Maternal Selenium Deficiency in Mice Alters Offspring Glucose Metabolism and Thyroid Status in a Sexually Dimorphic Manner

Synergistic Effect of Maternal Micronutrient Supplementation on ORFV DNA Vaccine Immune Response in a Pregnant Model

Contagious ecthyma is a contagious zoonotic disease caused by the Orf virus that can infect farm animals and humans, but no vaccine is available for pregnant mothers. Excessive oxidative stress during pregnancy can suppress the vaccine immune response in pregnant mothers; hence, maternal micronutrient supplementation could effectively improve the immune response, health, and oxidative status during pregnancy. In this study, we employed an 8-week-old pregnant rat model to receive a single intramuscular dose of 200 µg of ORF DNA vaccine with or without vitamin E and selenium supplementation to evaluate their effect on immune responses (specific IgG and IgG isotypes), oxidative stress, liver enzymes, and blood glucose levels in maternal-neonatal serum and milk secretions. Additionally, antioxidant-related gene expressions were analyzed in the maternal placenta and pups' liver. The results showed that supplementation of vitamin E and selenium with ORF DNA vaccination increased the production of specific antibody and IgG isotypes (IgG1 and IgG2a) and reduced the oxidative stress in neonatal-maternal serum and milk compared to both the control group and those vaccinated without supplementation (p < 0.05). Notably, the ORF DNA vaccine did not cause oxidative stress and hepatic damage. However, combined supplementation of vitamin E and selenium with DNA vaccination significantly decreased serum malondialdehyde (MDA) levels and improved the antioxidant-related enzyme activities of glutathione peroxidase (GPX), superoxide dismutase 1 (SOD1), and selenoprotein P (SELP) in the maternal placenta and liver of pups (p < 0.05). In conclusion, maternal supplementation of vitamin E and selenium enhanced the immune responses of the ORF DNA vaccine by mitigating oxidative stress in pregnant rats and could thus be a promising strategy for better health outcomes for both mothers and neonates.

Effects of Gestational Diabetes Mellitus and Selenium Deficiency on the Offspring Growth and Blood Glucose Mechanisms of C57BL/6J Mice

This study aimed to explore the effects and mechanisms of maternal gestational diabetes mellitus (GDM) and selenium (Se) deficiency on the growth and glucose metabolism of offspring. Female C57BL/6J mice were divided into four groups as follows: a control group, a GDM group, a Se deficiency group, and a GDM with Se deficiency group. GDM animal models were established via S961. Pregnant mice fed their offspring until weaning. Then, offspring continued to be fed with a basic diet until adulthood. Body weight and fasting blood glucose were measured weekly. Se content, oxidative stress indicators, and the protein expression of the PI3K/Akt signaling pathway were detected. GDM increased susceptibility to obesity in lactating offspring, with gender differences observed in adult offspring. The effect of Se deficiency on SOD activity only appeared in female offspring during adulthood but was shown in male offspring during weaning though it disappeared during adulthood. GDM and Se deficiency increased the risk of abnormal glucose metabolism in female offspring from weaning to adulthood but gradually decreased in male offspring. The influence on the expression of PI3K/Akt signaling pathway-related proteins showed the same trend. GDM and Se deficiency affected the growth and glucose metabolism of offspring through oxidative stress and PI3K/Akt signaling pathway-related proteins, and gender differences existed.

Calcium Supplementation on Glucose Tolerance, Oxidative Stress, and Reproductive Outcomes of Diabetic Rats and Their Offspring

Diabetes mellitus increases the risk of obstetric complications, morbidity, and infant mortality. Controlled nutritional therapy with micronutrients has been employed. However, the effect of calcium (Ca2+) supplementation on diabetic pregnancy is unclear. We aimed to evaluate whether diabetic rats supplemented with Ca2+ during pregnancy present better glucose tolerance, redox status, embryonic and fetal development, newborn weight, and the prooxidant and antioxidant balance of male and female pups. For this, newborn rats received the beta-cytotoxic drug streptozotocin for inducing diabetes on the day of birth. In adulthood, these rats were mated and treated with Ca2+ twice a day from day 0 to day 20 of pregnancy. On day 17, the pregnant rats were submitted to the oral glucose tolerance test (OGTT). At the end of pregnancy, they were anesthetized and killed to collect blood and pancreas samples. The uterine horns were exposed for an evaluation of maternal reproductive outcomes and embryofetal development, and the offspring's liver samples were collected for redox status measurement. Nondiabetic and diabetic rats supplemented with Ca2+ showed no influence on glucose tolerance, redox status, insulin synthesis, serum calcium levels, and embryofetal losses. The reduced rate of newborns classified as adequate for gestational age (AGA) and higher rates of LGA (large) and small (LGA) newborns and higher -SH and GSH-Px antioxidant activities in female pups were observed in diabetic dams, regardless of supplementation. Thus, maternal supplementation caused no improvement in glucose tolerance, oxidative stress biomarkers, embryofetal growth and development, and antioxidants in pups from diabetic mothers.

NAC1 confines virus-specific memory formation of CD4+ T cells through the ROCK1-mediated pathway

Nucleus accumbens-associated protein 1 (NAC1), a transcriptional cofactor, has been found to play important roles in regulating regulatory T cells, CD8⁺ T cells, and antitumor immunity, but little is known about its effects on T-cell memory. In this study, we found that NAC1 expression restricts memory formation of CD4⁺ T cells during viral infection. Analysis of CD4⁺ T cells from wild-type (WT) and NAC1-deficient (^-/- ) mice showed that NAC1 is essential for T-cell metabolism, including glycolysis and oxidative phosphorylation, and supports CD4⁺ T-cell survival in vitro. We further demonstrated that a deficiency of NAC1 downregulates glycolysis and correlates with the AMPK-mTOR pathway and causes autophagy defective in CD4⁺ T cells. Loss of NAC1 reduced the expression of ROCK1 and the phosphorylation and stabilization of BECLIN1. However, a forced expression of ROCK1 in NAC1^-/- CD4⁺ T cells restored autophagy and the activity of the AMPK-mTOR pathway. In animal experiments, adoptively transferred NAC1^-/- CD4⁺ T cells or NAC1^-/- mice challenged with VACV showed enhanced formation of VACV-specific CD4⁺ memory T cells compared to adoptively transferred WT CD4⁺ T cells or WT mice. This memory T-cell formation enhancement was abrogated by forcing expression of ROCK1. Our study reveals a novel role for NAC1 as a suppressor of CD4⁺ T-cell memory formation and suggests that targeting NAC1 could be a new approach to promoting memory CD4⁺ T-cell development, which is critical for an effective immune response against pathogens.

Adverse perinatal conditions and the developmental origins of thyroid dysfunction-Lessons from Animal Models

PURPOSE

Nutritional, hormonal, and environmental status during development can predispose the individual to obesity and endocrine diseases later in life, an association known as metabolic programming. In general, weight loss or gain are seen in thyroid disorders, and thyroid function can be affected by body adiposity. In addition, hyper- and hypothyroidism can be related to metabolic programming. Our aim was to gather evidence that regardless of the type or critical window of metabolic imprinting, offspring exposed to certain adverse perinatal conditions have a higher risk of developing thyroid dysfunction.

METHODS

We reviewed literature data that relate insults occurring during pregnancy and/or lactation to short- and long-term offspring thyroid dysfunction in animal models.

RESULTS

Few studies have addressed the hypothalamic-pituitary-thyroid axis and thyroid dysfunction related to metabolic programming. The literature shows that under- and overnutrition, exposure to endocrine disruptors, early weaning, maternal thyroid disease and maternal high-fat diet can induce alterations in offspring thyroid function in a sex-dependent manner.

CONCLUSION

Based on the few available data, mainly in rodent models, we can conclude that diet, hormones, and environmental contaminants are related to the developmental origins of later thyroid dysfunction by interrupting the normal maturation of the thyroid gland.

Maternal micronutrient disturbance as risks of offspring metabolic syndrome

Metabolic syndrome (MetS) is defined as a constellation of individual metabolic disturbances, including central obesity, hypertension, dyslipidemia, and insulin resistance. The established pathogenesis of MetS varies extensively with gender, age, ethnic background, and nutritional status. In terms of nutritional status, micronutrients are more likely to be discounted as essential components of required nutrition than macronutrients due to the small amount required. Numerous observational studies have shown that pregnant women frequently experience malnutrition, especially in developing and low-income countries, resulting in chronic MetS in the offspring due to the urgent and increasing demands for micronutrients during gestation and lactation. Over the past few decades, scientific developments have revolutionized our understanding of the association between balanced maternal micronutrients and MetS in the offspring. Examples of successful individual, dual, or multiple maternal micronutrient interventions on the offspring include iron for hypertension, selenium for type 2 diabetes, and a combination of folate and vitamin D for adiposity. In this review, we aim to elucidate the effects of maternal micronutrient intake on offspring metabolic homeostasis and discuss potential perspectives and challenges in the field of maternal micronutrient interventions.

The association between serum selenium level and gestational diabetes mellitus: A systematic review and meta-analysis

BACKGROUND

The relationship between serum selenium level and gestational diabetes mellitus (GDM) is controversial. The purpose is to update and summarize previous studies to understand the relationship in more detail.

METHODS

PubMed, The Cochrane Library, EMBASE, Web of science, CNKI, WANFANG DATA and Cqvip were searched for studies published up to 3 September 2021. The random-effects model was used to measure the combined estimation. The overall effect was reported in a standard mean difference (SMD) and 95% confidence interval (95% CI). All data were analysed by Review Manager 5.4.

RESULTS

Twenty-seven studies involving 1588 patients with GDM and 2450 healthy pregnant women contributed to this meta-analysis. Selenium level was significantly lower in women with GDM than those without GDM (SMD = -1.29; 95% CI: -1.60 to -0.97, p < 0.00001). Subgroup analyses showed that such trend was consistent within the non-European population (Asia: SMD = -1.44; 95% CI: -1.79 to -1.08, p < 0.00001; Africa: SMD = -2.62; 95% CI: -4.50 to -0.74, p = 0.006) and in the second and third trimesters (the second trimester: SMD = -1.41; 95% CI: -1.82 to -0.99, p < 0.00001; the third trimester: SMD = -1.54; 95% CI: -2.09 to -0.98, p < 0.00001), but not within the European population (SMD = -0.47; 95% CI: -1.09 to 0.16, p = 0.14) or in the first trimester (SMD = -0.52; 95% CI: -1.13 to 0.10, p = 0.10).

CONCLUSIONS

This meta-analysis showed that the serum selenium level of patients with GDM was lower than that in healthy pregnant women, especially within the non-European population and in the second and third trimesters.

Critical Role of Maternal Selenium Nutrition in Neurodevelopment: Effects on Offspring Behavior and Neuroinflammatory Profile

Research in both animals and humans shows that some nutrients are important in pregnancy and during the first years of life to support brain and cognitive development. Our aim was to evaluate the role of selenium (Se) in supporting brain and behavioral plasticity and maturation. Pregnant and lactating female rats and their offspring up to postnatal day 40 were fed isocaloric diets differing in Se content—i.e., optimal, sub-optimal, and deficient—and neurodevelopmental, neuroinflammatory, and anti-oxidant markers were analyzed. We observed early adverse behavioral changes in juvenile rats only in sub-optimal offspring. In addition, sub-optimal, more than deficient supply, reduced basal glial reactivity in sex dimorphic and brain-area specific fashion. In female offspring, deficient and sub-optimal diets reduced the antioxidant Glutathione peroxidase (GPx) activity in the cortex and in the liver, the latter being the key organ regulating Se metabolism and homeostasis. The finding that the Se sub-optimal was more detrimental than Se deficient diet may suggest that maternal Se deficient diet, leading to a lower Se supply at earlier stages of fetal development, stimulated homeostatic mechanisms in the offspring that were not initiated by sub-optimal Se. Our observations demonstrate that even moderate Se deficiency during early life negatively may affect, in a sex-specific manner, optimal brain development.

Selenium Deficiency during Pregnancy in Mice Impairs Exercise Performance and Metabolic Function in Adult Offspring

Selenium deficiency during the perinatal period programs metabolic dysfunction in offspring. Postnatal exercise may prevent the development of programmed metabolic disease. This study investigated the impact of selenium deficiency on offspring exercise behavior and whether this improved metabolic health. Female C57BL/6 mice were randomly allocated to control (NormalSe, >190 μg/Se/kg, n = 8) or low-selenium (LowSe, <50 μg/Se/kg, n = 8) diets from four weeks before mating. Male offspring were weaned at postnatal day (PN) twenty-four and placed on a normal chow diet. At PN60, mice were placed in cages with bi-directional running wheels and monitored until PN180. LowSe offspring had a reduced average weekly running speed and distance (p < 0.05). LowSe offspring exhibited glucose intolerance, with increased peak blood glucose (p < 0.05) and area under the curve following an intra-peritoneal injection of glucose (p < 0.05). Furthermore, mRNA expression of several selenoproteins within cardiac and skeletal muscle were increased in LowSe offspring (p < 0.05). The results indicated that selenium deficiency during development reduces exercise behavior. Furthermore, exercise does not prevent programmed glucose intolerance in low-selenium offspring. This highlights that exercise may not be the optimal intervention for metabolic disease in offspring impacted by selenium deficiency in early life.

A Comprehensive Review on Selenium and Its Effects on Human Health and Distribution in Middle Eastern Countries

Selenium (Se) is an important microelement with numerous positive effects on human health and diseases. It is important to specify that the status and consumption of Se are for a specific community as the levels of Se are extremely unpredictable between different populations and regions. Our existing paper was based on the impacts of Se on human health and disease along with data on the Se levels in Middle Eastern countries. Overall, the findings of this comprehensive review show that the consumption and levels of Se are inadequate in Middle Eastern nations. Such findings, together with the growing awareness of the importance of Se to general health, require further work primarily on creating an acceptable range of blood Se concentration or other measures to determine optimal Se consumption and, consequently, to guarantee adequate Se supplementation in populations at high risk of low Se intake.

Gaps in the knowledge of thyroid hormones and placental biology

Thyroid hormones (THs) are required for the growth and development of the foetus, stimulating anabolism and oxygen consumption from the early stages of pregnancy to the period of foetal differentiation close to delivery. Maternal changes in the hypothalamic–pituitary thyroid axis are also well known. In contrast, several open questions remain regarding the relationships between the placenta and the maternal and foetal TH systems. The exact mechanism by which the placenta participates in regulating the TH concentration in the foetus and mother and the role of TH in the placenta are still poorly studied. In this review, we aim to summarize the available data in the area and highlight significant gaps in our understanding of the ontogeny and cell-specific localization of TH transporters, TH receptors and TH metabolic enzymes in the placenta in both human and rodent models. Significant deficiencies also exist in knowledge of the contribution of genomic and nongenomic effects of TH on the placenta and finally how the placenta reacts during pregnancy when the mother has thyroid disease. By addressing these key knowledge gaps, improved pregnancy outcomes and management of women with thyroid alterations may be possible.

Effects of Selenium Supplementation on Rumen Microbiota, Rumen Fermentation, and Apparent Nutrient Digestibility of Ruminant Animals: A Review

Enzymes excreted by rumen microbiome facilitate the conversion of ingested plant materials into major nutrients (e.g., volatile fatty acids (VFA) and microbial proteins) required for animal growth. Diet, animal age, and health affect the structure of the rumen microbial community. Pathogenic organisms in the rumen negatively affect fermentation processes in favor of energy loss and animal deprivation of nutrients in ingested feed. Drawing from the ban on antibiotic use during the last decade, the livestock industry has been focused on increasing rumen microbial nutrient supply to ruminants through the use of natural supplements that are capable of promoting the activity of beneficial rumen microflora. Selenium (Se) is a trace mineral commonly used as a supplement to regulate animal metabolism. However, a clear understanding of its effects on rumen microbial composition and rumen fermentation is not available. This review summarized the available literature for the effects of Se on specific rumen microorganisms along with consequences for rumen fermentation and digestibility. Some positive effects on total VFA, the molar proportion of propionate, acetate to propionate ratio, ruminal NH3-N, pH, enzymatic activity, ruminal microbiome composition, and digestibility were recorded. Because Se nanoparticles (SeNPs) were more effective than other forms of Se, more studies are needed to compare the effectiveness of synthetic SeNPs and lactic acid bacteria enriched with sodium selenite as a biological source of SeNPs and probiotics. Future studies also need to evaluate the effect of dietary Se on methane emissions.

The Effect and Potential Mechanism of Maternal Micronutrient Intake on Offspring Glucose Metabolism: An Emerging Field

Diabetes has become the most common metabolic disease around the world. In addition to genetic and environmental factors in adulthood, the early life environment is critical to the progression of diabetes in adults, especially the environment during the fetal period; this concept is called “fetal programming.” Substantial evidence has illustrated the key role of early life macronutrient in programming metabolic diseases. Recently, the effect of maternal micronutrient intake on offspring glucose metabolism during later life has become an emerging field. This review focuses on updated human and animal evidence about the effect of maternal micronutrient status on offspring glucose metabolism and the underlying mechanism.

Effect of maternal apical periodontitis on the final step of insulin signalling and inflammatory pathway in the adult male offspring of rats

AIM

To evaluate the final step of insulin signalling, inflammatory pathway (related to the inhibition of insulin signalling), peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α) protein content and DNA methylation in the Slc2a4 gene promoter region in the skeletal muscle of adult male offspring of rats with apical periodontitis (AP) in a single tooth or in four teeth.

METHODOLOGY

Female Wistar rats were distributed into three groups: a control group, a group with one tooth with AP and a group with four teeth with AP. Thirty days after induction of AP, female rats from all groups were mated with healthy male rats. When male offspring reached 75 days of age, the following analyses were performed in the gastrocnemius muscle (GM): insulin-stimulated Akt serine and threonine phosphorylation status; NF-κB p50 and p65 subunits phosphorylation status; GLUT4, TNF-α and PGC-1α protein content by Western blotting; GLUT4 and TNF-α gene expression by real-time polymerase chain reaction (PCR); and DNA methylation in the Slc2a4 gene promoter region by restriction digestion and real-time PCR. Analysis of variance was performed, followed by Tukey's post hoc test. p values <.05 were considered to be statistically significant.

RESULTS

Maternal AP in four teeth decreased insulin-stimulated Akt serine and threonine phosphorylation status, reduced GLUT4 gene expression and its protein content, and increased NF-κB p50 and p65 subunits phosphorylation status in the GM of adult offspring. There were no alterations in the parameters analysed in the GM of adult offspring of rats with AP in a single tooth. In addition, maternal AP did not affect TNF-α gene expression and its protein content, PGC-1α protein content and DNA methylation in the Slc2a4 gene promoter region in the GM of adult offspring.

CONCLUSIONS

Maternal AP in four teeth was associated with impairment in the final step of insulin signalling in the GM of adult male offspring in rats. An increase in NF-κB activity may be involved in this decrease in insulin signalling. This study demonstrates the impact of maternal AP on the health of offspring, demonstrating the importance of maintaining adequate maternal oral health to prevent diseases in adult offspring in rats.

Maternal selenium deficiency in mice promotes sex-specific changes to urine flow and renal expression of mitochondrial proteins in adult offspring

Selenium deficiency during pregnancy can impair fetal development and predispose offspring to thyroid dysfunction. Given that key selenoproteins are highly expressed in the kidney and that poor thyroid health can lead to kidney disease, it is likely that kidney function may be impaired in offspring of selenium-deficient mothers. This study utilized a mouse model of maternal selenium deficiency to investigate kidney protein glycation, mitochondrial adaptations, and urinary excretion in offspring. Female C57BL/6 mice were fed control (>190 µg selenium/kg) or low selenium (<50 µg selenium/kg) diets four weeks prior to mating, throughout gestation, and lactation. At postnatal day (PN) 170, offspring were placed in metabolic cages for 24 hr prior to tissue collection at PN180. Maternal selenium deficiency did not impact selenoprotein antioxidant activity, but increased advanced glycation end products in female kidneys. Male offspring had reduced renal Complex II and Complex IV protein levels and lower 24 hr urine flow. Although renal aquaporin 2 (Aqp2) and arginine vasopressin receptor 2 (Avpr2) mRNA were not altered by maternal selenium deficiency, a correlation between urine flow and plasma free T4 concentrations in male but not female offspring suggests that programed thyroid dysfunction may be mediating impaired urine flow. This study demonstrates that maternal selenium deficiency can lead to long-term deficits in kidney parameters that may be secondary to impaired thyroid dysfunction. Considering the significant burden of renal dysfunction as a comorbidity to metabolic diseases, improving maternal selenium intake in pregnancy may be one simple measure to prevent lifelong disease.

The Role of Maternal Weight in the Hierarchy of Macrosomia Predictors; Overall Effect of Analysis of Three Prediction Indicators

So far it has not been established which maternal features play the most important role in newborn macrosomia. The aim of this study is to provide assessment of a hierarchy of twenty six (26) maternal characteristics in macrosomia prediction. A Polish prospective cohort of women with singleton pregnancy (N = 912) which was recruited in the years 2015–2016 has been studied. Two analyses were performed: for probability of macrosomia > 4000 g (n = 97) (vs. 755 newborns 2500–4000 g); and for birthweight > 90th percentile (n = 99) (vs. 741 newborns 10–90th percentile). A multiple logistic regression was used (with 95% confidence intervals (CI)). A hierarchy of significance of potential predictors was established after summing up of three prediction indicators (NRI, IDI and AUC) calculated for the basic prediction model (maternal age + parity) extended with one (test) predictor. ‘Net reclassification improvement’ (NRI) focuses on the reclassification table describing the number of women in whom an upward or downward shift in the disease probability value occurred after a new factor had been added, including the results for healthy and ill women. ‘Integrated discrimination improvement’ (IDI) shows the difference between the value of mean change in predicted probability between the group of ill and healthy women when a new factor is added to the model. The area under curve (AUC) is a commonly used indicator. Results. The macrosomia risk was the highest for prior macrosomia (AOR = 7.53, 95%CI: 3.15–18.00, p < 0.001). A few maternal characteristics were associated with more than three times higher macrosomia odds ratios, e.g., maternal obesity and gestational age ≥ 38 weeks. A different hierarchy was shown by the prediction study. Compared to the basic prediction model (AUC = 0.564 (0.501–0.627), p = 0.04), AUC increased most when pre-pregnancy weight (kg) was added to the base model (AUC = 0.706 (0.649–0.764), p < 0.001). The values of IDI and NRI were also the highest for the model with maternal weight (IDI = 0.061 (0.039–0.083), p < 0.001), and (NRI = 0.538 (0.33–0.746), p < 0.001). Adding another factor to the base model was connected with significantly weaker prediction, e.g., for gestational age ≥ 38 weeks (AUC = 0.602 (0.543–0.662), p = 0.001), (IDI = 0.009 (0.004; 0.013), p < 0.001), and (NRI = 0.155 (0.073; 0.237), p < 0.001). After summing up the effects of NRI, IDI and AUC, the probability of macrosomia was most strongly improved (in order) by: pre-pregnancy weight, body mass index (BMI), excessive gestational weight gain (GWG) and BMI ≥ 25 kg/m². Maternal height, prior macrosomia, fetal sex-son, and gestational diabetes mellitus (GDM) occupied an intermediate place in the hierarchy. The main conclusions: newer prediction indicators showed that (among 26 features) excessive pre-pregnancy weight/BMI and excessive GWG played a much more important role in macrosomia prediction than other maternal characteristics. These indicators more strongly highlighted the differences between predictors than the results of commonly used odds ratios.

Low levels of arsenic exposure during pregnancy and maternal and neonatal thyroid hormone parameters: The determinants for these associations

BACKGROUND

The potential maternal and neonatal thyrotoxicity associated with exposure to arsenic during pregnancy is very limited and unclear.

OBJECTIVES

This study aimed to examine the associations between arsenic exposure levels in maternal and cord serum and maternal and neonatal thyroid hormone parameters in a prospective birth cohort study.

METHODS

The study including 2089 mother-neonate pairs was based upon Ma'an Shan birth cohort study in China. The exposure variables including maternal serum arsenic levels in the first, second and third trimester and average arsenic exposure level during pregnancy and cord serum arsenic level. Maternal serum TSH and FT4 levels in the first, second and third trimester and cord serum TSH and FT4 levels were determined using the electrochemiluminescence immunoassay with Cobas Elecsys 411. Linear mixed models were used to examine associations between arsenic exposure variables during pregnancy and maternal thyroid hormone parameters, and multiple linear regression analyses were used to examine associations between arsenic exposure during pregnancy and neonatal thyroid hormone parameters. Bayesian kernal machine regression (BKMR) analyses based on a kernel function were also used to examine the effects of exposure to metal mixtures (arsenic, mercury, cadmium and selenium).

RESULTS

The geometric means of arsenic exposure levels across 3 trimesters were 1.74 μg/L, 1.81 μg/L and 1.99 μg/L, respectively, and 1.90 μg/L in cord serum; the geometric means of maternal FT4 levels across 3 trimesters were 16.91 pmol/L, 11.91 pmol/L and 13.16 pmol/L, respectively, and 16.10 pmol/L in cord serum; the geometric means of maternal TSH levels across 3 trimesters were 1.27 μIU/mL, 2.32 μIU/mL and 2.08 μIU/mL, respectively, and 8.47 μIU/mL in cord serum. Maternal serum arsenic levels in the first, seond, third trimester and average arsenic exposure level during pregnancy were all not associated with maternal thyroid hormone parameters after adjustment for all the covariates, the adjusted β (95% CI) were -0.002 (-0.10 to 0.09), 0.05 (-0.05 to 0.16), -0.09 (-0.17 to 0.003) and -0.05 (-0.22 to 0.11) for maternal FT4, respectively; and -0.005 (-0.04 to 0.03), -0.003 (-0.04 to 0.03), -0.004 (-0.03 to 0.02) and -0.01 (-0.06 to 0.04) for maternal lnTSH, respectively. Maternal serum arsenic levels in the first, second trimester and average arsenic exposure level during pregnancy were all inversely associated with neonatal FT4 level after adjustment for all the confounders, the adjusted β (95% CI) were -0.19 (-0.31 to -0.07), -0.14 (-0.26 to -0.01), -0.22 (-0.42 to -0.02), respectively; and cord serum arsenic level was positively related with neonatal TSH level, the adjusted β (95% CI) were 0.04 (0.001 to 0.08). The adverse joint toxic effect of the four metals in maternal serum in the first trimester and in cord serum on neonatal thyroid hormone parameters were also found.

CONCLUSIONS

In this study, exposure to low levels of arsenic during pregnancy could directly affect neonatal thyroid hormone parameters without being mediated by maternal effect of exposure, and maternal serum arsenic levels in the first, second trimester and average arsenic exposure level during pregnancy and cord serum arsenic level may be risk factors affecting neonatal thyroid hormones. These findings indicate that neonates are more sensitive to the thyrotoxicity of arsenic exposure even at low levels. In addition, the adverse joint toxic effect of metal mixtures is also worthy of attention.

Minerals in Pregnancy and Their Impact on Child Growth and Development

During pregnancy, women undergo metabolic and physiological changes, and their needs are higher, to maintain growth and development of the fetus. If the nutritional status of the expectant mother is not satisfactory, some maternal and neonatal complications can occur. In the second and third trimester of pregnancy, there is a reserve of nutrients in the fetus that can be utilized after birth; thereby, children present an accelerated growth in the first years of life, which is a proven response to the available nutrition pattern. However, if such a pattern is insufficient, there will be deficits during development, including brain function. Therefore, despite many recent published works about gestational nutrition, uncertainties still remain on the mechanisms of absorption, distribution, and excretion of micronutrients. Further elucidation is needed to better understand the impacts caused either by deficiency or excess of some micronutrients. Thus, to illustrate the contributions of minerals during prenatal development and in children, iodine, selenium, iron, zinc, calcium, and magnesium were selected. Our study sought to review the consequences related to gestational deficiency of the referred minerals and their impact on growth and development in children born from mothers with such deficiencies

A Review of the Potential Interaction of Selenium and Iodine on Placental and Child Health

A healthy pregnancy is important for the growth and development of a baby. An adverse pregnancy outcome is associated with increased chronic disease risk for the mother and offspring. An optimal diet both before and during pregnancy is essential to support the health of the mother and offspring. A key mediator of the effect of maternal nutrition factors on pregnancy outcomes is the placenta. Complicated pregnancies are characterized by increased oxidative stress in the placenta. Selenium and iodine are micronutrients that are involved in oxidative stress in placental cells. To date, there has been no comprehensive review investigating the potential synergistic effect of iodine and selenium in the placenta and how maternal deficiencies may be associated with increased oxidative stress and hence adverse pregnancy outcomes. We undertook a hypothesis-generating review on selenium and iodine, to look at how they may relate to pregnancy complications through oxidative stress. We propose how they may work together to impact pregnancy and placental health and explore how deficiencies in these micronutrients during pregnancy may impact the future health of offspring.

Serum Microelements in Early Pregnancy and their Risk of Large-for-Gestational Age Birth Weight

Excessive birth weight has serious perinatal consequences, and it “programs” long-term health. Mother’s nutritional status can be an important element in fetal “programming”; microelements such as selenium (Se), zinc (Zn), copper (Cu), and iron (Fe) are involved in many metabolic processes. However, there are no studies assessing the relationship of the microelements in the peri-conceptual period with the risk of excessive birth weight. We performed a nested case control study of serum microelements’ levels in the 10–14th week of pregnancy and assessed the risk of large-for-gestational age (LGA) newborns using the data from a prospective cohort of pregnant women recruited in 2015–2016 in Poznań, Poland. Mothers delivering LGA newborns (n = 66) were examined with matched mothers delivering appropriate-for-gestational age (AGA) newborns (n = 264). Microelements’ levels were quantified using mass spectrometry. The odds ratios of LGA (and 95% confidence intervals) were calculated by multivariate logistic regression. In the whole group, women with the lowest quartile of Se had a 3 times higher LGA risk compared with women in the highest Se quartile (AOR = 3.00; p = 0.013). Importantly, the result was sustained in the subgroup of women with the normal pre-pregnancy BMI (AOR = 4.79; p = 0.033) and in women with a male fetus (AOR = 6.28; p = 0.004), but it was not sustained in women with a female fetus. There were no statistical associations between Zn, Cu, and Fe levels and LGA. Our study provides some preliminary evidence for the relationships between lower serum Se levels in early pregnancy and a higher risk of large-for-gestational age birth weight. Appropriate Se intake in the periconceptual period may be important for optimal fetal growth.

Analysis of Selenoprotein Expression in Response to Dietary Selenium Deficiency During Pregnancy Indicates Tissue Specific Differential Expression in Mothers and Sex Specific Changes in the Fetus and Offspring

The human selenoproteome is comprised of ~25 genes, which incorporate selenium, in the form of selenocysteine, into their structure. Since it is well known that selenium is important to maternal health and foetal development during pregnancy, this study aimed at defining the impact of selenium deficiency on maternal, placental, foetal and offspring selenoprotein gene expression. Female C57BL/6 mice were randomly allocated to control (>190 μg/kg) or low selenium (<50 μg/kg) diets four weeks prior to mating and throughout gestation. At embryonic day (E)18.5, pregnant mice were sacrificed followed by collection of maternal and foetal tissues. A subset of mice littered down, and offspring were monitored from postnatal day (PN) 8, weaned at PN24 and sacrificed at PN180, followed by tissue collection. Following RNA extraction, the expression of 14 selenoproteins was assessed with qPCR in liver, kidneys, muscle and placenta. Selenium deficiency downregulated expression (P_trt < 0.05) of many selenoproteins in maternal tissues and the placenta. However, foetal selenoprotein expression was upregulated (P_trt < 0.05) in all tissues, especially the kidneys. This was not reflected at PN180; however, a sexually dimorphic relationship in selenoprotein expression was observed in offspring. This study demonstrates the selenoproteome is sensitive to dietary selenium levels, which may be exacerbated by pregnancy. We concluded that transcriptional regulation of selenoproteins is complex and multifaceted, with expression exhibiting tissue-, age- and sex-specificities.