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

Prenatal alcohol exposure and attention-deficit/hyperactivity disorder independently predict greater substance use in young adulthood

BACKGROUND

The degree to which prenatal alcohol exposure (PAE) may influence alcohol and drug use in adulthood is difficult to determine. That is because PAE is highly correlated with environmental factors, including low socioeconomic status and exposure to parental drinking, and with behavioral problems, such as, attention-deficit/hyperactivity disorder (ADHD), which are correlated with alcohol use and abuse.

METHODS

Participants were 121 young adults from our Detroit Longitudinal Cohort study. Mothers were recruited during pregnancy and interviewed about their alcohol consumption using a timeline follow-back procedure. At 19 years, their offspring were interviewed regarding current and past use of alcohol, cigarettes, and other illicit drugs.

RESULTS

PAE was associated with greater alcohol, cannabis, and cigarette use. PAE, assessed using overall alcohol intake during pregnancy and alcohol dose per occasion, was associated with larger quantities of alcohol per occasion and greater alcohol tolerance in early adulthood. These effects persisted after control for demographic background, sex, age and education of participant, home environment, other prenatal drug exposure, and postnatal alcohol and drug use by the primary caregiver. Whereas ADHD predicted average alcohol consumed/month during young adulthood, PAE predicted alcohol dose/drinking occasion, and the effect on dose/occasion was not mediated by ADHD.

CONCLUSIONS

The effects of PAE on alcohol and cannabis use in young adulthood are not attributable to being reared in an environment that is socioeconomically disadvantaged or in one in which there is extensive maternal drinking. Furthermore, PAE was related to enhanced alcohol tolerance in young adults, a risk factor for alcohol use disorder later in life. Although ADHD was associated with greater alcohol consumption in early adulthood, it did not mediate the effect of PAE on offspring's alcohol use.

Ethanol's disruptive effects upon early breathing plasticity and blood parameters associated with hypoxia and hypercapnia

Early ethanol exposure affects respiratory neuroplasticity; a risk factor associated with the Sudden Infant Death Syndrome. High and chronic ethanol doses exert long-lasting effects upon respiratory rates, apneic episodes and ventilatory processes triggered by hypoxia. The present study was performed in 3-9-day-old rat pups. Respiratory processes under normoxic and hypoxic conditions were analyzed in pups intoxicated with different ethanol doses which were pre-exposed or not to the drug. A second major goal was to examine if acute and/or chronic early ethanol exposure affects blood parameters related with hypercapnic or hypoxic states. In Experiment 1, at postnatal day 9, animals previously treated with ethanol (2.0 g/kg) or vehicle (0.0 g/kg) were tested sober or intoxicated with 0.75, 1.37 or 2.00 g/kg ethanol. The test involved sequential air conditions defined as initial normoxia, hypoxia and recovery normoxia. Motor activity was also evaluated. In Experiment 2, blood parameters indicative of possible hypoxic and hypercapnic states were assessed as a function of early chronic or acute experiences with the drug. The main results of Experiment 1 were as follows: i) ethanol's depressant effects upon respiratory rates increased as a function of sequential treatment with the drug (sensitization); ii) ethanol inhibited apneic episodes even when employing the lowest dose at test (0.75 g/kg); iii) the hyperventilatory response caused by hypoxia negatively correlated with the ethanol dose administered at test; iv) ventilatory long-term facilitation (LTF) during recovery normoxia was observed in pups pre-exposed to the drug and in pups that received the different ethanol doses at test; v) self-grooming increased in pups treated with either 1.37 or 2.00 g/kg ethanol. The main result of Experiment 2 indicated that acute as well as chronic ethanol exposure results in acidosis-hypercapnia. The results indicate that early and brief experiences with ethanol are sufficient to affect different respiratory plasticity processes as well as blood biomarkers indicative of acidosis-hypercapnia. An association between the LTF process and the acidosis-hypercapnic state caused by ethanol seems to exist. The mentioned experiences with the drug are sufficient to result in an anomalous programming of respiratory patterns and metabolic conditions.

Unraveling the molecular mechanisms involved in alcohol intake and withdrawal in adolescent mice exposed to alcohol during early life stages

Alcohol interferes with foetal development and prenatal alcohol exposure can lead to adverse effects known as foetal alcohol spectrum disorders. We aimed to assess the underlying neurobiological mechanisms involved in alcohol intake and withdrawal in adolescent mice exposed to alcohol during early life stages, in discrete brain areas. Pregnant C57BL/6 female mice were exposed to binge alcohol drinking from gestation to weaning. Subsequently, alcohol seeking and taking behaviour were evaluated in male adolescent offspring, as assessed in the two-bottle choice and oral self-administration paradigms. Brain area samples were analysed to quantify AMPAR subunits GluR1/2 and pCREB/CREB expression following alcohol self-administration. We measured the expression of mu and kappa opioid receptors both during acute alcohol withdrawal (assessing anxiety alterations by the EPM test) and following reinstatement in the two-bottle choice paradigm. In addition, alcohol metabolism was analysed by measuring blood alcohol concentrations under an acute dose of 3 g/kg alcohol. Our findings demonstrate that developmental alcohol exposure enhances alcohol intake during adolescence, which is associated with a decrease in the pCREB/CREB ratio in the hippocampus, prefrontal cortex and striatum, while the GluR1/GluR2 ratio showed a decrease in the hippocampus. Moreover, PLAE mice showed behavioural alterations, such as increased anxiety-like responses during acute alcohol withdrawal, and higher BAC levels. No significant changes were identified for mu and kappa opioid receptors mRNA expression. The current study highlights that early alcohol exposed mice increased alcohol consumption during late adolescence. Furthermore, a diminished CREB signalling and glutamatergic neuroplasticity are proposed as underpinning neurobiological mechanisms involved in the sensitivity to alcohol reinforcing properties.

Neonatal alcohol exposure augments voluntary ethanol intake in the absence of potentiated anxiety-like behavior induced by chronic intermittent ethanol vapor exposure

Individuals fetally exposed to alcohol have a disproportionate risk for developing lifetime alcohol dependence, an association that may be confounded by the presence of comorbid conditions, such as anxiety. Anxiety is also observed following fetal alcohol exposure and is known to exacerbate ethanol consumption, highlighting the utility of animal models to assess this relationship. The present study evaluated the impact of third-trimester equivalent ethanol exposure on ethanol consumption and anxiety-like, marble burying behavior in adult, male C57BL/6 mice following exposure to chronic intermittent ethanol vapor, proposed to model dependence. Neonatal mice (P5-6, 2.5-3.0 g) were administered one injection of saline or ethanol (2.5 g/kg, subcutaneously [s.c.]). Pre-vapor marble burying and limited-access two-bottle choice ethanol intake (15% v/v, 2 h) were comparable in adults (8 weeks of age) across neonatal treatment groups. Five consecutive drinking sessions were repeated 72 h after each weekly ethanol vapor exposure procedure for a total of five vapor/drinking cycles. Consistent with prior research, an increase in voluntary ethanol drinking was observed in vapor-exposed, neonatal saline-treated mice throughout the study starting after the second vapor cycle compared to both air-exposed control groups. In neonatal ethanol-treated mice, this increase in ethanol intake and preference following vapor exposure was accelerated, being observed after the first vapor cycle, and observed at an augmented level compared to vapor-exposed, neonatal saline-treated mice and air controls for both neonatal conditions. Conversely, marble burying was enhanced equivalently in vapor-exposed mice from either neonatal treatment group relative to their respective air-exposed controls. These data recapitulate clinical observations of enhanced sensitivity for alcohol dependence following developmental alcohol exposure, which may reflect enhanced motivational drive rather than potentiated negative affect. The present model will facilitate the future exploration of mechanisms that underlie increased risk for alcohol use after early developmental exposure.

Effects of prenatal alcohol and cigarette exposure on offspring substance use in multiplex, alcohol-dependent families

BACKGROUND

Prenatal exposures to alcohol, cigarettes, and other drugs of abuse are associated with numerous adverse consequences for affected offspring, including increased risk for substance use and abuse. However, maternal substance use during pregnancy appears to occur more often in those with a family history of alcohol dependence. Utilizing a sample that is enriched for familial alcohol dependence and includes controls selected for virtual absence of familial alcohol dependence could provide important information on the relative contribution of familial risk and prenatal exposures to offspring substance use.

METHODS

A sample of multigenerational families specifically ascertained to be at either high or low risk for developing alcohol dependence (AD) provided biological offspring for a longitudinal prospective study. High-risk families were selected based on the presence of 2 alcohol-dependent sisters. Low-risk families were selected on the basis of minimal first and second-degree relatives with AD. High-risk (HR = 99) and Low-risk offspring (LR = 110) were assessed annually during childhood and biennially in young adulthood regarding their alcohol, drug, and cigarette use. At the first childhood visit, mothers were interviewed concerning their prenatal use of substances.

RESULTS

High-risk mothers were more likely to use alcohol, cigarettes, and other drugs during pregnancy than low-risk control mothers, and to consume these substances in greater quantities. Across the sample, prenatal exposure to alcohol was associated with increased risk for both offspring cigarette use and substance use disorders (SUD), and prenatal cigarette exposure was associated with increased risk for offspring cigarette use. Controlling for risk status by examining patterns within the HR sample, prenatal cigarette exposure remained a specific predictor of offspring cigarette use, and prenatal alcohol exposure was specifically associated with increased risk for offspring SUD.

CONCLUSIONS

Women with a family history of SUD are at increased risk for substance use during pregnancy. Both familial loading for alcohol dependence and prenatal exposure to alcohol or cigarettes are important risk factors in the development of offspring substance use. An inadequate assessment of family history may obscure important interactions between familial risk and prenatal exposures on offspring outcomes.

Adolescents' use of alcohol, tobacco and illicit drugs in relation to prenatal alcohol exposure: modifications by gender and ethnicity

AIMS

The study aimed to investigate (a) the association between low to moderate prenatal alcohol exposure (PAE) and the use of alcohol, tobacco and illicit drugs in adolescence and (b) whether the associations are modified by gender and ethnicity.

METHODS

The subjects of the study were 5922 children and adolescents, aged from 11 to 17 years, enrolled in the cross-sectional German Health Interview and Examination Survey for Children and Adolescents (the KiGGS study). Information on PAE is based on parental self-report questionnaires. Use of alcohol, tobacco and illicit drugs was assessed through self-report questionnaires for adolescents.

RESULTS

Low to moderate PAE was associated with an increased risk of drinking alcohol (adjusted odds ratio (OR) 1.73, 95% confidence interval (CI) 1.34, 2.18) and also of illicit drug use (adjusted OR 1.62, 95% CI 1.23, 2.14). The associations between PAE and the use of alcohol, tobacco and illicit drugs differed according to gender and ethnicity. Gender-stratified analyses resulted in adverse effects of PAE on drinking alcohol, smoking and illicit drug use in females; however, in German males, the associations disappeared. Stronger associations between PAE and the outcome measures were found in non-Germans.

CONCLUSIONS

Our findings indicate that low to moderate levels of maternal alcohol intake during pregnancy are a risk factor for use of alcohol, tobacco and illicit drugs by the offspring, with stronger associations in females and non-Germans.

Prenatal ethanol (EtOH) exposure alters the sensitivity of the adult dentate gyrus to acute EtOH exposure

BACKGROUND

Prenatal ethanol (EtOH) exposure results in a spectrum of structural, cognitive, and behavioral abnormalities, collectively termed "fetal alcohol spectrum disorders" (FASDs). The hippocampal formation, an area of the brain strongly linked with learning and memory, is particularly vulnerable to the teratogenic effects of EtOH. Prenatal EtOH exposure can lead to long-lasting impairments in the ability to process spatial information, as well as produce long-lasting deficits in the ability of animals to exhibit long-term potentiation (LTP), a biological model of learning and memory processing. These deficits also have the ability to facilitate EtOH and/or other drug abuse later in life. This study sought to determine prenatal EtOH exposure altered the effects of acute EtOH application on synaptic plasticity.

METHODS

Prenatal EtOH exposure was modeled using a liquid diet where dams were given 1 of 3 diets: (i) a liquid diet containing EtOH (35.5% EtOH-derived calories), (ii) a liquid diet, isocaloric to the EtOH diet, but with maltose-dextrin substituting for the EtOH-derived calories, and (iii) an ad libitum diet of standard rat chow. Extracellular recordings from transverse brain slices (350 μm) prepared from 50- to 70-day-old rats, following prenatal EtOH exposure (gestational day 1 to 21). LTP was examined in the dentate gyrus following acute EtOH exposure (0, 20, or 50 mM) in these slices.

RESULTS

Prenatal EtOH exposure attenuated LTP in the adult dentate gyrus. In control offspring, acute application of EtOH in adulthood attenuated (20 mM) or blocked (50 mM) LTP. Conversely, the effect of acute EtOH application on LTP was not as pronounced in prenatal EtOH offspring.

CONCLUSIONS

Prenatal EtOH exposure alters the sensitivity of the adult dentate gyrus to acute EtOH application producing a long-lasting tolerance to the inhibitory effects of EtOH. This decreased sensitivity may provide a mechanism promoting the formation of drug-associated memories and help explain the increased likelihood of developing an alcohol dependency often observed in individuals with FASDs.

Prenatal ethanol exposure increases ethanol intake and reduces c-Fos expression in infralimbic cortex of adolescent rats

Prenatal ethanol exposure significantly increases later predisposition for alcohol intake, but the mechanisms associated with this phenomenon remain hypothetical. This study analyzed (Experiment 1) ethanol intake in adolescent inbred WKAH/Hok Wistar rats prenatally exposed to ethanol (2.0g/kg) or vehicle, on gestational days 17-20. Subsequent Experiments (2, 3 and 4) tested several variables likely to underlie the effect of gestational ethanol on adolescent ethanol preference, including ethanol-induced locomotor activation (LMA), ethanol-induced emission of ultrasonic vocalizations (USVs) after exposure to a rough exteroceptive stimulus, and induction of the immediate early gene C-fos in brain areas associated with processing of reward stimuli and with the retrieval and extinction of associative learning. Prenatal ethanol induced a two-fold increase in ethanol intake. Adolescents exhibited significant ethanol-induced LMA, emitted more aversive than appetitive USVs, and postnatal ethanol administration significantly exacerbated the emission of USVs. These effects, however, were not affected by prenatal ethanol. Adolescents prenatally exposed to ethanol as fetuses exhibited reduced neural activity in infralimbic cortex (but not in prelimbic cortex or nucleus accumbens core or shell), an area that has been implicated in the extinction of drug-mediated associative memories. Ethanol metabolism was not affected by prenatal ethanol. Late gestational exposure to ethanol significantly heightened drinking in the adolescent offspring of an inbred rat strain. Ethanol-induced LMA and USVs were not associated with differential ethanol intake due to prenatal ethanol exposure. Prenatal ethanol, however, altered basal neural activity in the infralimbic prefrontal cortex. Future studies should analyze the functionality of medial prefrontal cortex after prenatal ethanol and its potential association with predisposition for heightened ethanol intake.

Prenatal ethanol exposure leads to greater ethanol-induced appetitive reinforcement

Prenatal ethanol significantly heightens later alcohol consumption, but the mechanisms that underlie this phenomenon are poorly understood. Little is known about the basis of 'this effect of prenatal ethanol on the sensitivity to ethanol's reinforcing effects. One possibility is that prenatal ethanol exposure makes subjects more sensitive to the appetitive effects of ethanol or less sensitive to ethanol's aversive consequences. The present study assessed ethanol-induced second-order conditioned place preference (CPP) and aversion and ethanol-induced conditioned taste aversion (CTA) in infant rats prenatally exposed to ethanol (2.0 g/kg) or vehicle (water) or left untreated. The involvement of the κ opioid receptor system in ethanol-induced CTA was also explored. When place conditioning occurred during the ascending limb of the blood-ethanol curve (Experiment 1), the pups exposed to ethanol in utero exhibited greater CPP than untreated controls, with a shift to the right of the dose-response curve. Conditioning during a later phase of intoxication (30-45 min post-administration; Experiment 2) resulted in place aversion in control pups exposed to vehicle during late gestation but not in pups that were exposed to ethanol in utero. Ethanol induced a reliable and similar CTA (Experiment 3) in the pups treated with vehicle or ethanol during gestation, and CTA was insensitive to κ antagonism. These results suggest that brief exposure to a moderate ethanol dose during late gestation promotes ethanol-mediated reinforcement and alters the expression of conditioned aversion by ethanol. This shift in the motivational reactivity to ethanol may be an underlying basis of the effect of prenatal ethanol on later ethanol acceptance.

Consilient research approaches in studying gene x environment interactions in alcohol research

This review article discusses the importance of identifying gene-environment interactions for understanding the etiology and course of alcohol use disorders and related conditions. A number of critical challenges are discussed, including the fact that there is no organizing typology for classifying different types of environmental exposures, many key human environmental risk factors for alcohol dependence have no clear equivalents in other species, much of the genetic variance of alcohol dependence in human is not 'alcohol specific', and the potential range of gene-environment interactions that could be considered is so vast that maintaining statistical control of Type 1 errors is a daunting task. Despite these and other challenges, there appears to be a number of promising approaches that could be taken in order to achieve consilience and ecologically valid translation between human alcohol dependence and animal models. Foremost among these is to distinguish environmental exposures that are thought to have enduring effects on alcohol use motivation (and self-regulation) from situational environmental exposures that facilitate the expression of such motivations but do not, by themselves, have enduring effects. In order to enhance consilience, various domains of human approach motivation should be considered so that relevant environmental exposures can be sampled, as well as the appropriate species to study them in (i.e. where such motivations are ecologically relevant). Foremost among these are social environments, which are central to the initiation and escalation of human alcohol consumption. The value of twin studies, human laboratory studies and pharmacogenetic studies is also highlighted.

Effects of prenatal and postnatal maternal ethanol on offspring response to alcohol and psychostimulants in long evans rats

An important factor that may influence addiction liability is exposure during the early life period. Exposure to ethanol, early in life, can have long-lasting implications on brain function and drugs of abuse response later in life. In the present study we investigated the behavioral responses to ethanol and to psychostimulants in Long Evans rats that have been exposed to pre- and postnatal ethanol. Since a relationship between heightened drug intake and susceptibility to drug-induced locomotor activity/sensitization has been demonstrated, we tested these behavioral responses, in control and early life ethanol-exposed animals. The young adult male and female progeny were tested for locomotor response to alcohol, cocaine and d-amphetamine. Sedative, rewarding effects of alcohol and alcohol consumption were measured. Our results show that early life ethanol exposure behaviorally sensitized animals to subsequent ethanol and psychostimulants exposure. Ethanol-exposed animals were also more sensitive to the hyperlocomotor effects of all drugs of abuse tested and to those of the dopamine receptor agonist apomorphine. Locomotor sensitization to repeated injections of cocaine was facilitated in ethanol-exposed animals. Ethanol-induced conditioned place preference was also facilitated in ethanol-exposed animals. Ethanol consumption and preference were increased after early life ethanol exposure and this was associated with decreased sensitivity to the sedative effects of ethanol. The altered behavioral responses to drugs of abuse were associated with decreased striatal dopamine transporter and hippocampal NMDAR binding. Our results outline an increased vulnerability to rewarding and stimulant effects of ethanol and psychostimulants and support the epidemiological and clinical data that suggested that early chronic exposure to ethanol may increase the propensity for later self-administration of ethanol or other substances.

Using drinking in the dark to model prenatal binge-like exposure to ethanol in C57BL/6J mice

Animal models of prenatal ethanol exposure are necessary to more fully understand the effects of ethanol on the developing embryo/fetus. However, most models employ procedures that may produce additional maternal stress beyond that produced by ethanol alone. We employed a daily limited-access ethanol intake model called Drinking in the Dark (DID) to assess the effects of voluntary maternal binge-like ethanol intake on the developing mouse. Evidence suggests that binge exposure may be particularly harmful to the embryo/fetus, perhaps due to the relatively higher blood ethanol concentrations achieved. Pregnant females had mean daily ethanol intakes ranging from 4.2 to 6.4 g/kg ethanol over gestation, producing blood ethanol concentrations ranging from 115 to 182 mg/dL. This level of ethanol intake produced behavioral alterations among adolescent offspring that disappeared by adulthood, including altered sensitivity to ethanol's hypnotic actions. The DID model may provide a useful tool for studying the effects of prenatal ethanol exposure in mice.

Acute sensitivity and acute tolerance to ethanol in preweanling rats with or without prenatal experience with the drug

The present study examined behavioral sensitivity and acute tolerance to ethanol in infants with or without a moderate prenatal ethanol experience. During gestational days 17-20 dams received 0.0 or 2.0 g/kg ethanol. On postnatal day 13 pups were administered 0.0, 0.5 or 2.5 g/kg ethanol prior to assessment of locomotion. One third of the pups were evaluated at 5-10, 30-35 and 60-65 min after ethanol administration; another third was tested only during the last two post-administration periods; and the remaining third was tested only at 60-65 min. At 30-35 min blood ethanol levels were similar to those attained at 60-65 min. The main results of the study were: (a) The 2.5 g/kg ethanol dose induced biphasic motor effects: stimulation 5-10 min after drug administration and sedation after 30-35 or 60-65 min. (b) Infants exhibited acute tolerance to ethanol's sedative effects. (c) Although pups prenatally treated with ethanol exhibited heightened locomotor activity levels, acute sensitivity and tolerance were not affected by prenatal treatment. In summary, infants are sensitive to biphasic motor consequences of ethanol and readily exhibit acute tolerance to ethanol's sedative effects. In addition, moderate prenatal ethanol exposure was sufficient to induce hyper-reactivity in the offspring without affecting habituation.

The development of alcohol use disorders

Pathological alcohol use is a complex and costly problem. This chapter focuses on recent developments in the etiology of alcohol use disorders. Literature is reviewed from the fields of epidemiology, genetics, personality, neuropsychology, parenting, and social influences. In addition, theoretical models that describe pathways to the development of alcohol use disorders are presented. Particular emphasis is given to ways in which genetic, environmental, psychopharmacological, and personological literatures can inform one another.

Maternal alcohol consumption increases sphingosine levels in the brains of progeny mice

The effect of 'binge' alcohol upon sphingolipid metabolism in the fetal alcohol syndrome (FAS) was examined in pregnant mice (C57BL/6J) by administering a single dose of alcohol during the third trimester (gestational day 15-16). The control mice were administered a sucrose solution of equal caloric value. Brains from progeny at postnatal days 5, 15, 21 and 30 were dissected into three regions, and sphingolipid concentrations of the brain regions were determined including assay of monoglycosylceramide, ceramide, sphingosine and sphingomyelin. We found that a single dose of ethanol induces an elevation of sphingosine (2-3.5-fold) in the brain of progeny. The level of brain ceramide at a dose of 1.5 g/kg was significantly higher than control. Alcohol consumption during pregnancy induces neuronal loss in progeny brains. Our result suggests that the elevation of sphingosine in progeny brain induced by maternal alcohol consumption may be responsible for observed neuronal loss in FAS.

Increased ethanol intake after prenatal ethanol exposure: studies with animals

This review analyses the most relevant studies in which ethanol intake was measured after prenatal exposure to the drug. Despite the variety in methodology, in most such studies this prenatal experience induced a higher consumption of ethanol. Several variables that may affect the expression of this phenomenon are discussed, such as gender, age at testing, period of ethanol exposure, ethanol dose and conditions during the test. The mechanisms proposed in all these studies to explain the increased ethanol intake effect are also discussed. Some of these mechanisms are related to the teratological effects of the drug on the neurochemical systems involved in the reinforcing effects of abuse drugs, as well as on the regulatory systems of stress response. Another explanation of this phenomenon is also proposed in terms of associative learning. Specifically, the increased ethanol intake effect may be the result of a conditioned preference for ethanol acquired by the fetus when exposed to the drug during the last days of gestation.

Interactions between prenatal ethanol exposure and postnatal learning about ethanol in rat pups

Exposure to ethanol during the last days of gestation (1 or 2/kg) has been shown to induce greater ethanol intake as well as enhanced ethanol palatability in infant rats compared to pups without previous experience with the drug. This higher acceptance of ethanol seems to result from the prenatal association between the chemosensory aspects of ethanol and its reinforcing properties; the latter mediated at least in part by the opioid system. A series of experiments analyzed how this prenatal experience with ethanol affected postnatal conditioning of the flavor of ethanol. In the first experiment, pups exposed prenatally to ethanol (2g/kg during gestational days 17-20) were tested for acquisition and extinction of a conditioned aversion to the taste of ethanol (conditioned stimulus), employing lithium chloride as the aversive unconditioned stimulus. In the next two experiments, pups with the same prenatal exposure to ethanol were tested for the extinction of an aversion, employing three (Experiment 2) or one (Experiment 3) conditioning trials, using a high dose of ethanol (3g/kg) as the aversive agent. The first experiment showed that prenatal ethanol exposure delayed the postnatal acquisition of a conditioned aversion to the taste of ethanol. In the next two experiments, the same effect was observed during the extinction trials. These results provide additional support to the hypothesis of an appetitive associative memory established prenatally as a consequence of fetal ethanol exposure.

Fetal or Infantile Exposure to Ethanol Promotes Ethanol Ingestion in Adolescence and Adulthood: A Theoretical Review

BACKGROUND

Despite good evidence that ethanol abuse in adulthood is more likely the earlier human adolescents begin drinking, it is unclear why the early onset of drinking occurs in the first place. A review of experimental studies with animals complemented by clinical, epidemiologic and experimental studies with humans supports the idea that precipitating conditions for ethanol abuse occur well before adolescence, in terms of very early exposure to ethanol as a fetus or infant. Experimental studies with animals indicate, accordingly, that ethanol intake during adolescence or adulthood is potentiated by much earlier exposure to ethanol as a fetus or infant.

METHODS

Two broad theoretical frameworks are suggested to explain the increase in affinity for ethanol that follows very early exposure to ethanol, one based on effects of mere exposure and the other on associative conditioning. Studied for 50 years or more in several areas of psychology, "effects of mere exposure" refers to enhanced preference expressed for flavors, or just about any stimuli, that are relatively familiar. An alternative framework, in terms of associative conditioning, is guided by this working hypothesis: During ethanol exposure the fetus or infant acquires an association between ethanol's orosensory (odor/taste) and pharmacological consequences, causing the animal subsequently to seek out ethanol's odor and taste.

RESULTS AND CONCLUSIONS

The implication that ethanol has rewarding consequences for the fetus or young infant is supported by recent evidence with perinatal rats. Paradoxically, several studies have shown that such early exposure to ethanol may in some circumstances make the infant treat ethanol-related events as aversive, and yet enhanced intake of ethanol in adolescence is nevertheless a consequence. Alternative interpretations of this paradox are considered among the varied circumstances of early ethanol exposure that lead subsequently to increased affinity for ethanol.

Prenatal ethanol preferentially enhances reactivity of the dopamine D1 but not D2 or D3 receptors in offspring

Reports of prenatal ethanol (ETOH) effects on the dopamine system are inconsistent. In an attempt to clarify this issue, dams were given 35% ethanol-derived calories as the sole nutrient source in a liquid diet from the 10th through the 20th day of gestation (ETOH). Controls were pair-fed (PF) an isocaloric liquid diet or given ad libitum access to laboratory chow (LC). Prenatal exposure to both liquid diets reduced body weight of offspring relative to LC controls, more so for ETOH than for PF exposure. Prenatal ETOH also decreased litter size and viability, relative to both LC and PF control groups. On postnatal days 21-23, male and female offspring were given an injection of saline vehicle or one of eight specific dopamine receptor agonists or antagonists. Immediately after injection subjects were placed in individual observation cages, and over the following 30 min, eight behaviors (square entries, grooming, rearing, circling, sniffing, yawning, head and oral movements) were observed and quantified. No prenatal treatment effects on drug-induced behaviors were observed for dopamine D2 (Apomorphine, DPAT or Quinpirole) or D3 (PD 152255, Nafadotride, Apo or Quin effects on yawning) receptor agonists or antagonists, or for the vehicle control. In contrast, prenatal treatment effects were seen with drugs affecting the dopamine D1 receptor. Both D1 agonists (SKF 38393) and antagonists (SCH 23390 and high doses of spiperone) altered behaviors, especially oral and sniffing behaviors, in a manner which suggested enhanced dopamine D1 drug sensitivity in both ETOH and PF offspring relative to LC controls. These results suggest that at this age, both sexes experience a prenatal undernutrition-linked increase in the behavioral response to dopamine D1 agonists and antagonists, which can be intensified by gestational exposure to alcohol.

Long lasting effects of rearing by an ethanol-consuming dam on voluntary ethanol consumption by rats

For exposure to alcohol early in life to potentiate alcohol abuse in adolescence or adulthood, consequences of early exposure to alcohol must be of considerable duration. In two experiments using Norway rats as subjects, we examined effects of exposure during weaning to a dam consuming ethanol on adolescents' later affinity for ethanol. In a preliminary experiment, we offered rat pups a choice between 8% ethanol and water for 7 days immediately after they were weaned at 26 days of age. Pups whose dam had ingested 8% ethanol for 6 days either immediately or 1 week before we weaned them drank more ethanol than pups whose dam drank only water during the same period. Independent groups of rats reared by a dam consuming 8% ethanol from postnatal days 18 to 26 and tested 1, 2, 4 or 6 weeks later all drank significantly more 8% ethanol at testing than did pups whose dam drank only water. Our data also provided confirmation of previous reports of an experience-independent greater affinity for ethanol in younger rats.

Neonatal responsiveness to alcohol odor and infant alcohol intake as a function of alcohol experience during late gestation

It has been previously suggested that maternal alcohol intoxication during the last days of pregnancy promotes fetal experiences that include chemosensory processing of the drug. In this study pregnant Wistar-derived rats were administered saline or one of two alcohol doses (1 or 2 g/kg) during gestational days 17-20. Immediately after birth, pups were tested in regard to motor-eliciting properties of the odor of amniotic fluid or alcohol, or of these stimuli presented as a configuration. Saline controls showed significantly shorter duration of overall motor activity and head movements when stimulated with the biological cue (amniotic fluid) than when exposed to a novel stimulus (ethanol alone or configured with the amniotic fluid). The opposite pattern was found in pups with prenatal experience with the higher alcohol dose. In a second experiment, the impact of similar alcohol treatments on infant consumption of different tastants, including alcohol and a configuration of sucrose and quinine, was tested. This configuration appears to mimic psychophysical properties of ethanol. Consumption of water, sucrose, or quinine was unaffected by the prenatal status of the subjects. Antenatal alcohol experience with the lower alcohol dose (1 g/kg) increased both alcohol and sucrose-quinine consumption. The 2 g/kg alcohol animals also ingested more sucrose-quinine relative to saline controls. As a whole, the results confirm the hypothesis that an intrauterine alcohol sensory memory selectively affects neonatal recognition of the alcohol's olfactory attributes and infant intake of either alcohol or solutions that share certain sensory equivalence with this psychopharmacological agent.

In utero ethanol exposure retards growth and alters morphology of cortical cultures: GM1 reverses effects

Ethanol, a developmental neurotoxin, alters plasma membranes' physicochemical properties affecting embryogenesis, cell migration, differentiation, and synaptogenesis. In a previous study using a model for fetal alcohol effects, GM1 ganglioside treatment was shown to reduce ethanol-induced accumulation of endogenous GM1 and fatty acid ethyl esters in rat fetuses. The present study was initiated to define further the in utero effects of ethanol and the capacity of GM1 treatment to ameliorate such effects. Wistar dams were exposed to ethanol (intragastrically) on gestation day (GD) 7 and GD8 and GD13 and GD14. GM1 ganglioside (10 mg/kg, im) was given 24 hr before ethanol administration. Cortical cultures were derived from GD15 and GD20 fetuses. GM1, which is highly localized on the cellular plasma membrane outer surface of CNS cells, was used as a marker molecule to assess cell integrity. Cholera toxin/antitoxin/fluorescence immunohistochemistry was used to localize GM1. Results indicate that the brief in utero exposure to ethanol affected cell growth and morphology. A marked retardation of cell development and arborization was observed as early as 24 hr after plating. Ethanol-exposed cells evidenced considerably altered GM1 localization. Such alterations likely reflect losses of membrane integrity. These in utero ethanol-induced pathologies are remarkably diminished in cultures derived from ethanol-exposed fetuses of dams treated with GM1.

The development of beta 1-adrenoceptors in brown adipose tissue following prenatal alcohol exposure

Prenatal alcohol exposure delays the development of thermoregulation in newborn rats. Newborns generate heat by the sympathetic nervous system's activation of nonshivering thermogenesis in brown adipose tissue (BAT). In this study, the effects of prenatal alcohol exposure on the development of the beta-adrenergic receptor system of BAT was investigated by assessing the number and pharmacological properties of beta-adrenergic receptors in BAT in 1-, 5-, 10-, and 20-day-old offspring. Pregnant dams were given either a liquid diet with 35% of the calories derived from alcohol, a liquid diet without alcohol for any effects of the liquid diet administration, or ad lib food and water. Offspring from the alcohol prenatal treatment group had a greater number of beta 1 adrenergic receptors compared to offspring from both from the pair-fed and lab chow control groups, which did not differ from each other. The greater number of receptor sites in 5-day-old subjects suggests that the number of binding sites in alcohol-exposed BAT cells continues to rise due to the absence of sufficient neurotransmitter, and perhaps reflects a delay in the arrival of sympathetic nervous system neurons. During the second and third postnatal weeks, when NE concentrations are rising and reaching asymptotic levels, the number of beta 1 adrenergic receptors in BAT of control subjects is decreasing. This expected compensatory "downregulation" response in receptor concentration was not seen in BAT from subjects exposed to alcohol prenatally. These findings may have important implications for understanding the effects of prenatal alcohol exposure on developing plasticity in the peripheral nervous system.

Prenatal ethanol exposure: susceptibility to convulsions and ethanol's anticonvulsant effect in amygdala-kindled rats

The present experiments assessed the effects of prenatal ethanol exposure on the susceptibility to convulsions and on the anticonvulsant effect of ethanol using the electrical kindling model of epilepsy in rats. Adult male Sprague-Dawley rats from prenatal ethanol (E), pair-fed (PF), and ad libitum-fed control (C) treatment groups were tested following the implantation of a stimulation electrode in the left amygdala complex. The same rats were tested in four consecutive experiments. Both E and PF rats showed a slightly slower rate of kindling than C rats, as measured by convulsion class but not as measured by forelimb clonus duration (experiment 1). However, the groups did not differ significantly in the electrical stimulation threshold for kindled convulsions (experiment 2). Furthermore, prenatal ethanol exposure had no significant effect on the dose-response curve for ethanol's (0, 0.9, 1.1, 1.3, and 1.5 g/kg, ip) anticonvulsant effect (experiment 3), or on the rate of tolerance development to ethanol's (1.5 g/kg, ip) anticonvulsant effect (experiment 4) on kindled convulsions. Thus, prenatal exposure to ethanol does not appear to have long-term effects on the susceptibility to convulsions or on the anticonvulsant effect of ethanol in adult male rats in the kindling model as used in the present experiments.

Reduction of fatty acid ethyl ester accumulation by ganglioside GM1 in rat fetus exposed to ethanol

The biochemical mechanism of alcohol teratogenicity is not known. We have demonstrated that alcohol administration to pregnant rats during gestation days (GD) 6 and 7 and/or 13 and 14 leads to significant accumulation of ethyl esters of long chain fatty acids (FAEEs) in both maternal and fetal organs. This observation extends the report of Bearer et al. (Pediat Res 31: 492-495, 1992) who detected the presence of metabolites in maternal and fetal organs of pregnant C57B1/6J mice exposed to alcohol on GD 7 and/or GD 14. The ethyl esters of arachidonic, linoleic, oleic, stearic and palmitic acids were major metabolites detected in both maternal and fetal organs. It was also demonstrated that detectable levels of FAEEs remain 14 days (GD 20) after initial exposure to alcohol on GD 7. Ganglioside GM1 treatment 1 and 24 hr prior to alcohol exposure on both GD 7 and/or GD 14 reduced the accumulation of FAEEs. A similar regimen was shown to prevent development of tolerance to alcohol in the adult pups exposed to alcohol in utero in our previous studies. Thus, the ganglioside GM1 may have therapeutic value in reducing neurobehavioral effects of alcohol exposure in utero.

Reduced sensitivity to the effects of clonidine on ethanol-stimulated locomotor activity in adult mouse offspring prenatally exposed to ethanol

Prenatal exposure to ethanol (EtOH) alters developing catecholamine (CA) systems and acute sensitivity to the locomotor stimulant effects of EtOH. As an extension of previous work involving CA agents, this study addressed whether prenatal EtOH exposure influences central norepinephrine (NE) systems by examining the motoric effects of the direct alpha 2 adrenoreceptor agonist clonidine given alone and in combination with a low-dose stimulant challenge of EtOH. Standard lab chow or liquid diets containing either 25% EtOH-derived calories (EDC), or 0% EDC (pair-fed group) were given to pregnant C3H/He mice on gestation days 6-18. At 90 days of age, male offspring from each prenatal treatment group were monitored for 10 minutes in an open field following IP injections of clonidine (0, 0.0125, 0.025, or 0.05 mg/kg) and either EtOH (1.5 g/kg) or saline. In control offspring, clonidine suppressed locomotor activity and attenuated the stimulant response to EtOH in a dose-dependent fashion. In contrast, clonidine given alone did not suppress, but appeared to stimulate, activity in prenatal EtOH-exposed offspring. Furthermore, the ability of clonidine to attenuate the locomotor stimulant properties of EtOH was greatly reduced in prenatal EtOH-exposed animals. Taken together, these results indicate a shift to the right in the dose-response function for clonidine in prenatal EtOH-exposed offspring relative to control mice. Further, the results suggest that prenatal exposure to EtOH may result in long-lasting alterations in developing central NE systems, particularly presynaptic alpha 2 adrenoreceptor sensitivity.

Ganglioside GM1 reduces fetal alcohol effects in rat pups exposed to ethanol in utero

We have investigated the effect of in utero ethanol exposure and ganglioside GM1 pretreatment on the endogenous ganglioside profile of the rat fetal brain. Prenatal ethanol exposure on gestation day (GD) 7 and GD8 and/or GD13 and GD14 leads to a very significant increase in the ganglioside GM1 content in at least 50% of the pup brains when assayed on GD20. This treatment protocol also results in significant decrease in the content of polysialogangliosides GD1a, GT1b, and GQ1b. GM1 treatment of pregnant dams before ethanol administration prevented this alteration in pup brain ganglioside profile. Ganglioside GM1 pretreatment appears to block the cellular membrane changes associated with fetal alcohol effects and thereby minimizes alterations in brain maturation and associated behavioral dysfunction.

Effects of prenatal ethanol exposure on later sensitivity to the low-dose stimulant actions of ethanol in mouse offspring: possible role of catecholamines

The purpose of this study was to examine whether prenatal ethanol (EtOH) exposure alters later sensitivity to the low-dose stimulant effects of EtOH. Because the locomotor stimulant effects of EtOH are thought to be mediated, at least in part, by activation of brain monoamine systems, and because prenatal EtOH exposure has been shown to alter brain monoamine activity, it was hypothesized that prenatal EtOH exposure may alter sensitivity to the stimulant actions of EtOH. To test this hypothesis, sensitivity to the locomotor stimulant effects of various challenge doses of EtOH was examined in male and female offspring from prenatal alcohol (A), pair-fed (PF), and lab chow (LC) groups at different ages. In addition, to address the hypothesis further, sensitivity to the catecholamine synthesis inhibitor alpha-methyl-p-tyrosine (AMPT) was examined in these offspring, as well. Results indicated that male offspring prenatally exposed to EtOH exhibited reduced baseline activity and a blunted stimulant response to all challenge doses of EtOH (0.75-1.5 g/kg) in comparison with control offspring at 30 days of age, but these effects appeared to "normalize" at 70 days of age. Female EtOH-exposed offspring also exhibited a reduced baseline level of activity relative to control offspring, as well as a blunted stimulant response to the lowest challenge dose of EtOH (0.75 g/kg) at 30 days of age, and these effects persisted into adulthood. The stimulant response to higher doses of EtOH did not significantly differ among prenatal treatment groups in young or adult female offspring. However, because baseline activity was significantly lower in female EtOH-exposed offspring than control offspring, the stimulant response to these doses of EtOH (1.125 and 1.5 g/kg) was relatively greater than that for PF and LC offspring. Importantly, none of the differences in performance among the prenatal treatment groups could be attributed to an alteration in EtOH pharmacokinetics, because blood EtOH levels measured immediately following the 10-min test session were similar for all prenatal treatment groups across all of the EtOH test doses. Further, a similar response profile as that observed following EtOH challenge at 70 days of age was obtained following phenobarbital challenge (10-40 mg/kg). Finally, whereas AMPT (50-400 mg/kg) dose-dependently antagonized the stimulant effects of EtOH in all prenatal treatment groups, this effect of AMPT was significantly greater in mice prenatally exposed to EtOH in comparison with control offspring.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of prenatal alcohol exposure on uncoupling protein in brown adipose tissue in neonatal rats

Thermoregulatory deficits observed in neonatal rats exposed prenatally to alcohol may be due to peripheral and/or central dysfunction. One of the major mechanisms available to newborn mammals to generate heat is "nonshivering thermogenesis" in brown adipose tissue (BAT). In this study, the effects of prenatal alcohol exposure on the functional status of brown adipose tissue was assessed by immunoblot analysis of the content of mitochondrial uncoupling protein (UCP). BAT excised from 1- and 20-day-old male and female offspring from either alcohol-treated, pair-fed controls or standard control dams were analyzed. There were no effects of prenatal alcohol exposure on the UCP content. There was, however, a significant increase due to age. These results suggest that thermoregulatory deficits seen in alcohol-exposed offspring are not due to a deficiency in the concentration of mitochondrial UCP, and indicate a more central mechanism.

Chronic administration of alcohol in the developing rat: expression of functional tolerance and alcohol olfactory aversions

Three experiments were designed to evaluate the acquisition and expression of tolerance to ethanol in preweanling rats. Administrations were begun on Postnatal Day 13 (PD13) and continued, on alternating days, through PD23. Following either three or five administrations of a 2.5 g/kg dose of ethanol, animals expressed tolerance to the motor-impairing consequences of acute ethanol, as measured through attenuated latencies to perform a righting reflex. However, no tolerance was evident when it was assessed through the hypothermic response to ethanol delivery (Experiment 1). The results of subsequent experiments suggested that this tolerance was not due to lower levels of ethanol in the blood and brain of the chronically exposed subjects (Experiment 2) nor to the development of behavioral tolerance, such as learning to perform the motor task in the presence of intoxication (Experiment 3). Additional tests determined that tolerance level did not alter the infant rats' ability to learn about the orosensory cues associated with ethanol delivery. Specifically, tests confirmed previous studies that an aversion to ethanol odor was formed as a result of the chronic administration procedure, presumably due to the animals associating the orosensory properties of eliminated ethanol during intoxication with the aversive consequences of this state. These results provide evidence that tolerance can develop in the preweanling rat, and that at least one measure (righting reflex) can be used to assess its development early in life.

Effects of in utero administration of alcohol on alcohol sensitivity in adult rats

In utero exposure to alcohol has been associated with many physical deficits and behavioral abnormalities. The purpose of these studies was to determine the effects of in utero administration of alcohol on behaviors related to tolerance and sensitivity to alcohol in adult rats. Pregnant rats were maintained on a liquid diet containing alcohol [35% ethanol-derived calories (EDC)] throughout pregnancy. Offspring manifested physical characteristics of Fetal Alcohol Syndrome. The 35% EDC group was able to stay on a wooden dowel longer and at higher blood alcohol concentrations than were pair-fed controls. Following a hypnotic dose of alcohol, rats in the 35% EDC group slept longer than pair-fed controls. A greater alcohol-induced hypothermic effect was seen in females in the 35% EDC group than in controls. Treatment did not affect rate of metabolism of alcohol. These studies suggest that in utero administration of alcohol may be a factor in determining an individual's sensitivity and tolerance to alcohol and possibly their preference for alcohol.

Acute ethanol intoxication during pregnancy: postnatal effects on the behavioral response to serotonin agents

Pregnant wistar rats were treated on the eighth day of gestation (GD 8) with two IP injections, spaced by 4 h, of either ethanol (2.9 g/kg in 24% v/v saline solution, EG) or saline (SG). Other pregnant females did not received any type of IP injections (absolute control group, ACG). Offspring were tested at 45 or 90 days of age. At 45 days of age, EG showed an increased behavioral response (forepaw treading and hindlimb abduction) to the 5-HT1 agonist, 5-methoxy-N,N-dymethyltryptamine. In addition, an enhanced "wet-dog" shakes behavioral response to 5-HT2 agonist, 5-hydroxy-L-tryptophan, was also observed in EG as compared to ACG and SG. On the contrary, at 90 days, EG exhibited a diminished behavioral reactivity to 5-HT1 and 5-HT2 agonists as compared to SG. These results demonstrated that acute administration of ethanol on GD 8 induced long-lasting changes in the functioning of central serotonergic systems.

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.

Apomorphine-induced motor behavior in rats exposed prenatally to alcohol

We psychopharmacologically examined dopamine function in rats exposed to ethanol prenatally. Pregnant rats received liquid diets of 35% or 0% ethanol-derived calories (EDC), or ad lib lab chow (LC). Twenty-eight-day-old offspring received systemic doses of apomorphine chosen to stimulate predominantly presynaptic (0.02 or 0.1 mg/kg) or postsynaptic dopamine receptors (2.0 or 5.0 mg/kg). Behavior was scored automatically for 60 min in an "open field." For males, prenatal ethanol exposure resulted in a dose-response shift to the left for locomotor activity. Females exposed to the liquid diet, with or without ethanol, showed less of an increase in locomotor activity following the 5.0 mg/kg dose of apomorphine than did LC controls. There were no effects of prenatal treatment on repetitious motor behavior in the automated "open field" or on stereotypy scored by direct observation in separate groups of rats. The results are consistent with an hypothesis that prenatal ethanol exposure alters the sensitivity of postsynaptic (perhaps mesolimbic) dopamine systems important to locomotor activity in young male rats.

Responses to ethanol challenge in long- and short-sleep mice prenatally exposed to alcohol

Individual sensitivity to alcohol may influence the severity of functional deficits due to prenatal alcohol exposure. To examine this hypothesis, Long-Sleep (LS) and Short-Sleep (SS) mice, selectively bred for differences in ethanol-induced narcosis, were intubated with either 2.9 g/kg ethanol (E) or an isocaloric amount of sucrose (S) twice per day on days 7 through 15 of pregnancy. An untreated control group (C) was maintained for each line. Offspring were fostered to lactating Rockland-Swiss mice at birth. Males and females from each litter were challenged with an acute dose of ethanol (3.8 g/kg) at 30 days of age. Measures of sleep time duration, waking blood ethanol concentrations (BEC), rectal temperatures, heart rate, and ethanol clearance were obtained to examine whether the acute effects of ethanol are altered by prenatal alcohol exposure. Prenatal alcohol exposure did not differentially affect responses to ethanol challenge within either genotype. Ethanol-induced hypothermia, heart-rate depression, and sleep time did differ between genotypes, with LS more affected than SS mice. Ethanol clearance rates were faster for SS than LS mice. These results suggest postnatal pharmacological responses to acute ethanol challenge are not altered by prenatal alcohol exposure in LS and SS mice. Prenatal alcohol-exposed offspring of both mouse genotypes showed lower average heart rate responses than controls, suggesting this measure may be a sensitive indicator of prenatal alcohol effects in mice.

Effects of prenatal ethanol exposure on ethanol-induced locomotor activity in rats

In adulthood, offspring with Fetal Alcohol Effects exhibit different responses to ethanol than nonexposed offspring; however, the majority of this research has utilized high levels of ethanol prenatally with resultant behavioural and/or physical anomalies. The present research focused on moderate prenatal ethanol exposure and subsequent challenge with low doses of ethanol. Following impregnation, female rats were exposed to between 3-4 g/kg of ethanol in a saccharin solution daily in a voluntary free-choice with water during one of each trimester or during all trimesters. There was a no-ethanol control group which received saccharin only as well as a group of foster dams who drank only water. At 30 days of age, male offspring were tested in an open-field after injection of either 1 g/kg ethanol or a comparable volume of saline. Rats exposed prenatally to ethanol in the second trimester showed enhanced locomotor activity. However, rats exposed prenatally to ethanol in either the first, third or during all trimesters showed no significant augmentation in activity. The results are discussed in terms of the adverse effects of moderate levels of prenatal ethanol exposure on fetal neurochemical development, specifically, the excitatory and inhibitory systems.

Paternal and maternal alcohol consumption: effects on offspring in two strains of rats

Long-Evans and Sprague-Dawley male rats were given liquid alcohol diets containing 35%, 17.5%, or 0% ethanol-derived calories (EDC). The latter two groups were pair fed to the higher alcohol diet group. A fourth group received lab chow and water ad libitum to assess the role of paternal undernutrition associated with alcohol consumption. After three or four weeks of diet consumption, these males were bred to females of the same strain. Pregnant females were divided into similarly treated alcohol groups and were fed these diets beginning on gestation Day 8, thus creating a factorial study with strain, paternal, and maternal alcohol consumption as main factors. Paternal alcohol consumption was associated with decreased litter size, decreased testosterone levels, and a strain-related effect on offspring activity. Offspring activity decreased for those sired by 35% and 17.5% EDC Long-Evans fathers. Activity also decreased for offspring sired by 17.5% EDC Sprague-Dawley fathers but increased for those sired by 35% EDC fathers. Paternal alcohol consumption did not affect postnatal mortality or passive avoidance learning of offspring. Maternal alcohol consumption was associated with lower birth weights, lower offspring weights at weaning, increased postnatal mortality, and poorer passive avoidance learning. However, offspring activity was not affected. In a separate study, levels of alcohol in the testes were found to be somewhat, but not significantly, lower than blood alcohol levels. DNA taken from sperm of Long-Evans males consuming alcohol, migrated farther under pulsed field electrophoresis than DNA from control fathers, suggestive of an alcohol-related effect on sperm DNA.

Acute alcohol intoxication paired with aversive reinforcement: ethanol odor as a conditioned reinforcer in rat pups

Previous research has suggested that infant rats process ethanol sensory properties during acute alcohol intoxication. The present study was designed in order to examine if alcohol odor could act as an aversive conditioned stimulus after the organism experiences the state of intoxication paired with nociceptive stimulation (footshock). In a first experiment 11-day-old pups received intragastric alcohol administration (1.5 g/kg). At different postabsorptive intervals footshock was presented (0-30, 30-60, 60-90, or 90-120 min). An explicitly unpaired control group which experienced footshock prior to the state of intoxication was also employed. All animals were subsequently tested in terms of alcohol intake and ethanol locational odor preferences. Both assessments indicated that pups which were exposed to the unconditioned peripheral stimulus 30-60 min after receiving ethanol expressed strong alcohol aversions. In a second experiment pups were exposed to footshock during this postabsorptive interval. Twenty four hours later, pups experienced ambient ethanol odor paired with soft or rough texture surfaces. Differential texture aversions were registered in experimental animals when compared with controls which suffered the state of intoxication explicitly unpaired with footshock, or unpaired presentations of ethanol odor and the tactile stimuli under consideration. These results appear to support the hypothesis concerning orosensory processing during an acute state of intoxication. Additionally it seems that the hedonic value of sensory attributes of this drug varies as a function of associative processes occurring during such a state.

Response to an ethanol challenge dose on sleep time and blood alcohol level in Wistar rats prenatally exposed to ethanol during gestational day 8

Pregnant albino rats were treated during the eighth day of gestation (GD 8), with two IP injections, spaced by 4 hours, of either ethanol (2.9 g/kg in 24% v/v saline solution) or saline. Maternal blood alcohol levels reached a peak of 457 mg/dl 60 min after the second dose. At the age of 45 days, an equal number of male and female offspring were injected with 3.5 g/kg ethanol and sleep time and blood ethanol levels were determined upon awakening. Ethanol metabolic rate was studied in other individuals injected with the same dose of ethanol and the slope of the linear descending portion of the curves was calculated. Animals that received ethanol in utero exhibited shorter sleep time and higher blood ethanol levels at the moment of awakening than controls. The rate of ethanol metabolism was similar in both groups. These results show that an acute intoxication with ethanol during GD 8 induced long-term changes in the CNS of offspring which caused reduced sensitivity to ethanol hypnotic effects.

Prenatal ethanol exposure impairs lesion-induced plasticity in a dopaminergic synapse after maturity

This study examined the consequences of alcohol (ethanol) exposure during fetal life on lesion-induced dopaminergic synapse responsiveness (plasticity) in the olfactory tubercle of the adult rat. Normally, in the olfactory tubercle, olfactory bulbectomy elicits alterations in pre- and postsynaptic dopaminergic markers, including, respectively, (1) increased tyrosine hydroxylase activity and immunoreactivity, which is associated with dopaminergic axon sprouting, and (2) increased dopaminergic receptor density and potentiated dopamine activation of adenylate cyclase. We have utilized biochemical and quantitative immunocytochemical methodology to examine these synaptic markers in olfactory bulbectomized or sham-operated adult rats. These animals were offspring of dams which were administered one of the following diets during pregnancy: (1) liquid diet containing 35% ethanol-derived calories ad libitum; (2) liquid diet containing an isocaloric amount of maltose-dextrin instead of ethanol, pair-fed; or (3) unaltered liquid diet ad libitum. The results show that prenatal alcohol exposure leads to suppression of the lesion-elicited dopaminergic synapse responsiveness in the olfactory tubercle. There were no significant differences between offspring born to control and pair-fed animals, indicating that the observed abnormalities were not due to alterations in their nutritional status. In conclusion, the present data are a biochemical and quantitative immunocytochemical demonstration of impaired lesion-induced synaptic responsiveness. This renders a new dimension in support of previous evidence indicating that prenatal alcohol exposure leads to altered neuroanatomical, neuroendocrinological and behavioral responsiveness to various challenges. Such impaired synaptic responsiveness may underlie brain functional abnormalities characteristic of fetal alcohol syndrome.

Thiamine deficiency in utero alters response to ethanol in adulthood

To determine whether prenatal thiamine deficiency, a frequent concomitant of alcoholism, reduces the response to ethanol during adulthood in the rat as does ethanol exposure in utero (Abel et al. 1981), pregnant Sprague-Dawley rats received either control or thiamine deficient diets together with daily injections of the thiamine antagonist pyrithiamine. At 7 months of age, male offspring were exposed to precisely regulated ethanol vapor concentrations in an inhalation chamber for 24 h and blood ethanol concentrations (BECs) and ethanol-induced intoxication were determined. Prenatally thiamine deficient rats and controls were indistinguishable in terms of appearance, body and liver weights, and the ratios of liver to body weight and brain to liver weight. However, total body water was significantly greater, and BECs and behavioral impairment were decreased, in the experimental rats. These findings indicate that prenatal thiamine deprivation is associated with reduced pharmacologic effect of ethanol as a result of increases in its volume of distribution and rate of metabolism.

Absence of differential motoric and thermic responses to clonidine in young rats exposed prenatally to alcohol

We studied the involvement of altered noradrenergic function in the behavioral consequences of fetal ethanol exposure. Pregnant rats were fed a liquid diet containing 35% Ethanol-Derived Calories (EDC), pair-fed a 0% EDC diet with sucrose substituted isocalorically for ethanol, or fed ad lib lab chow. In Experiment 1, offspring from these prenatal treatment groups were injected with the alpha-adrenergic agonist clonidine (0.5 or 2.0 mg/kg) at 10 or 42 days of age and showed age-characteristic, dose-dependent increases in locomotor activity, exploration, forelimb treading, and catalepsy. In Experiment 2, offspring were injected with clonidine (0.25 or 1.0 mg/kg) at 10, 14, or 18 days of age, and locomotor activity and wall-climbing were observed in a warm chamber (33 degrees C). Catalepsy and rectal temperature were also scored. There were no significant differential effects of clonidine on any prenatal treatment group at any age for any measure of activity or rectal temperature. The results do not support the hypothesis that fetal ethanol exposure alters noradrenergic systems in behaviorally significant ways.

Effects of ethanol on mature offspring of mice given ethanol during pregnancy

Male offspring of mice maintained on isocaloric liquid diets containing either 20% ethanol or sucrose derived calories during pregnancy were tested on their ability to discriminate different ethanol doses as adults. They were trained to lever-press for a food reward on each of two levers in an operant chamber, and were then maintained on an FR20 reinforcement schedule. After response rates stabilized, ethanol discrimination training was initiated by reinforcing only responses made on the drug appropriate-lever after i.p. injections of ethanol (1.0 g/kg) or water. After learning to discriminate the 1.0 g dose, the animals' ability to discriminate doses of 0.25, 0.50, 0.75, 1.0, and 1.5 g/kg was assessed by determining the percentage of responses made on the drug lever during a 2-min test period. Compared to sucrose controls, mice exposed to alcohol in utero learned the lever response more slowly and were less responsive to injected ethanol as evidenced by a reduced effect of the drug on response rates and by a reduction in their ability to discriminate the presence of injected ethanol. The results indicate that prenatal ethanol exposure can have long term consequences which reduce the effects of ethanol in fully mature animals.