Maternal cocaine use and cigarette smoking in pregnancy in relation to amino acid transport and fetal growth

Effect of Dietary Protein Intake from Different Sources on Maternal and Umbilical Cord Plasma Amino Acid Levels

SCOPE

To assess the associations of dietary protein intake from different sources during pregnancy with maternal and umbilical cord plasma amino acid levels.

METHODS AND RESULTS

The study includes 216 pregnant women and 39 newborns from the Tongji Birth Cohort in Wuhan, China. The study examines the levels of 21 amino acids in maternal and cord plasma samples using ultra-performance liquid chromatography with tandem mass spectrometry. A significant positive relationship is observed between dietary protein intake from refined grains and maternal plasma cysteine levels. Dietary protein intake from dairy products is positively associated with maternal plasma levels of sulfur amino acid (mainly cystine), but negatively associated with maternal plasma levels of glutamic acid. In addition, the study observes that pre-pregnancy body mass index and parity may be potential determinants of maternal plasma amino acid levels, whereas a history of passive smoking during pregnancy is an important factor influencing cord plasma amino acid levels.

CONCLUSIONS

These findings suggest that dietary protein intakes from specific sources during pregnancy may affect maternal plasma levels of amino acids.

The association between plasma metabolites and future risk of all-cause mortality

BACKGROUND

Metabolite profiles provide snapshots of the overall effect of numerous exposures accumulated over life courses, which may lead to health outcomes in the future.

OBJECTIVE

We hypothesized that the risk of all-cause mortality is linked to alterations in metabolism earlier in life, which are reflected in plasma metabolite profiles. We aimed to identify plasma metabolites associated with future risk of all-cause mortality.

METHODS

Through metabolomics, 110 metabolites were measured in 3833 individuals from the Malmö Diet and Cancer-Cardiovascular Cohort (MDC-CC). A total of 1574 deaths occurred within an average follow-up time of 22.2 years. Metabolites that were significantly associated with all-cause mortality in MDC-CC were replicated in 1500 individuals from Malmö Preventive Project re-examination (MPP), among whom 715 deaths occurred within an average follow-up time of 11.3 years.

RESULTS

Twenty two metabolites were significantly associated with all-cause mortality in MDC-CC, of which 13 were replicated in MPP. Levels of trigonelline, glutamate, dimethylglycine, C18-1-carnitine, C16-1-carnitine, C14-1-carnitine, and 1-methyladenosine were associated with an increased risk, while levels of valine, tryptophan, lysine, leucine, histidine, and 2-aminoisobutyrate were associated with a decreased risk of all-cause mortality.

CONCLUSION

We used metabolomics in two Swedish prospective cohorts and identified replicable associations between 13 metabolites and future risk of all-cause mortality. Novel associations between five metabolites-C18-1-carnitine, C16-1-carnitine, C14-1-carnitine, trigonelline, and 2-aminoisobutyrate-and all-cause mortality were discovered. These findings suggest potential new biomarkers for the prediction of mortality and provide insights for understanding the biochemical pathways that lead to mortality.

Structural changes, increased hypoxia, and oxidative DNA damage in placenta due to maternal smokeless tobacco use

BACKGROUND

Smokeless tobacco (SLT) consumption during pregnancy is a well-recognized health risk that causes placental damage including hypoxia and oxidative damage. Although consumption of SLT by women varies from region to region, majority of tea leave pluckers consume SLT for relieving stress and pain. Still, the effects of SLT consumption have not been evaluated in tea garden workers (TGW). While previous studies have attempted to report effects of cigarette smoke using in vitro model, hypoxia-inducible factor (HIF)-1α expression in human placentae from pregnant women exposed to SLT has not been previously studied. This study was aimed to explore the effects of SLT consumption on placental structure, expression of HIF-1α and oxidative DNA damage in sample population of TGW.

METHODS

A total of 51 placentae were collected from SLT users and nonusers (n = 30 and 21, respectively) with full-term normal delivery, who were involved in the plucking of tea leaves during pregnancy in tea plantation. Low birth weight (LBW, i.e., weight <2,500 g) and normal birth weight (NBW) groups among both SLT user and nonuser were compared for the stated parameters. Placental tissues were processed for transmission electron microscopy (TEM) study and immunohistochemical analysis for the expression of HIF-1α and 8-hydroxy-2'-deoxyguanosine (8-OHdG).

RESULTS

Altered ultrastructural characteristics were observed in the tertiary villi of LBW group among SLT users which included endothelial cells protrusion into capillary lumen, degenerated nuclei, significant thickening of trophoblast basement membrane and vasculo-syncytial membrane, abnormalities of the microvilli, swollen or damaged mitochondria, and dilatation in endoplasmic reticulum cisternae. Furthermore, significant reduction in the perimeter, area, and number of the stromal capillary of the tertiary villi of placenta were found in LBW group as compared with NBW group from the SLT users. Enhanced expression for HIF-1α and oxidative DNA damage (8-OHdG) biomarker was observed in SLT users as compared with nonusers.

CONCLUSIONS

Maternal SLT exposure during pregnancy may be associated with villus hypoxia and consequently oxidative DNA damage. It is presumed that deleterious effect of SLT exposure on placenta could result in impairment of placental barrier, and restrict nutrient and oxygen supply from mother to fetus, and thus could be a cause of fetal growth restriction.

Impact of gestational electronic cigarette vaping on amino acid signature profile in the pregnant mother and the fetus

Background

Electronic cigarettes (e-cigs) are a form of tobacco product that has become increasingly popular over the past decade. Despite the known health consequences of tobacco product exposure during pregnancy, a substantial number of daily smokers will continue to smoke during pregnancy. Our current knowledge on the effects of e-cig aerosol exposure during pregnancy is limited to a small number of animal studies, which have identified several e-cig aerosol-induced disruptions to the physiology of normal development.

Methods

To further assess the impact of prenatal e-cig aerosol exposure on maternal and fetal health, we examined the amino acid signature profiles in maternal and fetal plasma, as well as in the fetal lungs, a sensitive target organ for prenatal tobacco product exposure. Pregnant Sprague Dawley rats were randomly assigned to one of three groups and were exposed to either e-cig aerosols containing nicotine, e-cig aerosols without nicotine, or room air. Dams were exposed utilizing a state-of-the-art custom engineered e-cig vaping system that is compatible with commercially available e-cig atomizers and enables a translational inhalation delivery method comparable to human vaping.

Results

We determined that gestational exposure to e-cig aerosols results in significant alterations to the amino acid profile in the maternal and fetal compartments, including the fetal lungs. The data shows a targeted disruption to the nitric oxide pathway, branched-chain amino acid metabolism, fetal protein synthesis, and urea cycle.

Conclusion

The data presented herein provides additional support that gestational e-cig aerosol exposure can impact crucial biological processes and exemplifies the need for extensive research on exposure to e-cig aerosols.

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First report of e-cig induced alterations to maternal/fetal amino acid profile.

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Translational vaping paradigm utilizing custom engineered vaping system.

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Analysis of amino acids show gestational e-cig exposure has significant effects.

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Fetal lungs may be a sensitive target to gestational e-cig aerosol exposure.

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Marker of dysregulation in branched-chain amino acid metabolism and urea cycle.

Passively inhaled tobacco smoke - pregnancy and neonatal outcomes in correlation with placental histopathology

INTRODUCTION

We aimed to investigate the effect of maternal passive smoking (MPS) during pregnancy-on placental pathology and pregnancy outcomes.

METHODS

A prospective case-control study. We recruited low-risk laboring women at 37+0-41 + 0 weeks between 9/2019-7/2020. MPS was defined as exposure to in-house spouse tobacco smoking of >20 cigarettes/day in the absence of maternal active-smoking. In attempt to "purify" the effect of MPS on placental pathology-we excluded cases with preeclampsia, diabetes, suspected fetal growth restriction (FGR), preterm labor, and illicit drug use. Maternal characteristics, pregnancy outcomes, and placental pathology were compared between the MPS group and a control group matched for gestational age, maternal age, and delivery date. Placental lesions were classified according to the "Amsterdam" criteria. The study was powered to detect a 33% difference in placental malperfusion lesions. Multivariable regression was performed to identify independent associations with placental malperfusion lesions.

RESULTS

In labor, the MPS group (n = 115) had higher rates of meconium stained amniotic fluid (MSAF, p < 0.001) and non-reassuring fetal heart-rate (NRFHR,p = 0.006), compared to controls (n = 115). Neonates in the MPS group had higher rates of undiagnosed FGR (p = 0.01) and NICU admissions (p = 0.004). The MPS group had higher rates of placental-hypoplasia (p = 0.02) and fetal vascular malperfusion (FVM) lesions (p = 0.04). In regression analysis MPS was associated with FVM lesions independent of background confounders (aOR = 1.24 95% CI 1.10-2.65).

DISCUSSION

In otherwise low-risk pregnancies, MPS was associated with higher rates of MSAF, NRFHR, undiagnosed FGR, and NICU admissions, probably mediated via placental FVM. These worrisome findings mandate patient counseling and further investigation in larger population-based studies.

The Burden of Adverse Neonatal Outcome among Antenatal Substance Users in Ethiopia: A Systematic Review and Meta-Analysis

Background. Substances mainly khat, alcohol and cigarette are used during pregnancy in Ethiopia. However, to this date, there is no pooled evidence about the burden of adverse neonatal outcomes among the substance users during pregnancy in the country. Methods. Eligible primary studies were accessed from 4 international data bases (Google Scholar, Science Direct, Scopus, and PubMed). The required data were extracted from these studies and then exported to stata version 14 for analysis. Subgroup analyses were conducted for evidence of heterogeneity. Results. A total of 2298 neonates were included from 7 studies. Among these neonates, 530(23.06%) were those whose mothers used substance during pregnancy (exposed group) whereas 1768 neonates were those whose mothers didn’t use substance during pregnancy (controls group). The pooled prevalence of adverse neonatal outcome among the exposed mothers was 38.32% (95% CI: 29.48%, 47.16%; I² = 76.3%) whereas it was 16.29% (95% CI: 9.45%, 23.13%) among the controls. Adverse neonatal outcome was most burdensome among cigarette smokers 45.20% (95% CI: 37.68%, 52.73%; I² = .00%) when compared with khat chewers 34.00% (95% CI: 20.87%, 47.13%) and alcohol drinkers 38.47% (95% CI: 17.96%, 58.98%). Low birth weight 42.00% (95% CI: 18.01%, 65.99%; I² = 91.8%) was the most common adverse birth outcome. Conclusion. It was found that adverse neonatal outcomes were much more burdensome among antenatal substance users than the controls. Therefore, mothers should be enabled to quit using substance before pregnancy. Besides, strict comprehensive screening of every pregnant mother should be made at antenatal care clinics for early identification and management of antenatal substance use.

The effect of substance use during pregnancy on neonatal outcomes in Ethiopia: A systematic review and meta-analysis

BACKGROUND

Substance use during pregnancy mainly khat chewing (20%) and alcohol drinking (18.1%) are commonly practiced in Ethiopia. However, the effect of using these substances has not been studied nationally yet. Thus, this study was aimed to examine national evidence about the effect of substance use during pregnancy on birth outcome in the country, 2020.

METHODS

Primary studies were accessed through Google scholar, HINARI, SCOPUS and PubMed databases. The methodological and evidence quality of the included studies were critically appraised by the modified Newcastle-Ottawa quality assessment tool scale adapted for observational studies. From eligible studies, two authors extracted author/year, study region, study design, sample size and reported effect of antenatal substance use on birth outcome on an excel spreadsheet. During critical appraisal and data extraction, disagreements between the two authors were resolved by the involvement of a third author. The extracted data were then exported to stata version 14. Effect sizes were pooled using the fixed-effects model due to homogenous primary studies (I2 = 0.0%). Presence of publication bias was detected from asymmetry of funnel plot and statistically significant Egger's test (p = 0.000).

RESULTS

In this systematic review and meta-analysis, a total of 5,343 mother-neonate pairs were included from 15 studies. Alcohol, khat, cigarette and narghile were used during pregnancy, and significant adverse birth outcomes attributable to these substances were reported. From the pooled effect of alcohol use, drinking mothers were twice (95%CI: AOR = 2.16; 1.16, 3.17) likely to have newborns with birth defect; 9 times (95% CI: AOR = 9.39; 2.84, 15.94) more prone to own low birth weight neonates; and 1.9 times more prone to deliver preterm neonates (95% CI: AOR = 1.93; 0.52, 3.33) than the nondrinkers. Khat users were 2.4 times (95%CI: AOR = 2.4; 1.11, 5.19) more likely to have congenitally defected neonates; and 3.1 times (95%CI: AOR = 3.19; 1.01, 5.37) more risked to possess low birth weight neonates. Furthermore, antenatal cigarette smokers (95% CI: AOR = 4.36 (1.75, 6.98)) and narghile users (95% CI: AOR = 20.1; 3.94, 103) were at 4 and 20 times more likelihood of having low birth weight neonates as compared to their counterparts.

CONCLUSION

Prematurity, low birth weight and congenital malformation were the investigated adverse effects of antenatal substance use in Ethiopia. Therefore, the existing public health efforts should be encouraged to help women stop using these substances completely before pregnancy. Moreover, increasing public awareness about the potential negative impacts of substance use during pregnancy on birth outcome would be of greatest importance for comprehensive prevention of the problem.

Fetal Growth Restriction in Hypertensive vs. Heavy Smoking Women-Placental Pathology, Ultrasound Findings, and Pregnancy Outcomes

We compared placental pathology, ultrasonographic findings, and obstetric outcomes, in gestations complicated by fetal growth restriction (FGR) with either a background of hypertensive disorder or heavy tobacco cigarette smoking. The medical records and placental pathology reports of pregnancies complicated with FGR (birthweight < 10th percentile) between December 2008 and May 2018 from a single tertiary center were reviewed. Placental pathology, ultrasound findings, and pregnancy outcomes were compared between hypertensive patients (HTN) and heavy smokers (SMO). We included 213 pregnancies: 129 (60.6%) in the SMO group and 84 (39.4%) in the HTN group. The HTN group was characterized by a higher BMI (p = 0.01), higher rates of Cesarean deliveries (p = 0.006), and a lower gestational age at delivery (35.6 ± 3.8 vs. 37.5 ± 2.9 weeks, p < 0.001). The HTN group had higher rates of placental weights < 10th percentile (p = 0.04) and maternal vascular malperfusion lesions (p < 0.001), while the SMO group had higher rates of inflammatory lesions (p = 0.04). On ultrasound, the HTN group had a higher head/abdomen circumference ratio (p < 0.001) and more abnormal Doppler studies (< 0.001). Neonates in the HTN group had lower birthweights (p < 0.001) and higher rates of NICU admissions (p = 0.002) and adverse neonatal outcome (p = 0.006). On multivariable analysis, gestational age at delivery (aOR = 0.65, 95%CI 0.55-0.87), hypertensive disorders (aOR = 1.8, 95%CI = 1.21-4.81), placental MVM lesions (aOR = 1.23, 95%CI = 1.08-5.02), and the combination of HTN+MVM (aOR = 2.63, 95%CI 1.78-7.30) were independently associated with adverse neonatal outcome. Hypertension and smoking may lead to FGR in different pathways as the two groups significantly differed in maternal characteristics, placental pathology, ultrasound findings, and neonatal outcomes. A hypertensive disorder probably represents a more hostile maternal environment than smoking and these pregnancies would probably benefit from closes monitoring.

Fetal growth in environmental epidemiology: mechanisms, limitations, and a review of associations with biomarkers of non-persistent chemical exposures during pregnancy

BACKGROUND

Non-persistent chemicals, such as phthalates, environmental phenols, organophosphate pesticides, and others, are challenging to study because of their ubiquity in the environment, diverse exposure routes, and high temporal variability of biomarkers. Nonetheless, there is interest in understanding how gestational exposure to these chemicals may affect fetal growth, as perturbations to normal fetal growth are related to a plethora of adverse health outcomes in childhood and adulthood.

METHODS

The purpose of this review is to describe the state of the science on this topic. We searched PubMed for studies that included both 1) biomarkers of non-persistent chemicals collected during pregnancy and 2) fetal growth outcomes measured at birth (e.g., birth weight) or by ultrasound in utero (e.g., estimated fetal weight).

RESULTS

The bulk of the literature we found uses biomarkers measured at a single time point in pregnancy and birth weight as the primary measure of fetal growth. There is a small, but growing, body of research that uses ultrasound measures to assess fetal growth during pregnancy. In addition to summarizing the findings of the publications we identified, we describe inconsistencies in methodology, areas for improvement, and gaps in existing knowledge that can be targeted for improvement in future work. This literature is characterized by variability in methodology, likely contributing to the inconsistency of results reported. We further discuss maternal, placental, and fetal pathways by which these classes of chemicals may affect fetal growth.

CONCLUSIONS

To improve understanding of how everyday chemical exposures affect fetal growth, and ultimately lifelong health outcomes, mechanisms of toxicant action should be considered alongside improved study designs for future hypothesis-driven research.

Placental H3K27me3 establishes female resilience to prenatal insults

Although sex biases in disease presentation are well documented, the mechanisms mediating vulnerability or resilience to diseases are unknown. In utero insults are more likely to produce detrimental health outcomes for males versus females. In our mouse model of prenatal stress, male offspring experience long-term dysregulation of body weight and hypothalamic pituitary adrenal stress axis dysfunction, endophenotypes of male-biased neurodevelopmental disorders. Placental function is critical for healthy fetal development, and we previously showed that sex differences in placental O-linked N-acetylglucosamine transferase (OGT) mediate the effects of prenatal stress on neurodevelopmental programming. Here we show that one mechanism whereby sex differences in OGT confer variation in vulnerability to prenatal insults is by establishing sex-specific trophoblast gene expression patterns and via regulation of the canonically repressive epigenetic modification, H3K27me3. We demonstrate that high levels of H3K27me3 in the female placenta create resilience to the altered hypothalamic programming associated with prenatal stress exposure.

Sex differences in placental O-linked N-acetylglucosamine transferase (OGT) activity mediate the effects of prenatal stress on neurodevelopmental programming. Here authors provide evidence that OGT confers variation in vulnerability to prenatal insults by establishing sex-specific trophoblast gene expression via regulation of H3K27me3.

Postnatal Cardiovascular Consequences in the Offspring of Pregnant Rats Exposed to Smoking and Smoking Cessation Pharmacotherapies

Approximately 20% of pregnant women smoke despite intentions to quit. Smoking cessation drugs, such as nicotine replacement therapy (NRT) and bupropion, are recommended treatments. Adverse cardiovascular outcomes in offspring have raised concerns about NRT's safety during pregnancy. However, the effect of bupropion is unknown. Using a rat model, we determined whether NRT and bupropion interventions during pregnancy are safer than continued smoking on offspring's cardiovascular function. Male offspring of controls and dams exposed to cigarette smoke (1.6 packs/day, inhalation), nicotine (2 mg/kg/d subcutaneously), and bupropion (13 mg/kg twice daily orally) were assessed for fetoplacental weight, cardiac function, blood pressure, and vascular reactivity. Fetoplacental weights were decreased and spontaneous beating and intracellular calcium in neonatal cardiomyocytes were increased in smoking, nicotine, and bupropion offspring; however, these effects were more accentuated in smoking followed by nicotine and bupropion offspring. Increased heart rate and decreased cardiac output, stroke volume, and left ventricular percent posterior wall thickening were observed in smoking, nicotine, and bupropion offspring. The left ventricular mass was reduced in smoking and nicotine but not in bupropion offspring. Blood pressure was higher with decreased endothelium-dependent relaxation and exaggerated vascular contraction to angiotensin II in smoking and nicotine offspring, with more pronounced dysfunctions in smoking than nicotine offspring. Maternal bupropion did not impact offspring's blood pressure, endothelium-dependent relaxation, and vascular contraction. In conclusion, maternal nicotine intervention adversely affects offspring's cardiovascular outcomes, albeit less severely than continued smoking. However, bupropion causes cardiac derangement in offspring but does not adversely affect blood pressure and vascular function.

The effects of maternal smoking on pregnancy outcome and placental histopathology lesions

OBJECTIVE

To study the effects of maternal smoking on pregnancy outcome and placental histopathology findings.

MATERIALS & METHODS

Maternal and labor characteristics and pathological reports were compared between term placentas of complicated and uncomplicated pregnancies of: heavy smokers (>10 cigarettes per day, H-smokers), moderate smokers (<10 cigarettes per day, M-smokers) and non-smokers (controls, N-smokers).

RESULTS

Birth-weights were lower in the H-smokers and M-smokers as compared to the N-smokers (p<0.001), with a higher rate of small for gestational age (SGA): 18.2%, 19.2% and 11.4%, respectively (p=0.01). Deliveries among smokers were characterized by higher rates of abnormal fetal heart rate tracings during labor as compared to non-smokers (p=0.01). Rates of placental maternal and fetal stromal-vascular supply lesions was similar between the groups.

CONCLUSIONS

Maternal smoking is associated with higher rates of SGA. Tobacco's potential influence is probably through the disruption of normal placental epigenetic patterns, not expressed in placental histopathology lesions.

Nicotine Directly Induces Endoplasmic Reticulum Stress Response in Rat Placental Trophoblast Giant Cells

Nicotine exposure during pregnancy leads to placental insufficiency impairing both fetal and neonatal development. Previous studies from our laboratory have demonstrated that in rats, nicotine augmented endoplasmic reticulum (ER) stress in association with placental insufficiency; however, the underlying mechanisms remain elusive. Therefore, we sought to investigate the possible direct effect of nicotine on ER stress in Rcho-1 rat placental trophoblast giant (TG) cells during differentiation. Protein and/or mRNA expression of markers involved in ER stress (eg, phosphorylated PERK, eIF2α, CHOP, and BiP/GRP78) and TG cell differentiation and function (eg, Pl-1, placental growth factor [Pgf], Hsd11b1, and Hsd11b2) were quantified via Western blot or real-time polymerase chain reaction. Nicotine treatment led to dose-dependent increases in the phosphorylation of PERK[Thr981] and eIF2α[Ser51], whereas pretreatment with a nicotinic acetylcholine receptor (nAChR) antagonist (mecamylamine hydrochloride) blocked the induction of PERK phosphorylation, verifying the direct involvement of nicotine and nAChR binding. We next investigated select target genes known to play essential roles in placental TG cell differentiation and function (Pl-1, Pgf, Hsd11b1, and Hsd11b2), and found that nicotine significantly augmented the mRNA levels of Hsd11b1 in a dose-dependent manner. Furthermore, using tauroursodeoxycholic acid, a safe bile acid known to improve protein chaperoning and folding, we were able to prevent nicotine-induced increases in both PERK phosphorylation and Hsd11b1 mRNA levels, revealing a potential novel therapeutic approach to reverse the deleterious effects of nicotine exposure in pregnancy. Collectively, these results implicate that nicotine, acting through its receptor, can directly augment ER stress and impair placental function.

Adverse effects of perinatal nicotine exposure on reproductive outcomes

Nicotine exposure during pregnancy through cigarette smoking, nicotine replacement therapies or e-cigarette use continues to be a widespread public health problem, impacting both fetal and postnatal health. Yet, at this time, there remains limited data regarding the safety and efficacy in using these nicotine products during pregnancy. Notably, reports assessing the effect of nicotine exposure on postnatal health outcomes in humans, including reproductive health, are severely lacking. Our current understanding regarding the consequences of nicotine exposure during pregnancy is limited to a few animal studies, which do not comprehensively address the underlying cellular mechanisms involved. This paper aims to critically review the current knowledge from human and animal studies regarding the direct and indirect effects (e.g. obesity) of maternal nicotine exposure, regardless of its source, on reproductive outcomes in pregnancy and postnatal life. Furthermore, this review highlights several key cellular mechanisms involved in these adverse reproductive deficits including oxidative stress, inflammation, and endoplasmic reticulum (ER) stress. By understanding the interplay of the cellular mechanisms involved, further strategies could be developed to prevent the reproductive abnormalities resulting from exposure to nicotine in utero and influence informed clinical guidelines for pregnant women.

The omniscient placenta: Metabolic and epigenetic regulation of fetal programming

Fetal development could be considered a sensitive period wherein exogenous insults and changes to the maternal milieu can have long-term impacts on developmental programming. The placenta provides the fetus with protection and necessary nutrients for growth, and responds to maternal cues and changes in nutrient signaling through multiple epigenetic mechanisms. The X-linked enzyme O-linked-N-acetylglucosamine transferase (OGT) acts as a nutrient sensor that modifies numerous proteins to alter various cellular signals, including major epigenetic processes. This review describes epigenetic alterations in the placenta in response to insults during pregnancy, the potential links of OGT as a nutrient sensor to placental epigenetics, and the implications of placental epigenetics in long-term neurodevelopmental programming. We describe the role of placental OGT in the sex-specific programming of hypothalamic-pituitary-adrenal (HPA) axis programming deficits by early prenatal stress as an example of how placental signaling can have long-term effects on neurodevelopment.

Maternal nicotine exposure leads to impaired disulfide bond formation and augmented endoplasmic reticulum stress in the rat placenta

Maternal nicotine exposure has been associated with many adverse fetal and placental outcomes. Although underlying mechanisms remain elusive, recent studies have identified that augmented endoplasmic reticulum (ER) stress is linked to placental insufficiency. Moreover, ER function depends on proper disulfide bond formation—a partially oxygen-dependent process mediated by protein disulfide isomerase (PDI) and ER oxidoreductases. Given that nicotine compromised placental development in the rat, and placental insufficiency has been associated with poor disulfide bond formation and ER stress, we hypothesized that maternal nicotine exposure leads to both placental ER stress and impaired disulfide bond formation. To test this hypothesis, female Wistar rats received daily subcutaneous injections of either saline (vehicle) or nicotine bitartrate (1 mg/kg) for 14 days prior to mating and during pregnancy. Placentas were harvested on embryonic day 15 for analysis. Protein and mRNA expression of markers involved in ER stress (e.g., phosphorylated eIF2α, Grp78, Atf4, and CHOP), disulfide bond formation (e.g., PDI, QSOX1, VKORC1), hypoxia (Hif1α), and amino acid deprivation (GCN2) were quantified via Western blot and/or Real-time PCR. Maternal nicotine exposure led to increased expression of Grp78, phosphorylated eIF2α, Atf4, and CHOP (p<0.05) in the rat placenta, demonstrating the presence of augmented ER stress. Decreased expression of PDI and QSOX1 (p<0.05) reveal an impaired disulfide bond formation pathway, which may underlie nicotine-induced ER stress. Finally, elevated expression of Hif1α and GCN2 (p<0.05) indicate hypoxia and amino acid deprivation in nicotine-exposed placentas, respectively, which may also cause impaired disulfide bond formation and augmented ER stress. This study is the first to link maternal nicotine exposure with both placental ER stress and disulfide bond impairment in vivo, providing novel insight into the mechanisms underlying nicotine exposure during pregnancy on placental health.

Maternal and fetal metabonomic alterations in prenatal nicotine exposure-induced rat intrauterine growth retardation

Prenatal nicotine exposure causes adverse birth outcome. However, the corresponding metabonomic alterations and underlying mechanisms of nicotine-induced developmental toxicity remain unclear. The aims of this study were to characterize the metabolic alterations in biofluids in nicotine-induced intrauterine growth retardation (IUGR) rat model. In the present study, pregnant Wistar rats were intragastrically administered with different doses of nicotine (0.5, 1.0 and 2.0 mg/kg d) from gestational day (GD) 11-20. The metabolic profiles of the biofluids, including maternal plasma, fetal plasma and amniotic fluid, were analyzed using (1)H nuclear magnetic resonance (NMR)-based metabonomic techniques. Prenatal nicotine exposure caused noticeably lower body weights, higher IUGR rates of fetal rats, and elevated maternal and fetal corticosterone (CORT) levels compared to the controls. The correlation analysis among maternal, fetal serum CORT levels and fetal bodyweight suggested that the levels of maternal and fetal serum CORT presented a positive correlation (r=0.356, n=32, P<0.05), while there was a negative correlation between fetal (r=-0.639, n=32, P<0.01) and maternal (r=-0.530, n=32, P<0.01) serum CORT level and fetal bodyweight. The fetal metabonome alterations included the stimulation of lipogenesis and the decreased levels of glucose and amino acids. The maternal metabonome alterations involved the enhanced blood glucose levels, fatty acid oxygenolysis, proteolysis and amino acid accumulation. These results suggested that prenatal nicotine exposure is associated with an altered maternal and fetal metabonome, which may be related to maternal increased glucocorticoid level induced by nicotine.

Cigarette smoking during pregnancy regulates the expression of specific nicotinic acetylcholine receptor (nAChR) subunits in the human placenta

Smoking during pregnancy is associated with low birth weight, premature delivery, and neonatal morbidity and mortality. Nicotine, a major pathogenic compound of cigarette smoke, binds to the nicotinic acetylcholine receptors (nAChRs). A total of 16 nAChR subunits have been identified in mammals (9 α, 4 β, and 1 δ, γ and ε subunits). The effect of cigarette smoking on the expression of these subunits in the placenta has not yet been determined, thus constituting the aim of this study. Using RT-qPCR and western blotting, this study investigated all 16 mammalian nAChR subunits in the normal healthy human placenta, and compared mRNA and protein expressions in the placentas from smokers (n = 8) to controls (n = 8). Our data show that all 16 subunit mRNAs are expressed in the normal, non-diseased human placenta and that the expression of α2, α3, α4, α9, β2 and β4 subunits is greater than the other subunits. For mRNA, cigarette smoke exposure was associated with increased expression of the α9 subunit, and decreased expression of the δ subunit. At the protein level, expression of both α9 and δ was increased. Thus, cigarette smoking in pregnancy is sufficient to regulate nAChR subunits in the placenta, specifically α9 and δ subunits, and could contribute to the adverse effects of vasoconstriction and decreased re-epithelialisation (α9), and increased calcification and apoptosis (δ), seen in the placentas of smoking women.

Effects of maternal tobacco-smoke exposure on fetal growth and neonatal size

Exposure to tobacco smoke, through both active and passive measures, has a significant impact on women's health, including effects on the cardiovascular, pulmonary and reproductive systems. Of particular interest is the effect of smoking on pregnancy outcomes. One crucial outcome that has been linked to the subsequent development of both neonatal and adult disease is intrauterine or fetal growth restriction. In this article, we will summarize the effects of smoking on newborn size and fetal growth. We will review evidence showing that tobacco consumption during pregnancy leads to a reduction in birthweight, largely through affecting specific anthropometric measures and newborn body composition. We will highlight the role of genetic susceptibility to these effects and discuss how smoking cessation prior to the third trimester results in a reduction in the risk of fetal growth restriction.

Impact of smoking exposure change on infant birth weight among a cohort of women in a prenatal smoking cessation study

INTRODUCTION

Despite the known harmful effects of smoking during pregnancy, the highly addicted find it difficult to quit. Decreased smoking may be regarded as a means of harm reduction. There is limited information on the benefits of smoking reduction short of quitting. This study used salivary cotinine to assess the impact of change in smoking exposure on birth weight in full-term infants.

METHODS

In a prenatal smoking cessation study, smoking status was validated by saliva cotinine at baseline and end of pregnancy (EOP). Salivary cotinine ≥15 ng/ml defined active smoking. Based on salivary cotinine, women were grouped as nonsmoking/quit, light exposure (<150 ng/ml), and heavy exposure (≥150 ng/ml) at baseline and EOP. EOP and baseline smoking status were stratified to form smoking exposure change groups. Mean birth weight was compared among those who quit, reduced, maintained, and increased.

RESULTS

Smoking cessation was associated with a 299 g increase in birth weight compared with sustained heavy smoking, p = .021. Reduced exposure from heavy to light was associated with a 199 g increase in birth weight compared with sustained heavy exposure, a 103 g increase compared with increased exposure, and a 63 g increase compared with sustained light exposure. Differences among continuing smokers were not statistically significant.

CONCLUSIONS

Although not statistically significant, the increase in infant birth weight associated with reduction from heavy to light exposure suggests potential for benefit. The only statistically significant comparison was between quitters and sustained heavy smokers, confirming that smoking cessation should remain the goal for pregnant women.

Tobacco smoking: patterns, health consequences for adults, and the long-term health of the offspring

Tobacco use started several centuries ago and increased markedly after the invention of the cigarette making machine. Once people start smoking they find it difficult to quit the habit. This is due to the addictive effect of nicotine in tobacco smoke. Various epidemiologic and laboratory studies clearly showed that smoking is associated with various diseases such as heart diseases, asthma and emphysema and the associated increase in morbidity and mortality of smokers. Several studies implicate nicotine as the causative factor in tobacco smoke. Apart from nicotine, various carcinogens also occur in tobacco smoke resulting in an increase in the incidence of cancer in smokers. While the smoking habit is decreasing in developed countries, tobacco use increases in the developing countries. Smoking prevalence is also highest in poor communities and amongst those with low education levels. It is important to note that, although ther is a decline in the number of smokers in the developed countries, there is a three to four decades lag between the peak in smoking prevalence and the subsequent peak in smoking related mortality. It has been shown that maternal smoking induces respiratory diseases in the offspring. There is also evidence that parental smoking may program the offspring to develop certain diseases later in life. Various studies showed that maternal nicotine exposure during pregnancy and lactation via tobacco smoke of nicotine replacement therapy (NRT), program the offspring to develop compromised lung structure later in life with the consequent compromised lung function. This implies that NRT is not an option to assist pregnant or lactating smokers to quit the habit. Even paternal smoking may have an adverse effect on the health of the offspring since it has been shown that 2nd and 3rd hand smoking have adverse health consequences for those exposed to it.

Effect of maternal age and growth on placental nutrient transport: potential mechanisms for teenagers' predisposition to small-for-gestational-age birth?

Teenagers have an increased risk of delivering small-for-gestational-age (SGA) infants. Young maternal age and continued skeletal growth have been implicated as causal factors. In growing adolescent sheep, impaired placental development and nutrient transfer cause reduced birth weight. In human pregnancies, SGA is associated with reduced placental amino acid transport. Maternal growth has no effect on placental morphology or cell turnover, but growing teenagers have higher birth weight:placental weight ratios than nongrowing teenagers. We hypothesized that placental nutrient transporter activity would be affected by maternal age and/or growth status. Placentas from teenagers and adults were collected. Teenagers were defined as growing or nongrowing based on knee height measurements. System A amino acid transporter activity was quantified as sodium-dependent uptake of [(14)C]methylaminoisobutyric acid into placental fragments. Teenagers had lower placental system A activity than adults (P < 0.05). In adults, placental system A activity was lower in SGA infants than appropriate-for-gestational-age (AGA) infants (P < 0.05). In teenagers, AGA and SGA infants had lower placental system A activity than AGA infants born to adults (P < 0.05). Placental system A activity was higher in growing teenagers than in nongrowing teenagers (P < 0.001). Placental mRNA expression of system A transporter isoforms SLC38A1 and -2 was lower in teenagers than in adults (P < 0.05) but did not differ between growing and nongrowing teenagers. There was no difference in transporter protein expression/localization between cohorts. Teenagers have inherently reduced placental transport, which may underlie their susceptibility to delivering SGA infants. Growing teenagers appear to overcome this susceptibility by stimulating the activity, but not expression, of system A transporters.

Prenatal cocaine exposure and small-for-gestational-age status: effects on growth at 6 years of age

OBJECTIVE

To evaluate the impact of prenatal cocaine exposure and small-for-gestational-age (SGA) status on childhood growth.

STUDY DESIGN

Cocaine exposure was defined by history or meconium metabolites. Hierarchical linear modeling was used to examine cocaine exposure and SGA status on growth, while controlling for exposure to other drugs and alcohol use.

RESULTS

At birth cocaine-exposed infants (n=364) had significantly lower growth parameters compared to non-exposed children (n=771). At 6 years, weight was similar between exposed and unexposed children. SGA infants continued to be growth impaired. There was a significant interaction between prenatal cocaine exposure and SGA status at 6 years. The negative effects of cocaine on weight and height were greater among non-SGA than SGA children (432 vs. 280 gm, and 0.7 and 0.5 cm, respectively) while negative effects of SGA status on weight and height were larger in non-cocaine exposed compared to the exposed children (2.3 kg vs.1.6 kg and 2.2 and 1.0 cm).

CONCLUSIONS

Children exposed to prenatal cocaine were similar in weight to non-exposed children at 6 years of age. Cocaine had an unexplained greater detrimental effect on non-SGA than SGA children. SGA status at birth has an independent detrimental effect on childhood growth.

Triply troubled: criminal behaviour and mental health in a cohort of teenage pregnant substance misusers in treatment

BACKGROUND

Teenage substance misuse and pregnancy are major public health problems in the UK, where the most recent figures on maternal deaths suggest that they have doubled among young substance misusers. In general, little is known about their pregnancy outcomes.

AIMS

The aims of this study were to describe the characteristics of a sample of teenage pregnant drug users in the UK, to examine their psychosocial risk and complicating factors at presentation, to evaluate adherence to current national guidelines and to assess the adequacy of guidelines in relation to identified characteristics.

METHODS

A six-year records survey of young people attending a specialist adolescent drug misuse service in the west midlands of the UK.

RESULTS

Ten pregnant adolescents were identified from records. These girls have had unstable or abusive experiences through childhood, half having other substance misusers in the family. All were with substantially older partners, who were also substance misusers. All had required a mental health assessment and 90% had a history of self-harm. There were no maternal or neonatal deaths, and only one girl had a miscarriage, but in four cases, the child had to be fostered.

CONCLUSIONS

To our knowledge, this is the first analysis of this kind in the UK. Available guidelines were followed, but our findings suggest that more detailed and comprehensive guidelines are required. Preventive measures through education are likely to be hampered by the early age at which these girls cease attending school.

Pharmacogenomics of maternal tobacco use: metabolic gene polymorphisms and risk of adverse pregnancy outcomes

OBJECTIVE

To assess whether functional maternal or fetal genotypes along well-characterized metabolic pathways (ie, CYP1A1, GSTT1, and CYP2A6) may account for varying associations with adverse outcomes among pregnant women who smoke.

METHODS

DNA samples from 502 smokers and their conceptuses, alongside women in a control group, were genotyped for known functional allelic variants of CYP1A1 (Ile462Val AA>AG/GG), GSTT1(del), and CYP2A6 (Lys160His T>A). Modification of the association between smoking and outcome by genotype was evaluated. Outcomes included birth weight, pregnancy loss, preterm birth, small for gestational age, and a composite outcome composed of the latter four components plus abruption.

RESULTS

No interaction between maternal or fetal genotype of any of the polymorphisms and smoking could be demonstrated. In contrast, the association of smoking with gestational age-adjusted birth weight (birth weight ratio) was modified by fetal GSTT1 genotype (P for interaction=.02). Fetuses with GSTT1(del) had a mean birth weight reduction among smokers of 262 g (P=.01), whereas in fetuses without the GSTT1(del) the effect of tobacco exposure was nonsignificant (mean reduction 87 g, P=.16). After adjusting for confounding, results were similar.

CONCLUSION

Fetal GSTT1 deletion significantly and specifically modifies the effect of smoking on gestational age-corrected birth weight.

Epigenetics in the placenta

Epigenetics is focused on understanding the control of gene expression beyond what is encoded in the sequence of DNA. Central to growing interest in the field is the hope that more can be learned about the epigenetic regulatory mechanisms underlying processes of human development and disease. Researchers have begun to examine epigenetic alterations - such as changes in promoter DNA methylation, genomic imprinting, and expression of miRNA - to learn more about epigenetic regulation in the placenta, an organ whose proper development and function are crucial to the health, growth, and survival of the developing fetus. A number of studies are now making important links between alterations to appropriate epigenetic regulation in the placenta and diseases of gestation and early life. In addition, these studies are adding important insight into our understanding of trophoblast biology and differentiation as well as placental immunology. Examining epigenetic alterations in the placenta will prove especially important in the search for biomarkers of exposure, pathology, and disease risk and can provide critical insights into the biology of development and pathogenesis of disease. Thus, epigenetic alterations may aid in disease diagnosis and prognosis as well as in targeting new treatment and prevention strategies.

Influence of maternal nicotine exposure on neonatal rat oxidant-antioxidant system and effect of ascorbic acid supplementation

There have been a few studies that examined the oxidative stress effects of nicotine during pregnancy and lactation. We aimed to determine the adverse effects of maternal nicotine exposure during pregnancy and lactation on oxidant-antioxidant system, and to determine a protective effect of ascorbic acid (Asc). Gravid rats were assigned into four groups. In Group 1, pregnant rats received 6-mg/kg/day nicotine subcutaneously during pregnancy from 1 to 21 days of gestation and lactation (until postnatal day 21). Group 2 received nicotine and Asc for the same period. In Group 3, the rats received nicotine during lactation. Control pregnant rats (Group 4) received only saline subcutaneously. Serum malondialdehyde (MDA), myeloperoxidase (MPO), and superoxide dismutase (SOD) levels were determined at 21 days of age. Nicotine exposure decreased birth weight and pregnancy weight gain. MDA values of the rat pups exposed to nicotine in both Groups 1 and 2 were higher than those of control and Group 3. SOD and MPO values of the groups were similar. Mean birth weight and serum MDA levels of Groups 1 and 2 were similar. Nicotine exposure via placental transfer increases oxidative stress as manifested by an increase in MDA level. Asc supplementation does not prevent the adverse effects of maternal nicotine exposure.

Excretion of biliary compounds during intrauterine life

In adults, the hepatobiliary system, together with the kidney, constitute the main routes for the elimination of several endogenous and xenobiotic compounds into bile and urine, respectively. However, during intrauterine life the biliary route of excretion for cholephilic compounds, such as bile acids and biliary pigments, is very poor. Although very early in pregnancy the fetal liver produces bile acids, bilirubin and biliverdin, these compounds cannot be efficiently eliminated by the fetal hepatobiliary system, owing to the immaturity of the excretory machinery in the fetal liver. Therefore, the potentially harmful accumulation of cholephilic compounds in the fetus is prevented by their elimination across the placenta. Owing to the presence of detoxifying enzymes and specific transport systems at different locations of the placental barrier, such as the endothelial cells of chorionic vessels and trophoblast cells, this organ plays an important role in the hepatobiliary-like function during intrauterine life. The relevance of this excretory function in normal fetal physiology is evident in situations where high concentrations of biliary compounds are accumulated in the mother. This may result in oxidative stress and apoptosis, mainly in the placenta and fetal liver, which might affect normal fetal development and challenge the fate of the pregnancy. The present article reviews current knowledge of the mechanisms underlying the hepatobiliary function of the fetal-placental unit and the repercussions of several pathological conditions on this tandem.

Is the association of maternal smoking and pregnancy-induced hypertension dependent on fetal growth?

OBJECTIVE

The risk of pregnancy-induced hypertension (PIH) is decreased by smoking, but the mechanisms remain unclear. Our objective was to determine whether this association is dependent on decreased fetal growth.

METHODS

A population-based, retrospective cohort study in the United States was performed consisting of nulliparous women who delivered a singleton birth (n = 8,025,295) between 1995 and 2002. Fetal growth was defined as birthweight for gestational age and characterized as less than 1, 1-2, 3-4, 5-9, 10-19, ..., 90 or greater centiles. Risk and relative risk of PIH before and after adjusting for confounders were estimated.

RESULTS

Smoking was associated with decreased risk of PIH with up to a 46% decreased risk of PIH for growth-restricted babies (less than the 10th centile). This association, however, decreased with increasing birthweight centile and was nonsignificant at 20th or greater centile among heavy smokers, at 60th or greater centile for moderate, and 80th or greater centile for light smokers.

CONCLUSION

Smoking was primarily associated with decreased risk of PIH among growth-restricted babies.

The effects of smoking in pregnancy on factors influencing fetal growth

AIM

To evaluate the influence of maternal smoking during pregnancy on factors influencing fetal growth.

METHODS

Thirty newborns of smoking mothers were prospectively compared with 60 newborns of non-smoking mothers. Pre-albumin, albumin, triglycerides, glucose, insulin, insulin-like growth factor I, IGF binding protein 3, pH, lactic acid, erythropoietin and hemoglobin concentrations were measured in umbilical cord blood.

RESULTS

Infants of smoking mothers had a significantly lower birth weight (3418 +/- 533 vs. 3863 +/- 503 g; p < 0.001), length (50.5 +/- 2,6 vs. 52.3 +/- 1.9 cm; p < 0.001) and head circumference (34.6 +/- 1.8 vs. 35.8 +/- 1.1 cm; p < 0.001) than controls. They also had significantly lower insulin (3.2 (2.0-4.9) vs. 5.8 (4.6-7.1) mU/L; p = 0.008), insulin-like growth factor I (54.4 +/- 32.5 vs. 93.8 +/- 54.5 microg/L; p = 0.001) and IGF binding protein 3 (1664 +/- 432 vs. 1943 +/- 421 microg/L; p = 0.01) concentrations, than controls. Infants of smoking mothers also had significantly higher hemoglobin (167 +/- 14 vs. 157 +/- 13 g/L; p = 0.002) and erythropoietin (42.3 (25.1-72.4) vs. 26.3 (21.9-30.9) U/L; p = 0.03) than controls, but not pH or lactate concentrations. There was no significant difference in pre-albumin, albumin, triglycerides and glucose concentrations.

CONCLUSIONS

Smoking during pregnancy causes symmetrical fetal growth impairment, possibly due to decreased oxygen transport to the fetus and decreased concentrations of fetal insulin, insulin-like growth factor I and IGF binding protein 3.

Cocaine Detection in Maternal and Neonatal Hair: Implications to Fetal Toxicology

Cocaine use during pregnancy is difficult to ascertain, and maternal reports are likely to be inaccurate. Presently, the dose-response characteristics between maternal cocaine use and fetal exposure and adverse effects are unknown. Clinically, some babies are harmed, whereas others are not adversely affected. Taking advantage of the fact that cocaine and its metabolite benzoylecgonine (BE) accumulate and can be detected months after exposure in maternal and neonatal hair, an analytical test for cocaine and BE was developed by the authors. The aim of this study was to describe the characteristics of maternal and neonatal hair cocaine as biomarkers of fetal exposure. Of nearly 10,000 cases, all mother-child pairs in whom at least one had cocaine and/or BE detected in hair were identified. The relationship between maternal and neonatal levels was studied. When available, these data were also compared with meconium levels of cocaine. Median cocaine concentration was 10-fold higher in hair of the mothers compared with the neonates (3.56 ng/mg vs 0.31 ng/mg of hair). Infants' cocaine in hair was positively correlated with maternal cocaine and BE in hair (r2 = 0.41 and r2 = 0.22, respectively, P < 0.001 for both correlations). Infants' BE was also correlated with maternal cocaine and BE concentrations in hair (r2 = 0.50 and r2 = 0.27, P < 0.001 for both correlations). Thirty-nine (40%) babies had negative cocaine and BE results despite their mothers being positive. Mothers whose infants were cocaine-positive had a median hair cocaine concentration of 7.34 ng/mg, significantly higher than those whose infants were negative (1.25 ng/mg). Maternal cocaine levels below 0.24 ng/mg may serve as a relative threshold for detectable fetal exposure during the third trimester of pregnancy. Fetal hair grows in the last trimester. Hence, a positive neonatal hair indicates maternal use after pregnancy became known, a strong indicator of maternal addiction. Transplacental exposure to cocaine of babies of addicted mothers is highly variable. The dose-response relationship of both cocaine and BE between maternal and neonatal hair suggests that the placenta protects some fetuses but not others. More research is needed to understand the mechanisms leading to placental defense against cocaine.

Exposure to smoke during development: fetal programming of adult disease

It is well established that smoking has potent effects on a number of parameters including food intake, body weight, metabolism, and blood pressure. For example, it is well documented that 1) there is an inverse relationship between smoking and body weight, and 2) smoking cessation is associated with weight gain. However, there is increasing evidence that smoking can exert deleterious effects on energy balance through maternal exposure during fetal development. Specifically, there appears to be an increased incidence of metabolic disease (including obesity), and cardiovascular disease in children and adults that were exposed to smoke during fetal development. The present review will examine the relationship between maternal smoke and adult disease in offspring. The epidemiological studies highlighting this relationship will be reviewed as well as the experimental animal models that point to potential mechanisms underlying this relationship. A better understanding of how smoking effects changes in energy balance may lead to treatments to ameliorate the long-lasting effects of perinatal exposure to smoke as well as increasing the health benefits associated with smoking cessation.

Endocrine regulation of human fetal growth: the role of the mother, placenta, and fetus

The environment in which the fetus develops is critical for its survival and long-term health. The regulation of normal human fetal growth involves many multidirectional interactions between the mother, placenta, and fetus. The mother supplies nutrients and oxygen to the fetus via the placenta. The fetus influences the provision of maternal nutrients via the placental production of hormones that regulate maternal metabolism. The placenta is the site of exchange between mother and fetus and regulates fetal growth via the production and metabolism of growth-regulating hormones such as IGFs and glucocorticoids. Adequate trophoblast invasion in early pregnancy and increased uteroplacental blood flow ensure sufficient growth of the uterus, placenta, and fetus. The placenta may respond to fetal endocrine signals to increase transport of maternal nutrients by growth of the placenta, by activation of transport systems, and by production of placental hormones to influence maternal physiology and even behavior. There are consequences of poor fetal growth both in the short term and long term, in the form of increased mortality and morbidity. Endocrine regulation of fetal growth involves interactions between the mother, placenta, and fetus, and these effects may program long-term physiology.

Imprinted genes and their role in human fetal growth

Growth is defined as the progressive increase in size and is listed as one of the eight main characteristics of life. In human gestation the most rapid growth phase is from 16 to 32 weeks when first there is both cell number and size increase and then from 32 weeks onwards there is continued size increase (Pollack and Divon, 1992). The mechanism of growth in utero is of fundamental interest to clinicians and scientists because of its implications for neonatal health. Growth is multifactorial in origin with both genetics and environment contributing equally large parts. Despite this complexity analysis of the candidate genes involved is possible using simple tissue biopsies at the relevant stages of development. Of particular interest in understanding fetal growth is the analysis of a group of genes that show a parent-of-origin effect known as genomic imprinting. Imprinted genes are not only found in eutherian (placental) and metatherian (marsupial) mammals but surprisingly also in plants. Nevertheless, their evolution in mammals appears to be linked primarily to placentation. It is thought to result from a potential conflict between the parents in terms of the drive to successfully propagate their own separate genes and the mother's added drive for her survival through the pregnancy to reproduce again. This means that the mother wants to restrict fetal growth and the father to enhance it.

Cadmium reduces 11 beta-hydroxysteroid dehydrogenase type 2 activity and expression in human placental trophoblast cells

Cadmium, a common environmental pollutant and a major constituent of tobacco smoke, has been identified as a new class of endocrine disruptors with a wide range of detrimental effects on mammalian reproduction. During human pregnancy, maternal cadmium exposure, via the environment and/or cigarette smoking, leads to fetal growth restriction (FGR), but the underlying mechanisms are unknown. Although a substantial amount of evidence suggests that cadmium may affect fetal growth indirectly via the placenta, the molecular targets remain to be identified. Given that reduced placental 11 beta-hydroxysteroid dehydrogenase type 2 (11 beta-HSD2, encoded by HSD11B2 gene) is causally linked to FGR, the present study was undertaken to examine the hypothesis that cadmium induces FGR in part by targeting placental HSD11B2. Using cultured human trophoblast cells as a model system, we showed that cadmium exposure resulted in a time- and concentration-dependent decrease in 11 beta-HSD2 activity, such that an 80% reduction was observed after 24-h treatment at 1 microM. It also led to a similar decrease in levels of 11 beta-HSD2 protein and mRNA, suggesting that cadmium reduced 11 beta-HSD2 expression. Furthermore, cadmium diminished HSD11B2 promoter activity, indicative of repression of HSD11B2 gene transcription. In addition, the effect of cadmium was highly specific, in that other divalent metals (Zn(2+), Mg(2+), and Mn(2+)) as well as nicotine and cotinine (a major metabolite of nicotine) did not alter 11 beta-HSD2 activity. Taken together, these findings demonstrate that cadmium reduces human placental 11 beta-HSD2 expression and activity by suppressing HSD11B2 gene transcription. Thus the present study identifies placental 11 beta-HSD2 as a novel molecular target of cadmium. It also reveals a molecular mechanism by which this endocrine disruptor may affect human placental function and, consequently, fetal growth and development.

Human placenta: a human organ for developmental toxicology research and biomonitoring

Pregnant mothers are exposed to a wide variety of foreign chemicals. This exposure is most commonly due to maternal medication, lifestyle factors, such as smoking, drug abuse, and alcohol consumption, or occupational and environmental sources. Foreign compounds may interfere with placental functions at many levels e.g. signaling, production and release of hormones and enzymes, transport of nutrients and waste products, implantation, cellular growth and maturation, and finally, at the terminal phase of placental life, i.e. delivery. Placental responses may also be due to pharmaco-/toxicodynamic responses to foreign chemicals, e.g. hypoxia. On the other hand, placental xenobiotic-metabolizing enzymes can detoxify or activate foreign chemicals, and transporters either enhance or prevent cellular accumulation and transfer across the placenta. The understanding of what xenobiotics do to the placenta and what the placenta does to the xenobiotics should provide the basis for the use of placenta as a tool to investigate and predict some aspects of developmental toxicity. This review aims to give an update of the fate and behavior of xenobiotics in the placenta from the viewpoint of xenobiotic-metabolizing enzymes and transporters. Their response levels will be described according to gestational status and methods used. The effects of foreign chemicals on placental metabolizing enzymes will be discussed. Also, interactions in the transporter protein level will be covered. The role of the placenta in contributing to developmental effects and fetotoxicity will be examined. The toxicological effects of maternal medications, smoking, and environmental exposures (dioxins, pesticides) as well as some possibilities for biomonitoring will be highlighted.

The adverse effects of maternal smoking on the human placenta: A review

Studies of placental pathologies associated with maternal cigarette smoking have led to many interesting observations. For example, maternal smoking impairs human placental development by changing the balance between cytotrophoblast (CTB) proliferation and differentiation. It is likely that chronic exposure to tobacco constituents in early pregnancy can affect placental development directly or indirectly by reducing blood flow, which creates a pathologically hypoxic environment. To understand this process at a molecular level, tissue samples from non-smoking and smoking mothers were studied to determine whether active and/or passive cigarette smoke exposure affects CTB expression of molecules that govern cellular responses to oxygen tension: the von Hippel-Lindau tumor suppressor protein (pVHL), hypoxia-inducible transcription factors (HIFs) and vascular endothelial growth factor-A (VEGF). The results show that maternal smoking dysregulates CTB expression of all three types of molecules. In addition, cell columns and proliferating cells were reduced while there was a corresponding increase in cell islands. All three phenomena were most obvious in the placentas of heavy smokers. Interestingly, a subset of the aforementioned effects can be detected in samples obtained from women who were passively exposed to cigarette smoke during pregnancy. These observations suggest that tobacco constituents exert direct effects on CTB proliferation and differentiation and help to explain the mechanisms by which smoking negatively effects human pregnancy outcome.

The effect of controlled drugs on the unborn child and fetus

Illicit substance abuse is more prevalent than thought in women of a child bearing age and its incidence is increasing. Although maternal factors, such as poor socioeconomic status, diet, smoking, alcohol and infection, have detrimental effects on the fetuses of drug-abusing mothers, harm is increased due to the pharmacological activity of the drugs themselves. This article reviews the pharmacophysiological interactions between mother and fetus, describes the general effects of substance abuse during each trimester and details the deleterious effects on the fetus of the more commonly abused controlled drugs.

Maternal smoking, intrauterine growth restriction, and placental apoptosis

Pregnant women who smoke are at greater risk of delivering a growth-restricted infant than nonsmoking mothers. We wanted to see if apoptosis could be involved in the mechanisms behind smoke-induced growth restriction, and our aim was to compare apoptosis in the placenta of smoking mothers giving birth to growth-restricted infants and nonsmoking mothers with infants of appropriate weight. The project was conducted at the Magee--Womens Hospital and Magee--Womens Research Institute, University of Pittsburgh, PA. Histological sections from 20 placentas were selected from smoking mothers who had given birth to small-for-gestational-age infants (birth weight < or = 2 SD). The controls were gestational-age matched nonsmoking mothers with infants having appropriate-for-gestational-age weight. The TUNEL method was used to demonstrate DNA fragmentation in nuclei, and a monoclonal antibody M30, specific for a neo-epitope on cytokeratin 18, was used to identify apoptotic epithelial cells. The positive nuclei (TUNEL) and positive cells (M30-positive cytoplasm) were counted blindly both in villous tissue and in decidual/basal plate tissue. M30-positive cells in villous tissues were significantly increased in placentas from smoking mothers compared to nonsmoking mothers. When evaluated by the TUNEL method, the difference between the two groups of women was not significant. Our study shows that apoptosis was increased in the placentas of smoking mothers with growth-restricted infants. The difference between the two groups was mainly in the syncytiotrophoblast layer and in connection with perivillous fibrin deposition. Cigarette smoke with reduction in blood flow has previously been shown to increase apoptosis, and it is possible that this could be one of the mechanisms playing a role in the growth restriction.

Fibrin-type fibrinoid in placentae from pregnancies associated with maternal smoking: association with villous trophoblast and impact on intervillous porosity

Smoking during pregnancy perturbs maternal haemostasis via activated coagulation which could include greater coagulation (fibrin-type fibrinoid deposition) in the placental intervillous space. This might affect intervillous haemodynamics and transport of oxygen and nutrients to the fetus. Fibrin deposits could influence the sizes and numbers of intervillous spaces ('pores') and perivillous fibrin could reflect changes in the nature or activity of trophoblast. Here, we test whether or not smoking is associated with differences in the composition of villous trophoblast, the amounts and patterns of fibrin and, hence, the dimensions and numbers of intervillous pores. Random samples of placentae were taken from pregnancies classified according to smoking status (non-smokers, light smokers, heavy smokers). Stereology was used to estimate volumes of intervillous space and fibrin, test for differences in trophoblast composition and patterns of fibrin deposition at the villous surface, and determine the impact of deposits on the mean volumes and theoretical numbers of intervillous pores. No group differences were found in total volumes or surfaces of trophoblast or total volume of intervillous fibrin. However, the total surfaces of syncytial knots declined in smokers and the surfaces of syncytial bridges increased. Particularly in heavy smokers, this was associated with reduced deposits of perivillous fibrin at syncytial knots. In all placentae, the greatest deposits occurred where there was trophoblast denudation. Little fibrin was seen on thin regions of syncytium. Regardless of smoking status, intervillous fibrin reduced intervillous pore size and increased pore number. However, heavy smokers had larger pores. Reductions in syncytial knots are consistent with reports that smoking reduces the incidence of trophoblast apoptosis whilst increases in syncytial bridges are consistent with enhanced branching angiogenesis. Results confirm that perivillous fibrin accumulates preferentially at denudation sites. They also suggest that smoking perturbs the normal pattern of fibrin deposition, that the impact is greater in heavy smokers and that the placental site is privileged or active in terms of fibrinolytic or anti-coagulatory activity. This activity seems to reside in thin regions of syncytium.

The pathophysiology of cocaine abuse

Cocaine is a naturally occurring alkaloid that increases dopamine concentrations in the reward centers of the brain. There has been a marked increase in cocaine abuse over the last two decades. A neuropsychological stimulant, cocaine also reduces somnolence, increases alertness and improves concentration. However, cocaine abuse has many pathophysiological consequences. These fall broadly into four groups: pathology associated with a drug abusing lifestyle, pathology that occurs whilst intoxicated with (but not directly due to) the drug, pathology associated with drug administration and pathology resulting from pharmacological action of the drug. This review provides a detailed description of the physiological, pharmacological, and pathological effects of cocaine, and highlights the forensic and medicolegal implications of cocaine abuse.

Birth to age 7 growth of children prenatally exposed to drugs: a prospective cohort study

Prenatal exposure to cocaine, alcohol, and cigarettes has been linked to decreased birth weight and length. Unclear, however, is whether growth deficits persist into childhood. Women who were pregnant, African-American, not HIV-positive, and who delivered singleton infants were extensively screened throughout pregnancy for cocaine, alcohol, cigarette, and other illicit drug use. Of the approximately 1100 eligible subjects, 665 families were located at a 7-year postbirth follow-up and 540 participated. After appropriate control for potential confounders and prenatal exposures, prenatal exposure to cocaine, alcohol, and cigarettes each independently predicted birth weight and length. At age 7, prenatal cocaine exposure was significantly related to height deficits after accounting for other prenatal exposures and significant confounders. Children at age 7 exposed to cocaine in utero were up to 1 in. shorter and twice as likely to fall below the 10th percentile in height as the control children after accounting for other significant confounders including other prenatal exposures. Maternal age moderated the relation between prenatal exposures and child growth. Children born to women over 30 and exposed to cocaine were up to 2 in. shorter and four times more likely to have clinically significant height deficits at age 7. Children of older women and exposed to moderate-to-high levels of alcohol prenatally were up to 14 lb lighter and five times more likely to fall below the 10th percentile in weight. Similar growth restriction was not associated with prenatal exposures for children born to younger mothers. These outcomes add to the growing body of literature detailing long-term effects of prenatal drug exposure, suggesting differential effects for cocaine and alcohol, and indicating that maternal age may moderate these effects. Mechanisms for growth restriction and failure of catch-up under conditions of prenatal exposures are presented, suggesting further study of these developmental outcomes.

Fetal pharmacotherapy

Rapid progress has recently been encountered in pharmacologically treating the unborn baby. This unique area of drug therapy raises new methodological and ethical questions. This article is a systematic review of known modalities of fetal pharmacotherapy, and aims to highlight essential principles, difficulties and controversies in fetal pharmacotherapy. Unique pharmacokinetic features of pregnancy, the placenta and the fetus govern maternal-to-fetal drug transfer. Ethically, it is important that the mother and family are appropriately informed about the evidence in favour of specific fetal therapy, its risks and alternatives. Antenatal use of corticosteroids for lung maturation is an example of adequate methodology, leading to clear results. In contrast, the initial hopes in antenatal use of phenobarbital were based on less than optimal methodology. Folic acid for the prevention of neural tube defects is the first instance of fetal therapy that has led to the prevention of a major malformation. Serious infections, such as HIV, Group B streptococcus and toxoplasmosis highlight the need for controlled, randomised studies to prevent fetal infection. With scores of new modalities of fetal therapy likely to be introduced in the next few years, it will be important to adhere to the best possible methodology and execution, in order to address optimally the needs of the fetus.

In vitro ischemia-reperfusion injury in term human placenta as a model for oxidative stress in pathological pregnancies

Oxidative stress is a prominent feature of the placenta in many complications of pregnancy, such as preeclampsia. The cause is primarily unknown, although ischemia-reperfusion injury is one possible mechanism. Our aim was to test this hypothesis by examining the oxidative status of human placental tissues during periods of hypoxia and reoxygenation in vitro. Rapid generation of reactive oxygen species was detected using the fluorogenic probe, 2',7'-dichlorofluorescein diacetate, when hypoxic tissues were reoxygenated. The principal sites were the villous endothelium, and to a lesser extent the syncytiotrophoblast and stromal cells. Increased concentrations of heat shock protein 72, nitrotyrosine residues, and 4-hydroxy-2-nonenal were also observed in the villous endothelial and underlying smooth muscle cells, and in the syncytiotrophoblast. Furthermore, preloading placental tissues with the reactive oxygen species scavengers desferrioxamine and alpha-phenyl-N-tert-butylnitrone reduced levels of oxidative stress after reoxygenation. These changes are consistent with an ischemia-reperfusion injury, and mirror those seen in preeclampsia. Consequently, in vitro hypoxia/reoxygenation may represent a suitable model system for investigating the generation of placental oxidative stress in preeclampsia and other complications of pregnancy.

Placental transport and metabolism of amino acids

This review examines the placental transport and metabolism of amino acids, with a special emphasis on unifying and interpreting in-vivo and in-vitro data. For a variety of technical reasons, in-vivo studies, which quantify placental amino-acid fluxes and metabolism, have been relatively limited, in comparison to in-vitro studies using various placental preparations. Following an introduction to placental amino-acid uptake and transfer to the fetus, the review attempts to reconcile in-vitro placental transport data with in-vivo placental data. Data are discussed with reference to the measured delivery rates of amino acids into the fetal circulation and the contribution of placental metabolism to this rate for many amino acids. The importance of exchange transporters in determining efflux from the placenta into the fetal circulation is presented with special reference to in-vivo studies of non-metabolizable and essential amino acids. The data which illustrate the interconversion and nitrogen exchange of three groups of amino acids, glutamine-glutamate, BCAAs and serine-glycine, within the placenta are discussed in terms of the potential role such pathways may serve for other placenta functions. The review also presents comparisons of the sheep and human placentae in terms of their in-vivo amino-acid transport rates.