[Effect of maternal vitamin D deficiency on lung morphogenesis and platelet-derived growth factor-A expression in rat offspring].

OBJECTIVE: To study the effect of maternal vitamin D deficiency on lung morphogenesis and platelet-derived growth factor-A (PDGF-A) expression in rat offspring. METHODS: Sprague-Dawley (SD) female rats were randomly divided into two groups: normal control and vitamin D deficiency, with 6 rats in each group. The vitamin D deficiecy group was kept away from light and fed with the forage without vitamin D. After 2 weeks, the rats were mated with normal SD male rats. The morphological changes of fetal rat lungs on day 20 of gestation and 1-day-old neonatal rat lungs were observed by light microscope and electronic microscope. The levels of PDGF-A mRNA and protein in fetal and neonatal rat lungs were measured by reverse transcriptase-polymerase chain reaction (RT-PCR) technique and Western blot method respectively. RESULTS: Under the light microscope, smaller alveolar space, smaller diameter of the respiratory membrane and thicker alveolus mesenchyma were observed in lungs of fetal and neonatal rats from the vitamin D deficiency group compared with the controls (P<0.05). Under the electronic microscope, fewer lamellar bodies but more glycogen deposition in intracytoplasm were observed in the lungs of fetal rats from the vitamin D deficiency group compared with the controls. There was an increased number of empty lamellar bodies in neonatal rats from the vitamin D deficiency group. The levels of PDGF-A mRNA and protein in lungs of fetal and neonatal rats from the vitamin D deficiency group were significantly lower than the controls (P<0.05). CONCLUSIONS: Maternal vitamin D deficiency during pregnancy may inhibit the development of lung morphogenesis and PDGF-A expression in late fetal and neonatal rats. The low expression of PDGF-A may be involved in the inhibitory effect of vitamin D deficiency on the lung development.

Developmental vitamin D deficiency increases foetal exposure to testosterone.

BACKGROUND: Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders which are more common in males. The 'prenatal sex steroid' hypothesis links excessive sex-steroid exposure during foetal life with the behavioural differences observed in ASD. However, the reason why sex steroid exposure may be excessive remains unclear. Epidemiological studies have identified several environmental risk factors associated with ASD, including developmental vitamin D (DVD) deficiency. We have demonstrated in an animal model that DVD-deficiency is associated with a hyper-inflammatory response in placentas from male but not female foetuses. Vitamin D also regulates the expression of several steroidogenic enzymes in vitro. Therefore using this animal model, we have examined whether DVD-deficiency leads to increased sex-steroid levels in both the maternal and foetal compartments. METHODS: Female rats are fed a vitamin D deficient diet from 6 weeks before mating until tissue collection at embryonic day 18. We examined the levels of testosterone, androstenedione and corticosterone in maternal plasma, foetal brains and amniotic fluid. We further examined gene expressions of steroidogenic enzymes and DNA methylation of aromatase promoters in foetal brains as a potential molecular mechanism regulating testosterone expression. RESULTS: We show that DVD-deficiency increases testosterone levels in maternal blood. We also show elevated levels of testosterone and androstenedione in the amniotic fluid of female but not male DVD-deficient foetuses. Testosterone levels were also elevated in DVD-deficient male brains. Vitamin D, like other steroid-related hormones, regulates gene expression via methylation. Therefore we examined whether the significant elevation in testosterone in male brains was due to such a potential gene-silencing mechanism. We show that the promoter of aromatase was hyper-methylated compared to male controls. LIMITATIONS: A reduction in aromatase, in addition to causing excessive testosterone, could also lead to a reduction in estradiol which was not examined here. CONCLUSIONS: This study is the first to show how an epidemiologically established environmental risk factor for ASD may selectively elevate testosterone in male embryonic brains. These findings provide further mechanistic support for the prenatal sex steroid theory of ASD.

The essentiality of vitamin D metabolites for embryonic chick development.

Laying hens maintained on 1,25-dihydroxyvitamin D3 as their sole source of vitamin D produce eggs which appear normal but which produce embryos having a defective upper mandible and which die at 18 to 19 days of embryonic life. Hens maintained on 25-hydroxyvitamin D3, on the other hand, produce normal embryos. Hens fed a vitamin D deficient diet produce eggs which develop the same embryonic defect. Injection of the affected eggs from the 1,25-dihydroxyvitamin D3 fed hens with vitamin D3, 25-hydroxyvitamin D3, or 1,25-dihydroxyvitamin D3 greatly increases the percentage of normal embryos. It therefore appears that 1,25-dihydroxyvitamin D3 is not transferred from hen to egg in sufficient amounts to support embryonic development and that vitamin D or its metabolites, or both, are necessary for normal chick embryo development.

In utero vitamin D deficiency predisposes offspring to long-term adverse adipose tissue effects.

The fetal period represents an important window of susceptibility for later obesity and metabolic disease. Maternal vitamin D deficiency (VDD) during pregnancy is a global concern that may have long-lasting consequences on offspring metabolic health. We sought to determine whether a VDD in utero environment affects fetal adipose tissue development and offspring metabolic disease predisposition in adulthood. Furthermore, we sought to explore the extent to which the VDD intrauterine environment interacts with genetic background or postnatal environment to influence metabolic health. Eight-week-old P0 female C57BL/6J mice were fed either a VDD diet or sufficient diet (VDS) from four weeks before pregnancy (periconception) then bred to male Avy/a mice. Females were maintained on the diets throughout gestation. At weaning, Avy/a and a/a male F1 offspring were randomized to low-fat (LFD) or high-fat diet (HFD) until 19 weeks of age, at which point serum and adipose tissue were harvested for analyses. Mice born to VDD dams weighed less at weaning than offspring born to VDS dams but experienced rapid weight gain in the four weeks post weaning, and acquired a greater ratio of perigonadal (PGAT) to subcutaneous (SQAT) than control offspring. Additionally, these mice were more susceptible to HFD-induced adipocyte hypertrophy. Offspring of VDD dams also had greater expression of Pparg transcript. These novel findings demonstrate that in utero VDD, an easily correctable but highly prevalent health concern, predisposes offspring to long-term adipose tissue consequences and possible adverse metabolic health complications.

Does 'imprinting' with low prenatal vitamin D contribute to the risk of various adult disorders?

Hypovitaminosis D is a candidate risk-modifying factor for a diverse range of disorders apart from rickets and osteoporosis. Based on epidemiology, and on in vitro and animal experiment, vitamin D has been linked to multiple sclerosis, certain cancers (prostate, breast and colorectal), insulin-dependent diabetes mellitus and schizophrenia. I hypothesise that low pre- and perinatal vitamin D levels imprint on the functional characteristics of various tissues throughout the body, leaving the affected individual at increased risk of developing a range of adult-onset disorders. The hypothesis draws from recent advances in our understanding of the early origin of adult disease and proposes a 'critical window' during which vitamin D levels may have a persisting impact on adult health outcomes. Methods to test the hypothesis are outlined. If correct, the hypothesis has important implications for public health. Careful attention to maternal vitamin D status could translate into diverse improvements in health outcomes for the following generation.

The effect of in ovo boron supplementation on bone mineralization of the vitamin D-deficient chicken embryo.

It has been hypothesized that boron (B) is an essential element for animals, but its action will vary greatly depending on the nutriture of the organism. One of the nutrients implicated as having an interaction with boron is cholecalciferol (Vit D3). This study was carried out to determine if such an interaction exists. The study was conducted utilizing vitamin D-deficient chicken embryos that were injected through the shell at 8 d of embryogenesis with carrier (NaCl and/or acetone), B (0.5 mg), B + Vit D3 (0.5 mg and 0.3 microgram, respectively), or Vit D3 (0.3 or 1.5 micrograms). The in ovo concomitant administration of boron and vitamin D enhanced (p less than 0.05) the hatchability of the vitamin D-deficient embryos. Furthermore, boron and/or vitamin D3 increased (p less than 0.05) the percent of bone ash and decreased (p less than 0.05) the exaggerated height of the proliferative zone of the epiphyseal growth plate normally observed in vitamin D deficiency, suggesting a more rapid bone formation. The results provide further evidence supporting the hypothesis that boron plays a role in bone mineralization through an interaction with vitamin D.

Survival of vitamin D-deficient embryos: time and choice of cholecalciferol or its metabolites for treatment in ovo.

Vitamin D-deficient (-D) Japanese quail embryos [from hens fed 1,25-dihydroxycholecalciferol (1,25-(OH)2D3)] die at Day 15 of incubation from severe calcium deficiency. Single doses of 125 ng cholecalciferol, 600 ng 24,25-dihydroxycholecalciferol [24,25-(OH)2D3], or 100 ng 1,25-(OH)2D3 were found to increase hatchability when injected into eggs prior to incubation. Cholecalciferol could be used from 125 to 1,250 ng per egg with no detrimental effects on hatchability, whereas single doses of 1,25-(OH)2D3 lower or higher than 100 ng per egg reduced hatchability. Injection of 125 ng cholecalciferol per egg supported the hatching of -D embryos when eggs were treated as late as 10 days of incubation. Sharply reduced hatchability occurred when cholecalciferol was injected at Day 11 or 12 of incubation. Experiments designed to evaluate the physiological state of 1-day-old quail treated with a single dose of cholecalciferol metabolites in ovo prior to incubation revealed that chicks had hypocalcemia, reduced total calcium content, and a six- to sevenfold increase in renal 25-hydroxycholecalciferol-1-hydroxylase activity. On the other hand, chicks from eggs treated with cholecalciferol were relatively normal. It appears that cholecalciferol administered in ovo is the compound of choice for supporting sustained development of the skeleton, mobilization of shell calcium, and prevention of hypocalcemia, probably because cholecalciferol is utilized slowly as needed to support development of the chick skeleton.

Fetal thymus development in vitamin D deficient rats.

The morphological characteristics of the thymus in vitamin D-deficient rats were evaluated in utero. The thymus weight, thymus weight/body weight ratio and histological findings were found to be similar when the vitamin D-deficient rats were compared with the control animals. It is therefore concluded that vitamin D is not required for the morphological development of rat thymus.

Maternal vitamin D deficiency alters the expression of genes involved in dopamine specification in the developing rat mesencephalon.

Schizophrenia is a neurodevelopment disorder that is strongly associated with alterations in dopamine neurotransmission. Common features of animal models of schizophrenia include behavioural, cognitive and/or pharmacological abnormalities reflective of aberrant DA signaling. The aim of this study was to examine the expression of genes important for dopaminergic development and maturation within the embryonic mesencephalon using an epidemiologically-informed animal model of schizophrenia, the developmental vitamin D (DVD) deficient rat model. Two groups of female Sprague-Dawley rats were fed either a diet replete (1000IU/kg) or deplete (0IU/kg) of vitamin D, mated and foetal mesencephalon collected at embryonic day (E) E12 or E15. Using real time-PCR, the DVD-deficient embryos had a significant reduction in factors crucial in specifying dopaminergic phenotype, such as Nurr1 and p57Kip2. No group differences were found for Lmx1b or Ptx3. Reductions in these specification factors may alter the ontogeny of DA neurons and may ultimately help to explain the behavioural abnormalities reported in adult offspring from this model.

Vitamin D deficiency and pregnancy: from preconception to birth.

Vitamin D is important for bone health, as well as an increasing number of other health outcomes. Here we discuss the evidence relating to vitamin D in pregnancy, from preconception to the perinatal period. During pregnancy extra calcium required for fetal skeletal growth is attained by both maternal bone resorption and increased absorption from dietary sources, necessitating increased maternal vitamin D. Many women have low vitamin D status during pregnancy and may require supplementation, although optimal serum levels and intake required to achieve those levels is not yet well defined. Evidence from animal studies, with some supportive human evidence, suggests that fertility may be impaired in mothers with low vitamin D. During pregnancy, maintaining vitamin D and calcium levels may decrease the risks of pre-eclampsia, while gestational diabetes mellitus appears to be more common in those with low vitamin D status, although there is insufficient evidence of causality. The evidence in relation to increased risks of bacterial vaginosis and caesarean section similarly requires confirmation in carefully designed observational and experimental studies. This review outlines the emerging evidence that maternal vitamin D status during pregnancy is important for the health of the mother and offspring across a range of possible health outcomes.

Developmental vitamin D deficiency alters dopamine turnover in neonatal rat forebrain.

There is growing evidence that low vitamin D impacts adversely on brain development. The current study investigated the impact of developmental vitamin D (DVD) deficiency on dopamine and serotonin metabolism in the neonatal rat brain. DVD-deficiency resulted in an altered dopaminergic metabolic profile in the forebrain, with a decrease in the conversion of dihydroxyphenylacetic acid (DOPAC) to homovanillic acid (HVA). Correspondingly, expression of the enzyme required for this conversion, catechol-O-methyl transferase (COMT), was decreased. These results suggest that DVD-deficiency influences dopamine turnover during development.

Maternal food consumption during pregnancy and asthma, respiratory and atopic symptoms in 5-year-old children.

BACKGROUND: Associations between maternal vitamin E, vitamin D and zinc intakes during pregnancy and asthma, wheeze and eczema in 5-year-old children have previously been reported. A study was undertaken to investigate whether maternal intake of specific foods during pregnancy is associated with asthma and allergic outcomes in the same children. METHODS: A longitudinal birth cohort study was conducted in 1,924 children born to women recruited during pregnancy. Maternal diet during pregnancy was assessed by food frequency questionnaire (FFQ). Cohort children were followed up at 5 years by symptom questionnaire and FFQ. Food groups of interest were fruit, vegetables, fruit juice, whole grain products, fish, dairy products and fat spreads. Trends across outcome groups defined by level of food intake are presented. RESULTS: 1,253 children participated at 5 years and maternal FFQ data were available for 1,212. No consistent associations were found between childhood outcomes and maternal intake of the analysed foods except for apples and fish. Maternal apple intake was beneficially associated with ever wheeze (OR highest vs lowest tertile 0.63, 95% CI 0.42 to 0.95), ever asthma (OR 0.54, 95% CI 0.32 to 0.92) and doctor-confirmed asthma (OR 0.47, 95% CI 0.27 to 0.82) in the children. Maternal fish consumption was beneficially associated with doctor-confirmed eczema (OR >or=1/week vs never 0.57, 95% CI 0.35 to 0.92). CONCLUSION: There was no evidence for associations between maternal intake of most foods during pregnancy and asthma, respiratory and allergic outcomes in 5-year-old children, except for apples and fish. Consumption of apples and fish during pregnancy may have a protective effect against the development of childhood asthma and allergic disease.

The RXRalpha ligand-dependent activation function 2 (AF-2) is important for mouse development.

We have engineered a mouse mutation that specifically deletes the C-terminal 18 amino acid sequence of the RXRalpha protein. This deletion corresponds to the last helical alpha structure (H12) of the ligand-binding domain (LBD), and includes the core of the Activating Domain of the Activation Function 2 (AF-2 AD core) that is thought to be crucial in mediating ligand-dependent transactivation by RXRalpha. The homozygous mutants (RXRalpha af2(o)), which die during the late fetal period or at birth, exhibit a subset of the abnormalities previously observed in RXRalpha -/- mutants, often with incomplete penetrance. In marked contrast, RXRalpha af2(o)/RXRbeta -/- and RXRalpha af2(o)/RXRbeta -/- /RXRgamma -/- compound mutants display a large array of malformations, which nearly recapitulate the full spectrum of the defects that characterize the fetal vitamin A-deficiency (VAD) syndrome and were previously found in RAR single and compound mutants, as well as in RXRalpha/RAR(alpha, beta or gamma) compound mutants. Analysis of RXRalpha af2(o)/RAR(alpha, beta or gamma) compound mutants also revealed that they exhibit many of the defects observed in the corresponding RXR alpha/RAR compound mutants. Together, these results demonstrate the importance of the integrity of RXR AF-2 for the developmental functions mediated by RAR/RXR heterodimers, and hence suggest that RXR ligand-dependent transactivation is instrumental in retinoid signalling during development.