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 controversial. This study investigated the effects of a prolonged zinc-deficient diet on selected intestinal enzyme activities and morphology. Twenty-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, lactase) activities in jejunal and ileal mucosa as well as in feces were measured. Morphological changes were examined under the microscope at the end of the experiment. The activity of intestinal alkaline phosphatase was lower in zinc-deficient and pair-fed groups than that in ad libitum control group. Time-dependent decrease in activity of alkaline phosphatase in feces was more apparent in zinc-deficient group than that in the other two groups. The maltase and sucrase activities decreased in jejunal but not in ileal mucosa in zinc-deficient group. The maltase activity in feces decreased during the final 2 weeks of the experiment, but the sucrase and lactase activities did not in zinc-deficient group. The activity of disaccharidase in intestinal mucosa and in feces 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 brush 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 maltase activity in feces of rats. (C) 1996 Wiley-Liss, Inc.