Spatial and temporal patterns of expression of 11beta-hydroxysteroid dehydrogenase types 1 and 2 messenger RNA and glucocorticoid receptor protein in the murine placenta and uterus during late pregnancy

To gain insight into the role of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) enzymes and actions of glucocorticoids in the murine placenta and uterus, the expression pattern of the mRNA for 11beta-HSD1 and 11beta-HSD2 and the glucocorticoid receptor (GR) protein were determined from Embryonic Day 12.5 (E12.5, term = E19) to E18.5 by in situ hybridization and immunohistochemistry, respectively. Consistent with its putative role in regulating the transplacental passage of maternal glucocorticoid to the fetus, 11beta-HSD2 mRNA was highly expressed in the labyrinthine zone (the major site of maternal/fetal exchange) at E12.5, and its level decreased dramatically at E16.5, when it became barely detectable. Remarkably, the silencing of 11beta-HSD2 gene expression coincided with the onset of 11beta-HSD1 gene expression in the labyrinth at E16.5 when moderate levels of 11beta-HSD1 mRNA were detected and maintained to E18.5. By contrast, neither 11beta-HSD1 mRNA nor 11beta-HSD2 mRNA were detected in any cell types within the basal zone from E12.5 to E18.5. Moreover, the expression of 11beta-HSD1 and 11beta-HSD2 in the decidua exhibited a high degree of cell specificity in that the mRNA for both 11beta-HSD1 and 11beta-HSD2 was detected in the decidua-stroma but not in the compact decidua. A distinct pattern was also observed within the endometrium where the mRNA for 11beta-HSD1 was expressed in the epithelium, whereas that for 11beta-HSD2 was confined strictly to the stroma. By comparison, the expression of GR in the placenta and uterus was ubiquitous and unremarkable throughout late pregnancy. In conclusion, the present study demonstrates for the first time remarkable spatial and temporal patterns of expression of 11beta-HSD1 and 11beta-HSD2 and GR in the murine placenta and uterus and highlights the intricate control of not only transplacental passage of maternal glucocorticoid to the fetus but also local glucocorticoid action during late pregnancy.     

Adaptive responses by mouse early embryos to maternal diet protect fetal growth but predispose to adult onset disease

Poor maternal nutrition during pregnancy can alter postnatal phenotype and increase susceptibility to adult cardiovascular and metabolic diseases. However, underlying mechanisms are largely unknown. Here, we show that maternal low protein diet (LPD), fed exclusively during mouse preimplantation development, leads to offspring with increased weight from birth, sustained hypertension, and abnormal anxiety-related behavior, especially in females. These adverse outcomes were interrelated with increased perinatal weight being predictive of later adult overweight and hypertension. Embryo transfer experiments revealed that the increase in perinatal weight was induced within blastocysts responding to preimplantation LPD, independent of subsequent maternal environment during later pregnancy. We further identified the embryo-derived visceral yolk sac endoderm (VYSE) as one mediator of this response. VYSE contributes to fetal growth through endocytosis of maternal proteins, mainly via the multiligand megalin (LRP2) receptor and supply of liberated amino acids. Thus, LPD maintained throughout gestation stimulated VYSE nutrient transport capacity and megalin expression in late pregnancy, with enhanced megalin expression evident even when LPD was limited to the preimplantation period. Our results demonstrate that in a nutrient-restricted environment, the preimplantation embryo activates physiological mechanisms of developmental plasticity to stablize conceptus growth and enhance postnatal fitness. However, activation of such responses may also lead to adult excess growth and cardiovascular and behavioral diseases.     

Gestational changes in concentrations of selenium and zinc in the porcine fetus and the effects of maternal intake of selenium

The effect of maternal dietary selenium (Se) and gestation on the concentrations of Se and zinc (Zn) in the porcine fetus were determined. Mature gilts were randomly assigned to treatments of either adequate (0.39 ppm Se) or low (0.05 ppm Se) dietary Se. Gilts were bred and fetuses were collected throughout gestation. Concentrations of Se in maternal whole blood and liver decreased during gestation in sows fed the low-Se diet compared to sows fed the Se-supplemented diet. Maternal intake of Se did not affect the concentration of Se in the whole fetus; however, the concentration of Se in fetal liver was decreased in fetuses of sows fed the low-Se diet. Although fetal liver Se decreased in both treatments as gestation progressed, the decrease was greater in liver of fetuses from sows fed the low-Se diet. Dietary Se did not affect concentrations of Zn in maternal whole blood or liver or in the whole fetus and fetal liver. The concentration of Se in fetal liver was lower but the concentration of Zn was greater than in maternal liver when sows were fed the adequate Se diet. These results indicate that maternal intake of Se affects fetal liver Se and newborn piglets have lower liver Se concentrations compared to their dams, regardless of the Se intake of sows during gestation. Thus, the piglet is more susceptible Se deficiency than the sow.     

High and Low Protein∶ Carbohydrate Dietary Ratios during Gestation Alter Maternal-Fetal Cortisol Regulation in Pigs

Imbalanced maternal nutrition during gestation can cause alterations of the hypothalamic-pituitary-adrenal (HPA) system in offspring. The present study investigated the effects of maternal low- and high-protein diets during gestation in pigs on the maternal-fetal HPA regulation and expression of the glucocorticoid receptor (GR), mineralocorticoid receptor (MR), 11β-hydroxysteroid dehydrogenase 1 and 2 (11β-HSD1 and 11β-HSD2) and c-fos mRNAs in the placenta and fetal brain. Twenty-seven German Landrace sows were fed diets with high (HP, 30%), low (LP, 6.5%) or adequate (AP, 12.1%) protein levels made isoenergetic by varying the carbohydrate levels. On gestational day 94, fetuses were recovered under general anesthesia for the collection of blood, brain and placenta samples. The LP diet in sows increased salivary cortisol levels during gestation compared to the HP and AP sows and caused an increase of placental GR and c-fos mRNA expression. However, the diurnal rhythm of plasma cortisol was disturbed in both LP and HP sows. Total plasma cortisol concentrations in the umbilical cord vessels were elevated in fetuses from HP sows, whereas corticosteroid-binding globulin levels were decreased in LP fetuses. In the hypothalamus, LP fetuses displayed an enhanced mRNA expression of 11β-HSD1 and a reduced expression of c-fos. Additionally, the 11β-HSD2 mRNA expression was decreased in both LP and HP fetuses. The present results suggest that both low and high protein∶carbohydrate dietary ratios during gestation may alter the expression of genes encoding key determinants of glucocorticoid hormone action in the fetus with potential long-lasting consequences for stress adaptation and health.     

Maternal periconceptional and gestational low protein diet affects mouse offspring growth, cardiovascular and adipose phenotype at 1 year of age

Human and animal studies have revealed a strong association between periconceptional environmental factors, such as poor maternal diet, and an increased propensity for cardiovascular and metabolic disease in adult offspring. Previously, we reported cardiovascular and physiological effects of maternal low protein diet (LPD) fed during discrete periods of periconceptional development on 6-month-old mouse offspring. Here, we extend the analysis in 1 year aging offspring, evaluating mechanisms regulating growth and adiposity. Isocaloric LPD (9% casein) or normal protein diet (18% casein; NPD) was fed to female MF-1 mice either exclusively during oocyte maturation (for 3.5 days prior to mating; Egg-LPD, Egg-NPD, respectively), throughout gestation (LPD, NPD) or exclusively during preimplantation development (for 3.5 days post mating; Emb-LPD). LPD and Emb-LPD female offspring were significantly lighter and heavier than NPD females respectively for up to 52 weeks. Egg-LPD, LPD and Emb-LPD offspring displayed significantly elevated systolic blood pressure at 52 weeks compared to respective controls (Egg-NPD, NPD). LPD females had significantly reduced inguinal and retroperitoneal fat pad: body weight ratios compared to NPD females. Expression of the insulin receptor (Insr) and insulin-like growth factor I receptor (Igf1r) in retroperitoneal fat was significantly elevated in Emb-LPD females (P<0.05), whilst Emb-LPD males displayed significantly decreased expression of the mitochondrial uncoupling protein 1 (Ucp1) gene compared to NPD offspring. LPD females displayed significantly increased expression of Ucp1 in interscapular brown adipose tissue when compared to NPD offspring. Our results demonstrate that aging offspring body weight, cardiovascular and adiposity homeostasis can be programmed by maternal periconceptional nutrition. These adverse outcomes further exemplify the criticality of dietary behaviour around the time of conception on long-term offspring health.     

Maternal diets enriched in olive oil regulate lipid metabolism and levels of PPARs and their coactivators in the fetal liver in a rat model of gestational diabetes mellitus

In a rat model of gestational diabetes mellitus (GDM) programmed in the offspring of neonatal streptozotocin-induced (nSTZ) diabetic rats, lipids are accumulated in the fetal liver in a sex-dependent way. Here, we evaluated whether maternal diets enriched in olive oil in rats that will develop GDM ameliorate lipid metabolic impairments in the fetal livers. Pregnant offspring of control and nSTZ diabetic rats (F0) were fed a 6% olive oil-supplemented diet throughout the F1 gestation. We evaluated maternal metabolic parameters as well as lipid content, expression of lipid metabolizing enzymes and protein expression of PLIN2, PPARs and PPAR coactivators in the fetal livers. The offspring of nSTZ diabetic rats developed GDM regardless of the maternal treatment. Hypertriglyceridemia in GDM rats was prevented by the olive oil-enriched maternal treatment. In the livers of male fetuses of GDM rats, the maternal olive oil-supplemented diet prevented lipid overaccumulation and prevented the increase in PPARγ and PPARδ levels. In the livers of female fetuses of GDM rats, the maternal olive oil supplementation prevented the increase in PPARδ levels and the reduction in PGC1α levels, but did not prevent the reduced lipid content. Control and GDM rats showed a reduction of lipid metabolic enzymes in the fetal livers, which was associated with reduced levels of the PPAR coactivators PGC-1α and SRC-1 in males and of SRC-1 in females. These results suggest powerful effects of a maternal olive oil-supplemented diet in the fetal liver, possibly providing benefits in the fetuses and offspring from GDM rats.     

Chronic umbilical cord compression results in accelerated maturation of lung and brown adipose tissue in the sheep fetus during late gestation

Umbilical cord compression (UCC) sufficient to reduce umbilical blood flow by 30% for 3 days, results in increased fetal plasma cortisol and catecholamines that are likely to promote maturation of the fetal lung and brown adipose tissue (BAT). We determined the effect of UCC on the abundance of uncoupling protein (UCP)1 (BAT only) and -2, glucocorticoid receptor (GR), and 11beta-hydroxysteroid dehydrogenase (11beta-HSD)1 and -2 mRNA, and mitochondrial protein voltage-dependent anion channel (VDAC) and cytochrome c in these tissues. At 118 +/- 2 days of gestation (dGA; term approximately 145 days), 14 fetuses were chronically instrumented. Eight fetuses were then subjected to 3 days of UCC from 125 dGA, and the remaining fetuses were sham operated. All fetuses were then exposed to two 1-h episodes of hypoxemia at 130 +/- 1 and 134 +/- 1 dGA before tissue sampling at 137 +/- 2 dGA. In both tissues, UCC upregulated UCP2 and GR mRNA, plus VDAC and cytochrome c mitochondrial proteins. In lung, UCC increased 11beta-HSD1 mRNA but decreased 11beta-HSD2 mRNA abundance, a pattern reversed for BAT. UCC increased UCP1 mRNA and its translated protein in BAT. UCP2, GR, 11beta-HSD1 and -2 mRNA, plus VDAC and cytochrome c protein abundance were all significantly correlated with fetal plasma cortisol and catecholamine levels, but not thyroid hormone concentrations, in the lung and BAT of UCC fetuses. In conclusion, chronic UCC results in precocious maturation of the fetal lung and BAT mitochondria, an adaptation largely mediated by the surge in fetal plasma cortisol and catecholamines that accompanies UCC.     

Tissue-specific programming expression of glucocorticoid receptors and 11 beta-HSDs by maternal perinatal undernutrition in the HPA axis of adult male rats.

Maternal undernutrition leads to intrauterine growth retardation and predisposes to the development of pathologies in adulthood. The hypothalamo-pituitary-adrenal axis is a major target of early-life programming. We showed previously that perinatal maternal 50% food restriction leads to hypothalamo-pituitary-adrenal axis hyperactivity and disturbs glucocorticoid feedback in adult male rats. To try to better understand these alterations, we studied several factors involved in corticosterone sensitivity. We showed that unlike the restricted expression of 11 beta-HSD2 mRNA, the 11 beta-HSD1, glucocorticoid, and mineralocorticoid receptor genes are widely distributed in rat. In contrast to the hypothalamus, we confirmed that maternal undernutrition modulates hippocampal corticosterone receptor balance and leads to increased 11 beta-HSD1 gene expression. In the pituitary, rats exhibited a huge increase in both mRNA and mineralocorticoid receptor binding capacities as well as decreased 11 beta-HSD1/11 beta-HSD2 gene expression. Using IN SITU hybridization, we showed that the mineralocorticoid receptor gene was expressed in rat corticotroph cells and by other adenopituitary cells. In the adrenal gland, maternal food restriction decreased 11beta-HSD2 mRNA. This study demonstrated that maternal food restriction has both long-term and tissue-specific effects on gene expression of factors involved in glucocorticoid sensitivity and that it could contribute, via glucocorticoid excess, to the development of adult diseases.     

Intracrine induction of 11beta-hydroxysteroid dehydrogenase type 1 expression by glucocorticoid potentiates prostaglandin production in the human chorionic trophoblast

Glucocorticoids are involved in the modulation of the release of parturition hormones from the fetal membranes and placenta, where their actions are determined by the prereceptor glucocorticoid metabolizing enzyme 11beta-hydroxysteroid dehydrogenase (11beta-HSD). Two distinct isozymes of 11beta-HSD have been characterized. In the fetal membranes, 11beta-HSD1 is the predominate isozyme; it converts biologically inert 11-ketone glucocorticoid metabolites into active glucocorticoids. Sequence analysis of the cloned 11beta-HSD1 gene revealed a putative glucocorticoid response element in the promoter region. However, whether glucocorticoids modulate 11beta-HSD1 expression in the fetal membranes is unknown. In this study, 11beta-HSD1 and glucocorticoid receptor (GR) were coexpressed in the chorionic trophoblast. Radiometric conversion assay and Northern blot analysis revealed that both 11beta-HSD1 reductase activity and mRNA levels were increased by dexamethasone (1 microM, 0.1 microM) in the cultured chorionic trophoblast, and the effects were blocked by GR antagonist RU486 (1 microM). Prior induction of 11beta-HSD1 by dexamethasone potentiated the subsequent stimulation of prostaglandin H synthetase 2 expression and secretion of prostaglandin E(2) by cortisone in the chorionic trophoblast. There is colocalization of 11beta-HSD1 and GR in the chorionic trophoblast. By binding to GR, glucocorticoids induce the expression of 11beta-HSD1 by a possible intracrine mechanism, thereby amplifying the actions of glucocorticoids on prostaglandin production in the fetal membranes. This cascade of events initiated by glucocorticoids may play an important role in the positive feed-forward mechanisms of labor.     

The ontogeny of genes related to ovine fetal cardiac growth

The objective of this study was to determine the ontogenetic profiles in left and right ventricle of genes implicated in cardiac growth, including mineralocorticoid (MR) and glucocorticoid (GR) receptor, 11 beta-hydroxysteroid dehydrogenase (11beta-HSD) 1 and 2 and genes of the angiotensin system and insulin-like growth factor (IGF) family. Samples from left and right ventricles (LV, RV) were collected from hearts of sheep fetuses at 80, 100, 120, 130, and 145 days of gestation and from newborn lambs. Quantitative real-time PCR was performed to determine the MR, GR, 11beta-HSD 1 and 2, angiotensin converting enzyme (ACE) 1 and 2, IGF1, IGF2, IGF receptors IGF-1R and IGF-2R, and IGF-binding proteins (IGFBP) 2 and 3. In the LV, MR and GR both decreased toward term. In the RV, MR and GR expression did not decrease, but both 11beta-HSD 1 and 2 mRNA levels increased after birth. ACE1 expression in LV and RV sharply increases just before parturition, whereas ACE2 decreased in the LV and RV in late gestation. IGF2, IGF2R, and IGFBP2 expression levels substantially decreased in late gestation in LV and RV; IGF2R also decreased with age in LV. These patterns suggest that reduced expression of genes related to IGF and angiotensin II action occur as proliferative activity declines and terminal differentiation occurs in the late gestation fetal heart.     

Chronic Protein Restriction in Mice Impacts Placental Function and Maternal Body Weight before Fetal Growth

Mechanisms of resource allocation are essential for maternal and fetal survival, particularly when the availability of nutrients is limited. We investigated the responses of feto-placental development to maternal chronic protein malnutrition to test the hypothesis that maternal low protein diet produces differential growth restriction of placental and fetal tissues, and adaptive changes in the placenta that may mitigate impacts on fetal growth. C57BL/6J female mice were fed either a low-protein diet (6% protein) or control isocaloric diet (20% protein). On embryonic days E10.5, 17.5 and 18.5 tissue samples were prepared for morphometric, histological and quantitative RT-PCR analyses, which included markers of trophoblast cell subtypes. Potential endocrine adaptations were assessed by the expression of Prolactin-related hormone genes. In the low protein group, placenta weight was significantly lower at E10.5, followed by reduction of maternal weight at E17.5, while the fetuses became significantly lighter no earlier than at E18.5. Fetal head at E18.5 in the low protein group, though smaller than controls, was larger than expected for body size. The relative size and shape of the cranial vault and the flexion of the cranial base was affected by E17.5 and more severely by E18.5. The junctional zone, a placenta layer rich in endocrine and energy storing glycogen cells, was smaller in low protein placentas as well as the expression of Pcdh12, a marker of glycogen trophoblast cells. Placental hormone gene Prl3a1 was altered in response to low protein diet: expression was elevated at E17.5 when fetuses were still growing normally, but dropped sharply by E18.5 in parallel with the slowing of fetal growth. This model suggests that nutrients are preferentially allocated to sustain fetal and brain growth and suggests the placenta as a nutrient sensor in early gestation with a role in mitigating impacts of poor maternal nutrition on fetal growth.     

Maternal selenium deficiency increases hydrogen peroxide and total lipid peroxides in porcine fetal liver

To investigate the role of selenium (Se) in the developing porcine fetus, prepubertal gilts (n=42) were randomly assigned to either Se-adequate (0.39 ppm Se) or Se-deficient (0.05 ppm Se) gestation diets 6 wk prior to breeding. Maternal and fetal liver was collected at d 30, 45, 70, 90, and 114 of pregnancy. Concentrations of Se in maternal liver decreased during gestation in gilts fed the low-Se diet. The activity of cellular glutathione peroxidase (GPx) was decreased at d 30 and 45 of gestation in liver of gilts fed the low-Se diet. Concentrations of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) were greater in liver homogenates from gilts fed the low-Se diet. Within the fetuses, liver Se decreased in those fetuses of gilts fed the low-Se diet. Although the activity of GPx in fetal liver was not affected by the maternal diet, concentrations of H₂O₂ and MDA in fetal liver were greater in fetuses from gilts fed the low-Se diet. Maternal liver GPx activity was approx 12-fold greater than fetal liver GPx activity regardless of dietary treatment. These results indicate that maternal dietary Se intake affects fetal liver Se concentration and feeding a low-Se diet during gestation increases oxidative stress to the fetus, as measured by fetal liver H₂O₂ and MDA.     

Effects of maternal diabetes on the development of carbohydrate metabolizing enzymes in fetal rat liver

Effects of streptozotocin-induced maternal diabetes on fetal hepatic carbohydrate-metabolizing enzyme development and hormonal status has been explored in the rat. Hepatic glycogen synthase a activity of the normal fetus rose to a maximum at 20 days of gestation, then fell prior to parturition. In fetuses of diabetic mothers, this prepartum decline was curtailed, resulting in enhanced synthase a activity and increased glycogen content in fetal livers at term. Elevation in hepatic synthase a in fetuses of diabetic mothers was due, not to altered interconversion between existing synthase a and b, but to equivalent increases in both forms of the enzyme. Both hepatic and free plasma corticosterone levels were elevated in fetuses of diabetic mothers and may be responsible for the enhanced development of total glycogen synthase observed in these fetuses. In normal fetuses hepatic phosphofructokinase and pyruvate kinase activities also rose to maxima at 20 days, then declined prior to term. In fetuses of diabetic mothers pyruvate kinase activity attained higher than normal maximal levels and phosphofructokinase activity fell more gradually, thus resulting in elevations in both enzyme activities at term. Augmentations in these glycolytic enzymes are compatible with hyperinsulinemia observed in fetuses of diabetic mothers. The following conclusions may be drawn from these findings. During late fetal life developmental patterns of rate-limiting hepatic glycogen-synthesizing and glycolytic enzymes are adapted to glucose utilization. In the normal fetus these patterns reverse at term, thereby promoting glucose mobilization, which prepares the fetus for abrupt deprivation of maternal glucose at birth. Maternal diabetes results in retardation of these reversal processes, presumably due to elevations in fetal glucocorticoid and insulin levels. Glycogenolytic and glucogenic capacities are thereby impaired in these fetuses.     

Effects of cortisol or corticotropin administration on hepatic 3-hydroxy-3-methylglutaryl-CoA reductase activity and plasma lipids in the pregnant rat and fetuses

Pregnant rats were given pharmacological doses of cortisol or ACTH or no hormone from gestation day 9 to 19 and maternal and fetal hepatic 3-hydroxy-3-methylglutaryl-CoA reductase activity and plasma cholesterol studied on gestation day 20. Reductase activity was also studied in the maternal and fetal adrenal of the rats given cortisol or no hormone. Cortisol administration increased the maternal and fetal plasma cholesterol but had no effect on the hepatic active (phosphorylated) 3-hydroxy-3-methylglutaryl-CoA reductase activity when compared to untreated rats. Total (active + inactive) 3-hydroxy-3-methylglutaryl-CoA reductase activity, however, was reduced in maternal liver but not altered in the fetal liver by cortisol. The maternal cortisol treatment decreased the fetal, but not maternal, adrenal 3-hydroxy-3-methylglutaryl-CoA reductase total enzyme activity. The data support a hypothesis that utilization of plasma cholesterol for adrenal steroidogenesis may be an important determinant of plasma cholesterol homeostasis in the rat fetus. Maternal ACTH administration increased the foetal but not maternal plasma cholesterol, whilst active 3-hydroxy-3-methylglutaryl-CoA reductase activity was increased in the pregnant rat but not her fetuses. This result may suggest coordination of hepatic active reductase activity with adrenal cholesterol utilization in the pregnant rat. The reason for the fetal hypercholesterolaemia caused by ACTH, which is not known to cross the placenta, is uncertain. The studies, however, indicate that fetal cholesterol homeostasis and the rate limiting enzyme of cholesterol synthesis is influenced by maternal glucocorticoid administration.     

Effect of maternal diet on fetal hepatic lipogenesis.

The effects of: a, maternal diet; b, cyclic-3',5'-adenosinemonophosphate (cyclic AMP) and c, clofibrate on hepatic lipogenesis in fetal rats were studied. The experimental diets contained 22% protein, 40--50% carbohydrate, adequate vitamins, and minerals. In addition, the fat-containing diets were supplemented with either 15% corn oil, 25% corn oil, or 5% cholesterol + 10% oleic acid. In the clofibrate feeding studies, 0.3% (w/v) of the ethyl ester was added to a stock ration or to fat-free diet. Lipogenesis was measured in liver slices incubated with [2-14C]pyruvate, [1-14C]acetate, or 3H2O. In addition, activities of lipogenic enzymes were measured in cytosol fractions from liver homogenates. The effec-s of the experimental diets on liver composition were also examined. Lipogenic activity was higher in fetal than in maternal liver. When 15% corn oil was added to the maternal diet, fatty acid synthesis in fetal liver did not decrease as it did in maternal liver. Maternal fasting decreased fetal fatty acid synthesys by 50% when measured with 14C and less than 10% when measured with 3H2O. Although the addition of cholesterol to the maternal diet decreased cholesterol synthesis in maternal liver, no such decrease was observed in fetal liver. Changes in enzyme activities paralleled alterations in lipogenesis in maternal but not in fetal liver. Corn oil feeding or fasting increased the rate of transfer of linoleate from the dam to the fetus. However, accumulation of linoleate in fetal liver did not correlate with a decreased rate of fatty acid synthesis as it did in maternal liver. Maternal hepatic glycogen stores were depleted by fasting, but glycogen levels in fetal liver remained high under these conditions.     

Magnesium deficiency in pregnant rats alters methylation of specific cytosines in the hepatic hydroxysteroid dehydrogenase-2 promoter of the offspring

Prenatal under-nutrition involves changes in the epigenetic regulation of specific genes. Maternal magnesium (Mg) deficiency affects maternal glucocorticoid metabolism, but the mechanisms underlying changes in glucocorticoid homeostasis of offspring are not well understood. In this study, we investigated the effects of feeding pregnant rats a Mg-deficient diet (0.003% magnesium) on the methylation of cytosine-guanine (CpG) dinucleotides in hepatic glucocorticoid genes of neonatal offspring, compared with controls (0.082% magnesium). Methylation of CpG dinucleotides in the peroxisome proliferator-activated receptor α (Ppara), glucocorticoid receptor (Nr3c1) and 11β-hydroxysteroid dehydrogenase-2 (Hsd11b2) promoters in the liver were measured by pyrosequencing. Quantitative real-time PCR was used to assess hepatic mRNA expression of each gene. Mean methylation of the Hsd11b2 promoter in the Mg-deficient offspring (33.2%) was higher than in controls (10.4%). This was due to a specific increase at CpG dinucleotides 1 (20.0% vs. control 10.1%), 2 (58.8% vs. 17.0%), 3 (29.7% vs. 6.2%) and 4 (38.7% vs. 8.8%) (p < 0.05). Ppara and Nr3c1 methylation status and expression did not differ between the groups. No significant difference was noted between male and female pups, which were equally represented. Therefore, a Mg-deficient diet alters glucocorticoid metabolism, predicting higher hepatic intracellular glucocorticoid concentrations, and is possibly a key mechanism that induces the metabolic complications of Mg deficiency.