Acute dietary zinc deficiency before conception compromises oocyte epigenetic programming and disrupts embryonic development.

Recent findings show that zinc is an important factor necessary for regulating the meiotic cell cycle and ovulation. However, the role of zinc in promoting oocyte quality and developmental potential is not known. Using an in vivo model of acute dietary zinc deficiency, we show that feeding a zinc deficient diet (ZDD) for 3-5 days before ovulation (preconception) dramatically disrupts oocyte chromatin methylation and preimplantation development. There was a dramatic decrease in histone H3K4 trimethylation and global DNA methylation in zinc deficient oocytes. Moreover, there was a 3-20 fold increase in transcript abundance of repetitive elements (Iap, Line1, Sineb1, Sineb2), but a decrease in Gdf9, Zp3 and Figla mRNA. Only 53% and 8% of mature eggs reached the 2-cell stage after IVF in animals receiving a 3 and 5 days ZDD, respectively, while a 5 day ZDD in vivo reduced the proportion of 2-cells to 49%. In vivo fertilized 2-cell embryos cultured in vitro formed fewer (38%) blastocysts compared to control embryos (74%). Likewise, fewer blastocyst and expanded blastocyst were collected from the reproductive tract of zinc deficient animals on day 3.5 of pregnancy. This could be due to a decrease in Igf2 and H19 mRNA in ZDD blastocyst. Supplementation with a methyl donor (SAM) during IVM restored histone H3K4me3 and doubled the IVF success rate from 17% to 43% in oocytes from zinc deficient animals. Thus, the terminal period of oocyte development is extremely sensitive to perturbation in dietary zinc availability.

Dietary methyl donor deficiency during pregnancy in rats shapes learning and anxiety in offspring.

Two important lines of research have enhanced our understanding of the molecular role of nutrition in influencing behavior. First, exposure to an adverse environment during early life can influence the long-term behavior of the offspring. Second, regulation of the nervous system development and functioning appears to involve epigenetic mechanisms that require a continuous supply of methyl group donors in food. We hypothesized that a maternal diet during pregnancy deficient in methyl donors (MDD) may lead to altered behavior in offspring through permanent changes in hippocampal DNA methylation. We used a rat model of prenatal dietary MDD to test this hypothesis in female offspring as they aged. Prenatal MDD reduced birth weight, litter size, and newborn viability. Aged female offspring of MDD mothers showed increased anxiety and increased learning ability in comparison with control diet group offspring. To explore the role of MDD on epigenetic mechanisms in the brain of adult offspring, we studied expression and methylation of 4 selected genes coding for glucocorticoid receptor, hydroxysteroid dehydrogenase 11 type 2, neuronatin, and reelin proteins in the hippocampus. No major group differences in methylation or expression of the studied genes were detected, except for a significant down-regulation of the reelin gene in the MDD female offspring. The prenatal MDD diet caused intrauterine growth restriction, associated with long-term effects on the behavior of the offspring. However, the observed behavioral differences between the MDD and control diet offspring cannot be explained by epigenetic regulation of the specific genes investigated in this study.

Brain histological changes in young mice submitted to diets with different ratios of n-6/n-3 polyunsaturated fatty acids during maternal pregnancy and lactation.

N-3 polyunsaturated fatty acids (n-3 PUFAs) are essential for brain development and function, but the appropriate quantity of dietary n-3 PUFAs and ratio of n-6/n-3 PUFAs have not been clearly determined. In this study, we investigated the effects of different dietary ratios of n-6/n-3 PUFAs on the brain structural development in mice and the expression of associated transcription factors. C57 BL/6J mice were fed with one of two categories of n-3 PUFA-containing diets (a flaxseed oil diet and a flaxseed/fish oil mixed diet) or an n-3 PUFA-deficient diet. For each of the n-3 PUFA diets, flaxseed oil or flaxseed/fish oil was combined with other oils to yield three different n-6/n-3 ratios, which ranged from 15.7:1 to 1.6:1. The feeding regimens began two months before mouse conception and continued throughout lactation for new pups. As compared with the n-3 PUFA-deficient diet, both the flaxseed oil n-3 PUFA diets and the flaxseed/fish oil n-3 PUFA diets significantly increased the expression levels of brain neuron-specific enolase, glial fibrillary acidic protein and myelin basic protein, somewhat dose-dependently, in new pup mice at 21 d and 42 d of age. The expression of PPAR-γ in the brains of pup mice was increased only at 7 d of age with the n-3 PUFA diet, and no changes in the expression of PPAR-α and PPAR-ß were found among all the diet groups. These results suggest that the higher intake amount of n-3 PUFAs with a low ratio of n-6/n-3 PUFAs at about 1-2:1, supplied during both maternal pregnancy and lactation, may be more beneficial for early brain development, and PPAR-γ may act in one of the pathways by which n-3 PUFAs promote early brain development.

Methyl donor deficiency affects fetal programming of gastric ghrelin cell organization and function in the rat.

Methyl donor deficiency (MDD) during pregnancy influences intrauterine development. Ghrelin is expressed in the stomach of fetuses and influences fetal growth, but MDD influence on gastric ghrelin is unknown. We examined the gastric ghrelin system in MDD-induced intrauterine growth retardation. By using specific markers and approaches (such as periodic acid-Schiff, bromodeoxyuridine, homocysteine, terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling, immunostaining, reverse transcription-polymerase chain reaction), we studied the gastric oxyntic mucosa cellular organization and ghrelin gene expression in the mucosa in 20-day-old fetuses and weanling pups, and plasma ghrelin concentration in weanling rat pups of dams either normally fed or deprived of choline, folate, vitamin B6, and vitamin B12 during gestation and suckling periods. MDD fetuses weighed less than controls; the weight deficit reached 57% at weaning (P < 0.001). Both at the end of gestation and at weaning, they presented with an aberrant gastric oxyntic mucosa formation with loss of cell polarity, anarchic cell migration, abnormal progenitor differentiation, apoptosis, and signs of surface layer erosion. Ghrelin cells were abnormally located in the pit region of oxyntic glands. At weaning, plasma ghrelin levels were decreased (-28%; P < 0.001) despite unchanged mRNA expression in the stomach. This decrease was associated with lower body weight. Taken together, these data indicate that one mechanism through which MDD influences fetal programming is the remodeling of gastric cellular organization, leading to dysfunction of the ghrelin system and dramatic effects on growth.

The sunspot theory of schizophrenia: further evidence, a change of mechanism, and a strategy for the elimination of the disorder.

The Gestational Zinc Deficiency Theory suggests that the schizophrenia is caused by a spectrum of damage, produced in utero, to zinc dependent fetal organs such as the brain, pancreas, pineal, testes etc. One problem encountered by the theory is how such deficiency could occur given that the disorder is fairly uniformly distributed across the planet. The original explanation, that seasonal variation in zinc availability was responsible is unconvincing and a search for clues led to an investigation of the Recency Theory which argues that schizophrenia was unknown before 1750 and that an "epidemic of insanity" began around 1780 and stabilized around 1900. The Sunspot Theory arose from the realization that Juckett and Rosenberg's finding of a strong correlation between solar activity and longevity might, with some modification, explain both changes in the incidence of the disorder and the origin of the maternal zinc deficiency. The twenty year shift required to give optimal correlation was explained by these authors as being caused by ionizing radiation induced changes to developing fetal germinal cells. In the sunspot theory it was suggested that the correlation between solar activity and schizophrenia incidence was due to changes in maternal zinc metabolism following microwave induced stress. In this article it will be shown that that mechanism was incorrect. A far better explanation is provided by assuming that geomagnetic field induced loss of pineal activity in the mother during pregnancy permanently affects pineal entrainment in the fetus. In addition it is shown that the loss of correlation between solar activity and longevity during the 1800 to 1830 period identified by Juckett and Rosenberg explains a hitherto inexplicable decline, between 1877 and 1887, in the rising graph of schizophrenia incidence. Finally, the hypothesis, if correct suggests that a strategy based on zinc and melatonin supplements given to at risk parents may go some way to eliminating the disorder.

Early postnatal iron repletion overcomes lasting effects of gestational iron deficiency in rats.

Iron deficiency anemia in early childhood causes developmental delays and, very likely, irreversible alterations in neurological functioning. One primary goal for the present study was to determine whether the effects of late gestational iron deficiency on brain monoamine metabolism, iron content, and behavioral phenotypes could be repaired with iron intervention in early lactation. Young pregnant rats were provided iron-deficient or control diets from mid-gestation (G15). At postnatal d 4 (P4), pups from iron-deficient dams were out-fostered either to other ID dams or control dams while pups of control dams were similarly fostered to other control dams. Dietary treatments continued to adulthood (P65) when brain iron and regional monoamines were evaluated. P4 iron repletion normalized body iron status, brain iron concentrations, monoamine concentrations, and monoamine transporter and receptor densities in most brain regions. Dopamine transporter densities in caudate and substantia nigra were lower in ID rats but were normalized with iron repletion. Serotonin transporter levels in most brain regions and open-field exploration were also normalized with iron repletion. The success of this approach of early postnatal iron intervention following iron deficiency in utero contrasts to a relative lack of success when the intervention is performed at weaning. These data suggest that a window of opportunity exists for reversing the detrimental effects of iron deficiency in utero in rats and provides strong support of intervention approaches in humans with iron deficiency during pregnancy.

Aspects of trace element interactions during development.

The origins of nutritional trace element deficiencies are summarized. Inadequate intake results in primary deficiency, whereas secondary or conditioned deficiencies can arise in several ways including trace element interactions. Evidence is presented and discussed for interactions of essential trace elements during prenatal and early postnatal development. Diets of widely different zinc and copper concentrations and ratios were fed to pregnant rats. Analysis of fetal outcome and copper and zinc concentrations of maternal and fetal livers showed that although there is an interaction between these metals it occurs only at levels of dietary copper deficiency. Iron and manganese interact so that high levels of one depress absorption of the other. Mice fed iron-supplemented diets had liver manganese concentrations lower than those of unsupplemented mice. Iron supplements at high but not low levels also depressed absorption of zinc. Conversely, zinc deficiency in pregnant rats caused higher than normal concentrations of iron in maternal and fetal liver. Trace element analyses of proprietary infant formulas indicate that in some, concentrations and ratios of these trace elements may be incorrect. The effects of essential trace element interactions during development should be further investigated. Caution is urged in considering levels of trace element supplements during pregnancy, lactation, or early childhood.