Zinc supplementation, small intestinal morphology and disaccharidases activity

Abstract

The present study examined the effect of increasing dietary zinc (Zn) concentrations in the weaning mouse diet and the lack of metallothionein (MT) expression on intestinal morphology and disaccharidases activity. MT‐I&II null (MT−/−) and wild‐type (MT−/−) female mice at 3.5 weeks of age were randomly allocated to be fed with 2 (2Zn), 15 (15Zn) and 50 (50Zn) mg Zn/kg diet for 5 weeks. Duodenal, jejunal and ileal segments were collected and either fixed in 10% formalin for histological analysis or snap frozen in liquid nitrogen for analysis of sucrase, lactase and maltase activities. No differences in body weight gained were observed between genotypes or dietary groups. Villus height and crypt depth were increased by 15% in MT+/+ mice compared to MT−/− mice. Duodenal disaccharidase activities were significantly higher in MT+/+ mice compared to MT−/− mice particularly those fed the 2Zn diet. At the 50Zn diet, jejunal sucrase and lactase activities were significantly higher in MT−/− (13313±2314 μmol glucose/well/min/g tissue; 4107±364; mean ±SEM) compared to MT+/+ mice (7054±608; 1818±174). Similarly, ileal lactase activities were higher in MT−/− (1480±192) compared to MT+/+ (629±353) mice particularly those fed the 2Zn diet. Increasing dietary Zn in the weaning diet did not affect disaccharidases expression in wild type mice. The presence of MT enhances the morphological and functional development of the gut.