Effects of gestational zinc deficiency in mice on growth and immune function

It has previously been reported that feeding mice a marginal zinc (Zn) diet (5 μg Zn/g) during the last two-thirds of pregnancy results in long term deleterious effects on the offsprings' growth and immune function compared to control (100 μg Zn/g) offspring. However, recent results in our laboratory using a similar protocol have not been as dramatic as those previously reported Since that study there has been modification of the diet employed. More importantly, virtually all commercial vendors now breed mouse colonies behind a pathogen free barrier. In the current study, we tested the hypothesis that differences in results were due to recent modifications in the diet, or due to a need for a more severe Zn deficiency to produce the previously reported effects. We compared the effect of feeding the original Luecke based diet which was low in several micronutrients along with low Zn (5 μg Zn/g), to those obtained by feeding our current diet in which only Zn is limiting. Effects of Zn deprivation on growth or immunoglobulins were not noted with either diet. We also tested lower levels of dietary Zn. Pup mortality was greater than 90% when diets contained 3.2 μg Zn/g or less, and 50% when diet contained 3.5 μg Zn/g, however, even with the 3.5 μg Zn/g, there were no persistent immune effects. Our data suggests that factor(s), possibly virus(es) and/or bacteria, specifically affecting immune cells during development, acting synergistically with Zn deficiency, resulted in the immune defects reported earlier.