The Effect of Prenatal Alcohol Exposure on Fetal Growth and Cardiovascular Parameters in a Baboon Model of Pregnancy

Associations between prenatal alcohol and tobacco exposure on Doppler flow velocity waveforms in pregnancy: a South African study

BACKGROUND

The negative impact of prenatal alcohol and tobacco exposure (PAE and PTE) on fetal development and birth outcomes are well described, yet pathophysiologic mechanisms are less clear. Our aim was to investigate (1) the associations between quantity, frequency and timing (QFT) of PAE and PTE with blood flow velocities in arteries of the fetal-placental-maternal circulation and (2) the extent to which combined effect of QFT of PAE and/or PTE and Doppler flow velocity waveforms (FWV) predict infant birth weight.

METHODS

The Safe Passage Study is a cohort based in urban Cape Town, South Africa. Recruitment occurred between 2007 and 2015. Information on QFT of PAE and PTE was collected prospectively at up to 4 occasions during pregnancy using a modified Timeline Follow-Back approach. Ultrasound examinations consisted of Doppler flow velocity waveforms of the uterine, umbilical (UA) and fetal middle cerebral arteries for the pulsatility index (PI) at 20-24 and 34-38 weeks. Exclusion criteria included: twin pregnancies, stillbirths, participants exposed to other drugs. The sample was divided into three groups (controls, PAE and PTE) and included 1396 maternal-fetal-dyads assessed during the second trimester; 1398 assessed during the third trimester.

RESULTS

PTE was associated with higher UA PI values in second and third trimesters (p < 0.001), compared to the PAE and control group. The total amount of cigarettes smoked during pregnancy was positively correlated with UA PI values (r = 0.087, p < 0.001). There was a positive correlation between cigarettes smoked per day in trimester one (r = 0.091, p < 0.01), and trimester two (r = 0.075, p < 0.01) and UA PI (in trimester two), as well as cigarettes smoked per day in trimester two (r = 0.058, p < 0.05) and trimester three (r = 0.069, p < 0.05) and the UA PI in trimester three. Generalized additive models indicated that PAE in trimester two, PTE in trimester one and Doppler FWV in trimester three were significant predictors of birth weight in this sample.

CONCLUSION

In our study, PTE in trimesters two and three resulted in increased vascular resistance of the placenta. These findings highlight nuance in associations between PAE, PTE and blood flow velocities in arteries of the fetal-placental-maternal circulation and birth weight, suggesting that quantity and timing are important factors in these relationships.

Vascular Effects, Potential Pathways and Mediators of Fetal Exposure to Alcohol and Cigarette Smoking during Pregnancy: A Narrative Review

(1) Background: Programming of atherosclerosis results in vascular structure and function alterations, which may be attributed to fetal exposure to maternal tobacco smoking, alcohol consumption and several lifestyle factors in the first few years of life. This review aims to study the effects of teratogen exposure in utero on vascular dysfunction in offspring and consider mediators and pathways originating from the fetal environment. (2) Methods: Eligible studies were identified in the PubMed, Scopus and Web of Science databases. After the full-text screening, 20 articles were included in the narrative synthesis. (3) Results: The literature presents evidence supporting the detrimental effects of fetal exposure to tobacco smoking on vascular alterations in both human and animal studies. Alcohol exposure impaired endothelial dilation in animal studies, but human studies on both tobacco and alcohol exposure are still sparse. Reduction in nitric oxide (NO) bioavailability and alterations in the epigenome in infants through the upregulation of pro-oxidative and proinflammatory genes may be the common denominators. (4) Conclusion: While maternal smoking and alcohol consumption have more negative outcomes on the infant in the short term, several factors during the first few years of life may mediate the development of vascular dysfunction. Therefore, more prospective studies are needed to ascertain the long-term effects of teratogen exposure, specifically in South Africa.

Path analysis of the impact of prenatal alcohol on adult vascular function

BACKGROUND

The vascular system may be particularly vulnerable to prenatal alcohol exposure (PAE). Alterations in angiogenesis and epigenetic changes to vascular development have been implicated as a probable mechanism for this vulnerability.

METHODS

We assessed the long-term impact of prenatal alcohol exposure (PAE) on adult vascular health using a prospective cohort first identified while in utero. Participants with no PAE (n = 37, mean age = 36.7 [SD = 1.6] years) were compared to participants with PAE (n = 51, mean age = 36.3 [SD = 1.7] years). Their vascular health was assessed by arterial blood pressure (BP) and peripheral arterial tonometry, which yields an index of endothelial function (reactive hyperemia index) and a measure of arterial stiffness (augmentation index). Blood samples were collected to assess cholesterol levels and insulin resistance (glucose, hemoglobin A1C, and insulin). Path analysis was used to examine the direct and indirect effects of PAE on vascular health after adjusting for other known physical outcomes.

RESULTS

Participants with a history of PAE weighed less, trended towards being shorter, had smaller body mass, and had more alcohol-related dysmorphic features than those without PAE. Path analysis suggested that the impact of PAE on BP was through its indirect relationships with height, body mass index, and dysmorphic features and resulted in protective effects relative to the Contrast group who were disproportionately overweight. PAE was also found to have a direct negative effect on endothelial function. An index of total alcohol-related dysmorphic features was negatively had both a direct effect on arterial stiffness and an indirect effect on endothelial function.

CONCLUSIONS

Prenatal alcohol exposures' impact on vascular function is not independent of other common physical and environmental factors but endothelial function and arterial stiffness seemed most compromised after controlling for these other factors. Level of alcohol-related dysmorphic features seems to be predictive of more adverse effects than endothelial function and vascular stiffness.

Vascular Contributions to the Neurobiological Effects of Prenatal Alcohol Exposure

Fetal alcohol spectrum disorders (FASD) are often characterized as a cluster of brain-based disabilities. Though cardiovascular effects of prenatal alcohol exposure (PAE) have been documented, the vascular deficits due to PAE are less understood, but may contribute substantially to the severity of neurobehavioral presentation and health outcomes in persons with FASD.

Methods

We conducted a systematic review of research articles curated in PubMed to assess the strength of the research on vascular effects of PAE. 40 pertinent papers were selected, covering studies in both human populations and animal models.

Results

Studies in human populations identified cardiac defects, and defects in vasculature, including increased tortuosity, defects in basement membranes, capillary basal hyperplasia, endarteritis, and disorganized and diminished cerebral vasculature due to PAE. Preclinical studies showed that PAE rapidly and persistently results in vasodilation of large afferent cerebral arteries, but to vasoconstriction of smaller cerebral arteries and microvasculature. Moreover, PAE continues to affect cerebral blood flow into middle-age. Human and animal studies also indicate that ocular vascular parameters may have diagnostic and predictive value. A number of intervening mechanisms were identified, including increased autophagy, inflammation and deficits in mitochondria. Studies in animals identified persistent changes in blood flow and vascular density associated with endocannabinoid, prostacyclin and nitric oxide signaling, as well as calcium mobilization.

Conclusion

Although the brain has been a particular focus of studies on PAE, the cardiovascular system is equally affected. Studies in human populations, though constrained by small sample sizes, did link pathology in major blood vessels and tissue vasculature, including brain vasculature, to PAE. Animal studies highlighted molecular mechanisms that may be useful therapeutic targets. Collectively, these studies suggest that vascular pathology is a possible contributing factor to neurobehavioral and health problems across a lifespan in persons with a diagnosis of FASD. Furthermore, ocular vasculature may serve as a biomarker for neurovascular health in FASD.

Prenatal exposure to alcohol: mechanisms of cerebral vascular damage and lifelong consequences

Alcohol is a well-known teratogen, and prenatal alcohol exposure (PAE) leads to a greater incidence of many cardiovascular-related pathologies. Alcohol negatively impacts vasculogenesis and angiogenesis in the developing fetal brain, resulting in fetal alcohol spectrum disorders (FASD). Ample preclinical evidence indicates that the normal reactivity of cerebral resistance arterioles, which regulate blood flow distribution in response to metabolic demand (neurovascular coupling), is impaired by PAE. This impairment of dilation of cerebral arteries may carry implications for the susceptibility of the brain to cerebral ischemic damage well into adulthood. The focus of this review is to consolidate findings from studies examining the influence of PAE on vascular development, give insights into relevant pathological mechanisms at the vascular level, evaluate the risks of ethanol-driven alterations of cerebrovascular reactivity, and revisit different preventive interventions that may have promise in reversing vascular changes in preclinical FASD models.

Supplementation with sodium butyrate protects against antibiotic-induced increases in ethanol consumption behavior in mice

BACKGROUND

We have recently reported that oral treatment of adult male C57BL/6J mice with a non-absorbable antibiotic cocktail resulted in an increase in ethanol intake and in significant reductions in butyrate-producing gut microbiota populations. This work led us to hypothesize that reduction in butyrate levels within the gut is linked to antibiotic-induced increases in voluntary ethanol consumption.

OBJECTIVE

This study tested whether ad libitum sodium butyrate supplementation can prevent antibiotic-induced ethanol consumption in mice.

METHODS

Sodium butyrate was provided to adult male C57BL/6J mice in drinking water alone or in combination with antibiotic cocktail. Effects on ethanol (20%) intake were measured using drinking in the dark and modified 2-bottle choice paradigms. Body parameters, food and liquid intake, cecum, and adipose tissues were measured during and/or at the conclusion of the drinking in the dark study. Cecal 16s rRNA was analyzed for microbiota diversity and changes in specific bacterial phyla/species.

RESULTS

In drinking in the dark, sodium butyrate supplementation prevented antibiotic-induced increases in ethanol intake without altering basal ethanol consumption. Furthermore, sodium butyrate supplementation lowered ethanol preference in the 2-bottle choice study. Ethanol intake was correlated to specific bacterial phyla/species. Sodium butyrate did not affect the changes in microbiota diversity and composition induced by antibiotic cocktail.

CONCLUSIONS

The findings support a role of gut microbiota-derived butyrate in regulating alcohol-induced behaviors. Additionally, the work contributes to efforts in development of novel microbiome-based strategies as novel preventative and intervention-based therapeutics to address alcohol use disorder.

Effects of early daily alcohol exposure on placental function and fetal growth in a rhesus macaque model

BACKGROUND

Prenatal alcohol exposure is the most common cause of birth defects and intellectual disabilities and can increase the risk of stillbirth and negatively impact fetal growth.

OBJECTIVE

To determine the effect of early prenatal alcohol exposure on nonhuman primate placental function and fetal growth. We hypothesized that early chronic prenatal alcohol would alter placental perfusion and oxygen availability that adversely affects fetal growth.

STUDY DESIGN

Rhesus macaques self-administered 1.5 g/kg/d of ethanol (n=12) or isocaloric maltose-dextrin (n=12) daily before conception through the first 60 days of gestation (term is approximately 168 days). All animals were serially imaged with Doppler ultrasound to measure fetal biometry, uterine artery volume blood flow, and placental volume blood flow. Following Doppler ultrasound, all animals underwent both blood oxygenation level-dependent magnetic resonance imaging to characterize placental blood oxygenation and dynamic contrast-enhanced magnetic resonance imaging to quantify maternal placental perfusion. Animals were delivered by cesarean delivery for placental collection and fetal necropsy at gestational days 85 (n=8), 110 (n=8), or 135 (n=8). Histologic and RNA-sequencing analyses were performed on collected placental tissue.

RESULTS

Placental volume blood flow was decreased at all gestational time points in ethanol-exposed vs control animals, but most significantly at gestational day 110 by Doppler ultrasound (P<.05). A significant decrease in total volumetric blood flow occurred in ethanol-exposed vs control animals on dynamic contrast-enhanced magnetic resonance imaging at both gestation days 110 and 135 (P<.05); moreover, a global reduction in T₂∗, high blood deoxyhemoglobin concentration, occurred throughout gestation (P<.05). Similarly, evidence of placental ischemic injury was notable by histologic analysis, which revealed a significant increase in microscopic infarctions in ethanol-exposed, not control, animals, largely present at middle to late gestation. Fetal biometry and weight were decreased in ethanol-exposed vs control animals, but the decrease was not significant. Analysis with RNA sequencing suggested the involvement of the inflammatory and extracellular matrix response pathways.

CONCLUSION

Early chronic prenatal alcohol exposure significantly diminished placental perfusion at mid to late gestation and also significantly decreased the oxygen supply to the fetal vasculature throughout pregnancy, these findings were associated with the presence of microscopic placental infarctions in the nonhuman primate. Although placental adaptations may compensate for early environmental perturbations to fetal growth, placental blood flow and oxygenation were reduced, consistent with the evidence of placental ischemic injury.

Alcohol use in pregnancy and its impact on the mother and child

AIMS

To review the impact of prenatal alcohol exposure on the outcomes of the mother and child.

DESIGN

Narrative review.

SETTING

Review of literature.

PARTICIPANTS

Mothers and infants affected by prenatal alcohol use.

MEASUREMENTS

Outcomes of mothers and children.

FINDINGS

Prenatal alcohol exposure is one of the most important causes of preventable cognitive impairment in the world. The developing neurological system is exquisitely sensitive to harm from alcohol and there is now also substantial evidence that alcohol-related harm can extend beyond the individual person, leading to epigenetic changes and intergenerational vulnerability and disadvantage. There is no known safe level or timing of drinking for pregnant or lactating women and binge drinking (> four drinks within 2 hours for women) is the most harmful. Alcohol-exposure increases the risk of congenital problems, including Fetal Alcohol Spectrum Disorder (FASD) and its most severe form, Fetal Alcohol Syndrome (FAS).

CONCLUSION

The impact of FASD and FAS is enduring and life-long with no current treatment or cure. Emerging therapeutic options may mitigate the worst impact of alcohol exposure but significant knowledge gaps remain. This review discusses the history, epidemiology and clinical presentations of prenatal alcohol exposure, focusing on FASD and FAS, and the impact of evidence on future research, practice and policy directions.

Management of the Cardiovascular Complications of Substance Use Disorders During Pregnancy

PURPOSE OF REVIEW

Substance use disorder in pregnancy and subsequent cardiovascular complications are on the rise in the USA. The care of pregnant women with substance use disorder is complex, and requires a thorough understanding of mechanisms of action, pathophysiology, and cardiovascular response during pregnancy. The goal of this review is to provide information about the most common drugs of abuse in pregnancy and to recommend management guidelines.

RECENT FINDINGS

Pregnant women with substance use disorder are at increased risk of significant cardiovascular complications, both as a direct effect of acute intoxication as well as the secondary risk from infection and cardiotoxicity associated with chronic use. This risk must be considered in the antepartum management, delivery, and postpartum periods. Understanding the increased cardiovascular risk of pregnant women with substance use disorder, as well as specific drug interactions, anesthesia considerations, best practices, and management considerations, is important for all clinicians caring for this population.

Ethanol exposure in prenatal and early postnatal induced cardiac injury in rats: involvement of oxidative stress, Hsp70, ERK 1/2, JNK, and apoptosis in a 3-month follow-up study

Alcohol exposure during pregnancy induces a wide range of structural and functional abnormalities in the fetal heart. However, the underlying mechanism of this phenomenon is not well known. This study was undertaken to elucidate probable mechanisms of myocardial damage induced by prenatal and early postnatal ethanol treatment. Pregnant Wistar rats received ethanol 4.5 g/kg BW once per day from the seventh day of gestation (GD7) throughout lactation. The oxidative stress injury of the myocardium in pups was evaluated by measuring levels of oxidative stress biomarkers. Histopathological examinations and Western blot were performed to evaluate histological features, apoptosis, and molecular alterations in the myocardial tissue of male pups on the postnatal day 21 (PN-21) and postnatal day 90 (PN-90). The results showed that maternal ethanol consumption caused oxidative stress (impaired total antioxidant capacity and malondialdehyde), histological changes, and apoptosis of the myocardium in the pups on PN-21 and PN-90. At the molecular levels, Western blot analysis revealed that ethanol modulated the protein expression of p-ERK1/2, p-JNK, and Hsp70 in the myocardial tissue of the pups after 21 and 90 days of birth compared with the controls. These findings revealed that maternal ethanol intake induced cardiac toxicity in part, mediated by oxidative stress and apoptosis in the pups. A further mechanism study revealed that ethanol enhanced ERK1/2 and JNK phosphorylation and Hsp70 protein expression.

Fetal Cerebral Artery Mitochondrion as Target of Prenatal Alcohol Exposure

Prenatal alcohol exposure results in an array of developmental abnormalities known as fetal alcohol spectrum disorders (FASDs). Despite the high prevalence of FASDs, therapeutic interventions against accidental or intended exposure of developing fetuses to alcohol are limited. This review outlines current knowledge about mitochondria in cerebral blood vessels as a potential target for anti-FASDs intervention. First, it describes the multifaceted role of mitochondria in maintaining the cerebral artery diameter as shown in adult tissue. Second, current literature on alcohol-driven damage of mitochondrial morphology and function in several fetal tissues, including liver, heart, and brain is summarized. The functional consequences of alcohol exposure in these organs include morphological enlargement of mitochondria, increased oxidative stress, and alteration of cellular respiration. These studies point to a tissue-specific effect of alcohol on mitochondrial function and a particular vulnerability of fetal mitochondria to alcohol exposure when compared to adult counterparts. Third, recent work from our group describing persistent changes in fetal baboon cerebral artery proteome following three episodes of prenatal alcohol exposure is reviewed. In conclusion, the consequences of prenatal alcohol exposure on cerebral artery mitochondria constitute an open field of investigation and, eventually, a point of therapeutic intervention against FASDs.

Proteomic Analysis of Baboon Cerebral Artery Reveals Potential Pathways of Damage by Prenatal Alcohol Exposure

Alcohol is one of the most widely misused substances in the world. Alcohol consumption by pregnant women often results in an array of fetal developmental abnormalities, but the damage to the fetus by alcohol remains poorly understood. The limited knowledge regarding the molecular targets of alcohol in the developing fetus constitutes one of the major obstacles in developing effective pharmacological interventions that could prevent fetal damage after alcohol consumption by pregnant women. The fetal cerebral artery is emerging as an important mediator of fetal cerebral damage by maternal alcohol drinking. In the present work, we conduct proteomics analysis of cerebral (basilar) artery lysates of near-term fetal baboons to search for protein targets of fetal alcohol exposure. Our study demonstrates that 3 episodes of binge alcohol exposure during the second trimester-equivalent of human pregnancy are sufficient to render profound changes in fetal cerebral artery proteome. These changes persisted, as they were detected in near-term fetuses. In particular, the relative abundance of 238 proteins differed significantly between control and alcohol-exposed fetuses. Enrichment analysis pointed at the group of metabolic activity proteins as a major class targeted by alcohol. Western blotting confirmed upregulation of the aldehyde dehydrogenase 6 family member A1 (ALDH6A1) in cerebral artery lysates from alcohol-exposed fetuses. This upregulation translated to greater ALDH activity of cerebral artery lysate of near-term fetuses following prenatal alcohol exposure when compared with controls.

Gestational Age-Dependent Interplay between Endocannabinoid Receptors and Alcohol in Fetal Cerebral Arteries

Alcohol (ethanol) is one of the most widely consumed drugs. Alcohol consumption by pregnant women may result in a range of fetal abnormalities termed fetal alcohol spectrum disorders (FASDs). The cerebrovascular system is emerging as a critical target of alcohol in the developing brain. We recently showed that three episodes of prenatal alcohol exposure resulting in 80 mg/dL alcohol in maternal blood during mid-pregnancy up-regulated anandamide-induced dilation of fetal cerebral arteries. Moreover, ethanol dilated fetal cerebral arteries via cannabinoid (CB) receptors. Whether a critical role of fetal cerebral artery CB system in responses to alcohol was maintained throughout the gestation, remains unknow.

MAIN METHODS

Pregnant baboons (second trimester equivalent) were subjected to three episodes of either alcohol or control drink infusion via gavage. Cerebral arteries from mothers and near-term female fetuses were in vitro pressurized for diameter monitoring.

KEY FINDINGS

Near-term fetal and maternal arteries exhibited similar ability to develop myogenic tone, to constrict in presence of 60 mM KCl, and to respond to 10 µM anandamide. Fetal and maternal arteries largely failed to dilate in presence of 63 mM ethanol. No differences were detected between arteries from control and alcohol-exposed baboon donors. Therefore, previously observed ethanol-induced dilation of fetal cerebral arteries and up-regulation of CB components in response to fetal alcohol exposure during mid-pregnancy was transient and disappeared by near-term.

Physiology of the Endocannabinoid System During Development

The endocannabinoid (eCB) system comprises endogenously produced cannabinoids (CBs), enzymes of their production and degradation, and CB-sensing receptors and transporters. The eCB system plays a critical role in virtually all stages of animal development. Studies on eCB system components and their physiological role have gained increasing attention with the rising legalization and medical use of marijuana products. The latter represent exogenous interventions that target the eCB system. This chapter summarizes knowledge in the field of CB contribution to gametogenesis, fertilization, embryo implantation, fetal development, birth, and adolescence-equivalent periods of ontogenesis. The material is complemented by the overview of data from our laboratory documenting the functional presence of the eCB system within cerebral arteries of baboons at different stages of development.

Prenatal Alcohol Exposure, Anesthesia, and Fetal Loss in Baboon Model of Pregnancy

Approximately half of pregnant women engage in alcohol consumption some time during pregnancy. On the other hand, a small percentage of pregnant women undergo surgery and anesthesia at some time during pregnancy. In emergencies, anesthesia has to be administered to patients who are under alcohol intoxication. Anesthetic management during pregnancy while patients are intoxicated with alcohol is challenging. Here, we utilized a retrospective analysis of data available from 17 pregnant baboons that underwent anesthesia with alcohol exposure during mid-pregnancy. The analysis was designed to answer three questions: whether maternal vital signs remained stable under anesthesia combined with alcohol, whether maternal vital signs that were routinely monitored under anesthesia could serve as predictor(s) of fetal loss, and what the impact of the combined application of anesthesia and alcohol was on fetal loss. For the purpose of this retrospective analysis, we utilized vital sign (heart and respiratory rates, temperature, oxygen, carbon dioxide, systolic and diastolic blood pressure) and pregnancy outcome (miscarriage versus fetal survival through second trimester-equivalent of human pregnancy) records from 17 pregnant baboons that underwent gastric infusion of either control or alcohol-containing drink under isoflurane anesthesia during the second trimester-equivalent of human pregnancy. Half of the dams underwent a brief prior anesthetic episode for the purpose of gestational age confirmation. Thus, in our analysis, baboons were divided into four groups: "Control" without prior anesthesia, "Control" with prior anesthesia, "Alcohol" without prior anesthesia, and "Alcohol" with prior anesthesia. We did not detect any maternal vital sign in any of the groups that would be predictive of a fetal loss. However, prior anesthesia predisposed dams to the risk of lowering maternal systolic blood pressure and to a significant decrease in maternal oxygen level during the combined application of anesthesia and alcohol. Conceivably, our data showed the largest fetal loss in this group. The disruptive nature of anesthesia and alcohol on maternal vital parameters warns against the use of anesthesia in combination with alcohol during pregnancy.

Fetal Cerebral Circulation as Target of Maternal Alcohol Consumption

Alcohol (ethanol [EtOH]) is one of the most widely used psychoactive substances worldwide. Alcohol consumption during pregnancy may result in a wide range of morphological and neurodevelopmental abnormalities termed fetal alcohol spectrum disorders (FASD), with the most severe cases diagnosed as fetal alcohol syndrome (FAS). FAS and FASD are not readily curable and currently represent the leading preventable causes of birth defect and neurodevelopmental delay in the United States. The etiology of FAS/FASD remains poorly understood. This review focuses on the effects of prenatal alcohol exposure (PAE) on fetal cerebrovascular function. A brief introduction to the epidemiology of alcohol consumption and the developmental characteristics of fetal cerebral circulation is followed by several sections that discuss current evidence documenting alcohol-driven alterations of fetal cerebral blood flow, artery function, and microvessel networks. The material offers mechanistic insights at the vascular level itself into the pathophysiology of PAE.