Gestational vitamin D deficiency: long-term effects on the brain

Neonatal vitamin D status in relation to autism spectrum disorder and developmental delay in the CHARGE case-control study

Vitamin D appears essential for normal neurodevelopment and cognitive and behavioral function. We examined neonatal vitamin D in relation to the child's later diagnosis of autism spectrum disorder (ASD) or developmental delay (DD). Children aged 24-60 months enrolled in the population-based CHARGE case-control study were evaluated clinically for ASD (n = 357), DD (n = 134), or typical development (TD, n = 234) at the MIND Institute (Sacramento, CA) using standardized assessments. Total 25-hydroxyvitamin D (25[OH]D) was measured using sensitive isotope dilution liquid chromatography-tandem mass spectrometry in archived dried blood spots collected for the California Department of Public Health's Newborn Screening Program. Multinomial logistic regression was used to calculate ORs as measures of the associations between 25 nmol/L change in 25(OH)D and ASD and DD. Associations between 25(OH)D and scores on Mullen Scales of Early Learning and Vineland Adaptive Behavior Scales were assessed using robust linear regression. Effect modification was examined using stratified models and interaction product terms. Unadjusted mean (SD) 25(OH)D was lower for DD (73.2 [37.6]) than for TD (82.7 [39.3]) and ASD (80.1 [37.4]). After adjustment for maternal prepregnancy body mass index and education, a 25 nmol/L increase in total 25(OH)D was not associated with ASD (OR = 0.97; CI: 0.87-1.08) or DD (OR = 0.91; 95% CI: 0.78-1.06). Neonatal 25(OH)D was associated with significantly reduced ASD only in females (adjusted OR = 0.74; 95% CI: 0.55-0.99, Pinteraction  = 0.03), and significantly reduced DD only in non-Hispanic white children (adjusted OR = 0.79; 95% CI: 0.63-0.98, Pinteraction  = 0.11 for Hispanic, Pinteraction  = 0.31 for other), driven by DD children with trisomy 21. This study provides evidence that neonatal vitamin D could be associated with ASD in females and with DD in non-Hispanic white children. Autism Res 2019, 12: 976-988. © 2019 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: Vitamin D appears essential for brain development and function. We examined neonatal total 25-hydroxyvitamin D (25[OH]D) measured in dried blood spots in relation to later diagnoses of autism spectrum disorder (ASD) or developmental delay (DD) and related assessment scores. Higher neonatal 25(OH)D was associated with a 26% reduction in the odds for ASD only in females. After taking into account factors that could contribute to vitamin D status, a significant association with 21% reduced odds for DD was found only in non-Hispanic white children. Though results were nonsignificant overall, certain subgroups might benefit from higher neonatal vitamin D.

Vitamin D: effects on pregnancy, maternal, fetal and postnatal outcomes

A high prevalence of vitamin D deficiency and its negative consequences for health is identified as area of primary concern for scientists and clinicians worldwide. Vitamin D deficiency affects not only bone health but many socially significant acute and chronic diseases. Observational studies support that pregnant and lactating women, children and teenagers represent the high risk groups for developing vitamin D deficiency. Current evidence highlights a crucial role of vitamin D in providing the fetal life-support system and fetus development, including implantation, placental formation, intra - and postpartum periods. Hypovitaminosis D during pregnancy is associated with a higher incidence of placental insufficiency, spontaneous abortions and preterm birth, preeclampsia, gestational diabetes, impaired fetal and childhood growth, increased risk of autoimmune diseases for offsprings. Potential mechanisms for the observed associations contain metabolic, immunomodulatory and antiinflammatory effects of vitamin D. Epigenetic modifications in vitamin D-associated genes and fetal programming are of particular interest. The concept of preventing vitamin D deficiency is actively discussed, including supplementation in different ethnic groups, required doses, time of initiation and therapy duration, influence on gestation and childbirth. An adequate supply of vitamin D during pregnancy improves the maternal and fetal outcomes, short and long term health of the offspring. Still current data on relationship between maternal vitamin D status and pregnancy outcomes remains controversial. The large observational and interventional randomized control trials are required to create evidence-based guidelines for the supplementation of vitamin D in pregnant and lactating women.

Fok-I, Bsm-I, and Taq-I Variants of Vitamin D Receptor Polymorphism in the Development of Autism Spectrum Disorder: A Literature Review

The role of vitamin D in the development of autism spectrum disorder (ASD) is of intensified interest in medical science in recent years. Vitamin D has a significant role in neurogenesis, neuroprotection, and neurodevelopment. Due to the close association of vitamin D with the brain, it has been found that in the pathophysiology of several neuropsychiatric disorders vitamin D receptor (VDR) polymorphism plays a significant role. In this review article, we looked for a relation between VDR polymorphism and ASD. We systemically reviewed all the potential articles on the relation between VDR polymorphism and ASD. We found that several VDR variants FokI, BsmI, and TaqI polymorphisms are related to ASD. Even paternal VDR polymorphism can be a causative factor for ASD in the offspring. The relation between FokI (ff) genotype polymorphism and increased level of serum 1,25(OH)D3 in ASD patients is a very significant finding. Variation of ASD-related genotypes in different ethnic population raises a big question on whether the environmental factors also can do changes in human genotypes leading to ASD.

Impact of vitamin D on pregnancy-related disorders and on offspring outcome

Observational studies from all over the world continue to find high prevalence rates of vitamin D insufficiency and deficiency in many populations, including pregnant women. Beyond its classical function as a regulator of calcium and phosphate metabolism, vitamin D elicits numerous effects in the human body. Current evidence highlights a vital role of vitamin D in mammalian gestation. During pregnancy, adaptations in maternal vitamin D metabolism lead to a physiologic increase of vitamin D levels, mainly because of an increased renal production, although other potential sources like the placenta are being discussed. A sufficient supply of mother and child with calcium and vitamin D during pregnancy ensures a healthy bone development of the fetus, whereas lack of either of these nutrients can lead to the development of rickets in the child. Moreover, vitamin D insufficiency during pregnancy has consistently been associated with adverse maternal and neonatal pregnancy outcomes. In multitudinous studies, low maternal vitamin D status was associated with a higher risk for preeclampsia, gestational diabetes mellitus and other gestational diseases. Likewise, several negative consequences for the fetus have been reported, including fetal growth restriction, increased risk of preterm birth and a changed susceptibility for later-life diseases. However, study results are diverging and causality has not been proven so far. Meta-analyses on the relationship between maternal vitamin D status and pregnancy outcomes revealed a wide heterogeneity of studied populations and the applied methodology in vitamin D assessment. Until today, clinical guidelines for supplementation cannot be based on high-quality evidence and it is not clear if the required intake for pregnant women differs from non-pregnant women. Long-term safety data of vitamin D supplementation in pregnant women has not been established and overdosing of vitamin D might have unfavorable effects, especially in mothers and newborns with mutations of genes involved in vitamin D metabolism. Reliable data from large observational and interventional randomized control trials are urgently needed as a basis for any detailed and safe recommendations for supplementation in the general population and, most importantly, in pregnant women. This is of utmost importance, as ensuring a sufficient vitamin D-supply of mother and child implies a great potential for the prevention of birth complications and development of diseases.

Polymorphisms in Vitamin D Receptor Genes in Association with Childhood Autism Spectrum Disorder

Both genetic and environmental factors have been implicated in the etiology of autism spectrum disorder (ASD). This case-control study aimed to determine the association of single-nucleotide polymorphisms (SNPs) rs731276 (TaqI), rs1568820 (Cdx2), rs1544410 (BsmI), and rs2228570 (FokI) in the vitamin D receptor (VDR) gene with susceptibility of childhood ASD and severity of the disease. A total of 201 children with ASD and 200 healthy controls from the Han Chinese population were recruited. SNP genotyping was carried out by TaqMan probe-based real-time PCR using genomic DNA extracted from blood cells. Among four examined SNPs, only the CT genotype (odds ratio (OR) = 1.96, 95% confidence interval (CI) = 1.05-3.68, P = 0.0351) and the C allele (OR = 1.88, 95% CI = 1.02-3.46, P = 0.0416) of the rs731276 were significantly associated with increased risks of childhood ASD. None of the SNPs were associated with severity of childhood ASD. Our results reveal that certain polymorphisms in the VDR gene are a risk factor related to childhood ASD in the Han Chinese population.

Environmental factors influencing the risk of autism

Autism is a developmental disability with age of onset in childhood (under 3 years old), which is characterized by definite impairments in social interactions, abnormalities in speech, and stereotyped pattern of behaviors. Due to the progress of autism in recent decades, a wide range of studies have been done to identify the etiological factors of autism. It has been found that genetic and environmental factors are both involved in autism pathogenesis. Hence, in this review article, a set of environmental factors involved in the occurrence of autism has been collected, and finally, some practical recommendations for reduction of the risk of this devastating disease in children are represented.

Selected vitamin D metabolic gene variants and risk for autism spectrum disorder in the CHARGE Study

BACKGROUND

Vitamin D is essential for proper neurodevelopment and cognitive and behavioral function. We examined associations between autism spectrum disorder (ASD) and common, functional polymorphisms in vitamin D pathways.

METHODS

Children aged 24-60 months enrolled from 2003 to 2009 in the population-based CHARGE case-control study were evaluated clinically and confirmed to have ASD (n=474) or typical development (TD, n=281). Maternal, paternal, and child DNA samples for 384 (81%) families of children with ASD and 234 (83%) families of TD children were genotyped for: TaqI, BsmI, FokI, and Cdx2 in the vitamin D receptor (VDR) gene, and CYP27B1 rs4646536, GC rs4588, and CYP2R1 rs10741657. Case-control logistic regression, family-based log-linear, and hybrid log-linear analyses were conducted to produce risk estimates and 95% confidence intervals (CI) for each allelic variant.

RESULTS

Paternal VDR TaqI homozygous variant genotype was significantly associated with ASD in case-control analysis (odds ratio [OR] [CI]: 6.3 [1.9-20.7]) and there was a trend towards increased risk associated with VDR BsmI (OR [CI]: 4.7 [1.6-13.4]). Log-linear triad analyses detected parental imprinting, with greater effects of paternally-derived VDR alleles. Child GC AA-genotype/A-allele was associated with ASD in log-linear and ETDT analyses. A significant association between decreased ASD risk and child CYP2R1 AA-genotype was found in hybrid log-linear analysis. There were limitations of low statistical power for less common alleles due to missing paternal genotypes.

CONCLUSIONS

This study provides preliminary evidence that paternal and child vitamin D metabolism could play a role in the etiology of ASD; further research in larger study populations is warranted.

IV. The cognitive implications of obesity and nutrition in childhood

The prevalence of childhood obesity in the United States has tripled since the 1980s and is strongly linked to the early onset of several metabolic diseases. Recent studies indicate that lower cognitive function may be another complication of childhood obesity. This review considers the research to date on the role of obesity and nutrition on childhood cognition and brain health. Although a handful of studies point to a maladaptive relationship between obesity and aspects of cognitive control, remarkably little is known regarding the impact of fat mass on brain development and cognitive function. Further, missing from the literature is the role of nutrition in the obesity-cognition interaction. Nutrition may directly or indirectly influence cognitive performance via several pathways including provision of key substrates for optimal brain health, modulation of gut microbiota, and alterations in systemic energy balance. However, in the absence of malnutrition, the functional benefits of specific nutrient intake on particular cognitive domains are not well characterized. Here, we examine the literature linking childhood obesity and cognition while considering the effects of nutritional intake. Possible mechanisms for these relationships are discussed and suggestions are made for future study topics. Although childhood obesity prevalence rates in some developed countries have recently stabilized, significant disparities remain among groups based on sex and socioeconomic status. Given that the elevated prevalence of pediatric overweight and obesity may persist for the foreseeable future, it is crucial to develop a comprehensive understanding of the influence of obesity and nutrition on cognition and brain health in the pediatric population.

Dynamic changes in serum 25-hydroxyvitamin D during pregnancy and lack of effect on thyroid parameters

Background & Aims

To explore vitamin D status and its dynamic changes during pregnancy in women living in Northeast China. The association between 25-hydroxyvitamin D and serum calcium, phosphate and parathyroid hormone was studied. Because vitamin D deficiency or thyroid dysfunction/autoimmunity during pregnancy may lead to similar adverse events, the relationship between 25-hydroxyvitamin D and thyroid parameters was investigated.

Methods

Serum samples of 50 women (aged 22 to 36 years) were selected retrospectively. The samples were collected at gestational 8 weeks ±3 days, 20 weeks ±3 days and 32 weeks ±3 days for measurement of 25-hydroxyvitamin D, calcium, phosphate, parathyroid hormone, and thyroid parameters.

Results

The median 25-hydroxyvitamin D levels were 28.29, 39.23 and 40.03 nmol/L, respectively, from the first to the third trimester. The 25-hydroxyvitamin D concentration during the first trimester was significantly lower than the next two trimesters (p<0.01) and was unchanged between the second and the third trimester. Of these women, 96%, 78% and 76% showed 25-hydroxyvitamin D ≤50 nmol/L during each trimester. Season was associated with 25-hydroxyvitamin D during each trimester (p<0.05), and a significant association was found between calcium and 25-hydroxyvitamin D during the first and the second trimesters. Only triiodothyronine was associated with 25-hydroxyvitamin D in the first trimester (p = 0.024), but statistical significance was only a trend (p = 0.063) after excluding abnormal values. No association was observed between 25-hydroxyvitamin D and phosphate, parathyroid hormone, and other thyroid parameters.

Conclusions

Vitamin D deficiency during pregnancy was prevalent in women from Northeast China who did not use supplementation. No significant relationships were observed between 25-hydroxyvitamin D and thyroid parameters during pregnancy.

Review: the role of vitamin D in nervous system health and disease

Vitamin D and its metabolites have pleomorphic roles in both nervous system health and disease. Animal models have been paramount in contributing to our knowledge and understanding of the consequences of vitamin D deficiency on brain development and its implications for adult psychiatric and neurological diseases. The conflation of in vitro, ex vivo, and animal model data provide compelling evidence that vitamin D has a crucial role in proliferation, differentiation, neurotrophism, neuroprotection, neurotransmission, and neuroplasticity. Vitamin D exerts its biological function not only by influencing cellular processes directly, but also by influencing gene expression through vitamin D response elements. This review highlights the epidemiological, neuropathological, experimental and molecular genetic evidence implicating vitamin D as a candidate in influencing susceptibility to a number of psychiatric and neurological diseases. The strength of evidence varies for schizophrenia, autism, Parkinson's disease, amyotrophic lateral sclerosis, Alzheimer's disease, and is especially strong for multiple sclerosis.

Unconventional Neurogenic Niches and Neurogenesis Modulation by Vitamins

Although the generation of new neurons occurs in adult mammals, it has been classically described in two defined regions of the brain denominated neurogenic niches: the subventricular zone of the lateral ventricles and the subgranular zone of the dentate gyrus. In these regions, neural stem cells give rise to new neurons and glia, which functionally integrate into the existing circuits under physiological conditions. However, accumulating evidence indicates the presence of neurogenic potential in other brain regions, from which multipotent precursors can be isolated and differentiated in vitro. In some of these regions, neuron generation occurs at low levels; however, the addition of growth factors, hormones or other signaling molecules increases the proliferation and differentiation of precursor cells. In addition, vitamins, which are micronutrients necessary for normal brain development, and whose deficiency produces neurological impairments, have a regulatory effect on neural stem cells in vitro and in vivo. In the present review, we will describe the progress that has been achieved in determining the neurogenic potential in other regions, known as unconventional niches, as well as the characteristics of the neural stem cells described for each region. Finally, we will revisit the roles of commonly known vitamins as modulators of precursor cell proliferation and differentiation, and their role in the complex and tight molecular signaling that impacts these neurogenic niches.

Reduced serum concentrations of 25-hydroxy vitamin D in children with autism: relation to autoimmunity

BACKGROUND

Aside from the skeletal health affection, vitamin D deficiency has been implicated as a potential environmental factor triggering for some autoimmune disorders. Vitamin D might play a role in the regulation of the production of auto-antibodies. Immunomodulatory effects of vitamin D may act not only through modulation of T-helper cell function, but also through induction of CD4(+)CD25(high) regulatory T-cells. We are the first to investigate the relationship between serum levels of 25-hydroxy vitamin D and anti-myelin-associated glycoprotein (anti-MAG) auto-antibodies in autistic children.

METHODS

Serum levels of 25-hydroxy vitamin D and anti-MAG auto-antibodies were measured in 50 autistic children, aged between 5 and 12 years, and 30 healthy-matched children. Serum 25-hydroxy vitamin D levels 10-30 ng/mL and < 10 ng/mL were defined as vitamin D insufficiency and deficiency, respectively.

RESULTS

Autistic children had significantly lower serum levels of 25-hydroxy vitamin D than healthy children (P < 0.001) with 40% and 48% being vitamin D deficient and insufficient, respectively. Serum 25-hydroxy vitamin D had significant negative correlations with Childhood Autism Rating Scale (P < 0.001). Increased levels of serum anti-MAG auto-antibodies were found in 70% of autistic patients. Serum 25-hydroxy vitamin D levels had significant negative correlations with serum levels of anti-MAG auto-antibodies (P < 0.001).

CONCLUSIONS

Vitamin D deficiency was found in some autistic children and this deficiency may contribute to the induction of the production of serum anti-MAG auto-antibodies in these children. However, future studies looking at a potential role of vitamin D in the pathophysiology and treatment of autism are warranted.

The nonskeletal effects of vitamin D: an Endocrine Society scientific statement

Significant controversy has emerged over the last decade concerning the effects of vitamin D on skeletal and nonskeletal tissues. The demonstration that the vitamin D receptor is expressed in virtually all cells of the body and the growing body of observational data supporting a relationship of serum 25-hydroxyvitamin D to chronic metabolic, cardiovascular, and neoplastic diseases have led to widespread utilization of vitamin D supplementation for the prevention and treatment of numerous disorders. In this paper, we review both the basic and clinical aspects of vitamin D in relation to nonskeletal organ systems. We begin by focusing on the molecular aspects of vitamin D, primarily by examining the structure and function of the vitamin D receptor. This is followed by a systematic review according to tissue type of the inherent biological plausibility, the strength of the observational data, and the levels of evidence that support or refute an association between vitamin D levels or supplementation and maternal/child health as well as various disease states. Although observational studies support a strong case for an association between vitamin D and musculoskeletal, cardiovascular, neoplastic, and metabolic disorders, there remains a paucity of large-scale and long-term randomized clinical trials. Thus, at this time, more studies are needed to definitively conclude that vitamin D can offer preventive and therapeutic benefits across a wide range of physiological states and chronic nonskeletal disorders.

Vitamin D, the placenta and pregnancy

Impaired vitamin D status is common to many populations around the world. However, data suggest that this is a particular problem for specific groups such as pregnant women. This has raised important questions concerning the physiological and clinical impact of low vitamin D levels during pregnancy, with implications for classical skeletal functions of vitamin D, as well as its diverse non-classical actions. The current review will discuss this with specific emphasis on the classical calciotropic effects of vitamin D as well as the less well established immunological functions of vitamin D that may influence pregnancy outcome. The review also describes the pathways that are required for metabolism and function of vitamin D, and the various clinical complications that have been linked to impaired vitamin D status during pregnancy.

Association of modifiable and nonmodifiable factors with vitamin D status in pregnant women and neonates in Oakland, CA

There is little information on the contribution of modifiable vs nonmodifiable factors to maternal and neonatal vitamin D status in temperate regions of the United States. The purpose of this cross-sectional observation study conducted between December 2006 and February 2008 was to identify associations between observed and measured maternal characteristics and vitamin D status at term in pregnant women and their infants in a multiethnic community in Oakland, CA. Two hundred seventy-five pregnant women aged 18 to 45 years and carrying a singleton fetus were recruited and data from 210 mother-infant pairs were included in analyses. Analysis of covariance identified predictors of maternal and cord serum 25-hydroxyvitamin D [25(OH)D] in a multivariate model considering vitamin D intake, lifestyle factors, and skin pigmentation. Maternal serum 25(OH)D was significantly associated with season of delivery (P=0.0002), average daily D intake (P=0.0008), right upper inner arm pigmentation (P=0.0035), and maternal pre- or early-pregnancy body mass index (calculated as kg/m²) (P=0.0207). The same factors were significant for cord serum 25(OH)D, which was highly correlated with maternal serum 25(OH)D (r=0.79; P<0.0001). During the year, 54% of mothers and 90% of neonates had 25(OH)D <30 ng/mL (<75 nmol/L). Of women taking daily prenatal vitamin/mineral supplements (400 IU vitamin D), 50.7% had serum 25(OH)D <30 ng/mL (<75 nmol/L). In conclusion, 25(OH)D <30 ng/mL (<75 nmol/L) was prevalent in mothers and neonates across racial groups and seasons, and vitamin D status was associated with both modifiable and nonmodifiable risk factors.

Neonatal jaundice, autism, and other disorders of psychological development

OBJECTIVES

The goals were to study the association between neonatal jaundice and disorders of psychological development in a national, population-based cohort and to study whether gestational age, parity, and season of birth influenced that association.

METHODS

A population-based, follow-up study of all children born alive in Denmark between 1994 and 2004 (N = 733,826) was performed, with data collected from 4 national registers. Survival analysis was used to calculate hazard ratios (HRs).

RESULTS

Exposure to jaundice in neonates was associated with increased risk of disorders of psychological development for children born at term. The excess risk of developing a disorder in the spectrum of psychological development disorders after exposure to jaundice as a neonate was between 56% (HR: 1.56 [95% confidence interval [CI]: 1.05-2.30]) and 88% (HR: 1.88 [95% CI: 1.17-3.02]). The excess risk of infantile autism was 67% (HR: 1.67 [95% CI: 1.03-2.71]). This risk for infantile autism was higher if the child was conceived by a parous woman (HR: 2.71 [95% CI: 1.57-4.66]) or was born between October and March (HR: 2.21 [95% CI: 1.24-3.94]). The risk for infantile autism disappeared if the child was conceived by a primiparous woman (HR: 0.58 [95% CI: 0.18-1.83]) or was born between April and September (HR: 1.02 [95% CI: 0.41-2.50]). Similar risk patterns were found for the whole spectrum of autistic disorders.

CONCLUSIONS

Neonatal jaundice in children born at term is associated with disorders of psychological development. Parity and season of birth seem to play important roles.

Vitamin D receptor and enzyme expression in dorsal root ganglia of adult female rats: modulation by ovarian hormones

Vitamin D insufficiency impacts sensory processes including pain and proprioception, but little is known regarding vitamin D signaling in adult sensory neurons. We analyzed female rat dorsal root ganglia (DRG) for vitamin receptor (VDR) and the vitamin D metabolizing enzymes CYP27B1 and CYP24. Western blots and immunofluorescence revealed the presence of these proteins in sensory neurons. Nuclear VDR immunoreactivity was present within nearly all neurons, while cytoplasmic VDR was found preferentially in unmyelinated calcitonin gene-related peptide (CGRP)-positive neurons, colocalizing with CYP27B1 and CYP24. These data suggest that 1,25(OH)(2)D3 may affect sensory neurons through nuclear or extranuclear signaling pathways. In addition, local vitamin D metabolite concentrations in unmyelinated sensory neurons may be controlled through expression of CYP27B1 and CYP24. Because vitamin D deficiency appears to exacerbate some peri-menopausal pain syndromes, we assessed the effect of ovariectomy on vitamin D-related proteins. Two weeks following ovariectomy, total VDR expression in DRG dropped significantly, owing to a slight decrease in the percentage of total neurons expressing nuclear VDR and a large drop in unmyelinated CGRP-positive neurons expressing cytoplasmic VDR. Total CYP27B1 expression dropped significantly, predominantly due to decreased expression within unmyelinated CGRP-positive neurons. CYP24 expression remained unchanged. Therefore, unmyelinated CGRP-positive neurons appear to have a distinct vitamin D phenotype with hormonally-regulated ligand and receptor levels. These findings imply that vitamin D signaling may play a specialized role in a neural cell population that is primarily nociceptive.

Avoidance of vitamin D deficiency in pregnancy in the United Kingdom: the case for a unified approach in National policy

Prevalence of hypovitaminosis D in Western populations is high; pregnant women are identified as a high-risk group, especially if dark skinned. Consequences of severe clinical vitamin D deficiency in pregnancy can be life threatening to the newborn, while lesser degrees of hypovitaminosis D may have important long-term implications for offspring health. Past experiences with routine provision of 10 microg/d (400 IU/d) to all pregnant mothers suggest that this dose is sufficient to prevent overt neonatal complications of vitamin D deficiency. Recent data suggest that supplementation with dosages above 10 microg/d may be required for optimal health in the mother and child; however, further research is required for the assessment of the benefits and safety of supplementation with higher dosages. Lack of unified advice on vitamin D supplementation of pregnant mothers in the UK hinders the implementation of primary prevention strategies and is likely to leave some deficient mothers without supplementation.

The impact of methylmercury on 1,25-dihydroxyvitamin D3-induced transcriptomic responses in dolphin skin cells

The Atlantic bottlenose dolphin has been the focus of much attention owing to the considerable impact of environmental stress on its health and the associated implications for human health. Here, we used skin cells from the dolphin to investigate the protective role of the vitamin D pathway against environmental stressors. We previously reported that dolphin skin cells respond to 1,25-dihydroxyvitamin D3 (1,25D3), the bioactive metabolite of vitamin D3, by upregulation of the vitamin D receptor (VDR) and expression of several genes. Methylmercury is a highly bioaccumulative environmental stressor of relevance to the dolphin. We currently report that in dolphin cells sublethal concentrations of methylmercury compromise the ability of 1,25D3 to upregulate VDR, to transactivate a vitamin D-sensitive promoter, and to express specific target genes. These results help elucidate the effects of vitamin D and methylmercury on innate immunity in dolphin skin and potentially in human skin as well, considering similarities in the vitamin D pathway between the two species.