Maternal Ethanol Research Articles

Maternal ethanol ingestion and somatostatin level and binding in developing rat brain

The effect of maternal ethanol ingestion on 125I-labeled [Tyr11]somatostatin (SS) binding and somatostatin-like immunoreactivity (SLI) in the rat frontoparietal cortex and hippocampus of developing offspring was explored. Female Sprague-Dawley rats were given ethanol in the drinking water before pregnancy, during gestation, and while nursing, whereas controls received a standard diet and fresh water ad libitum. In the ethanol group, food intake decreased as ethanol consumption augmented, with the ethanol calories comprising greater than 30% of the total energy intake during pregnancy. Total energy intake was similar for the ethanol group and normal controls. Maternal alcohol ingestion is associated with an enhanced SLI level in the frontoparietal cortex and hippocampus on the day of birth. This study provided evidence of a selective decrease in SS receptor binding in frontoparietal cortex but not in hippocampus in the 0- to 10-day-old offspring of the ethanol-fed rats. The SS receptor number increased from day 0 to 10 in both control and ethanol groups. However, the affinity appeared to decrease significantly in the ethanol group during this period. At day 30, no differences were found between offspring of control and ethanol-treated rats in any of the parameters. These results suggest that the development of SS receptors in the rat frontoparietal cortex can be transitorily delayed by maternal ethanol ingestion.

The effects of maternal ethanol exposure on neurotransmission and second messenger systems: a quantitative autoradiographic study in the rat brain

The effects of maternal ethanol exposure on neurotransmission and second messenger systems were examined in rats using histochemistry and in vitro autoradiography. Thirty % ethanol was administered to pregnant rats from gestational day 7 to the day of delivery. Quantitative autoradiography was used to map muscarinic cholinergic, dopamine D 2, adenosine A 1 and inositol 1,4,5-trisphosphate binding sites, as well as to localize adenylate cyclase and protein kinase C. We found no difference in the patterns of staining with acetylcholinesterase and Timm's stain between control and prenatally ethanol-exposed rats on postnatal day (PN) 30. In the ethanol-exposed rats, [ 3H]forskolin binding sites were increased during early development in the CA1 subfield of the hippocampus and the occipital cortex; [ 3H]phorbol ester binding sites were increased in the cortex, striatum, and hippocampus; hippocampal muscarinic cholinergic sites were increased on PN4 and 30; adenosine A 1 binding was reduced on PN10 in most regions examined, but was increased in the CA1 subfield on PN30; dopamine D 2 receptor levels were significantly reduced on PN30 in the striatum; and IP 3 receptors were decreased in most regions studied, but particularly in the cerebellum. Thus, some of these changes were transient and others were long-lasting. Although histophathological abnormalities were minimal, the alterations of binding sites in the cerebellum (the coordination center) and in the hippocampus (related to memory and learning) that were detected may contribute to the behavioral and mental deterioration seen in the fetal alcohol syndrome.

Pathogenesis of ethanol‐induced hydronephrosis and hydroureter as demonstrated following in vivo exposure of mouse embryos

Urinary tract abnormalities have been noted to occur in 10-27% of individuals diagnosed as having Fetal Alcohol Syndrome. Among a wide range of functional and structural abnormalities, renal agenesis/hypoplasia, hydronephrosis, and ureteropelvic obstruction feature most prominently. This study was designed to examine the pathogenesis of ethanol-induced urinary tract abnormalities in a mouse model. C57Bl/6J mice were acutely exposed to two doses of ethanol (2.9 g/kg IP) administered 4 hours apart beginning on gestational day (GD) 9, hour 4. This resulted in an incidence of 40.7% urinary tract anomalies among GD18 fetuses. With the exception of duplicate ureter, urinary tract abnormalities consisted exclusively of hydroureter/hydronephrosis. Examination of GD13-17 fetuses revealed that the first grossly detectable differences in the urinary tracts of control vs. affected specimens occurred on GD16 and initially only involved ureteral changes. Hydronephrosis was first detected on GD17. A contributing factor to the development of hydronephrosis appears to be the abnormal location of the ureterovesicle junction which commonly involves duplicate ureteral lumens with resultant functional obstruction to urine flow at the distal end of the ureter. Study of the early pathogenetic changes which appear to result in the urinary tract malformations observed involved utilization of scanning electron microscopy, vital dye (Nile blue sulphate) staining of whole embryos, and analysis of histological sections. These studies revealed that 12 hours following initial maternal ethanol exposure, embryos have excessive amounts of cell death localized in the region of the developing mesonephric duct just proximal to the cloaca. Also affected were premigratory neural crest cells located just proximal to the posterior neuropore. We conclude that excessive amounts of ethanol-induced cell death in these selectively vulnerable populations could account for the subsequently observed urinary tract malformations.

Prenatal ethanol and the prepubertal sexually dimorphic nucleus of the preoptic area

The volume of the sexually dimorphic nucleus of the preoptic area of the hypothalamus (SDN-POA) was determined in 14–31-day-old male and female rats whose mothers received a liquid diet containing 5% w/v ethanol from day 8 of gestation to parturition. Pair-fed dams received as a nutritional control an equal volume of an isocaloric liquid diet with maltose-dextrin in place of ethanol. Normal controls had laboratory rat chow and water available ad lib. The SDN-POA volume of ethanol-exposed males was significantly reduced compared to the pair-fed and normal males, and became indistinguishable from the SDN-POA volumes of the pair-fed and normal females. Ethanol-treated females also had a markedly reduced SDN-POA volume compared to the pair-fed and normal females. Our findings indicate that the SDN-POA of prepubertal rats of both sexes is sensitive to the effects of in utero ethanol exposure. While plasma testosterone, progesterone and estradiol titers, which we measured in fetuses on gestation day 22, were differentially affected by maternal ethanol consumption, the alterations by themselves cannot adequately explain the effects of prenatal ethanol exposure on the developing SDN-POA.

Molecular Changes Associated with Ethanol‐Induced Growth Suppression in the Chick Embryo

In humans and in animal models the most frequently observed alcohol-related birth defect (ARBD) is intrauterine growth retardation (IUGR). The central nervous system (CNS) is sensitive to the growth inhibitory effects of in utero ethanol exposure and neonatal CNS alterations with associated behavioral deficits are a likely result of maternal ethanol consumption. Presently, little information exists as to the biochemical mechanism by which ethanol inhibits fetal CNS growth. Further, it is unknown if there are genetic differences in maternal or fetal responses to ethanol. Ongoing research using a chick model indicates that pharmacologically appropriate doses of ethanol (less than 30 mM) inhibit brain growth and reduce CNS 3',5'-cyclic adenosine monophosphate (cyclic AMP) with an associated 50% decrease in the binding of cyclic AMP by the regulatory subunit (RII) of protein kinase A. Furthermore, there is a specific loss of phosphorylation of RII by kinase catalytic subunit as a result of ethanol exposure. Because tissue cyclic AMP content and the degree of RII phosphorylation are important parameters for the regulation of protein kinase A catalytic activity, it is hypothesized that these alterations may be biochemical transformations that underlie ethanol-induced growth suppression.

The Effect of Maternal Ethanol Ingestion on Fetal Vitamin A in the Rat

The effect of maternal ethanol ingestion on fetal tissue vitamin A was investigated. Pregnant rats were pair-fed control diets or diets containing 36% of energy as ethanol. After 17 or 21 d gestation, fetuses were removed and fetal and maternal tissues were analyzed by HPLC for retinol and retinyl palmitate. Ethanol consumption resulted in fewer fetuses per pregnancy, increased number of resorptions, and increased numbers of gross fetal abnormalities. In maternal tissues, ethanol consumption resulted in greater lung and kidney vitamin A concentrations. In the fetuses of ethanol-consuming pregnancies, free retinol in liver was higher at d 17. However, fetal liver palmitate levels and total retinyl palmitate in liver, lung, and kidney were lower in ethanol-fed rats at d 21 of gestation. Fetal lung retinyl palmitate concentrations were greater at both d 17 and d 21, and kidney levels were also greater at d 21. In conclusion, the ingestion of ethanol by pregnant rats is associated with a reduction in fetal liver vitamin A levels and an elevation in the levels of lung and kidney vitamin A, indicating possible altered vitamin A metabolism as a result of ethanol consumption.

THE EFFECT OF MATERNAL ETHANOL INFUSION ON PLACENTAL BLOOD FLOW AND FETAL GLUCOSE METABOLISM IN SHEEP

Intravenous infusion of 1 g ethanol/min over 1 hr to seven catheterised pregnant ewes decreased blood flow on both sides of the placenta. The reductions in blood flow were maintained for at least 2 hr after the infusion of ethanol had ceased. Although blood flow was reduced, fetal blood gases were unchanged. Plasma glucose concentrations were unchanged by ethanol, but fetal glucose supply and consumption were both decreased following maternal ethanol infusions. If maintained by chronic alcohol consumption these changes could contribute to the growth retardation seen in the Fetal Alcohol Syndrome.

Lower Serum Thyroxine Levels in Rats following Prenatal Exposure to Ethanol

Fetal alcohol syndrome (FAS) is noted for poor growth, developmental delays, and mental retardation. In animals, prenatal alcohol exposure alters anatomical, physiological, and neurochemical maturation and produces behavioral changes similar to those in children. Since thyroid hormones are critical trophic factors for normal somatic and neural maturation, and since fetal thyroid hormones are profoundly affected by acute maternal ethanol administration, we hypothesized that postnatal effects of prenatal alcohol exposure may be related to abnormal thyroid hormone development. We report here that young rats exposed to alcohol in utero have significantly lower serum total thyroxine (T4) concentrations than normal and pair-fed control rats. The results suggest prenatal ethanol exposure may compromise thyroid development in ways not attributable to undernutrition or developmental delays alone. Lowered total T4 levels may be a teratogenic outcome of prenatal alcohol exposure, which could contribute to impaired growth, altered neural organization, and behavioral dysfunction.

Gestational Ethanol Consumption on Tissue Amino Acid Levels: Decreased Free Histidine and Tryptophan in Fetal Tissues with Concomitant Increase in Urinary Histamine Excretion

The effects of ethanol consumption during pregnancy on maternal, placental, and fetal tissue amino acid levels and metabolism were investigated. Pregnant Sprague-Dawley rats were given 35% ethanol-calorie liquid diet, ad libitum, from gestation day 7 to 21. Control rats were pair-fed with isocaloric sucrose substituted for ethanol. Ethanol consumption decreased fetal body weight and increased placental weight. Twenty-four amino acids were determined in six tissues (maternal plasma and liver, placenta, fetal plasma, liver, and brain) by HPLC with orthophthalaldehyde derivatization. The effects of ethanol on free amino acid levels differed from tissue to tissue. In general, ethanol affected more amino acids in maternal plasma, fetal plasma, and liver. Maternal liver, placenta, and fetal brain amino acids were more resistant to ethanol effect. Two essential amino acids, histidine and tryptophan, were consistently decreased in fetal tissues by maternal ethanol consumption. The values (ethanol vs. control, nmole/ml or g, mean +/- SEM, N = 20) of fetal plasma, liver, and brain for histidine were 51.8 +/- 6.0 vs. 85.3 +/- 4.5 (p = 0.001), 269.0 +/- 26.4 vs. 503.7 +/- 47.3 (p = 0.0004), and 117.9 +/- 7.7 vs. 154.6 +/- 8.7 (p = 0.0055), respectively; and for tryptophan were 105.7 +/- 3.1 vs. 132.2 +/- 4.1 (p = 0.0001), 128.8 +/- 3.7 vs. 144.3 +/- 6.0 (p = 0.0407), and 83.4 +/- 7.2 vs. 103.6 +/- 3.2 (p = 0.0198), respectively. Histidine was also decreased in placenta by ethanol (138.1 +/- 6.6 vs. 189.1 +/- 11.8 nmole/g, p = 0.0014).(ABSTRACT TRUNCATED AT 250 WORDS)

Development of neurotransmitter systems in the mouse embryo following acute ethanol exposure: A histological and immunocytochemical study

Acute maternal ethanol administration to C57B1/6J mice on gestational day 7 (GD7) results in facial and brain abnormalities similar to those reported in human fetal alcohol syndrome (FAS). Using this model, we assessed the damage to brain structures using histological methods and changes in developing neurotransmitter systems with immunocytochemistry. Cholinergic neurons in the forebrain were stained with a monoclonal antibody to choline acetyltransferase (ChAT). Catecholaminergic neurons in the midbrain and serotoninergic neurons in the hindbrain were stained with polyclonal antisera to tyrosine hydroxylase (TH) and serotonin (5-HT), respectively. Forebrain deficiencies, including loss of midline structures (olfactory bulbs, midline septation, medial septal area) and deficits in lateral and dorsal regions (neostriatum and cerebral cortex) were found in both GD14 embryos and GD18 fetuses. In severely affected offspring, complete loss of the septal region resulted in conjoined lateral ventricles and a reduction in the thickness of the ventricular zone surrounding the single ventricle, as well as a severe loss of ChAT neurons which would normally be located in this territory. However, no consistent changes were seen in the distribution or size of TH or 5-HT neuronal cell groups in the midbrain and hindbrain. These differences in effects on specific neurotransmitter systems reflect the fact that the forebrain is most severely affected by early ethanol administration, whereas the hindbrain is relatively spared. Such differential effects could produce an imbalance in developing neurotransmitter systems in the embryonic and fetal brain, which could explain some of the functional deficits observed in children with FAS.

Morphometric analysis of developing rat cerebral cortex following acute prenatal ethanol exposure

Morphologic alterations of fetal rat cerebral cortex were quantified by morphometric analysis following acute ethanol exposure on Gestational Day 14, a critical period of development of cerebral cortex. Pregnant rats were intubated with a total dose of 9 g/kg of ethanol on Gestational Day 14. Maternal blood ethanol levels ranged from 51 to 202 mg% during the period of ethanol exposure. Fetal brains were examined on Gestational Day 15, 24 h after the last dose of ethanol. The acute morphologic changes associated with ethanol exposure include enlargement of subventricular zone nuclei, cortical swelling, and dilation of pial blood vessels over the affected cortex. In some fetuses, cortical swelling was accompanied by the protrusion into the lateral ventricles of cytoplasmic blebs of ventricular zone cells. It is concluded that maternal ethanol exposure during a critical period of brain development produces measurable morphologic changes in fetal rat cerebral cortex within 24 h after ethanol exposure.

Changes in red nucleus neuronal development following maternal alcohol exposure.

The red nucleus of Swiss Webster mouse fetuses was examined for morphological changes following maternal ethanol exposure. Pregnant females were given a liquid diet containing 30% or 0% ethanol-derived calories. Changes in numerical density of neurons and in neuronal nuclear volume were found in the rostral red (RR) nucleus of ethanol-exposed pups but not in the caudal red (CR) nucleus. Because of the integrative nature of the RR, changes in neuronal morphology that might relate to synaptic connections could affect the behavioral response mechanisms of these offspring.

Effect of acute, multiple-dose ethanol on maternal and fetal blood gases and acid–base balance in the near-term pregnant ewe

The effect of ethanol on maternal and fetal blood gases and acid-base balance was determined in six conscious instrumented near-term pregnant ewes for maternal intravenous infusion of 3 g ethanol/kg total body weight administered as six doses of 0.5 g ethanol/kg total body weight over 8 h. Maternal and fetal blood ethanol concentrations, determined in two animals, were maximal at 8 h (3.74 and 3.82 mg/mL, respectively) and were virtually identical during the 24-h study. Maternal and fetal blood gases and acid-base balance were not significantly altered during and after ethanol administration compared with preinfusion values. The data demonstrate that, during near-term ovine pregnancy, the equivalent of a binge-type drinking episode does not produce fetal hypoxia or acidosis. Furthermore, these data do not support the postulated involvement of ethanol-induced fetal hypoxia in the mechanism of ethanol teratogenesis.

No effect of chronic ethanol administration on the activity of alcohol dehydrogenase and aldehyde dehydrogenases in the near-term pregnant guinea pig

The objective of this study was to determine the effect of chronic maternal administration of moderate-dose ethanol on alcohol dehydrogenase, low Km aldehyde dehydrogenase, and high Km aldehyde dehydrogenase activities in the guinea pig at near-term pregnancy. The activity of each enzyme in the maternal liver, fetal liver, and placenta of the guinea pig at 59 days of gestation (term, 66 days) was determined spectrophotometrically following chronic daily oral administration of two doses of 1 g ethanol/kg maternal body weight or isocaloric sucrose solution. There was no experimental evidence of ethanol-induced malnutrition in the mother or growth retardation in the fetus. There was a statistically significant increase (65%) in the microsomal cytochrome P-450 content of the maternal liver for the ethanol treatment compared with the sucrose treatment. The alcohol dehydrogenase, low Km aldehyde dehydrogenase, and high Km aldehyde dehydrogenase activities in the maternal liver, fetal liver, and placenta were not statistically different for the ethanol-treated compared with the sucrose-treated animals. This also was the case for the maternal blood and fetal blood ethanol and acetaldehyde concentrations, determined at 2h after maternal administration of 1 g ethanol/kg maternal body weight. These data demonstrate that the ethanol- and acetaldehyde-oxidizing enzyme activities in the maternal-placental-fetal unit of the guinea pig at near-term pregnancy were not changed by chronic administration of moderate-dose ethanol.

Maternal alcohol ingestion inhibits fetal glucose uptake and growth

The distribution of maternally-derived glucose was determined in selected tissues of fetuses from ethanol-fed (EF) rats and from pair-fed (PF) and ad lib-fed (AF) controls. Maternal ethanol ingestion resulted in reduced fetal brain and liver weights and lower liver and lung glycogen levels compared to those of the PF or AF control groups. In addition, experimental fetuses exhibited reduced uptake of maternally-derived [ 3H] 2-deoxy-D-glucose (2-DG) by placenta and fetal brain. Fetal body, liver, lung, and brain weights correlated with fetal plasma 3H activity and with the fetal:maternal plasma 3H ratio, an indicator of the rate of placental glucose transfer. Brain weight correlated with 2-DG content per gram tissue weight. These observations suggest that reduced nutrient availability due to impaired placental transfer plays a role in the intrauterine growth retardation associated with maternal ethanol ingestion.

Prenatal Ethanol Exposure Alters Adrenocortical Development of Offspring

Interactive effects of prenatal ethanol and maternal nutritional status on reproductive outcome and maternal and offspring adrenocortical activity were examined. Ethanol was administered to pregnant females in liquid diets (36% ethanol-derived calories) which were marginal or optimal in terms of requirements for pregnancy. Both pair-fed and ad libitum fed control groups were included. Females consuming ethanol from gestation Day 1 through parturition gained less weight, were delayed in parturition, and had fewer and smaller live born young than pair-fed or control females, regardless of whether they consumed marginal or optimal diets. Withdrawing ethanol on Day 21 of gestation attenuated many of ethanol's adverse effects on reproductive outcome. However, prenatal maternal ethanol intake altered adrenocortical activity/responsiveness of the mother, the fetus, and the preweaning offspring, regardless of maternal nutritional status. Relative adrenal weights and basal corticosterone levels were increased in the dam both prenatally and at parturition. Ethanol-exposed fetuses (A) had increased relative adrenal weights but lower basal corticosterone levels than pair-fed (PF) and control (C) fetuses on gestation Day 21. At birth, plasma and adrenal corticosterone levels were increased, while absolute adrenal weights and corticosterone binding globulin (CBG) binding capacity were decreased in A neonates. At 5 days of age, A pups showed reduced plasma corticoid responses to ether at 15 min poststress and to novelty or saline injection at 90-min post stress compared to PF and C pups. CBG binding capacity was also reduced in A pups. At 10 days of age, plasma corticosterone levels were lower overall in A and PF than in C pups following exposure to a number of different acute stressors while at 18 days plasma corticoids were decreased and adrenal corticosterone was increased in A compared to PF and/or C pups. These data support and extend previous studies indicating that in utero ethanol exposure alters postnatal adrenocortical development. This effect is specific to ethanol and unaltered by maternal nutritional status.

The effect of maternal protein malnutrition and ethanol exposure on EGF binding to neonatal rat hepatocytes

The effect of maternal protein malnutrition and ethanol exposure on EGF binding to neonatal rat hepatocytes

Disposition of ethanol and acetaldehyde in late pregnant rats and their fetuses.

The pattern of ethanol and acetaldehyde appearance in blood after an oral ethanol gavage (4 g/kg body wt) was not different at 12 or 21 days' gestation compared to virgin rats. Five min after maternal ethanol administration, concentrations of ethanol in fetal blood were lower than in maternal blood; however, at 15 min after ethanol administration, fetal and maternal blood levels were similar. Ethanol concentrations in fetal blood and amniotic fluid were already at equilibrium 5 min after ethanol administration. Acetaldehyde concentrations in fetal blood and in amniotic fluid were undetectable at all the times investigated, with the exception of fetuses from two pregnant rats studied 3 h after ethanol administration. Alcohol dehydrogenase activity in fetal liver and in placenta at late pregnancy was very low or undetectable, suggesting a very low rate of ethanol oxidation in vivo. After intravenous administration of acetaldehyde (10 mg/kg body wt), blood acetaldehyde concentrations were higher in pregnant than in virgin rats. Acetaldehyde concentrations in fetal blood and in amniotic fluid were similar to maternal blood at 2, 5, and 30 min after injection. When circulating concentrations of maternal and fetal acetaldehyde, obtained after either ethanol or acetaldehyde administration, were plotted, it was found that fetal blood concentrations of acetaldehyde were only detectable when maternal blood concentrations were greater than 80 microM. Concerning the acetaldehyde oxidation capacity, both the high and low affinity components of aldehyde dehydrogenase activity in fetal liver and placenta were very low as compared with maternal liver. However, aldehyde dehydrogenase activity in fetal liver was much higher than in placenta.(ABSTRACT TRUNCATED AT 250 WORDS)

PGE measurement in mouse embryos and uterine/embryo tissue

Embryonic tissue of rodents and other species has been reported to produce prostaglandins (PG) of the E series during gestation. We attempted to establish the presence of PGE in C57BL/6J mouse embryos and peri-embryonic tissue as an initial step in examining the role of maternal ethanol treatment on PG production. Gestation day 10 embryos were found not to produce or degrade PGE. However, a tissue complex which included embryonic tissue, peri-embryonic membranes, placenta and uterus was capable of producing PGE from both endogenous and exogenous arachidonic acid. Furthermore, in vivo and in vitro aspirin was able to suppress PGE production from this tissue. It is concluded that gestation day 10 C57BL/6J mouse embryonic tissue, unlike that of rat, is not capable of measurable PGE production. However, uterine and peri-embryonic tissues, needed to support pregnancy, are capable of significant PGE production.

Effects of multiple-dose maternal ethanol infusion on fetal cardiovascular and brain activity in lambs

Ethanol (2 gm/kg of maternal body weight administered in four equal doses of 0.5 gm/kg over 5 hours) was infused intravenously into nine chronically prepared pregnant ewes between 124 and 137 days' gestation. The data demonstrated a dose-response relationship between fetal arterial ethanol concentrations and the incidence of fetal breathing movements. Suppression of normal fetal electrocortical activity occurred at a low ethanol concentration and returned to control values at a time of very high arterial artanol concentrations. This experimental model of a binge drinking episode further supports the hypothesis that ethanol suppresses fetal breathing movements by a direct central mechanism rather than indirectly by alteration of electrocortical activity.