Brief Article
Copyright ©2011 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Jan 21, 2011; 17(3): 354-360
Published online Jan 21, 2011. doi: 10.3748/wjg.v17.i3.354
Dietary zinc and metallothionein on small intestinal disaccharidases activity in mice
Cuong D Tran, Johanna Cool, Cory J Xian
Cuong D Tran, Gastroenterology Unit, Children, Youth and Women’s Health Service, 72 King William Rd, North Adelaide, SA 5006, Australia
Cuong D Tran, Discipline of Physiology, School of Medical Sciences, The University of Adelaide, Adelaide, SA 5000, Australia
Johanna Cool, Discipline of Agricultural and Animal Science, School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA 5000, Australia
Cory J Xian, Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, SA 5001, Australia
Author contributions: Tran CD, Cool J and Xian CJ performed the majority of the experiments; Tran CD and Xian CJ were involved in editing the manuscript in addition to providing financial support for this work; Tran CD designed the study and wrote the manuscript.
Supported by (in part) the MS McLeod Post-Doctoral Fellowship obtained from the Women’s and Children’s Hospital Foundation (to Tran CD)
Correspondence to: Dr. Cuong D Tran, Gastroenterology Unit, Children, Youth and Women’s Health Service, 72 King William Rd, North Adelaide, SA 5006, Australia. cuong.tran@health.sa.gov.au
Telephone: +61-8-81616991 Fax: +61-8-81616088
Received: May 1, 2010
Revised: June 16, 2010
Accepted: June 23, 2010
Published online: January 21, 2011
Abstract

AIM: To examine the effect of increasing dietary zinc (Zn) intake and the lack of metallothionein (MT) expression on activity of small intestinal disaccharidases.

METHODS: MT-I and II knockout (MT-/-) and wild-type (MT+/+) female mice at 3.5 wk of age were randomly fed with a diet containing 2 (2 Zn), 15 (15 Zn) or 50 (50 Zn) mg Zn/kg (n = 8/group/genotype) for 5 wk. Small intestinal segments (duodenum, jejunum and ileum) were collected and either fixed in 10% formalin for histological analysis or snap frozen in liquid nitrogen for sucrase, lactase and maltase activity analyses.

RESULTS: Plasma Zn was significantly (P < 0.05) lower (33%) in MT-/- compared with MT+/+ mice fed the 2 Zn diet. Villus height and crypt depth were increased by approximately 15% in MT+/+ mice compared with MT-/- mice. Duodenal disaccharidase activities were significantly higher in MT+/+ compared with MT-/- mice particularly in those fed the 2 Zn diet. For the 50 Zn diet, jejunal sucrase and lactase activities were significantly higher in MT-/- (13 313 ± 2314; 4107 ± 364 μmol glucose/well/min/g tissue, respectively) compared with MT+/+ mice (7054 ± 608; 1818 ± 174). Similarly, ileal lactase activities were higher in MT-/- (1480 ± 192) compared with MT+/+ (629 ± 353) mice particularly those fed the 2 Zn diet.

CONCLUSION: Increasing dietary Zn has little effect on disaccharidases activity in MT wild-type mice. The presence of MT may enhance morphological and functional development of the gut.

Keywords: Lactase; Maltase; Sucrase; Metallothionein; Diet; Zinc