Researchers in Penn State's College of Agricultural Sciences have found in a mice study that female mice deprived of dietary zinc for a relatively short time before conception experienced fertility and pregnancy problems and had smaller, less-developed fetuses than mice that ingested zinc during the same times.
The findings have implications for human reproduction, scientists suggest. Going without zinc prior to ovulation had marked effects on the mice's reproductive functions. Zinc deficiency caused a high incidence of pregnancy loss, and embryos from the zinc-deficient diet group were an average of 38 percent smaller than those from the control group. Preconception zinc deficiency also caused approximately half of embryos to exhibit delayed or aberrant development.Defects in placenta development are a major cause of delayed embryo/fetal development because the developing embryos do not get enough nutrients to support normal growth.
In the zinc-deficient group, the fetal side of the placenta was much less developed. Consistent with delayed development of the placenta, expression of key placental genes was sharply curtailed in mice with zinc-deficient diets. Collectively, the findings provide evidence for the importance of preconception zinc in promoting optimal fertility and embryo, fetal and placenta development, explained Francisco Diaz, assistant professor of reproductive biology. "The mineral zinc acts as a catalytic, structural and signaling factor in the regulation of a diverse array of cellular pathways involving hundreds of enzymes and proteins," he said. "Given these wide-ranging roles, it is not surprising that insufficient zinc during pregnancy causes developmental defects in many species. We have known that for a long time. "However, the role of zinc during the preconception period in promoting later development during pregnancy is not clearly understood." In the six-month study, which was published online in a recent edition of Biology of Reproduction
, female mice were fed a control or a zinc-deficient diet for four to five days before ovulation.
Then, embryonic and/or placental development was evaluated on days three, six, 10, 12 and 16 of pregnancy. At each of those intervals, Xi Tian, recent Penn State doctoral student and now a postdoctoral scholar at the University of North Carolina, Chapel Hill, measured and evaluated fetuses, examining them with light microscopy and magnetic resonance imaging. She was assisted by co-authors Thomas Neuberger, assistant professor of biomedical engineering in Penn State's Huck Institutes of Life Sciences, working with the Penn State's High-Field Magnetic Resonance Imaging Facility, and Kate Anthony, research technician in animal science.