Effect of leptin on mouse trophoblast giant cells

Emerging Role of Leptin in Vascular and Placental Dysfunction in Preeclampsia

Leptin is a well-known metabolic hormone that plays diverse roles in various body functions, including growth, reproduction, and blood pressure regulation. In pregnancy, leptin produced from the placenta is crucial for ensuring proper fetal development and angiogenesis; however, pathological increases in leptin in maternal circulation are strongly associated with vascular endothelial dysfunction and preeclampsia. Leptin has a strong role in fertility and healthy pregnancy; however, numerous clinical reports over the last 2 decades show that leptin levels pathologically increase in patients with preeclampsia independent of metabolic status (ie, obesity). Despite this strong correlation, the role of leptin in preeclampsia is largely unexplored compared with other biomarkers likely due to differences in placental leptin production among mammals. Emerging literature has recently begun to shed light on this hormone in preeclampsia pathogenesis and uncovered some key mechanisms whereby pathologically elevated leptin production leads to cardiovascular complications for pregnant women.

Bta-miR-665 improves bovine blastocyst development through its influence on microtubule dynamics and apoptosis

Extracellular vesicles (EVs) contain microRNAs (miRNAs), which are important regulators of embryonic development. Nevertheless, little is known about the precise molecular processes controlling blastocyst development and quality. In a previous study, we identified bta-miR-665 as one of the miRNAs more abundantly present in extracellular vesicles of embryo-conditioned culture media of blastocysts compared to degenerate ones. Here, we investigated the effect and regulatory roles of bta-miR-665 in blastocyst development by supplementation of bta-miR-665 mimics or inhibitors to the culture media. Supplementation of bta-miR-665 mimics improved cleavage and blastocyst rate (P < 0.01), and blastocyst quality as indicated by increased inner cell mass rates and reduced apoptotic cell ratios (P < 0.01). Furthermore, supplementation of bta-miR-665 inhibitors had the opposite effect on these phenotypes. Low input transcriptome analysis and RT-qPCR revealed that bta-miR-665 acts on genes linked to microtubule formation and apoptosis/cell proliferation. These insights not only elucidate the important role of bta-miR-665 in embryo development, but also underscore its potential in improving reproductive efficiency in bovine embryo culture.

Implications of pregnancy on cardiometabolic disease risk: preeclampsia and gestational diabetes

Cardiometabolic disorders, such as obesity, insulin resistance, and hypertension, prior to and within pregnancy are increasing in prevalence worldwide. Pregnancy-associated cardiometabolic disease poses a great risk to the short- and long-term well-being of the mother and offspring. Hypertensive pregnancy, notably preeclampsia, as well as gestational diabetes are the major diseases of pregnancy growing in prevalence as a result of growing cardiometabolic disease prevalence. The mechanisms whereby obesity, diabetes, and other comorbidities lead to preeclampsia and gestational diabetes are incompletely understood and continually evolving in the literature. In addition, novel therapeutic avenues are currently being explored in these patients to offset cardiometabolic-induced adverse pregnancy outcomes in preeclamptic and gestational diabetes pregnancies. In this review, we discuss the emerging pathophysiological mechanisms of preeclampsia and gestational diabetes in the context of cardiometabolic risk as well as the most recent preclinical and clinical updates in the pathogenesis and treatment of these conditions.

Exercise enhances placental labyrinth trophoblast development by activation of PGC-1α and FNDC5/irisin†

Placental chorion/labyrinth trophoblasts are energy demanding which is met by the mitochondrial oxidative phosphorylation. Exercise enhances placental development and mitochondrial biogenesis, but the underlying mechanisms remain poorly understood. To address, female C57BL/6 J mice were randomly assigned into two groups: a control group and an exercise (EX) group. All animals were acclimated to treadmill exercise for 1 week before mating, but only the EX group was subjected to daily exercise during pregnancy from embryonic day (E) 1.5 to E16.5. Placenta were collected at E18.5 for biochemical and histochemical analyses, and primary trophoblast cells were isolated from the E18.5 placenta for further analyses. The data showed that exercise during pregnancy promoted the expression of syncytiotrophoblast cell markers, indicating trophoblast cell differentiation, which was closely associated with elevated mitochondrial biogenesis and oxidative metabolism in the E18.5 placenta. In addition, exercise during pregnancy activated peroxisome proliferator-activated receptor γ coactivator-1 α (PGC-1α), which was associated with upregulated placental α-ketoglutarate and the expression of isocitrate dehydrogenases and ten-eleven translocations, facilitating DNA demethylation of the Pgc1a promoter. Furthermore, exercise upregulated fibronectin type III domain containing 5 expression and the secretion of its cleaved form, irisin, which is known to activate PGC-1α. These data suggest that exercise-induced activation of PGC-1α, via epigenetic modifications, is responsible for promoting mitochondrial energy metabolism and chorion/labyrinth trophoblast development.

Current knowledge of leptin in wound healing: A collaborative review

Efficacious wound healing is still a major concern for global healthcare due to the unsatisfactory outcomes under the current treatments. Leptin, an adipocyte-derived hormone, mainly acts in the hypothalamus and plays crucial roles in various biological processes. Recently, an increasing number of researches have shown that leptin played an important role in the wound healing process. In this review, we presented a first attempt to capture the current knowledge on the association between leptin and wound healing. After a comprehensive review, the molecular mechanisms underlying leptin in wound healing were speculated to be correlated to the regulation of inflammation of the macrophage and lymphocytes, angiogenesis, re-epithelialization, proliferation, and differentiation of fibroblasts. The affected genes and the signal pathways were multiple. For example, leptin was reported to ameliorate wound healing by its anti-inflammatory action, which might be correlated to the activation STAT1 and STAT3 via p38 MAPK or JAK2. However, the understanding of the specific role in each process (e.g., inflammatory, proliferative, and maturation phase) of wound repair is not entirely clear, and further studies are still warranted in both macrostructural and microscale factors. Therefore, identifying and validating the biological mechanisms of leptin in wound healing is of great significance to develop potential therapeutic targets for the treatment of wound healing in clinical practice.

Maternal DNA Methylation During Pregnancy: a Review

Multiple environmental, behavioral, and hereditary factors affect pregnancy. Recent studies suggest that epigenetic modifications, such as DNA methylation (DNAm), affect both maternal and fetal health during the period of gestation. Some of the pregnancy-related risk factors can influence maternal DNAm, thus predisposing both the mother and the neonate to clinical adversities with long-lasting consequences. DNAm alterations in the promoter and enhancer regions modulate gene expression changes which play vital physiological role. In this review, we have discussed the recent advances in our understanding of maternal DNA methylation changes during pregnancy and its associated complications such as gestational diabetes and anemia, adverse pregnancy outcomes like preterm birth, and preeclampsia. We have also highlighted some major gaps and limitations in the area which if addressed might improve our understanding of pregnancy and its associated adverse clinical conditions, ultimately leading to healthy pregnancies and reduction of public health burden.

Transient Receptor Potential Vanilloid 6 (TRPV6) Proteins Control the Extracellular Matrix Structure of the Placental Labyrinth

Calcium-selective transient receptor potential Vanilloid 6 (TRPV6) channels are expressed in fetal labyrinth trophoblasts as part of the feto-maternal barrier, necessary for sufficient calcium supply, embryo growth, and bone development during pregnancy. Recently, we have shown a less- compact labyrinth morphology of Trpv6-deficient placentae, and reduced Ca²⁺ uptake of primary trophoblasts upon functional deletion of TRPV6. Trpv6^-/- trophoblasts show a distinct calcium-dependent phenotype. Deep proteomic profiling of wt and Trpv6^-/- primary trophoblasts using label-free quantitative mass spectrometry leads to the identification of 2778 proteins. Among those, a group of proteases, including high-temperature requirement A serine peptidase 1 (HTRA1) and different granzymes are more abundantly expressed in Trpv6^-/- trophoblast lysates, whereas the extracellular matrix protein fibronectin and the fibronectin-domain-containing protein 3A (FND3A) were markedly reduced. Trpv6^-/-placenta lysates contain a higher intrinsic proteolytic activity increasing fibronectin degradation. Our results show that the extracellular matrix formation of the placental labyrinth depends on TRPV6; its deletion in trophoblasts correlates with the increased expression of proteases controlling the extracellular matrix in the labyrinth during pregnancy.

Association of serum and follicular fluid leptin and in vitro Fertilization/ ICSI outcome: A systematic review and meta-analysis

There are conflicting reports regarding circulating leptin and its relationship between pregnancy outcomes in infertile women undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI). We performed a systematic review and meta-analysis to assess the association between serum or follicular fluid (FF) leptin concentrations reported for infertile women and their IVF outcome. A systematic search was undertaken in available databases (PubMed, Scopus, Web of Science, The Cochrane Library and Embase) to find studies published up to Aug 2020 and the standardized mean difference with 95 % confidence interval was taken from 14 eligible studies. Both graphical (funnel plots) and test methods (Egger's regression test and the Begg) assessed the presence of publication bias. Subgroup analysis was used to investigate the source of heterogeneity. Pooled effect sizes based on the eligible papers indicated that of there is no statistically significant correlation between leptin levels in follicular fluid and serum on the day of ovum pick-up (OPU) and day of HCG (human chorionic gonadotrophin) administration in pregnant and non-pregnant women who underwent IVF/ICSI cycles. However, combination of leptin in serum and/or FF with other parameters may be a useful marker to predict IVF outcome.

Morphology and gene expression in mouse placentas lacking leptin receptors

In the pregnant mouse, the hormone leptin is primarily produced by adipose tissue and does not significantly cross the placenta into fetal circulation. Nonetheless, leptin treatment during gestation affects offspring phenotypes. Leptin treatment also affects placental trophoblast cells in vitro, by altering proliferation, invasion and nutrient transport. The goal of the present study was to determine whether the absence of placental leptin receptors alters placental development and gene expression. Lepr^db-3j+ mice possessing only one functional copy of the leptin receptor were mated to obtain wildtype, Lepr^db-3j+ and Lepr^db-3j/db-3j conceptuses, which were then transferred to wildtype recipient dams. Placentas were collected at gestational d18.5 to examine placental morphology and gene expression. Placentas lacking functional leptin receptor had reduced weights, but were otherwise morphologically indistinguishable from control placentas. Relative mRNA levels, however, were altered in Lepr^db-3j/db-3j placentas, particularly transcripts related to amino acid and lipid metabolism and transport. Consistent with a previous in vitro study, leptin was found to promote expression of stathmin, a positive regulator of trophoblast invasion, and of serotonin receptors, potential mediators of offspring neurological development. Overall placental leptin receptor was found not to play a significant role in morphological development of the placenta, but to regulate placental gene expression, including in metabolic pathways that affect fetal growth.

Activities for leptin in bovine trophoblast cells

Leptin is involved in various reproductive processes in humans and rodents, including placental development and function. The specific ways that leptin influences placental development and function in cattle are poorly understood. This work was completed to explore how leptin regulates hormone, cytokine and metalloprotease transcript abundance, and cell proliferation in cultured bovine trophoblast cells. In the first set of studies, cells were cultured in the presence of graded recombinant bovine leptin concentrations (0, 10, 50, 250 ng/mL) for 6 or 24 h. Transcript profiles were examined from extracted RNA. Leptin supplementation did not affect abundance of the maternal recognition of pregnancy factor, interferon-tau (IFNT), but leptin increased (P < 0.05) abundance of chorionic somatomammotropin hormone 2 (CSH2; ie, placental lactogen) at both 6 and 24 h at each concentration tested. At 24 h, the greatest CSH2 abundance (P < 0.05) was detected in cells supplemented with 50 ng/mL leptin. Transcript abundance of the remodeling factor, metalloprotease 2 (MMP2), was greater (P < 0.05) in leptin-treated cells at 24 h but not at 6 h. The 24 h MMP2 response was greatest (P < 0.05) at 250 ng/mL. Transcript abundance for MMP9 was not altered by leptin treatment. In a separate set of studies, cell proliferation assays were completed. Leptin supplementation did not affect bovine trophoblast cell line proliferation at any dose tested. In conclusion, leptin supplementation did not affect bovine trophoblast cell proliferation or IFNT expression, but leptin increases CSH2 and MMP2 transcript abundance. Both of these factors are involved with peri-implantation and postimplantation placental development and function, and this implicates leptin as a potential mediator of early placental development and function in cattle.

Fetus-derived DLK1 is required for maternal metabolic adaptations to pregnancy and is associated with fetal growth restriction

Pregnancy is a state of high metabolic demand. Fasting diverts metabolism to fatty acid oxidation, and the fasted response occurs much more rapidly in pregnant women than in non-pregnant women. The product of the imprinted DLK1 gene (delta-like homolog 1) is an endocrine signaling molecule that reaches a high concentration in the maternal circulation during late pregnancy. By using mouse models with deleted Dlk1, we show that the fetus is the source of maternal circulating DLK1. In the absence of fetally derived DLK1, the maternal fasting response is impaired. Furthermore, we found that maternal circulating DLK1 levels predict embryonic mass in mice and can differentiate healthy small-for-gestational-age (SGA) infants from pathologically small infants in a human cohort. Therefore, measurement of DLK1 concentration in maternal blood may be a valuable method for diagnosing human disorders associated with impaired DLK1 expression and to predict poor intrauterine growth and complications of pregnancy.

Placental development in a mouse model of spinal muscular atrophy

Spinal Muscular Atrophy (SMA) is an autosomal recessive disorder, leading to fatal loss of motor neurons. It is caused by loss of function of the SMN gene, which is expressed throughout the body, and there is increasing evidence of dysfunction in non-neuronal tissues. Birthweight is one of most powerful prognostic factors for infants born with SMA, and intrauterine growth restriction is common. In the SMNΔ7 mouse model of SMA, pups with the disease lived 25% longer when their mothers were fed a higher fat, "breeder" diet. The placenta is responsible for transport of nutrients from mother to fetus, and is a major determinant of fetal growth. Thus, the present study tested the hypothesis that placental development is impaired in SMNΔ7 conceptuses. Detailed morphological characterization revealed no defects in SMNΔ7 placental development, and expression of key transcription factors regulating mouse placental development was unaffected. The intrauterine growth restriction observed in SMA infants likely does not result from impaired placental development.

Hyperleptinemia During Pregnancy Decreases Adult Weight of Offspring and Is Associated With Increased Offspring Locomotor Activity in Mice

Pregnant women who are obese or have gestational diabetes mellitus have elevated leptin levels and their children have an increased risk for child and adult obesity. The goals of this study were to determine whether offspring weights are altered by maternal hyperleptinemia, and whether this occurs via behavioral changes that influence energy balance. We used 2 hyperleptinemic mouse models. The first was females heterozygous for a leptin receptor mutation (DB/+), which were severely hyperleptinemic, and that were compared with wild-type females. The second model was wild-type females infused with leptin (LEP), which were moderately hyperleptinemic, and were compared with wild-type females infused with saline (SAL). Total food consumption, food preference, locomotor activity, coordinated motor skills, and anxiety-like behaviors were assessed in wild-type offspring from each maternal group at 3 postnatal ages: 4-6, 11-13, and 19-21 weeks. Half the offspring from each group were then placed on a high-fat diet, and behaviors were reassessed. Adult offspring from both groups of hyperleptinemic dams weighed less than their respective controls beginning at 23 weeks of age, independent of diet or sex. Weight differences were not explained by food consumption or preference, because female offspring from hyperleptinemic dams tended to consume more food and had reduced preference for palatable, high-fat and sugar, food compared with controls. Offspring from DB/+ dams were more active than offspring of controls, as were female offspring of LEP dams. Maternal hyperleptinemia during pregnancy did not predispose offspring to obesity, and in fact, reduced weight gain.

Pregnancy Hyperglycemia in Prolactin Receptor Mutant, but Not Prolactin Mutant, Mice and Feeding-Responsive Regulation of Placental Lactogen Genes Implies Placental Control of Maternal Glucose Homeostasis

Pregnancy is often viewed as a conflict between the fetus and mother over metabolic resources. Insulin resistance occurs in mothers during pregnancy but does not normally lead to diabetes because of an increase in the number of the mother's pancreatic beta cells. In mice, this increase is dependent on prolactin (Prl) receptor signaling but the source of the ligand has been unclear. Pituitary-derived Prl is produced during the first half of pregnancy in mice but the placenta produces Prl-like hormones from implantation to term. Twenty-two separate mouse genes encode the placenta Prl-related hormones, making it challenging to assess their roles in knockout models. However, because at least four of them are thought to signal through the Prl receptor, we analyzed Prlr mutant mice and compared their phenotypes with those of Prl mutants. We found that whereas Prlr mutants develop hyperglycemia during gestation, Prl mutants do not. Serum metabolome analysis showed that Prlr mutants showed other changes consistent with diabetes. Despite the metabolic changes, fetal growth was normal in Prlr mutants. Of the four placenta-specific, Prl-related hormones that have been shown to interact with the Prlr, their gene expression localizes to different endocrine cell types. The Prl3d1 gene is expressed by trophoblast giant cells both in the labyrinth layer, sitting on the arterial side where maternal blood is highest in oxygen and nutrients, and in the junctional zone as maternal blood leaves the placenta. Expression increases during the night, though the increase in the labyrinth is circadian whereas it occurs only after feeding in the junctional zone. These data suggest that the placenta has a sophisticated endocrine system that regulates maternal glucose metabolism during pregnancy.

Positive correlations between circulating adiponectin and MMP2 in preeclampsia pregnant

OBJECTIVE

The aims of the present study were to compare plasma concentrations of the adiponectin, leptin, metalloproteinases (MMP9 and MMP2) and its tissue inhibitors (TIMP1 and TIMP2) in preeclamptic (PE) and healthy pregnant (HP) groups and correlate them.

METHODS

A total of 105 pregnant women with pre-pregnancy body mass index (BMI) values ⩽ 30 kg/m(2) were enrolled for this study (59 PE and 46 HP). Biomarkers were measured using ELISAs.

RESULTS

Adiponectin (32%), leptin (45%), MMP2 (20%), TIMP1 (31%) and TIMP2 (23%) levels were higher in PE compared to HP (all P < 0.05). In addition there were positive correlations between adiponectin and MMP2 (r = 0.33; P = 0.03) and adiponectin and TIMP2 (r = 0.33; P = 0.03) in PE group, but not in HP.

CONCLUSION

Our findings show that adiponectin, leptin, MMP2, TIMP1 and TIMP2 levels are increased in PE and adiponectin may contribute to higher levels of MMP2 and TIMP2 in this disease.

An updated view of leptin on implantation and pregnancy: a review

The hormone leptin, which is thought to be primarily produced by adipose tissue, is a polypeptide that was initially characterized by its ability to regulate food intake and energy metabolism. Leptin appears to signal the status of body energy stores to the brain, resulting in the regulation of food intake and whole-body energy expenditure. Subsequently, it was recognized as a cytokine with a wide range of peripheral actions and is involved in the regulation of a number of physiological systems including reproduction. In the fed state, leptin circulates in the plasma in proportion to body adiposity in all species studied to date. However other factors such as sex, age, body mass index (BMI), sex steroids and pregnancy may also affect leptin levels in plasma. In pregnant mice and humans, the placenta is also a major site of leptin expression. Leptin circulates in biological fluids both as free protein and in a form that is bound to the soluble isoform of its receptor or other binding proteins such as one of the immunoglobulin superfamily members Siglec-6 (OB-BP1). Although the actions of leptin in the control of reproductive function are thought to be exerted mainly via the hypothalamic-pituitary-gonadal axis, there have also been reports of local direct effects of leptin at the peripheral level, however, these data appear contradictory. Therefore, there is a need to summarize the current status of research outcomes and analyze the possible reasons for differing results and thus provide researchers with new insight in designing experiments to investigate leptin effect on reproduction. Most importantly, our recent experimental data suggesting that reproductive performance is improved by decreasing concentrations of peripheral leptin was unexpected and cannot be explained by hypotheses drawn from the experiments of excessive exogenous leptin administration to normal animals or ob/ob mice.

DNA methylation as a biomarker for preeclampsia

BACKGROUND

Preeclampsia contributes significantly to pregnancy-associated morbidity and mortality as well as future risk of cardiovascular disease in mother and offspring, and preeclampsia in offspring. The lack of reliable methods for early detection limits the opportunities for prevention, diagnosis, and timely treatment.

PURPOSE

The purpose of this study was to explore distinct DNA methylation patterns associated with preeclampsia in both maternal cells and fetal-derived tissue that represent potential biomarkers to predict future preeclampsia and inheritance in children.

METHOD

A convenience sample of nulliparous women (N = 55) in the first trimester of pregnancy was recruited for this prospective study. Genome-wide DNA methylation was quantified in first-trimester maternal peripheral white blood cells and placental chorionic tissue from normotensive women and those with preeclampsia (n = 6/group).

RESULTS

Late-onset preeclampsia developed in 12.7% of women. Significant differences in DNA methylation were identified in 207 individual linked cytosine and guanine (CpG) sites in maternal white blood cells collected in the first trimester (132 sites with gain and 75 sites with loss of methylation), which were common to approximately 75% of the differentially methylated CpG sites identified in chorionic tissue of fetal origin.

CONCLUSION

This study is the first to identify maternal epigenetic targets and common targets in fetal-derived tissue that represent putative biomarkers for early detection and heritable risk of preeclampsia. Findings may pave the way for diagnosis of preeclampsia prior to its clinical presentation and acute damaging effects, and the potential for prevention of the detrimental long-term sequelae.

Leptin and the placental response to maternal food restriction during early pregnancy in mice

Several studies have demonstrated that maternal undernutrition or overnutrition during pregnancy can have negative consequences for the health of children born to these pregnancies, but the physiological mechanisms by which this occurs are not completely understood. During periods of food restriction, concentrations of leptin decline, whereas leptin is elevated in obesity, suggesting that it may play a role in the response to altered nutrition during pregnancy. This study compares placental development and global placental gene expression profiles at Day 11.5 in pregnant control mice, mice that were undernourished, and mice that were undernourished but given leptin. Placentas from mothers exposed to food restriction preserved the placental labyrinth zone at the expense of the junctional zone, an effect abrogated in the restricted plus leptin group, which had a significant decrease in the labyrinth zone area compared with controls. Similarly, there were more significant differences in gene expression between placentas from control and restricted plus leptin mothers (1128 differentially expressed genes) than between placentas of control and restricted mothers (281 differentially expressed genes). We conclude that the presence of high concentrations of circulating leptin during food restriction disrupts the normal adaptive response of the placenta to reduced energy availability.

The source of leptin, but not leptin depletion in response to food restriction, changes during early pregnancy in mice

Maternal food restriction during pregnancy results in adverse consequences for offspring, including obesity and cardiovascular disease. Early pregnancy is a critical period for this programming effect. Leptin is a regulator of energy homeostasis that also affects placental and fetal development. As food restriction results in decreased serum leptin levels, at least in non-pregnant animals, leptin depletion may be one mechanism by which food restriction affects development. The objective of this study was to test whether moderate food restriction affects serum leptin concentrations during the first half of pregnancy. We found that restriction to 50% of ad libitum consumption levels resulted in a significant decrease in serum leptin concentrations in both pregnant and non-pregnant female mice. There was no significant difference in serum leptin concentrations between non-pregnant females and at pregnancy day 11.5 when fed ad libitum. However, there was a difference in the source of leptin during pregnancy, with greater production in visceral fat in pregnant mice, and greater production in subcutaneous fat in non-pregnant mice. Leptin concentrations were dependent on time of day and time of sampling relative to feeding, particularly in restricted mice. There was a significant difference in serum leptin concentrations between fed and restricted mice when they were fed and sampled in afternoon, but not when they were fed and sampled in morning. We conclude that food restriction results in a significant decrease in leptin concentration during the first half of pregnancy in mice, but that detection of this relationship is subject to experimental design considerations.

Giant cell formation: the way to cell death or cell survival?

The study of giant cells in populations of different tumor cells and evaluation of their role in cancer development is an expanding field. The formation of giant cells has been shown to be followed by mitotic catastrophe, apoptosis, necrosis, and other types of cell elimination. Reports also demonstrate that giant cells can escape cell death and give rise to new cancer cells. However, it is not known if the programmed cell death is involved in this type of cell cycle disorders. Here we describe principal events that are observed during giant cell formation. We also consider the role of giant cells in cancer development, taking into account both published work and our own recent data in this field.

Metals in human placenta: focus on the effects of cadmium on steroid hormones and leptin

Cadmium and other metallic ions can act as metalloestrogens and endocrine disruptors of reproductive tissues and fetal development in mammals, including humans. The detrimental effects occur with respect to the synthesis of both steroid and polypeptide hormones in the placenta. Leptin is produced by the trophoblast and may regulate fetal organogenesis and development. In human term placentas, concentrations of toxic metals and their effects on steroidogenesis were assessed in healthy parturients (109 non-smokers and 99 smokers) in relation to tobacco smoking. Trace elements (cadmium, lead, iron, zinc and copper) were analyzed in placentas using atomic absorption spectroscopy, and steroid hormones (progesterone and estradiol) were assayed in placental samples by an enzyme-immunometric method. Cadmium concentrations were doubled in placentas of smokers as compared with non-smokers, and placental lead and zinc concentrations increased significantly. Placental concentrations of iron, copper, progesterone and estradiol did not differ. In addition, human trophoblast cells were co-cultured with 0, 5, 10 or 20 microm CdCl(2) for 96 h and leptin mRNA assessed by quantitative polymerase chain reaction. Leptin mRNA declined dose-responsively as a result of CdCl(2) exposure. Collectively, the results confirm that human placental tissue offers a unique opportunity to biomonitor cadmium exposure in both the maternal and the internal fetal environments. In addition, the results strongly suggest that cadmium may cause a decline in placental leptin synthesis, as we have previously shown for placental progesterone production. This may constitute further evidence of the endocrine-disrupting effects of cadmium, as a constituent of tobacco smoke, on reproduction in women.

Genes and signals regulating murine trophoblast cell development

A fundamental step in embryonic development is cell differentiation whereby highly specialised cell types are developed from a single undifferentiated, fertilised egg. One of the earliest lineages to form in the mammalian conceptus is the trophoblast, which contributes exclusively to the extraembryonic structures that form the placenta. Trophoblast giant cells (TGCs) in the rodent placenta form the outermost layer of the extraembryonic compartment, establish direct contact with maternal cells, and produce a number of pregnancy-specific cytokine hormones. Giant cells differentiate from proliferative trophoblasts as they exit the cell cycle and enter a genome-amplifying endocycle. Normal differentiation of secondary TGCs is a critical step toward the formation of the placenta and normal embryonic development. Trophoblast development is also of particular interest to the developmental biologist and immunobiologist, as these cells constitute the immediate cellular boundary between the embryonic and maternal tissues. Abnormalities in the development of secondary TGCs results in severe malfunction of the placenta. Herein we review new information that has been accumulated recently regarding the molecular and cellular regulation of trophoblast and placenta development. In particular, we discuss the molecular aspects of murine TGC differentiation. We also focus on the role of growth and transcription factors in TGC development.