Zinc Transporters in the Mouse Placenta Show a Coordinated Regulatory Response to Changes in Dietary Zinc Intake

Helston, R.M.; Phillips, S.R.; McKay, J.A.; Jackson, K.A.; Mathers, J.C.; Ford, D.

doi:10.1016/j.placenta.2006.07.002

« Previous Next »Placenta
Volume 28, Issue 5 , Pages 437-444, May 2007

Zinc Transporters in the Mouse Placenta Show a Coordinated Regulatory Response to Changes in Dietary Zinc Intake

R.M. Helston
- Institute for Cell and Molecular Biosciences, Human Nutrition Research Centre, University of Newcastle, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
- RMH and SRP contributed equally to this work.
S.R. Phillips
- Institute for Cell and Molecular Biosciences, Human Nutrition Research Centre, University of Newcastle, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
- RMH and SRP contributed equally to this work.
J.A. McKay
- Institute for Cell and Molecular Biosciences, Human Nutrition Research Centre, University of Newcastle, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
K.A. Jackson
- Institute for Cell and Molecular Biosciences, Human Nutrition Research Centre, University of Newcastle, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
J.C. Mathers
- Human Nutrition Research Centre, School of Clinical Medical Sciences, University of Newcastle, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
D. Ford
- Institute for Cell and Molecular Biosciences, Human Nutrition Research Centre, University of Newcastle, Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
- Corresponding author. Tel.: +44 191 222 5989; fax: +44 191 222 8684.

Accepted 3 July 2006. published online 16 August 2006.

Abstract

The aim of the study was to determine if the expression of zinc transporters in the mouse placenta is regulated by dietary zinc, commensurate with regulating the supply of zinc to the fetus. Mice were fed diets differing only in the concentration of zinc (moderately zinc-restricted (ZnR) – 15mgZn/kg; zinc-adequate (ZnA) – 50mgZn/kg; zinc-supplemented (ZnS) – 150mgZn/kg) from the onset of pregnancy until collection of tissue at day 17. Compared with mice fed the other diets, fetal weight was reduced in the ZnR group and total non-embryonic weight gain was reduced in mice fed the ZnS diet. Transcript levels of metallothionein and the zinc transporters ZnT1, ZnT4 and ZIP1 were reduced in the placenta of mice fed both the ZnR and ZnS diets compared with mice fed the ZnA diet. Placental ZnT7 and fetal liver metallothionein transcript levels did not differ significantly between mice fed the three diets and placental ZnT5 was reduced in mice fed the ZnS compared with the ZnA diet but did not differ significantly between the ZnA and ZnR diets. The pattern of mRNA expression in placenta was reflected at the protein level for ZnT1. Levels of ZnT5 protein were also highest in mice fed the ZnA diet. Both ZnT1 and ZnT5 were detected in the human villous syncytiotrophoblast by immunohistochemistry. The data indicate that the expression of zinc transporters in mouse placenta is responsive to dietary zinc supply but this modulation of expression is insufficient to maintain optimum fetal nutrition at even a modest level of dietary zinc restriction.