Effects of beer, wine, whiskey, and ethanol on pregnant rats and their offspring

Volume and type of alcohol during early pregnancy and the risk of miscarriage

BACKGROUND

Research on alcohol consumption during pregnancy and miscarriage spans over three decades, yet the relationship is still not well-understood.

OBJECTIVES

To assess the relationship between volume and type of alcohol consumed during pregnancy in relation to miscarriage.

METHODS

We utilized data from a population-based cohort study of pregnant women (n = 1061) of which 172 (16%) women had a miscarriage. Upon study entry, participants were asked about their alcohol consumption during pregnancy. Based on the average number of drinks per week, women were categorized into one of three categories: four or more drinks per week (n = 32, 3%), less than four drinks per week (n = 403, 38%), and no alcohol intake (n = 626, 59%). In addition, women were categorized by the type of alcohol beverage they consumed: beer only (n = 47, 4%), spirits only (n = 56, 5%), wine only (n = 160, 15%), or a combination of two or more types of alcohol (n = 172, 16%).

RESULTS

A significant increased risk of miscarriage (adjusted hazard ratio (aHR): 2.65; 95% confidence interval (CI): 1.38, 5.10) was found for women who drank four or more drinks a week. Our findings also suggest the relationship between alcohol intake during pregnancy and miscarriage is strongest for miscarriage occurring prior to 10 weeks of gestation. In addition, women who drank only spirits had more than a two-fold increased risk of miscarriage compared to women who abstained (aHR: 2.24; 95% CI: 1.32, 3.81). Conclusions/Importance: Future research assessing the factors that may contribute to an increased risk of miscarriage should consider the type of alcohol consumed.

Adverse reproductive effects of beer drinking

This short communication represents a systematic review of the literature about beer drinking during gestation. A Medline search was undertaken of articles based on the criterion that beer and pregnancy were in the abstract and central to the article. Manuscripts were to be published in English in peer review medical journals from 1981 to 2006. Beer is a commonly consumed alcoholic beverage among reproductive-age adults. Beer drinking males have an increased risk of contributing to pregnancy waste. Women consume beer before and after pregnancy recognition. Binge drinking appears to be a common drinking behavior, and those who binge drink have an increased risk of impaired fetal growth and offspring behavior. Beer consumption by lactating women might temporarily impair motor function of nursing infants. Evidence for potentiation of beer effects by congeners and by simultaneous use of substances of abuse is inconclusive.

Beer consumption in rats: the influence of ethanol content, food deprivation, and cocaine

A series of experiments examined various aspects of beer consumption in male Wistar rats. In the first experiment, rats were given home cage access to either beer or ethanol solutions under free access conditions. It was found that rats consumed greater amounts of moderate strength beer (2.7% ethanol by volume) or regular strength beer (5.0% ethanol) than equivalent dilute ethanol solutions in water. Consumption of 2.7% beer was greater than 5.0% beer and access to either beer, but not dilute ethanol, solutions caused substantial increases in total fluid intake per day. In the second experiment, individual rats given daily 30-min drink sessions consumed more 2.7% beer than 3.85% beer and more 3.85% than 5.0% beer. A "hangover" effect was evident after the first day of consumption of 5.0% beer with subsequent intake of this beer suppressed after high intake on first exposure. Intake of the low-strength beer approached intake of isocaloric (8.6%) sucrose solution. In a third experiment, a lick-based progressive ratio paradigm was implemented where rats had to emit progressively greater number of licks for a fixed volume (0.1 ml) of 2.7% beer or 8.6% sucrose. Using this paradigm, it was shown that food deprivation increased the motivation to consume beer and sucrose as shown by elevated break points (the highest ratio reached). Food deprivation also increased locomotor activity in the drinking environment. In contrast, cocaine (20 but not 10 mg/kg) caused a decrease in the break point for sucrose and beer, an effect probably mediated by the anorexic properties of the drug. It is concluded that rats will avidly consume beer, particularly of moderate alcohol content, but that such consumption may be mediated more by the nutritive and palatable characteristics of the beer rather than by the psychoactive effects of the alcohol it contains.

Low-to-moderate gestational alcohol use and intrauterine growth retardation, low birthweight, and preterm delivery

PURPOSE

Heavy drinking during pregnancy is an established risk factor for fetal alcohol syndrome and other adverse perinatal outcomes. However, there is still debate as to the effects of low-to-moderate drinking during pregnancy.

METHODS

This prospective investigation was based on 2714 singleton live births at Yale-New Haven Hospital during 1988-1992. Alcohol drinking during pregnancy was evaluated with respect to intrauterine growth retardation (IUGR), preterm delivery, and low birthweight.

RESULTS

Mild drinking, defined as > 0.10-0.25 oz of absolute alcohol per day, during the first month of pregnancy was associated with a protective effect on IUGR (OR, 0.39; 95% confidence interval (CI), 0.20-0.76). Overall, drinking during month 1 of pregnancy suggested a curvilinear effect on growth retardation, with consumption of > 1.00 oz of absolute alcohol per day showing increased risk. Drinking during month 7 was associated with a uniform increase in the odds of preterm delivery; the ORs were 2.88 (95% CI, 1.64-5.05) for light drinking and 2.96 (95% CI, 1.32-6.67) for mild-to-moderate alcohol consumption.

CONCLUSIONS

Differences in the risk estimates for IUGR and preterm delivery may indicate etiological differences that warrant further investigation of these outcomes and critical periods of exposure. Low birthweight is not a useful neonatal outcome for this exposure because it is a heterogeneous mix of preterm delivery and IUGR. Despite the observed protective effects of mild drinking on IUGR, the increased risk of preterm delivery with alcohol use supports a policy of abstinence during pregnancy.

Morphometric analysis of the postnatal mouse optic nerve following prenatal exposure to alcohol

Pregnant female mice were divided on day 12 post coitum into a control and an experimental group. The experimental group was given a single intraperitoneal dose of 0.015 ml/g body weight of 25% solution of alcohol in distilled water while the control group was exposed to a similar weight related dose of normal saline. The optic nerves were isolated from the offspring of both control and experimental groups at wk 2, 3 and 5 (i.e. during the juvenile period of postnatal development) and analysed by light and electron microscopy. Although in both groups the optic nerve grew in size rapidly during the period studied, the rate of growth in the experimental groups lagged behind that of the controls. The difference was initially significant but tailed off, so that by wk 5 it was no longer significant. The time of initial onset and progression of myelinogenesis in the optic nerve of alcohol exposed mice also lagged behind that of controls. In both groups the size distribution of the myelinated nerve fibres in the optic nerve was unimodal with a positive skewing for all ages. The spectrum of size distribution of the nerve fibres was, however, broader in controls than in the corresponding experimental groups. With increasing age the proportion of small and medium size fibres was greater in the experimental group than in the controls, while for the large diameter fibres the reverse was observed. It is suggested that this study may shed light on the teratogenic effect of 'binge' drinking during pregnancy and that it is the critical period when exposure occurs that is more important than the duration of administration.

Sexual orientation of male mouse offspring prenatally exposed to ethanol

Pregnant mice were intubated with either low (2 g/kg) or high (4 g/kg) dose of ethanol twice daily throughout the last third of the gestational period (from dg14 to dg18: gestational day; plug positive = dg 0). Ninety days after birth, the sexual orientation test was conducted on male offspring. This test was designed to observe a two-choice preference for either male or female partners in a setting in which the test animal could move freely between the two incentive compartments within which a stud male and an estrous female had been placed. We found that young adult males that had been exposed to ethanol prenatally have a decreased preference for the opposite sex and an increased preference for the same sex as a partner, although their physical development was apparently unaffected.

Tolerance to ethanol-induced hypothermia in adult rats following postnatal ethanol exposure

Rat pups of both genders were treated during the entire postnatal brain growth spurt (postnatal days 1-20) with ethanol (EE) utilizing an intragastric intubation technique. Two other groups of pups included isocaloric vehicle and handled control pups. Beginning on postnatal day 43 (TD1), and every seventh day subsequently (TD's 2, 3 and 4), the rats received an intraperitoneal dose of 2.2 g/kg ethanol. Their body temperatures were recorded at 0, 30, 60 and 90 minutes postinjection by use of a rectal probe. On the six days between measurements of ethanol-induced hypothermia, all rats were administered a daily dose of ethanol by intragastric intubation. Body growth of male and female pups was inhibited throughout the early treatment period. Body growth of adult females, but not males, was also depressed on TD's 1 and 2. Basal body temperature of EE male rats was selectively depressed at TD2, compared to the other groups. Although all groups showed tolerance to ethanol-induced hypothermia by TD2, there was a significant difference between males and females. Specifically, EE female rats showed a greater degree of tolerance when compared to EE males or control females.

Voluntary beer drinking by pregnant rats: offspring sensitivity to ethanol and preference for beer

Female Long-Evans rats were allowed voluntary access to beer, food and water for three weeks prior to mating and throughout gestation; and were compared to controls. Offspring were tested for sensitivity to ethanol and preference for beer at 29 and 85 days of age. Offspring of beer drinkers had long-term alterations in sensitivity to ethanol as adults, although rates of ethanol metabolism were unaffected. The nature of responsivity to ethanol as adults was sex-dependent. Male offspring of beer drinkers were delayed in maintaining baseline body temperature at 29 days with recovery at 85 days; and were tolerant to the hypothermic effects of ethanol at 29 and 85 days. Female offspring had prolonged latency to respond to pain and temperature; and were tolerant to the effects of ethanol on motor coordination at 29 and 85 days. Although preference of the offspring for beer was not affected by maternal beer drinking, the pattern of fluid intake by offspring of beer drinkers differed from controls.

Voluntary beer drinking by pregnant rats: offspring growth, development and behavior

A new model for voluntary beer drinking during gestation is presented. Female Long-Evans rats voluntarily drank 56 ml beer per day (pregestation) and 66 ml beer per day (gestation), resulting in an ethanol intake of 9.5 g/kg/day (pregestation) and 9.0 g/kg/day (gestation). Peak blood alcohol levels of dams were 192.5 mg/dl (pregestation) and 157 mg/dl (gestation). Body weights of male and female offspring of beer drinkers were greater than controls. Urinary pH levels were abnormally low at birth, and thymus/body weight ratios were high at birth. Abnormal spleen/body ratio and heart/body ratios were observed in 15- and 29-day-old female offspring of beer drinkers. No hyperactivity or developmental delays were observed. Male offspring of dams in the beer group were hypoactive on a few days of testing. Male and female offspring of beer drinking dams performed better than controls on some tests. This method for voluntary beer drinking by pregnant rats may be useful for identifying the subtle consequences of maternal beer drinking.

Preferential alcoholic embryopathy among contiguous siblings of Long-Evans rats

Ethanol exposure alters sex steroidogenesis and sexually dimorphic behaviors in rodent offspring. Contiguity to siblings of the same or opposite sex in utero also affects steroidogenesis and sexual dimorphism in rodents. The present study with Long-Evans rats shows that maternal exposure to ethanol during the critical period of rodent organogenesis preferentially affects body weights and increases malformations in offspring dependent on their in utero contiguity to siblings of the opposite sex.

An hypothesis regarding the origin of aneuploidy in man: indirect evidence from an experimental model

Recent studies have clearly demonstrated that aneuploidy may be induced in about 10 to 20% of oocytes and recently ovulated eggs when female mice are given an intragastric injection of a dilute solution of ethanol. Similar rates of aneuploidy have also been observed when recently ovulated eggs are briefly exposed in vitro to a dilute solution of ethanol in tissue culture medium. These findings are briefly reviewed, and observations made on the possible underlying mechanism of induction of chromosome malsegregation in the ethanol exposed groups. Attention is drawn to evidence from a wide range of studies on the effect of ethanol, acetaldehyde (its primary metabolite), and anaesthetics on cell division and chromosome segregation in an attempt to substantiate an hypothesis regarding the mode of action of these agents. In the light of this information, it is hypothesised that exposure to ethanol probably interferes with the normal functioning of the cytoskeletal elements of the spindle apparatus, or its precursor elements, during the first or second meiotic divisions. An attempt is also made to account for the very high incidence of aneuploid conceptuses in man, a high proportion of which are spontaneously aborted. It is hypothesised that exposure to ethanol and other spindle active agents during appropriate stages of oogenesis (in particular during the first meiotic division), and possibly also during spermatogenesis, may be important aetiological factors in a proportion of those cases of spontaneous abortion with a numerical chromosome anomaly for which no other obvious cause is recognised. If it is valid to extrapolate from these experimental findings to the clinical situation in man, it is suggested that attention should also be drawn to the potentially greater hazard to the conceptus which could result from maternal alcohol consumption at and shortly before conception.

The effects of high dose sporadic (binge) alcohol intake in mice

BALB/c and CBA/h mice were used to investigate the teratogenic effects of sporadic high doses of ethanol. Two consecutive days between days 8 and 11 of organogenesis were chosen on which to administer 0.5 ml of 20 percent ethanol by gavage. An additional group was similarly dosed for four consecutive days starting on the eighth day. All the mice were killed on day 18 of gestation and evidence of growth retardation and malformation in the offspring was sought by skeletal and soft tissue screening. The basic pharmacokinetics of ethanol intake were also investigated. The most marked effects of ethanol were an increase in resorptions, skeletal growth retardation and skeletal variants, however all appeared to be strain specific. The results confirm that ethanol is embryotoxic and suggest that animal models are appropriate for studying aspects of growth retardation.

Implication of the placenta in acetaldehyde-induced intrauterine growth retardation

Acetaldehyde (AcH) the proximal metabolite of ethanol was administered to pregnant CF rats intraperitoneally in single and triple doses (50, 75 and 100 mg/kg) on days 10, 11 and 12 of gestation and fetuses along with placentae were collected on day 21. Placentae were subjected to histological sectioning and the volume fractions of various zones of placenta were calculated using Weibels point counting techniques. There was no correlation between fetal weight and placental weight, but the fetal weight showed a positive correlationship with the percentage volume fraction of the labyrinthine zone suggesting that the reduction in the labyrinthine zone volume is probably responsible for intrauterine growth retardation following acetaldehyde maternal treatment.

Alcohol, alcoholism, and cancer

Certain types of cancer are clearly associated with alcohol abuse, although the role of ethanol in carcinogenesis--as a carcinogen, co-carcinogen, promoter, or "innocent bystander"--is not known with certainty. The impact of alcohol abuse on the management of the patient with cancer is also discussed.

Teratogenic effects of acetaldehyde in the rat

Acetaldehyde, the proximal metabolite of ethanol, was administered intraperitoneally in single and triple doses (50, 75, 100 mg/kg) to pregnant CF rats on days 10, 11 and 12 of gestation and fetuses were collected on day 21. Besides significant fetal resorptions, malformations were found which included edema, microcephaly, micrognathia, micromelia, hydrocephaly, exencephaly, hemorrhages etc. Somatometric measurements of fetuses (i.e. crown rump length, transumbilical distance and tail length) revealed significant growth retardation. Alizarin red-stained skeletal preparations showed considerable stunting. The placental weight and umbilical cord length were also significantly reduced. The close similarity of the pattern of acetaldehyde-induced fetal malformations with those resulting from maternal alcohol consumption during pregnancy is suggestive of the possible implication of acetaldehyde in the fetal alcohol syndrome.

Exposure of rats to alcohol in utero alters drug sensitivity in adulthood

Pregnant rats were intubated with alcohol (ethanol, 3 grams per kilogram) twice daily throughout gestation. Control animals received solutions of isocaloric sucrose. At birth, offspring were placed with untreated surrogate dams. Beginning at 6 months of age, the offspring were tested for their thermogenic responsiveness to various drugs and to cold. Prenatal exposure to alcohol resulted in tolerance to alcohol and cross-tolerance to pentobarbital and diazepam but did not affect responsiveness to cold. This pattern of effects suggest that prenatal exposure to alcohol produces specific long-term effects on the neural mechanisms underlying drug tolerance.