The effects of chronic and acute alcohol administration on fetal development in the rat

Ethanol inhibition of undifferentiated rat neural progenitor cell replication can be prevented by chlorogenic acid via the NFATc4/CSE signaling pathway

BACKGROUND

Prenatal ethanol exposure hinders oxidative stress-mediated neuroblast/neural progenitor cell proliferation by inhibiting G1-S transition, a process vital to neocortical development. We previously showed that ethanol elicits this redox imbalance by repressing cystathionine γ-lyase (CSE), the rate-limiting enzyme in the transsulfuration pathway in fetal brain and cultured cerebral cortical neurons. However, the mechanism by which ethanol impacts the CSE pathway in proliferating neuroblasts is not known. We conducted experiments to define the effects of ethanol on CSE regulation and the molecular signaling events that control this vital pathway. This enabled us to develop an intervention to prevent the ethanol-associated cytostasis.

METHODS

Spontaneously immortalized undifferentiated E18 rat neuroblasts from brain cerebral cortex were exposed to ethanol to mimic an acute consumption pattern in humans. We performed loss- and gain-of-function studies to evaluate whether NFATc4 is a transcriptional regulator of CSE. The neuroprotective effects of chlorogenic acid (CGA) against the effects of ethanol were assessed using ROS and GSH/GSSG assays as measures of oxidative stress, transcriptional activation of NFATc4, and expression of NFATc4 and CSE by qRT-PCR and immunoblotting.

RESULTS

Ethanol treatment of E18-neuroblast cells elicited oxidative stress and significantly reduced CSE expression with a concomitant decrease in NFATc4 transcriptional activation and expression. In parallel, inhibition of the calcineurin/NFAT pathway by FK506 exaggerated ethanol-induced CSE loss. In contrast, NFATc4 overexpression prevented loss of ethanol-induced CSE. CGA increased and activated NFATc4, amplified CSE expression, rescued ethanol-induced oxidative stress, and averted the cytostasis of neuroblasts by rescuing cyclin D1 expression.

CONCLUSIONS

These findings demonstrate that ethanol can perturb CSE-dependent redox homeostasis by impairing the NFATc4 signaling pathway in neuroblasts. Notably, ethanol-associated impairments were rescued by genetic or pharmacological activation of NFATc4. Furthermore, we found a potential role for CGA in mitigating the ethanol-related neuroblast toxicity with a compelling connection to the NFATc4/CSE pathway.

Maternal circulating miRNAs that predict infant FASD outcomes influence placental maturation

Maternal gestational circulating microRNAs, predictive of adverse infant outcomes, including growth deficits, following prenatal alcohol exposure, contribute to placental pathology by impairing the EMT pathway in trophoblasts.

Prenatal alcohol exposure (PAE), like other pregnancy complications, can result in placental insufficiency and fetal growth restriction, although the linking causal mechanisms are unclear. We previously identified 11 gestationally elevated maternal circulating miRNAs (_HEamiRNAs) that predicted infant growth deficits following PAE. Here, we investigated whether these _HEamiRNAs contribute to the pathology of PAE, by inhibiting trophoblast epithelial–mesenchymal transition (EMT), a pathway critical for placental development. We now report for the first time that PAE inhibits expression of placental pro-EMT pathway members in both rodents and primates, and that _HEamiRNAs collectively, but not individually, mediate placental EMT inhibition. _HEamiRNAs collectively, but not individually, also inhibited cell proliferation and the EMT pathway in cultured trophoblasts, while inducing cell stress, and following trophoblast syncytialization, aberrant endocrine maturation. Moreover, a single intravascular administration of the pooled murine-expressed _HEamiRNAs, to pregnant mice, decreased placental and fetal growth and inhibited the expression of pro-EMT transcripts in the placenta. Our data suggest that _HEamiRNAs collectively interfere with placental development, contributing to the pathology of PAE, and perhaps also, to other causes of fetal growth restriction.

Long-lasting neural circuit dysfunction following developmental ethanol exposure

Fetal Alcohol Spectrum Disorder (FASD) is a general diagnosis for those exhibiting long-lasting neurobehavioral and cognitive deficiencies as a result of fetal alcohol exposure. It is among the most common causes of mental deficits today. Those impacted are left to rely on advances in our understanding of the nature of early alcohol-induced disorders toward human therapies. Research findings over the last decade have developed a model where ethanol-induced neurodegeneration impacts early neural circuit development, thereby perpetuating subsequent integration and plasticity in vulnerable brain regions. Here we review our current knowledge of FASD neuropathology based on discoveries of long-lasting neurophysiological effects of acute developmental ethanol exposure in animal models. We discuss the important balance between synaptic excitation and inhibition in normal neural network function, and relate the significance of that balance to human FASD as well as related disease states. Finally, we postulate that excitation/inhibition imbalance caused by early ethanol-induced neurodegeneration results in perturbed local and regional network signaling and therefore neurobehavioral pathology.

Liquid-diet with alcohol alters maternal, fetal and placental weights and the expression of molecules involved in integrin signaling in the fetal cerebral cortex

Maternal alcohol consumption during pregnancy causes wide range of behavioral and structural deficits in children, commonly known as Fetal Alcohol Syndrome (FAS). Children with FAS may suffer behavioral deficits in the absence of obvious malformations. In rodents, the exposure to alcohol during gestation changes brain structures and weights of offspring. The mechanism of FAS is not completely understood. In the present study, an established rat (Long-Evans) model of FAS was used. The litter size and the weights of mothers, fetuses and placentas were examined on gestation days 18 or 20. On gestation day 18, the effects of chronic alcohol on the expression levels of integrin receptor subunits, phospholipase-Cγ and N-cadherin were examined in the fetal cerebral cortices. Presence of alcohol in the liquid-diet reduced the consumption and decreased weights of mothers and fetuses but increased the placental weights. Expression levels of β₁ and α₃ integrin subunits and phospholipase-Cγ₂ were significantly altered in the fetal cerebral cortices of mothers on alcohol containing diet. Results show that alcohol consumption during pregnancy even with protein, mineral and vitamin enriched diet may affect maternal and fetal health, and alter integrin receptor signaling pathways in the fetal cerebral cortex disturbing the development of fetal brains.

Astrocyte control of fetal cortical neuron glutathione homeostasis: up-regulation by ethanol

Ethanol increases apoptotic neuron death in the developing brain and at least part of this may be mediated by oxidative stress. In cultured fetal rat cortical neurons, Ethanol increases levels of reactive oxygen species (ROS) within minutes of exposure and reduces total cellular glutathione (GSH) shortly thereafter. This is followed by onset of apoptotic cell death. These responses to Ethanol can be blocked by elevating neuron GSH with N-acetylcysteine or by co-culturing neurons with neonatal cortical astrocytes. We describe here mechanisms by which the astrocyte-neuron gamma-glutamyl cycle is up-regulated by Ethanol, enhancing control of neuron GSH in response to the pro-oxidant, Ethanol. Up to 6 days of Ethanol exposure had no consistent effects on activities of gamma-glutamyl cysteine ligase or glutathione synthetase, and GSH content remained unchanged (p < 0.05). However, glutathione reductase was increased with 1 and 2 day Ethanol exposures, 25% and 39% for 2.5 and 4.0 mg/mL Ethanol by 1 day, and 11% and 16% for 2.5 and 4.0 mg/mL at 2 days, respectively (p < 0.05). A 24 h exposure to 4.0 mg/mL Ethanol increased GSH efflux from astrocyte up to 517% (p < 0.05). Ethanol increased both gamma-glutamyl transpeptidase expression and activity on astrocyte within 24 h of exposure (40%, p = 0.05 with 4.0 mg/mL) and this continued for at least 4 days of Ethanol treatment. Aminopeptidase N activity on neurons increased by 62% and 55% within 1 h of Ethanol for 2.5 and 4.0 mg/mL concentration, respectively (p < 0.05), remaining elevated for 24 h of treatment. Thus, there are at least three key points of the gamma-glutamyl cycle that are up-regulated by Ethanol, the net effect being to enhance neuron GSH homeostasis, thereby protecting neurons from Ethanol-mediated oxidative stress and apoptotic death.

Comparative effects of maternal prenatal and postnatal exposures to astemizole on reproductive parameters of rats

The prenatal and postnatal effects of administration of a nonsedative antihistamine H1, astemizole (ATZ), were compared. ATZ (10 mg/kg) was injected daily into female Wistar rats throughout pregnancy (prenatal treatment) or during the first 6 days of lactation (postnatal treatment). Neither treatment modified dam body weight. Prenatal exposure reduced offspring body weight and lead to a latter expression of the vaginal opening of female offspring. In addition, a long-term disruption of male reproductive behavior was observed, while female sexual behavior was not modified. The sexual activity index and the intromission frequency were increased in prenatally treated animals. Testes wet weight was reduced, but no modifications were detected in vas deferens or seminal vesicles. Postnatal treatment did not alter offspring body weight, open-field activity, sexual behavior and organ weight as well as did not delay testes descent but reduced the time until vaginal opening. Hypothalamic serotonin (5-HT), dopamine (DA) and noradrenaline (NA) as well as DA and NA metabolites were not modified by both prenatal and postnatal treatments. Increased striatal 3,4-dihydroxyphenylacetic acid (DOPAC) levels were observed after prenatal and postnatal treatments, while only postnatal 5-HT levels were increased. We propose that the present results indicate that prenatal ATZ exposure can have long-lasting organizational effects on reproductive behavior of male rats, while postnatal exposure to this drug did not alter mating behavior. In relation to female rats, prenatal and postnatal exposures to ATZ accelerated puberty but did not alter sexual behavior. Neurochemical data show that both treatments increased striatal dopaminergic system activity, suggesting a central ATZ effect after perinatal exposure.

Perinatal astemizole exposure in the rat throughout gestation: long-term behavioral and anatomic effects associated with reproduction

Astemizole (ATZ), a non-sedative antihistamine, which antagonize histamine at the level of H1 receptor, was administered daily to female Wistar rats as a 10-mg/kg dose throughout pregnancy. ATZ exposure reduced offspring body weight and delayed the pinna detachment and startle reflex without any modification of dams body weight during gestation. Long-term disruption of male reproductive behavior was seen in experimental animals, whereas female sexual behavior was not modified. In addition, no motor alterations were observed in female or males in adulthood. Testis wet weight was reduced, but no modifications were detected in vasa deferentia or seminal vesicle. We proposed that ATZ administration during pregnancy causes several effects mainly of a sexual nature by interfering either with the hormonal mechanism involved in the central nervous system masculinization or by a direct action of the drug on pups during the development.

The influence of ethanol exposure on insulin-like growth factor (IGF) type II receptors in fetal rat tissues

The effect of ethanol (ETOH) exposure on the IGF type II receptor concentration was examined in 18 and 20 day fetal rat tissues. Pregnant dams were fed an ETOH (36% of calories derived from ETOH; 6.6% v/v) liquid diet. Control fetuses were offspring of dams either pair-fed a control liquid diet or ad libitum-fed a standard pelleted lab chow. Fetal brain, heart, kidney, liver, lung and skeletal muscle were removed and whole homogenates from individual animals were analyzed. Results of immunoquantification of IGF type II receptors in whole tissue homogenates show that there is a trend towards increased receptor concentration between 18 and 20 days in all tissue and this trend is significant for lung, liver and muscle. There were no significant differences in receptor concentration between treatment groups. These studies suggest that during the later stages of fetal development, there is an increase in total IGF type II receptors and this increase is undisturbed by ETOH exposure.

In utero ethanol exposure elicits oxidative stress in the rat fetus

Prior studies in our laboratory have shown that exposure of cultured fetal rat hepatocytes to ethanol (E) blocks epidermal growth factor-dependent replication and that this is paralleled by cell membrane damage, mitochondrial dysfunction, membrane lipid peroxidation (LP), and enhanced generation of reactive oxygen species. These measures of E-mediated oxidative stress (OS) were mitigated by treatment with antioxidants, and cell replication could be normalized by maintaining cell glutathione (GSH) pools. We have now extended these studies to an in vivo model. Rats were administered E (4 g/kg, po) at 12-hr intervals on days 17 and 18 of gestation and killed on day 19, 1 hr following a final dose of E (a total of 5 doses). Fetal and maternal brain and liver were assayed for signs of OS. The 2-day in utero E exposure increased membrane LP in fetal brain as evidenced by increased malondialdehyde (MDA) levels from 1.76 +/- 0.12 SE (nMol/mg protein) to 2.00 +/- 0.08 (p < 0.05) and conjugated dienes from 0.230 +/- 0.006 SE (OD223/mg lipid) to 0.282 +/- 0.006 (p < 0.05). In fetal liver, MDA levels increased from 2.39 +/- 0.08 SE (nMol/mg protein) to 2.87 +/- 0.08 (p < 0.05), whereas dienes differed significantly only between ad libitum controls and the E and pair-fed control groups (p < 0.05). E decreased GSH levels in fetal brain by 19%, from 19.88 +/- 0.72 to 16.13 +/- 1.06 (nMol/mg protein) (p < 0.05). A 10% decrease in GSH was seen in fetal liver (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of ethanol on insulin-like growth factor-II release from fetal organs

This study examines the effect of ethanol (ETOH) exposure and nutrient restriction on the release of insulin-like growth factor (IGF)-II from 18- and 20-day explanted fetal organs. Fetuses were exposed to ETOH (E) in utero by feeding dams a 36% (calories derived from ETOH: 6.6% v/v) ETOH liquid diet. Control fetuses were offsprings of dams either pair-fed (P) a control liquid diet or ad libitum (A) fed a standard pelleted lab chow. Brain, heart, kidney, liver, lung, muscle, and placenta of fetuses from the same litter were pooled and explanted, and IGF-II concentration in explanted media was analyzed by radioimmunoassay. Maternal and fetal weights were determined during pregnancy and at sacrifice, respectively, to evaluate the influence of ETOH on growth. Both maternal and fetal weights were substantially reduced by ETOH on 18 and 20 days of gestation compared with both A and P controls. At 18 days of gestation, E fetuses (1.33 +/- 0.03 g) weighed less than either A (1.47 +/- 0.03 g) or P (1.54 +/- 0.04 g) fetuses. By 20 days, A mean fetal weight (4.19 +/- 0.23 g) was significantly greater than both P (3.74 +/- 0.06 g) and E (3.28 +/- 0.06 g) fetuses. IGF-II concentration in media from 18-day fetal explants was highest from E (brain, heart, liver, and placenta) and P tissues (kidney, lung, and muscle). IGF-II in media from A tissues (except placenta) was lower than both E and P levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Protective effect of Liv.52 on alcohol-induced fetotoxicity

The adverse effects of maternal alcohol consumption on the development of the fetus are well known. The adverse effects of ethanol on the liver are now believed to be due to acetaldehyde formed as an intermediate metabolite of ethanol. Liv.52 has been shown to bring about faster elimination of acetaldehyde from the body and thus prevent alcoholic liver damage. Other toxic effects of alcohol may also be due to acetaldehyde and may be prevented by Liv.52. In this study, rats were given 20% (v/v) ethanol in drinking water, during the gestation period, and the effect on maternal body weight and fetal outcome was noted. The protective effect of Liv.52 administration during the gestation period was studied. The results show that ethanol ingestion caused a decrease in gestational weight gain, total fetal weight, and number of live fetuses. There were increases in resorptions. Liv.52 administration reduced the deleterious effects of ethanol. The concentration of acetaldehyde in the amniotic fluid of ethanol-consuming animals was 0.727 microgram/ml. Liv.52 administration lowered it to 0.244 microgram/ml. The protective effect of Liv.52 could be due to the rapid elimination of acetaldehyde.

Human placental transfer of zinc: normal characteristics and role of ethanol

The fetal alcohol syndrome is primarily an impairment of growth and development. Zinc deficiency also causes abnormal fetal growth. Moreover, alcohol has been shown in some rodent studies to impair placental transport of zinc. The purpose of this investigation was to define better normal human placental zinc transport and the effects of alcohol on this process. To do this we employed the isolated perfused single cotyledon human term placental model, as well as the cultured human cytotrophoblast. In the perfused placental studies, it was shown that zinc is transferred by the placenta very slowly, about 6% of the rate of transport of antipyrine, a freely diffusible marker. The transfer is comparable in both directions, maternal to fetal and the reverse. Zinc does not cross the placenta against a zinc concentration gradient, in either direction. Rather there is good evidence of significant uptake (storage) of the zinc by the placenta on the recirculating compartment side of gradient studies. Moreover, when the perfusion fluid was low (0.2 g/100 ml) in albumin, about twice as much zinc accumulated in the perfused cotyledon and there was less zinc in the maternal compartment, as compared to perfusion with ten-fold higher (2.0 g/100 ml) albumin concentrations. Thus, ligand binding in the perfusate importantly influences placental zinc uptake. Interestingly, however, the increased placental binding of zinc did not translate into greater transfer of zinc to the fetal compartment. Thus, normal zinc transfer is slow, equal bidirectionally, and dependent on ligand binding in perfusate and placenta.(ABSTRACT TRUNCATED AT 250 WORDS)

Decreased glucose transporter 1 gene expression and glucose uptake in fetal brain exposed to ethanol

Using pregnant rats fed equicaloric liquid diets (AF, and libitum-fed controls; PF, pair-fed controls; EF, ethanol-fed), we have previously shown that maternal alcoholism produces a specific and significant decrease of glucose in the fetal brain, which is accompanied by growth retardation. To further define the mechanisms of ethanol-induced perturbations in fetal fuel supply, we have examined (i) the uptake of 2-deoxyglucose (2-DG) by dissociated brain cells from fetal rats that were exposed to ethanol in utero and (ii) the steady-state levels of the glucose transporter-1 (GT-1) mRNA. A 9% decrease in brain weight (P less than 0.001) and a 54.8% reduction in 2-DG uptake into brain cells (P less than 0.02) were found in offspring of EF mothers compared to the AF group. Brain weight correlated with the rate of 2-DG uptake (P less than 0.05). Northern blot analysis showed a 50% reduction of GT-1 mRNA in EF brain relative to that in the AF and PF groups. We conclude that glucose transport into the brain is an important parameter altered by maternal ethanol ingestion.

Interactive effects of ethanol and caffeine on rat fetal hepatocyte replication and EGF receptor expression

This study reports on the interactive effects of ethanol and caffeine on growth of rat fetal hepatocytes. Exposure of cultured rat fetal hepatocytes (RFH) to ethanol in concentrations above 1 mg/ml, causes a blockade of EGF-dependent cell replication along with an overexpression of surface EGF receptors (EGF-R). However, RFHs exposed for 24 hours to ethanol at a concentration of 1 mg/ml alone had little effect on cell replication. Caffeine, when combined with this concentration of alcohol, progressively impaired RFH growth by up to 100%. Caffeine alone up to 10 micrograms/ml, on the other hand, caused a progressive increase in RFH replication associated with a 69% enhancement of DNA synthesis. Caffeine concentrations in excess of 50 micrograms/ml had no effect on replicative capacity. Concomitant caffeine exposure had no effect on the ethanol-related increase in cell DNA content, yet it caused a further enhancement of the cell protein accural induced by ethanol alone. Caffeine (10 micrograms/ml) alone had no effect on EGF-R expression, while ethanol (2 mg/ml) increased it by almost 200%. Addition of caffeine to ethanol reduced this enhanced EGF binding by 45%. Scatchard analysis indicated that no treatment altered ligand affinity for the receptor, but that the alterations in binding caused by ethanol and the caffeine/ethanol combination reflected changes in binding capacity, in both low and high affinity components. It is concluded that (1) ethanol blocks EGF-mediated replication accompanied by a reduction in DNA synthesis, (2) caffeine alone at low concentrations has the opposite effect and can actually potentiate the EGF-mediated mitogenic response, (3) caffeine in combination with ethanol acts synergistically to reduce RFH replication.(ABSTRACT TRUNCATED AT 250 WORDS)

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)

Arrest of epidermal growth factor-dependent growth in fetal hepatocytes after ethanol exposure

Exposure of the fetal rat hepatocyte to ethanol in vitro blocks epidermal growth factor (EGF)-dependent cell replication. To define possible mechanisms for this growth arrest, we determined the effects of ethanol on EGF binding and EGF receptor (EGF-R) levels. During a 24-h exposure to ethanol (1.7 mg/ml, 31 mM), cell replication was completely blocked while EGF binding per cell doubled. This effect was no specific for EGF, with variable degrees of increased binding noted for insulin, transferrin, and glucagon. Significantly increased EGF binding was seen after 6 h of ethanol exposure, and both growth arrest and enhanced EGF binding were reversed within 12 h of ethanol withdrawal. Increases in both "high" and "low" affinity sites were seen, with no changes in the apparent Kd's. Total RNA, beta-actin mRNA, and EGF-R mRNA were increased 50-70% in ethanol exposed cells. However, direct measurements of EGF-R synthesis rates by [35S]methionine incorporation revealed no differences between control and ethanol exposed cells. Internalization of EGF-R was significantly altered by ethanol exposure. A 2-h incubation resulted in the internalization of 57% of the ligand in control cells, while only 31% of bound EGF was internalized in the ethanol exposed cells. Thus, the enhanced EGF binding may be due to decreased efficiency of internalization.

Effect of ethanol on human placental transport of model amino acids and glucose

Prior studies in rodents, sheep, and subhuman primates have shown that ethanol, especially after chronic exposure, inhibits the transport of amino acids by the placenta. A small decrease in glucose transport by rat placenta chronically exposed to ethanol has also been noted. With human placental slices, however, only pharmacological (high) concentrations of ethanol impaired uptake of amino acids, and there are no data on glucose transport. In the present study, the effect of brief exposure to ethanol on human placental transport of model amino acids and glucose was studied by two techniques not previously jointly employed for this--the perfused human placental cotyledon and human placental vesicle systems. The nonmetabolizable amino acids, alpha-aminoisobutyric (AIB) acid and cycloleucine (CLEU), as well as D-glucose, and nonmetabolized glucose (3-O-methyl-D-glucose), were used as probes. AIB and CLEU are transferred normally by active transport and D-glucose by facilitated transport from maternal to fetal compartments. The perfused placental system was exposed to ethanol (300-500 mg%) for 2-4 hr and the vesicles to 200-400 mg% ethanol for times varying from 10 min to 48 hr. There was no impairment of AIB, D-glucose, or 3-O-methyl-D-glucose transfer by ethanol using these techniques. Normally, about 60% of AIB transport by human placenta is sodium dependent. This component (using the vesicle system) was also not impaired by ethanol. Ethanol caused a very small decrease of CLEU clearance by the perfused human placenta (p = 0.05) but not using vesicles.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of ethanol on glucose turnover in pregnant rats

Glucose turnover was measured in term pregnant rats fed ethanol (30% of caloric intake) throughout gestation. Ethanol ingestion significantly reduced maternal weight gain and term fetal body weight when compared to pair-fed or ad libitum-fed controls. At term the blood glucose level and 6-3H-glucose turnover were reduced when compared to either control group. The rate of gluconeogenic recycling, indicated by the difference between 6-3H and 6-14C-glucose turnover determinations, was reduced by ethanol ingestion to half that of the control groups. Glucose turnover correlated with both conceptus weight and blood glucose level. Impaired maternal glucose homeostasis, including a reduced gluconeogenic response to the metabolic demands of late pregnancy, may thus contribute to the effects of ethanol on intrauterine growth.

Acetaldehyde production and transfer by the perfused human placental cotyledon

Fetal injury associated with maternal ethanol ingestion is a major cause of congenital anomalies and mental retardation. Studies with animals suggest that acetaldehyde, the primary hepatic oxidative metabolite of ethanol, may contribute to fetal damage. It is not known, however, whether acetaldehyde reaches the human fetus, either by placental production or transfer. Studies utilizing the perfused human placental cotyledon show that the human placenta oxidizes ethanol to acetaldehyde, releasing it into the fetal perfusate. Moreover, when acetaldehyde is present in the maternal perfusate, it is transferred to the fetal side, reaching approximately 50 percent of the maternal level. These findings suggest that the human placenta may play a pivotal role in the pathophysiology of ethanol-associated fetal injury.

Neonatal and maternal hair zinc levels in a nonhuman primate model of the fetal alcohol syndrome

The role of zinc deficiency in the etiology of ethanol-associated fetotoxicity was assessed by measurement of maternal and newborn hair zinc content in a nonhuman primate model of the fetal alcohol syndrome. The model best approximates the human situation for length of gestation and type of placentation, coupled with the ability to control for nutritional factors. All mothers received 110% of their minimum daily caloric requirements as a balanced, nutritionally complete diet, including a minimum of 3.5 mg zinc per day. Over a 2-year period, maternal hair samples from 17 pregnancies (using 12 females) were obtained at term. There were 16 live, full-term neonates (nine ethanol exposed and seven control) from whom samples were taken within 1 hr of birth. The ethanol-exposed infant monkeys had a significantly higher incidence of craniofacial dysmorphology and developmental delay compared to the controls. There was no difference in hair zinc levels between ethanol-exposed and control animals for either the mothers or the newborns. Neonatal levels were, however, consistently higher than corresponding maternal. Although the findings cannot exclude transient or early gestational zinc deficiency as a factor, they provide further evidence that ethanol (and/or its metabolites) is the proximate toxin in the type of fetal injury seen in the fetal alcohol syndrome.

Zinc, ethanol, and lipid peroxidation in adult and fetal rats

Studies were performed on adult and fetal rats receiving either a zinc-deficient (<0.5 ppm) diet and/or ethanol (20%) throughout pregnancy. Liver zinc levels were depressed in fetuses exposed toin utero zinc deficiency, but brain zinc levels were unchanged. Ethanol had no effect on the concentration of zinc in the several fetal and adult tissues studies. Lipid peroxidation, as measured by endogenous levels of malondialdehyde (MDA) increased following food restriction, zinc improverishment, and alcoholism in adult and fetal livers, but not in fetal brains. Generally, levels of MDA were highest when both zinc deficiency and the ingestion of alcohol occurred concurrently. Glutathione (GSH) was depressed by zinc restriction in several adult and fetal tissues, but not in the fetal brain. Ethanol alone had no effect on GSH levels. The activity of the enzyme glutathione peroxidase (GSH-Px) was not changed in either organism by alcohol or zinc deficiency.Overall, the data point to increased lipid peroxidation in maternal and fetal rat tissues following zinc depletion and/or treatment with alcohol and draw attention to the apparent vulnerability of the fetal liver toin utero alcoholism. By contrast, the fetal brain seems to be especially resistant to alcohol and zinc-related lipoperoxidation. An association is suggested between the increased lipoperoxidation accompanying zinc deficiency and reduced levels of GSH, but this does not appear to relate to changes in the activity of GSH-Px. A similar relationship is not evident with respect to the increased levels of MDA in fetal and adult livers following chronic alcohol intoxication. A possible basis for the zinc-GSH interaction is discussed.

A stage-dependent effect of ethanol on 9.5-day rat embryos grown in culture and the role played by the concomitant rise in osmolality

The effects of ethanol on the rat embryo undergoing organogenesis in vitro have been studied. We have shown that embryopathy is dependent on the stage of development at which explanted embryos were treated. The early neural plate (presomite) stage was highly sensitive to a 4-hour exposure of 300 mg/% ethanol, whereas embryos explanted 5 hours later, at the late head-fold (two to six somites) stage grew normally under the same conditions. We have also established that raised serum osmolality, associated with ethanol in serum, is responsible for some but not all of the teratogenic effect. This was shown by mimicking the rise in osmolality with hyperosmotic serum, containing glycerol, NaCl, or concentrated Hanks' salts. Dilution of this osmotic effect by the addition of distilled water in part reversed these embryopathic effects.

Stimulatory effects of ethanol on amino acid transport by rat fetal hepatocytes

Previous studies have indicated that acute, and especially chronic, maternal ethanol consumption can depress placental uptake of various amino acids. Since the fetal cell itself represents a second barrier to nutrients, one which may be altered by ethanol exposure, the effects of ethanol on amino acid net uptake by rat fetal hepatocytes was addressed. The present study determined that ethanol stimulated amino acid net uptake by fetal hepatocytes grown in monolayer culture. Fetal liver cells were grown in custom Williams' E medium (without L-arginine and with L-ornithine) and exposed to epidermal growth factor (0, 1, 2 or 5 ng per ml) and ethanol (1.7 +/- 0.1 or 3.9 +/- 0.2 mg per ml). Addition of ethanol (3.9 mg per ml) to the culture medium completely blocked measurable cell replication during a 48-hr exposure period. Fetal hepatocytes exposed to ethanol accrued both protein and water in a parallel fashion, both in excess of that by control cells. Ethanol (1.7 and 3.9 mg per ml) for 48 hr stimulated alpha-aminoisobutyric acid net uptake by fetal hepatocytes (p less than 0.05). Efflux was not affected (p greater than 0.05). The onset of this significant stimulation of net uptake was progressive and required in excess of 6 hr of contact with ethanol. This ethanol stimulation of alpha-aminoisobutyric acid net uptake persisted for at least 24 hr following ethanol withdrawal. The component(s) of alpha-aminoisobutyric acid net uptake stimulated by ethanol was independent of extracellular Na+.(ABSTRACT TRUNCATED AT 250 WORDS)

Polyamines and diamine oxidase activity in maternal, embryonal, and fetal tissues of rat after chronic ethanol consumption

The effects of maternal ethanol consumption for 4 weeks before and throughout gestation on polyamine content and diamine oxidase activity of maternal, embryonal and fetal tissues are reported. At the 12th day of pregnancy, a decrease of putrescine in the liver of the mother and marked increases in putrescine, cadaverine and spermidine in embryos were observed. At day 18, putrescine and cadaverine diminished in maternal liver and placenta, and no changes in amine content in fetal liver and brain were found. At day 12, diamine oxidase activity increased in maternal liver and placenta, whereas it greatly diminished in embryos. At day 18, enzyme activity decreased in maternal liver, placenta, fetal liver and brain. These results indicate that chronic ethanol ingestion induces alterations in polyamine concentrations and metabolism in growing and developing tissues during pregnancy that might contribute to the adverse effect of ethanol on conceptual development.

Growth patterns of rat body, brain, and cerebellum in fetal alcohol syndrome

Pregnant Sprague-Dawley rats were offered protein- and vitamin-enriched, nutritionally balanced, liquid ethanol diet, providing 35% of calories as ethanol, beginning on day 6 of gestation. Control animals were pair-fed identical liquid diet except that maltose-dextrins were substituted for ethanol. At birth the pups of both ethanol exposed and pair-fed mothers were surrogate-fostered by normal dams. Plasma concentrations of ethanol and thyroxine were determined in dams of experimental and control groups. Thyroxine concentrations were significantly reduced in ethanol-fed dams compared with pair-fed. Pups of both groups were killed at 0-1, 5, 7, 10, 14, 21, 28, 35, and 42 postnatal days. The crown-rump, crown-tail lengths, and weights of body, brain, and cerebellum were significantly reduced in ethanol-exposed pups compared with controls at all time sequences studied.

Pituitary and thyroid hormones in pregnant alcohol-fed rats and their fetuses

The effect of maternal alcohol consumption on serum and pituitary concentrations of hormones was investigated in pregnant rats and their fetuses. Rats were given 20% ethanol in water prior to pregnancy and 30% ethanol in water throughout gestation, with rat chow ad libitum (alcohol group), or water with an equicaloric diet in which corn starch was substituted for alcohol (pair-fed group), or rat chow and water ad libitum (ad libitum control group). Growth hormone (GH), prolactin (Prl), thyroid-stimulating hormone (TSH), thyroxine (T4), and triiodothyronine (T3) were measured in maternal serum, GH, Prl, and TSH in maternal pituitary, and GH, T4, and T3 in fetal serum. Fetuses of alcohol-fed rats weighed significantly less than fetuses of pair-fed or ad libitum controls. GH, Prl, and TSH were significantly reduced in the maternal serum of alcohol and pair-fed rats compared to ad libitum controls, but T4 and T3 did not differ among the three groups. Pituitary GH was reduced in the alcohol-fed rats, but pituitary Prl and TSH did not differ among the three groups. In the fetuses, neither GH nor T4 differed among the three groups. Fetal T3 was not detectable by this assay. It is suggested that alcohol ingestion affects maternal growth hormone levels, possibly by influencing either the synthesis or the release of the hormone from the pituitary gland. The other hormonal changes may be the result of the reduced food intake, rather than a specific effect of alcohol.

Organ growth and cellular development in ethanol-exposed rats

Effects of perinatal exposure to ethanol on growth and cellular development were investigated. Alcohol was administered in liquid diets designed to provide optimal nutrition during pregnancy. Pair-fed and ad lib control groups were included. The 3 groups of females were similar in body weight during gestation and lactation, and offspring weights were similar on gestation Day 21 and at birth. By Day 9 of lactation control pups weighted more than both alcohol and pair-fed pups which were similar in body weight. Weights of brain, heart, liver and kidney were reduced in alcohol pups compared to pair-feds and controls. Decreased liver weight reflected both decreased cell size and decreased protein content, but was primarily due to decreased caloric intake. Decreased heart weight appeared to result from a direct effect of ethanol on heart protein content. Even more marked were the adverse effects of ethanol on kidney protein content and kidney DNA (reflecting a decrease in cell number). In contrast, although both absolute brain weight and DNA content were decreased in ethanol-exposed offspring, relative brain weight was increased. Finally, maternal ethanol consumption significantly increased relative placenta weights as well as placental DNA and protein content.

Effects of prenatal alcohol exposure on behavior of aged rats

Pregnant rats were intubated with alcohol (3.5 g/kg, twice daily) on gestation days 11-21. Control animals were intubated with an isocaloric sucrose solution and were pair-fed and pair-watered to alcohol-treated dams. At birth, offspring were placed with non-treated surrogate dams. When animals were slightly more than 1 year of age, they were tested for passive avoidance learning, spontaneous alternation and activity. Groups did not differ in passive avoidance learning or spontaneous alteration but animals prenatally exposed to alcohol were more active than controls. Additional studies showed that this increased activity was not affected by testing animals in the presence of environmental stimuli such as objects which could be manipulated, or by odors from mouse shavings from male and female mice.

Alcohol-metabolizing enzymes in placenta and fetal liver: effect of chronic ethanol intake

Alcohol dehydrogenase and different subcellular distribution of aldehyde dehydrogenase (ALDH) in fetal liver and placenta at 15 and 21 days of gestation were studied in three different groups of pregnant rats: alcoholic, pair-fed, and rat solid chow diet animals. Chronic ethanol intake during pregnancy produced a decrease in fetal body and liver weight but an increase of placenta weight. No alcohol dehydrogenase was detected in placenta at any stage of gestation, nor in fetal liver at 15 days although a low activity was found at 21 days. No significant difference was observed from fetuses of alcoholic and nonalcoholic mothers. Subcellular aldehyde dehydrogenase distribution in placenta was similar to that in adult liver. Although no cytosolic ALDH was detected in fetal liver at any period of gestation, low activities were found in placenta and fetal liver at 15 days of pregnancy in other subcellular fractions. However, at 21 days the placental activity decreased while that of fetal liver increased markedly. The increase of the fetal liver ALDH was especially noticeable in the mitochondrial fraction in which the activity was approximately 10-fold higher than in the placenta mitochondrial fraction. A small decrease in placenta and fetal liver ALDH was observed in alcoholic rats. The role of the placenta ALDH in the acetaldehyde placental transfer is discussed.

Fetal alcohol syndrome: glucose and liver metabolism in term rat fetus and neonate

The combined effects of chronic ethanol ingestion and fasting (24-hr fast, except water, prior to delivery) were examined in term pregnant rats and their offspring. Rats fed liquid diet containing 5% (w/v) ethanol (EF) consumed fewer calories than those fed control diet and exhibited reduced weight gain relative to either ad libitum-fed (AF) or pair-fed (PF) controls. While the number of live fetuses at term was unaffected, fetal body and liver weights were reduced in EF litters. Blood glucose levels were significantly lower in EF fetuses although maternal glucose levels did not differ between the groups. Liver glycogen levels also were reduced in EF fetuses, without any change in plasma immunoreactive insulin or immunoreactive glucagon levels. Both active and total glycogen synthase and phosphorylase were significantly lower in livers of EF fetuses than in livers of control fetuses. After delivery, blood glucose and plasma immunoreactive insulin levels fell more slowly in EF neonates than in either control group, but EF neonates remained hypoglycemic at 4 hr postnatal, whereas glycemia in both control groups had recovered to normal. Plasma immunoreactive glucagon levels in EF were elevated during the first 2 hr following delivery relative to either AF or PF controls, and hepatic glycogen levels were reduced in EF neonates during the entire interval studied.

CONCLUSION

Fetal exposure to ethanol in utero and to a short maternal fasting prior to delivery results in fetal growth retardation, hypoglycemia, hypoinsulinemia, and liver glycogen depletion at term. Also, both glycogen synthase (active and total) and phosphorylase (active and total) were decreased as well.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of alcohol ingestion on zinc content of human and rat central nervous systems

The abundance of zinc in hippocampal mossy fibers has stimulated investigation of zinc status in various pathologic states in which behavioral or anatomic deficits involving the hippocampus are known to occur. Limited autopsy studies of chronic alcoholic humans have suggested that the content of zinc might be reduced in several brain regions whereas reported attempts to replicate these findings in ethanol-exposed experimental animals have produced inconsistent results. In this comparative study, the zinc concentration in 10 brain regions, all spinal cord segments, and microdissected hippocampal subfields was measured by isotope ratio mass spectrometry. A widespread 15 to 20% reduction in zinc content was observed in all regions of chronic alcoholics compared with controls but a selective involvement of hippocampus was not detected. In the experimental studies, groups of rats were exposed to ethanol by one of three routes: inhalation for 2 weeks, as an ethanol/liquid diet for 3 months, or a single intoxicating i.p. dose. Determinations of tissue uptake of radiozinc and of total zinc content were made. In contrast to human pathologic material, zinc pool size and tissue uptakes were not affected by experimental ethanol administration by any route. This study confirmed that a reduction in zinc concentration occurs in the central nervous system of chronic alcoholics. The animal studies indicated, however, that simple ethanol exposure, even for prolonged periods, does not perturb zinc metabolism in brain. Together, these observations argue that the abnormalities of zinc metabolism in chronic alcoholics are possibly secondary to homeostatic alterations associated with hepatic failure.

Zinc deficiency and the developing embryo

The effect ofin utero zinc deficiency on fetal development in rats is reviewed. Attention is paid to the primary biochemical lesion associated with zinc-related teratogenesis and special consideration is given to the central nervous system. Evidence is presented that the thymidine kinase salvage pathway, used for the synthesis of thymidine monophosphate in DNA synthesis, is depressed more in fetal brain tissue than in the liver. In addition, greater reliance appears to be placed on this pathway than onde novo synthesis in the fetal brain than in other tissues. Some consideration is given to the use of in vitro embryo culture in studies relating to neurogenesis, but evidence is presented of a greater capacity of explanted rat embryos to obtain zinc from maternal serum than occurs in vivo.The rapid onset of a teratogenic zinc deficiency following dietary zinc restriction is again highlighted and further studies are described which demonstrate the critical impact of a single feeding cycle, of 4 d duration, on maternal plasma zinc levels and on the extent and nature of the observed fetal abnormalities. Evidence is presented that by shifting the timing of the high dietary intake/low plasma zinc peak to coincide with a particular 48 h period between days 6 and 10 of pregnancy, the pattern of malformations thus obtained reflected the coincidence of the high dietary intake of zinc-deficient diet and the critical time of morphogenesis of several organ systems.Whereas diminished plasma zinc levels at term in zinc-deficient animals are generally well correlated with reduced growth and dysmorphogenesis of the offspring, the same is not always found in human studies. In some cases, elevated plasma zinc levels at parturition are found in mothers with growth-retarded children, or vice versa. Experimental studies with rats are reported that suggest that maternal zinc status at term may be higher in dams bearing pups stunted by exposure to a transient zinc deficiency early in pregnancy, which in turn may have reduced the demand for maternal zinc in the later stages of gestation.The protective effect of zinc on cadmium-induced teratogenesis is discussed, particularly in relation to findings concerning an interaction of these metals in the embryonic yolk sac and thus on preplacental embryonic nutrition. Possible interactions between alcohol and zinc deficiency are also considered and data are presented pointing to increased fetotoxicity and teratogenesis in the presence of both treatments and to a more specific interaction with respect to reduced cell numbers in the developing rat hippocampus. Malondialdehyde levels, which reflect the extent of lipid peroxidation in tissue, are reported to be substantially higher in microsomes from fetal rat livers whenin utero deficiency and gestational alcoholism are combined. The suggestion is made that alcohol and zinc deficiency act independently in the body, but overlap to some extent at the common biochemical locus of membrane lipid peroxidation.

Prenatal effects of alcohol

Suspicion of alcohol's teratogenic potential stretches back many centuries, but it is only recently that solid support for this possibility has been produced. There is now little doubt that alcohol can produce developmental defects, but there are many questions that still remain to be answered concerning the impact of alcohol on the conceptus. One major question that remains to be resolved is why only a small percentage of alcoholic women give birth to children with Fetal Alcohol Syndrome (FAS), whereas other alcoholic women who drink the same amount do not. Another important issue concerns the way in which alcohol produces its effects. Although one of the most likely ways in which alcohol's teratogenic actions are mediated appears to be via hypoxia, other mechanisms such as direct toxicity of alcohol or acetaldehyde may be involved. FAS refers to a pattern of defects in children born to alcoholic women. For a diagnosis of FAS to be made, the patient must have three main characteristics: (1) pre- and postnatal growth retardation (greater than or equal to 2 S.D. for length and weight), (2) facial anomalies, and (3) central nervous system dysfunction Pre- and postnatal growth retardation are the most reliable consequences of fetal alcohol exposure. In many cases, patients with the syndrome weigh less than 2500 g at birth and most do not exhibit postnatal 'catch-up growth' Among the distinctive facial anomalies seen in conjunction with the syndrome are absent-to-indistinct philtrum, epicanthic folds, thin upper lip and short upturned nose. Joint, limb and cardiac anomalies are also often present. Central nervous system dysfunction includes mental retardation, the most serious consequence of in utero alcohol exposure, hyperactivity, sleep disorders and miscellaneous behavioral difficulties. If only one or two of these broad characteristics are present and the mother is suspected of drinking during pregnancy, then a diagnosis of 'possible fetal alcohol syndrome,' or 'partial fetal alcohol syndrome,' or 'fetal alcohol effects,' or 'alcohol-related birth defects' may be made. However, without evidence of maternal drinking during pregnancy, this diagnosis is very tentative, since many of these effects are also observed in conjunction with many other congenital disorders.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of maternal ethanol ingestion during pregnancy and lactation on the structure and function of the postnatal rat liver plasma membrane. Assessement with [3H]prazosin binding to the hepatic alpha 1-adrenergic receptors

A liquid low-fat nutritionally adequate Metrecal diet in which alcohol contributed 37% of the total calories was given to pregnant rats and maintained during lactation. Control rats were pairfed with an isocaloric sucrose-Metrecal diet. After birth, litters were killed at different ages (days 1-30), and the results showed that growth and survival of progeny from the alcohol-treated rats were adversely affected. Likewise, the wet weights of livers from such pups were consistently less than from the pair-fed controls. The yield of hepatic plasma membrane protein per wet liver weight was constant and independent of either age or diet. Using [3H]prazosin as radioligand, equilibrium binding studies were carried out to monitor changes in the structure and function of the plasma membrane in the new-born pups concomitant with the development of alpha 1-adrenergic receptors. Results obtained with the alcohol-fed pups showed that the binding affinity (KD) was not altered throughout. However, the receptor density (Bmax) was decreased significantly. This decrease ranged from 60 to 70% in pups 6- to 15-days-old; 45% at 20 days; and 30% in pups at 25 and 30 days of age. These observations suggest that maternal ethanol ingestion affected the postnatal development of rat liver plasma membranes. Furthermore, by using the hepatic alpha 1-adrenergic receptor as a metabolic probe, we deduce that a possible impairment exists in the capacity of the alcoholic progeny to respond to the hormonal action of epinephrine. Such a defect may contribute to impaired growth and metabolism in these young animals.

Interactions between trace elements and alcohol in rats

Interactions between ethanol and trace elements are reviewed at two levels. The first concerns the effect of alcohol on the concentration and distribution of certain trace metals in the body; changes are described for copper, iron, manganese, selenium and zinc. The second relates to the possible protection afforded by some trace elements against alcohol-related damage. The significance of maternal zinc to the fetal alcohol syndrome is discussed in the light of evidence that pregnancy outcome in rats after gestational alcoholism is less favourable in zinc-deficient dams than in nutritionally replete animals. Cellular metabolism of ethanol may lead to the generation of damaging superoxide and hydroxyl radicals; several trace elements, notably zinc, manganese, selenium and copper, may function protectively as free radical scavengers and as antioxidants. Evidence is presented of increased lipid peroxidation in zinc-deficient tissues of Sprague-Dawley rats and of enhanced activity of Mn-superoxide dismutase in fetal and adults rats exposed to ethanol.

Acute embryopathic effects of ethanol in the Long-Evans rat

Thirty-two pregnant Long-Evans rats were divided into 10 groups of 3 or 4 pregnant rats, and each rat was given a single dose of 4 ml ethanol/kg (20 ml/kg of a 20% solution) between d 6 and 15 of gestation. An 11th group of 50 pregnant rats received distilled water and served as controls. Offspring body weights were decreased in groups of rats given ethanol as compared to controls (3.0-3.6 g, versus 3.9 g for controls). Total litter weight was decreased in dams given ethanol on d 6. Skeletal variants were seen in 13-78% of the offspring given ethanol, compared to 0.6% of the controls. Variations may be considered as additional signs of embryotoxicity. Malformations such as hydronephrosis, pelvic kidney, microcephalus, cranioschisis, and microphthalmia occurred in 72-100% of the ethanol treated offspring, as compared to 12% of controls. Hydronephrosis was most frequent on d 9 or 14, pelvic kidney on d 8 and 11, and microphthalmia from d 10-12. Cranioschisis was maximal on d 7, 11, and 15, and microcephalic offspring were most frequently born to dams given ethanol on d 7 or 14. Skeletal defects were usually single entities, while soft-tissue anomalies occurred in a consistent pattern. These results suggest that ethanol is a stage-specific teratogen in the rat at comparable exposure levels attained by many humans.

Interaction of alcohol and zinc in fetal dysmorphogenesis

The interaction of low doses of alcohol and marginal zinc deficiency during gestation was studied in pregnant mice and their fetuses. The combination of the two agents at subteratogenic doses was related to increased external and internal defects. Pregnant mice fed a diet containing 10 micrograms/g zinc were orally dosed with 2.0 micrograms/g of 50% ethanol for 18 days of pregnancy. Fetuses from these dams presented with more fetal defects than fetuses from control dams. Analysis of maternal livers showed a significant effect of alcohol on liver magnesium and zinc. Changes in fetal heart zinc levels were the only significant tissue effect of alcohol in the fetus.

Inhibition of placental amino acid uptake in rats following acute and chronic ethanol exposure

The effects of acute and chronic maternal ethanol consumption on in vitro placental uptake of alpha-aminoisobutyric acid (AIB), cycloleucine, L-alanine (Ala), L-leucine (Leu), and L-lysine (Lys) were determined. Ethanol (4 g/kg. po) administered 2 hr prior to sacrifice, reduced (p less than 0.05) placental villous net uptake of cycloleucine and Ala by 29%. Prior chronic ethanol consumption depressed (p less than 0.05) placental uptake of AIB (38%), cycloleucine (45%), Ala (35%), Leu (25%), and Lys (34%). In vitro exposure of previously untreated villous fragments for 2 hr to 2 mg/ml of ethanol reduced (p less than 0.05) the net uptake of AIB and cycloleucine by 24% and 31%, respectively, whereas the minimum concentration of acetaldehyde required to cause a significant inhibition was 310 microM for AIB and 465 microM for cycloleucine. Ethanol (3 mg/ml) had no effect on AIB or cycloleucine net uptake if sodium was omitted from the incubation media. The efflux of AIB (10(-6)M) and cycloleucine (10(-6)M) from villous tissue was unaffected (p less than 0.05) by either ethanol (3 mg/ml) or acetaldehyde (600 microM) and obeyed first order kinetics. It was concluded that acute, and especially chronic, maternal ethanol consumption can depress the placental uptake of a variety of amino acids in the rat and, in the acute setting, the effect was on a sodium-dependent system involved in amino acid influx into placental cells.

Method of ethanol administration as a confounding factor in studies of fetal alcohol syndrome

Female Sprague-Dawley rats were fed a complete liquid diet containing either 5.5% ethanol (mean daily intake of about 9g of ethanol per kg body weight) or an isocaloric amount of dextrose (control group), with additional water available ad libitum. The diets were fed for four weeks prior to and throughout pregnancy. On day 20 of gestation cardiac output and blood flow to the the placenta, heart, kidneys and uterus were measured and plasma osmolality and muscle dry weight were determined. No significant differences were seen between alcohol and control groups with respect to litter size, fetal weight, maternal cardiac output, blood flow to the placenta or other organs, plasma osmolality, or muscle dry weight. This contrasts with previous experiments in which a similar quantity of alcohol (as % calories) was offered in drinking water (equivalent to a mean daily ethanol intake of 10g/kg body weight). Under those conditions fetal weight was reduced, blood flow to the placenta was reduced, and plasma osmolality and muscle dry weight were increased, indicating a moderate degree of dehydration. It is concluded that the effect of ethanol ingestion is influenced by the mode of administration of the ethanol. Dehydration may be a confounding factor in studies of animal models of fetal alcohol syndrome, although it is not possible to rule out a differential metabolic response to alcohol, depending on the mode of administration.

The synthesis of myelin and brain subcellular membrane proteins in the offspring of rats fed ethanol during pregnancy

Pregnant Long-Evans rats received either: (1) liquid diet containing 5.15% ethanol; (2) liquid diet pair fed to (1) for total calories; or (3) liquid diet ad libitum. These special diets were administered from the 5th through the 18th days of gestation. Dams received standard laboratory chow and water ad libitum before and after the test interval. Additional dams received standard chow and water throughout the study. Birth weights of offspring in the ethanol group were lower than for offspring of the pair-fed or control groups, and their subsequent growth lagged behind the other groups. Neonate deaths in the ethanol group outnumbered other deaths. Eye opening was delayed, and brain weights appeared low from 16 to 30 days postnatal age, The onset of myelin synthesis was delayed by several days; however, by 30 days of age, the rate of myelin synthesis and net accumulation was comparable to the offspring of pair-fed controls. Thus, the effect of ethanol on brain myelination in the offspring of subject females appears as a delay in myelin initiation and cannot be fully explained by caloric undernourishment. An unexpected observation involved offspring of females fed standard chow throughout the study. The brain myelin concentration in this group was lower than for any of the other groups, which may relate to the higher fat content of the liquids diets and/or the comparatively slow weight gain of pregnant rats on standard chow.