intestinal mucosa and in fec es did not decrease (even increased in jejunal mucosa), although zinc content in the tissues or the excretion slightly decreased in pair-fed control group. The decreased villus height and crypt depth, flawed br ush border were observed in jejunum and ileum of zinc deficient group. The data indicate that administration of zinc-deficient diet resulted in decreased activity of alkaline phosphatase and maltase and induced morphological changes in the intestine and time-related decrease of m altase activity in feces of rats. (C) 1996 Wiley-Liss, Inc.