Increase in vasoactive prostaglandin E production after perfusion in human placental cotyledons

Candidate placental biomarkers for intrauterine alcohol exposure

BACKGROUND

Fetal alcohol spectrum disorder (FASD) is a leading cause of nongenetic mental retardation and other neurodevelopmental deficits. Earlier diagnosis of FASD would greatly improve prognosis for individuals and families affected by this disorder. Here, we identify candidate placental biomarkers in an animal model of FASD that recapitulates many aspects of human FASD.

METHODS

Pregnant Sprague-Dawley (SD) females were assigned to 1 of 3 diet groups on gestation day 8 (G8): Ethanol (E), Pair-fed (PF) or Control (C). E dams received ethanol-containing liquid diet and PF dams received isocaloric liquid diet in an amount that matched the paired E dam's diet consumption the previous day. Control dams received laboratory chow and water ad libitum. Whole placentae from individual fetuses were collected on gestational day 21 (G21) for analyses. Western blotting and quantitative real-time RT-PCR were used to measure protein and mRNA levels of placental iodothyronine deiodinase III (Dio3), thyroid hormone receptor α1 (TRα1), and glucocorticoid receptor (GR). Placental mRNA levels of insulin-like growth factor 2 (Igf-2), pleckstrin homology-like domain family A member 2 (Phlda2), and cyclin-dependent kinase inhibitor 1C (Cdkn1c) were also measured.

RESULTS

Placental protein and mRNA levels from ethanol (E)-consuming dams showed the following changes: increased Dio3, decreased TRα1, and decreased GR compared to both C and PF dams. Placental mRNA levels of intrauterine growth restriction (IUGR) markers Igf-2, Phlda2, and Cdkn1c were altered similarly in PF and E dams.

CONCLUSIONS

We propose the specific pattern of increased Dio3 and decreased TRα1 and GR protein levels in the placenta as selective biomarker for intrauterine alcohol exposure.

Ethanol and the placenta: A review

OBJECTIVE

In this paper we review published studies of alcohol exposure on placentation, placenta growth and function.

METHODS

We searched PubMed using the MeSH terms: placenta, ethanol, fetal alcohol syndrome and prenatal exposure with delayed effects. We searched the years 1996-2006 and used the references from other articles to expand our search. We limited the search to English only and human only. We excluded studies using choriocarcinoma and animal studies. We grouped the 66 papers into seven topic areas for ease of review.

RESULTS

Alcohol exposure is associated with placental dysfunction, decreased placental size, impaired blood flow and nutrient transport, endocrine changes, increased rates of stillbirth and abruption, umbilical cord vasoconstriction, and low birth weight.

CONCLUSIONS

Prenatal alcohol exposure has a broad range of adverse effects on placental development and function. Additional research on placental development from populations with heavy alcohol exposure should be encouraged. A tissue bank of placentas with detailed assessment of exposure to alcohol, smoking and other relevant data should be considered as a repository to support additional research.

Extreme prematurity: an alcohol-related birth effect

BACKGROUND

Rates of preterm delivery, a major proximate cause of perinatal morbidity and mortality, have been increasing. Prenatal alcohol exposure has been implicated in preterm delivery, although results have been inconsistent due to inadequate control for confounding factors, insufficient power, unreliable and inaccurate assessment of both exposure and gestational age, and lack of stratification of prematurity into severity levels. The purpose of this study was to examine the relation between maternal alcohol, cocaine and cigarette use during pregnancy, and extreme and mild preterm birth.

METHODS

Three thousand one hundred thirty consecutive gravidas were followed prospectively for antenatal substance use and had ultrasound confirmed pregnancy dating.

RESULTS

Alcohol and cocaine, but not cigarette use, were associated with increased risk of extreme preterm delivery after control for potential confounders. For every unit increase in alcohol exposure, risk of extreme preterm delivery increased significantly [odds ratio (OR) 34.8]. Furthermore, in women aged 30+, alcohol exposure was associated with mild prematurity. Abstention from alcohol while continuing to use cocaine and tobacco was related to a decrease in extreme prematurity of 41%.

CONCLUSIONS

The risk of extreme preterm delivery associated with alcohol use is substantial and similar in magnitude to other well-recognized risks. Increased accuracy in identifying exposure and the use of ultrasound to confirm gestational age dating likely contributed to the findings of the current study. These findings suggest that eliminating pregnancy alcohol use might substantially reduce the risk of preterm delivery.

The effect of maternal smoking and ethanol on fatty acid transport by the human placenta

The role of the placenta in controlling the supply of fatty acids to the fetus was investigated in term placentas from non-smokers (n5), smokers (>ten cigarettes/d;n5) and after addition of ethanol at 2 mg/ml (n4). The maternal side was of the placenta was perfusedex vivofor 90 min with a physiological mixture of fatty acids and fatty acid:human albumin ratio. There was no effect of smoking on the transfer of linoleic (LA, 18 : 2n-6), α-linolenic (αLN, 18 : 3n-3), arachidonic (AA, 20 : 4n-6) or docosahexaenoic acid (DHA, 22 : 6n-3), expressed per perfused area (calculated from H218O exchange). However, the presence of ethanol in the perfusate at a concentration of 2 mg/ml significantly reduced (P<0·01) the absolute rate of transfer of the twon-3 polyunsaturated fatty acids, αLN and DHA. This specific effect of ethanol on αLN and DHA also resulted in an altered selectivity for transfer of individual fatty acids. In the non-smoking control group the placenta selectively transferred polyunsaturated fatty acids to the fetus in the order DHA>AA>αLN>LA. The order of selectivity was unaltered in placentas from smokers, but the addition of ethanol to the perfusion medium altered the order of selectivity to AA>αLN>LA>DHA. The presence of ethanol in the perfusate was also associated with a significant reduction (P<0·05) in the clearance of H218O. These results suggest that the presence of ethanol at a concentration of 2 mg/ml may reduce the availability of polyunsaturated fatty acids to the developing fetus.

Age- and sex-related differences in alcohol and nicotine effects in C57BL/6J mice

The present studies were aimed to identify possible age- and/or sex-related differences in the effects of alcohol and nicotine. Study 1 examined age-related differences in alcohol and nicotine effects. Adolescent and adult C57BL/6J male mice were injected with alcohol or nicotine. Results indicated that alcohol and nicotine induced hypothermia and reduced locomotor activity in both adolescent and adult mice. In both dependent variables, adults were more affected than adolescents that received the same alcohol or nicotine dose. Study 2 examined possible sex-related differences in the effects of these drugs. Results replicated the aged-related differences revealed in Study 1 after alcohol or nicotine administration in male mice. No sex-related differences were observed in alcohol effects. However, young animals of both sexes and adult females appeared to be more resistant to nicotine effects. In both studies, blood alcohol concentrations and cotinine plasma concentrations were assessed. These results suggest that young C57BL/6J mice are more resistant to both alcohol and nicotine effects. In addition, adult females may be more resistant to acute nicotine effects on temperature and locomotion.

Characteristics of preterm delivery and low birthweight among 113,994 infants in Alberta: 1994-1996

This study examined the impact of infant and maternal factors on preterm delivery and low birthweight (LBW) in Alberta between January 1, 1994 and December 31, 1996. Data on 113,994 births were collected from vital statistics registration birth data. Logistic regression models for preterm and LBW delivery suggested the key risk factors were multiple and still birth (odds ratios > 22.0). Other characteristics included female gender, birth defects, nulliparous women, maternal age 35 and greater, unmarried, history of abortion, maternal smoking, maternal street drug use, and having less than 4 prenatal visits (odds ratios 0.86-2.54). Interactions between smoking and alcohol, and smoking and parity were noted. Efforts to improve the currently low rates (8.2%) of smoking cessation during pregnancy are required. Social, economic and medical factors associated with delayed childbearing and birth outcomes should be investigated.

Vascular function in alcohol-treated pregnant and nonpregnant mice

The effect of alcohol on maternal vascular adaptations to pregnancy is unknown. This study was designed to determine the effect of alcohol consumption on nitric oxide-mediated vascular function in mice during pregnancy. Female pregnant or nonpregnant C57BL/6J mice were fed a control diet or a liquid diet of 25% ethanol-derived calories for 13 days (from gestational days 6-18). Phenylephrine vasoconstriction was blunted in pregnancy compared with the nonpregnant state due to enhanced nitric oxide modulation, which was impaired by ethanol exposure. Although the EC50 and maximal responses to methacholine were not different in nonpregnant vs. pregnant mice, the nitric oxide component to methacholine-induced vasorelaxation was greater in the pregnant mice. Interestingly, alcohol affected only the pregnant animals in their response to methacholine. These data indicate that alcohol reduced the nitric oxide modulation of vascular response, which was more pronounced during pregnancy. These studies provide novel information regarding the effects of alcohol on the maternal vascular system during pregnancy and thereby contribute to further understanding of the adverse effects associated with prenatal alcohol exposure.

Alcohol tolerance and nicotine cross-tolerance in adolescent mice

The present experiment was designed to evaluate the development of tolerance to alcohol and cross-tolerance to nicotine in adolescent mice. C57BL/6J mice (30-40 days old) were injected IP with alcohol (2.5 g/kg) for 4 consecutive days. A control group received four saline injections. On the test day, all subjects received an alcohol injection. Tolerance to alcohol's hypothermic effect was observed. Mice (male and female) exposed to alcohol for the 4 previous days showed less hypothermic response to an alcohol challenge than animals injected for 4 days with saline and then challenged with alcohol. Tolerance to alcohol's motor incoordinating effects and differences in blood alcohol concentrations were not observed. Thirty days following alcohol treatment, the same mice received a single nicotine injection (1 mg/kg) to assess cross-tolerance. Nicotine's effect on locomotor activity (open field test) and rectal temperature varied as a function of prior adolescent alcohol exposure and gender. Specifically, female mice who had been exposed to alcohol administrations were more resistant to nicotine's effect on locomotion and temperature than saline-treated animals. In summary, these data demonstrate that adolescent mice develop tolerance to some, but not all, alcohol-induced responses, and that female mice are cross-tolerant to nicotine's effects on temperature and activity.

Effect of ethanol on thromboxane and prostacyclin production in the human placenta

Fetal alcohol syndrome (FAS) is frequently associated with intrauterine growth retardation (IUGR). One cause of ethanol-induced IUGR is thought to be related to increased pressor activity in the human placenta, resulting in decreased oxygenation and nutrient transport to the fetus. Thus, we have investigated the effect of ethanol on paracrine substances, such as thromboxane and prostacyclin, that act as vasoregulators within the intrauterine tissues. In these studies we have utilized the perfused single human cotyledon system to study the effect of ethanol on placental prostanoid production. We assessed the effect of longer (240 min) and more acute (60 min) exposure to ethanol on release of thromboxane B(2) (TxB(2)) and 6-keto-prostaglandin F(1 alpha) (6-keto-PGF(1 alpha)) at the maternal and fetal sides of the placenta. Thromboxane was increased by both longer and shorter ethanol exposure, especially on the fetal side of the placenta. Prostacyclin was essentially unchanged with exposure to ethanol. The thromboxane:prostacyclin ratio also tended to increase with both 60- and 240-min ethanol exposure, but a statistically significant increase was seen only at a few time points. In the 60-min ethanol exposure, an increase in thromboxane was observed both during and following exposure to ethanol. The increase in the thromboxane milieu observed with ethanol exposure may lead, at least in part, to the IUGR which is frequently associated with FAS. Prevention of this effect of ethanol on thromboxane production might be a beneficial intervention for FAS.

Ethanol and parturition: a role for prostaglandins

A common pattern of birth defects was reported in children born to alcoholic women over 20 years ago. Shortly thereafter the constellation of defects became known as the Fetal Alcohol Syndrome, and reports from around the world served to acknowledge the pervasiveness of the disorder. Simultaneously with the clinical reports, animal models were developed to characterize the full spectrum of the teratogenic effects of ethanol. Not only did these animal models serve to define the actions of ethanol on fetal growth and development at the molecular pharmacological, neuroanatomical, and behavioral level, but unintentionally, they have resulted in renewed scientific interest in the effects of ethanol on pregnancy and parturition itself. The purpose of this review is twofold. First we will consolidate and summarize data from both clinical and basic research that pertains to ethanol and parturition. These data will demonstrate that ethanol consumption during pregnancy results in both delayed as well as premature delivery depending upon the pattern of consumption and timing of exposure. With these data as a background, the second objective will be to present a theoretical case for prostaglandins as possible mediators of ethanol-induced effects on the onset of parturition.