The role of maternal alcohol damage on ethanol teratogenicity in the rat

Involvement of mTOR, JNK and PI3K in the negative effect of ethanol and metformin on the human first-trimester extravillous trophoblast HTR-8/SVneo cell line

Our aim was to investigate the effect of two xenobiotics to which pregnant woman may be exposed, the drug of abuse ethanol (EtOH) (and its metabolite acetaldehyde (ACA)) and the therapeutic agent metformin (METF), on placentation-related processes in an extravillous trophoblastic (EVTs) cell line (HTR-8/SVneo cells). EtOH, ACA and METF (24 h) significantly reduced cell proliferation rates, culture growth, viability and migratory capacity of HTR-8/SVneo cells. Moreover, both EtOH (100 μM) and METF (1 mM) increased the apoptosis index and inhibited ³H-deoxy-D-glucose (³H-DG) and ³H-folic acid (³H-FA) uptake. mTOR, JNK and PI3K intracellular signaling pathways were involved in the effect of EtOH upon ³H-FA uptake and in the effect of METF upon cell viability, and mTOR and JNK in the effect of EtOH upon cell viability and ³H-DG uptake. We show that EtOH and METF have a detrimental effect in placentation-related processes of HTR-8/SVneo cells. Moreover, mTOR, JNK and PI3K appear to mediate some of these negative effects.

Detrimental effects of ethanol and its metabolite acetaldehyde, on first trimester human placental cell turnover and function

Fetal alcohol spectrum disorder (FASD) describes developmental issues from high maternal alcohol intake, which commonly results in fetal growth restriction and long term morbidity. We aimed to investigate the effect of alcohol and acetaldehyde, on the first trimester placenta, the period essential for normal fetal organogenesis. Normal invasion and establishment of the placenta during this time are essential for sustaining fetal viability to term. We hypothesise that alcohol (ethanol) and acetaldehyde have detrimental effects on cytotrophoblast invasion, turnover and placental function. Taurine is an important amino acid for neuronal and physiological development, and so, its uptake was assayed in cells and placental explants exposed to alcohol or acetaldehyde. First trimester villous explants and BeWo cells were treated with 0, 10, 20, 40 mM ethanol or 0, 10, 20, 40 µM acetaldehyde. The invasive capacity of SGHPL4, a first trimester extravillous cytotrophoblast cell line, was unaffected by ethanol or acetaldehyde (p>0.05; N = 6). The cells in-cycle were estimated using immunostaining for Ki67. Proliferating trophoblast cells treated with ethanol were decreased in both experiments (explants: 40% at 20 mM and 40 mM, p<0.05, N = 8–9) (cell line: 5% at 20 mM and 40 mM, p<0.05, N = 6). Acetaldehyde also reduced Ki67-positive cells in both experiments (explants at 40 µM p<0.05; N = 6) (cell line at 10 µM and 40 µM; p<0.05; N = 7). Only in the cell line at 20 µM acetaldehyde demonstrated increased apoptosis (p<0.05; N = 6). Alcohol inhibited taurine transport in BeWo cells at 10 mM and 40 mM (p<0.05; N = 6), and in placenta at 40 mM (p<0.05; N = 7). Acetaldehyde did not affect taurine transport in either model (P<0.05; N = 6). Interestingly, system A amino acid transport in placental explants was increased at 10 µM and 40 µM acetaldehyde exposure (p<0.05; N = 6). Our results demonstrate that exposure to both genotoxins may contribute to the pathogenesis of FASD by reducing placental growth. Alcohol also reduces the transport of taurine, which is vital for developmental neurogenesis.

Vehicle selection for nonclinical oral safety studies

INTRODUCTION

The development of poorly soluble or permeable new chemical entities within the pharmaceutical industry often requires the use of nonstandard enabling nonclinical oral formulations. Despite this, the toxicity profile of many commonly used nonclinical vehicles is poorly understood. This lack of data can lead to unexpected formulation-related effects being observed in critical oral safety studies.

AREAS COVERED

This article summarizes the key considerations for formulation selection for oral nonclinical safety studies, and provides a strategy for appropriate development-phase formulation selection. The industry's use of oral nonclinical vehicles is reviewed, based on data from the FDA's Orange Book. Finally, a summary of the repeat dose oral toxicity of commonly used vehicles is presented.

EXPERT OPINION

The rapid identification of a suitable nonclinical oral formulation is a critical step in small-molecule drug development. In order to maintain flexibility and address the needs of a diverse set of new chemical entities (NCEs) with widely varying physiochemical properties, a "tool belt" of multiple oral formulations is recommended. The appropriate formulation is identified based on the goals of the study, as well as exposure required, species, duration and therapeutic indication of the NCE.

The effects of alcohol on fetal development

Prenatal exposure to alcohol has profound effects on many aspects of fetal development. Although alterations of somatic growth and specific minor malformations of facial structure are most characteristic, the effects of alcohol on brain development are most significant in that they lead to substantial problems with neurobehavioral development. Since the initial recognition of the fetal alcohol syndrome (FAS), a number of important observations have been made from studies involving both humans and animals. Of particular importance, a number of maternal risk factors have been identified, which may well be of relevance relative to the development of strategies for prevention of the FAS as well as intervention for those who have been affected. These include maternal age >30 years, ethnic group, lower socioeconomic status, having had a previously affected child, maternal under-nutrition, and genetic background. The purpose of this review is to discuss these issues as well as to set forth a number of questions that have not adequately been addressed relative to alcohol's effect on fetal development. Of particular importance is the critical need to identify the full spectrum of structural defects associated with the prenatal effects of alcohol as well as to establish a neurobehavioral phenotype. Appreciation of both of these issues is necessary to understand the full impact of alcohol on fetal development.

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.

Efeitos de bebidas alcóolicas em mães lactantes e suas repercussões na prole

Foi feita uma revisão de estudos sobre os efeitos ocasionados pelo consumo de bebidas alcóolicas por lactantes, analisando os múltiplos distúrbios metabólicos, nutricionais e psicológicos evidenciados no organismo materno e dos recém-nascidos. É enfatizada a necessidade de orientações clínico-nutricionais nos serviços de pré-natal e puericultura acerca dos riscos da ingestão de bebidas alcoólicas em qualquer quantidade, por mães no período de gestação e aleitamento.

Impairment of pyruvate dehydrogenase activity by acetaldehyde

The facial features that are characteristic of fetal alcohol syndrome (FAS) are strikingly similar to those seen in pyruvate dehydrogenase (PDH) deficiency. Furthermore, alcohol-induced central nervous system insult results in midline anomalies such as agenesis of the corpus callosum, which has also been described in several metabolic diseases, including PDH deficiency. The purpose of this work was to examine the effect of acetaldehyde on PDH in vitro. The activity of PDH was measured in the presence of acetaldehyde (10 microM-1 mM) by measuring the formation of the reduced form of nicotinamide-adenine dinucleotide at 340 nm. Pyruvate dehydrogenase was separated by using the sodium dodecyl sulfate-polyacrylamide gel electrophoresis technique after incubation with [1,2-(14)C]-acetaldehyde to detect the formation of covalent adducts autoradiographically. The effect of acetaldehyde on the phosphorylation of the complex was also determined autoradiographically after incubating of PDH with (32)P-adenosine triphosphate. The results of this study show that acetaldehyde impairs PDH activity by a mixed inhibition type mechanism (Kic=62.4+/-25.7 microM, Kiu=225+/-68 microM), which is not a result of the formation of covalent adducts with PDH, nor of a stimulation of phosphorylation or inactivation of the complex. Because PDH levels are low throughout development and that the competition between pyruvate and acetaldehyde may be enhanced due to ethanol-induced lowering of ambient pyruvate concentrations, we conclude that impairment of PDH may have a significant effect on the developing fetus.

The role of acetaldehyde in pregnancy outcome after prenatal alcohol exposure

It is not known why some heavy-drinking women give birth to children with alcohol-related birth defects (ARBD) whereas others do not. The objective of this study was to determine whether the frequency of elevated maternal blood acetaldehyde levels among alcoholics is in the range of ARBD among alcoholic women. MEDLINE was searched from 1980 to 2000 using the key words acetaldehyde, pharmacokinetics, and alcoholism for controlled trials reporting blood or breath acetaldehyde levels in alcoholics and nonalcoholics. Separately, using the key words fetal alcohol syndrome, epidemiology, prevalence, incidence, and frequency, articles were identified reporting ARBD incidences among the offspring of heavy drinkers. Of 23 articles reporting acetaldehyde levels in alcoholics, four met the inclusion criteria. Forty-three studies reported on the rate of ARBD in heavy drinkers, and 14 were accepted. Thirty-four percent of heavy drinkers had a child with ARBD, and 43% of chronic alcoholics had high acetaldehyde levels. The similar frequencies of high acetaldehyde levels among alcoholics and the rates of ARBD among alcoholic women provide epidemiologic support to the hypothesis that acetaldehyde may play a major role in the cause of ARBD.

Prenatal exposure to ethanol in rats: effects on liver energy level and antioxidant status in mothers, fetuses, and newborns

The fetal alcohol syndrome is a clinical condition that affects newborns from alcoholic mothers. It is not clear, however, whether ethanol consumption during gestation can affect liver functions of fetuses and newborns. In this study, we aimed to assess the effects of ethanol administration on body weight, liver energy level, and antioxidant status of mothers, fetuses, and newborns. Pregnant rats were exposed to ethanol during the third week of gestation. Body weight, survival, and liver concentration of gluthatione (GSH) and adenosintriphosphate (ATP) were measured. No differences were observed in body weight or in liver ATP and GSH between mothers exposed to ethanol and control animals. Conversely, fetuses from rats exposed to ethanol showed a marked decrease in GSH, ATP, and body weight when compared to those from control rats. Newborns exposed prenatally to ethanol were no different from those born to control mothers. This study suggests that an amount of ethanol that is not sufficient to determine a significant effect on mothers can, nevertheless, cause a marked decrease in growth and in liver antioxidant and energy status in fetuses. These parameters, however, return to control value one week after ethanol discontinuation.

Ethanol effects on postimplantation rat embryos: influence of zinc and methionine

Organic zinc salts and thiols, administered simultaneously, protect mice synergistically against ethanol toxicity. Moreover, chronic ethanol consumption could affect the bioavailability of zinc and amino acids such as methionine. This could result in impaired embryonic growth and development. The influence of zinc and methionine on ethanol-induced embryopathy was investigated by simultaneous administration of ethanol, zinc and methionine to pregnant rats from gestational day 6 through 12. Ethanol was given in the form of a liquid diet; zinc administered i.p., and methionine was given by gavage. The ethanol group received the liquid ethanol diet; the ethanol + zinc and methionine group received the ethanol diet, zinc and methionine; and the pair-fed control group was given an isocaloric control diet. On day 12 of gestation, embryos of ethanol alone treated rats revealed a significantly reduced embryonic protein content, number of somites, crown-rump length, and lower morphological score (embryological differentiation) compared to the pair-fed control embryos. However, embryonic growth and developmental parameters in the ethanol, zinc and methionine treated group were not significantly different from those exposed to ethanol alone.

Maternal risk factors in fetal alcohol syndrome: provocative and permissive influences

We present an hypothesis integrating epidemiological, clinical case, and basic biomedical research to explain why only relatively few women who drink alcohol during pregnancy give birth to children with alcohol-related birth defects (ARBDs), in particular, Fetal Alcohol Syndrome (FAS). We argue that specific sociobehavioral risk factors, e.g., low socioeconomic status, are permissive for FAS in that they provide the context for increased vulnerability. We illustrate how these permissive factors are related to biological factors, e.g., decreased antioxidant status, which in conjunction with alcohol, provoke FAS/ARBDs in vulnerable fetuses. We propose an integrative heuristic model hypothesizing that these permissive and provocative factors increase the likelihood of FAS/ARBDs because they potentiate two related mechanisms of alcohol-induced teratogenesis, specifically, maternal/fetal hypoxia and free radical formation.

Protective influence of zinc against the deleterious effects of ethanol in postimplantation rat embryos in vivo

Zinc is a cofactor for alcohol dehydrogenase, the ethanol metabolizing enzyme. Ethanol-induced zinc deficiency could decrease ethanol metabolism, resulting in an increase in circulating and tissue ethanol levels. This may cause retardation in embryonic growth and development. The influence of zinc supplementation on ethanol-induced embryopathy was studied by the simultaneous administration of ethanol and zinc to pregnant SD rats from gestational day 6 through 12. Ethanol was given in the form of a liquid diet and zinc was administered intraperitoneally. The ethanol group received the liquid ethanol diet, the ethanol+zinc group received the ethanol diet and zinc and the pair-fed control group was given an isocaloric control diet. Embryos were explanted from all groups on day 12 of gestation. Embryos of animals treated with ethanol alone exhibited a significantly higher rate of resorption and retarded embryonic growth and development compared to the pair-fed control group. The embryonic protein content, crown-rump length, the number of somites and embryonic morphological score were significantly reduced in the ethanol-treated group. In addition, serum zinc concentration also was lower. Compared to embryos from ethanol-treated animals, embryos from ethanol+zinc treated animals showed a significantly higher number of somites; cardiac development was more advanced and embryonic protein content was higher. These observations suggest that zinc supplementation of ethanol-treated pregnant rats may have some protective influence against the embryopathic effects of ethanol.

Developmental changes in the optic nerve related to ethanol consumption in pregnant rats: analysis of the ethanol-exposed optic nerve

Visual impairment is one of the most common ophthalmic abnormalities in fetal alcohol syndrome. Pathologic changes in optic nerve development related to alcohol consumption could be involved in this dysfunction. In order to assess the consequences of pre- and postnatal exposure to alcohol on the developing optic nerve, we administered an ethanol-containing liquid diet (5% w/v) before and during gestation and throughout lactation to rats and their offspring. A group of control animals were kept on a pair-fed isocaloric diet. The optic nerves were obtained at key stages from fetuses (21 days of gestation) and pups (4, 7, 14, 21 and 28 postnatal days). Samples of the optic nerve cross-section, behind the eyeball, were processed for analysis of gliogenesis, myelinogenesis, axonal growth, and remodelling events, using light and electron microscopy. Qualitative, morphometric, and immunocytochemical analyses, alternatively using anti-GFAP and anti-MBP antibodies, were carried out. Optic nerve cross-sections from prenatal and postnatal alcohol-exposed rats showed a decrease in size. Ultrastructural alterations and retarded development in macroglial cells, optic axons, and myelin sheath were also observed. The most prominent abnormalities were: damage of cytoplasmic organelles and disorganization of cytoskeleton in astrocytes; a decrease in free ribosome density and nuclear membrane inclusions in oligodendrocytes; and fragmentation of lamellae, aberrant myelin sheaths and intralamellar inclusions in myelin. These findings suggest that alcohol abuse during pregnancy is teratogenic to the optic nerve and closely related to the altered visual function.

Effects of prenatal alcohol exposure in mice: influence of an ADH inhibitor and a chronic inhalation study

In order to examine the effects of an alcohol dehydrogenase inhibitor on the embryotoxic effects of ethanol, pregnant ICR mice were treated with 100 mg/kg pyrazole prior to ethanol injection. I.p. treatment with 2 or 4 g/kg ethanol on day 7 of gestation increased the prenatal mortality rate and produced external and skeletal malformations in the offspring, and the embryotoxic effects were potentiated by pyrazole pretreatment, suggesting that ethanol rather than its metabolites is mainly responsible for the embryotoxicity. In the second experiment, we housed pregnant mice in an ethanol-vapor box for 3 or 6 days in order to examine the effects of prolonged low level exposure to alcohol. The maternal blood alcohol concentration was maintained approximately 0.03 mg/mL during inhalation. The inhalation treatment with ethanol increased the prenatal mortality rate, although teratogenicity was not shown.

Histomorphometric analysis of the epiphyseal growth plate in rats after prenatal alcohol exposure

We studied the effect of prenatal alcohol exposure on growth in the proximal tibial growth plate in 0- and 15-day-old rats, using histomorphometric methods. Body weight and tibial length were reduced in all alcohol-exposed rats. In 15-day-old rats, these parameters were lower than in the 15-day-old controls, thus showing a persistence of the effects of ethanol. The proximal tibial growth plate showed alterations, principally in 15-day-old rats. The most notable of these was a decrease in growth plate height produced by a significant reduction in hypertrophic zone height. Likewise, there were fewer cells in this zone in alcohol-exposed rats than in controls. This work shows that prenatal ethanol exposure induces growth retardation which may be due to growth plate alterations that might reflect impaired cell function.

Prenatal exposure to ethanol alters plasma membrane glycoproteins of astrocytes during development in primary culture as revealed by concanavalin A binding and 5'-nucleotidase activity

We have investigated the effect of prenatal exposure to ethanol on the extent of binding and surface distribution of the lectin concanavalin A (con A) on rat cortical astrocytes during the periods of proliferation and differentiation in primary culture. The enzymatic activity of the plasma membrane glycoprotein 5'-nucleotidase was also assessed. The cells were obtained from control fetuses (no exposure to ethanol) and from fetuses prenatally exposed to ethanol. The main findings were: 1) both proliferating and differentiating control astrocytes showed two distinct types of surface con A receptors that could correspond to high- and low-affinity binding sites; 2) the extent of con A binding was greater in mature than in proliferating control cells; 3) the distribution of con A on cell surface components changed with differentiation; 4) the activity of 5'-nucleotidase showed a substantial increment during the period of differentiation; and 5) prenatal exposure to ethanol clearly decreased the ability of astrocytes to bind con A, altered the surface distribution of the receptors for this lectin, and decreased the activity of 5'-nucleotidase. These effects were more marked in proliferating cells. In conclusion, it is shown that the extent of con A labeling and the activity of 5'-nucleotidase in astrocytes are dependent on the stage of cell differentiation and that prenatal exposure to ethanol alters the plasma membrane structure of these cells during development.

Ethanol alters astrocyte development: a study of critical periods using primary cultures

Using astrocytes obtained from 21-day-old rat fetuses, in primary culture, we have analyzed the effect of prenatal alcohol consumption on DNA and protein synthesis of astrocytes during their development. The variation in sensitivity of astrocytes to ethanol "in vitro" during the proliferation and maturation periods was also assessed. Control astrocytes showed peaks of DNA and protein synthesis at 8 and 15 days, respectively. A significant decrease in both DNA and protein synthesis was found in astrocytes from fetuses prenatally exposed to ethanol. This effect on DNA synthesis was also observed when control astrocytes were exposed to ethanol (100 mM) "in vitro" during the entire culture period. The effects on astrocytes of short term (48h) exposure to ethanol during the proliferation or differentiation periods on the above mentioned parameters and on the cell cycle as well as the possible recovery from these effects were also evaluated. Decreases in DNA and protein synthesis were found in both periods. However, DNA synthesis and content were more affected in astrocytes exposed to ethanol during the proliferation period. This effect correlates with an accumulation of cells in the G0/G1 phase of the cell cycle. On the other hand, when cells exposed to ethanol were cultured in alcohol-free medium to assess recovery, only cells exposed to ethanol during days 4 to 6 still showed DNA ethanol-induced effects at 21 days. In conclusion, our results show that ethanol consumption during gestation induces serious damage to cortical astrocyte progenitor cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Prenatal exposure to ethanol alters the synthesis and glycosylation of proteins in fetal hepatocytes

In the present work we have studied the effect of prenatal exposure to alcohol on the synthesis, glycosylation, and transport of proteins in fetal hepatocytes isolated from 21-day-old fetuses derived from control and chronic alcoholic rats. Protein synthesis was evaluated both in a cell-free system and in hepatocytes after (35S)methionine and (3H)leucine incorporation, respectively. Glycosylation was assessed using (3H)mannose and (3H)galactose as precursors. Protein synthesis was significantly decreased in treated hepatocytes. In control hepatocytes, quantitative electron microscope autoradiography showed that both (3H)leucine and (3H)mannose incorporation occur first in the rough endoplasmic reticulum (rER). Later the silver grains appeared over the Golgi apparatus, and, finally there was a transport towards the cell periphery. After pulse, silver grains corresponding to (3H)galactose incorporation appeared over the Golgi apparatus. The label then moved to the hepatocyte periphery. Alcohol treated hepatocytes showed a retention of grains over the Golgi apparatus with a diminution in the label at the cell periphery. These results indicate that prenatal exposure to alcohol induces a decrease in the synthesis of proteins in the hepatocyte as well as an alteration in the process of glycosylation and/or transport of secretory proteins.

Blood alcohol concentration and severity of microencephaly in neonatal rats depend on the pattern of alcohol administration

A rat model of third trimester fetal alcohol exposure was used to examine how the pattern of administration of a daily alcohol dose influences the pattern of blood alcohol concentrations (BACs) and the severity of brain growth restriction. Four groups of rats were artificially reared from postnatal days 4 to 10. Three of the groups received an equivalent daily dose of alcohol (6.6 g/kg/day) but in different daily patterns. To one group, the dose was administered continuously in a 2.5% (v/v) solution; in two other groups, the dose was condensed into either 7.5% or 15.0% (v/v) solutions. A fourth group (gastrostomy controls) received a formula containing maltose-dextrin, which was isocaloric to the 2.5% alcohol solution. BACs were determined twice daily at times designed to estimate the daily peak and minimum BACs. The rats were killed on postnatal day 10 and total brain weights, cerebellar weights and brainstem weights were measured. In each of the three groups given alcohol, the maximum BAC occurred on the afternoon of postnatal day 6. Thereafter, daily peak BAC declined progressively. The more concentrated the pattern of alcohol administration, the higher was the maximum BAC achieved and the more severe was the interference with brain growth. While the group receiving the alcohol dose in small continuous fractions (2.5%) did not exhibit any significant microencephaly, relative to gastrostomy controls, the groups receiving the dose in more concentrated forms (7.5% and 15.0%) exhibited significant brain growth restriction (reduced 19% and 31%, respectively, relative to controls).(ABSTRACT TRUNCATED AT 250 WORDS)