Biphasic action of ethanol

Effect of Ethanol on Brain Electrical Tissue Conductivity in Social Drinkers

BACKGROUND

How the biophysics of electrical conductivity measures relate to brain activity is poorly understood. The sedative, ethanol, reduces metabolic activity but its impact on brain electrical conductivity is unknown.

PURPOSE

To investigate whether ethanol reduces brain electrical tissue conductivity.

STUDY TYPE

Prospective.

SUBJECTS

Fifty-two healthy volunteers (aged 18-37 years, 22 females, 30 males).

FIELD STRENGTH/SEQUENCE

3 T, T1-weighted, multi-shot, turbo-field echo (TFE); 3D balanced fast-field echo (bFFE).

ASSESSMENT

Brain gray and white matter tissue conductivity measured with phase-based magnetic resonance electrical properties tomography (MREPT) compared before and 20 minutes after ethanol consumption (0.7 g/kg body weight). Differential conductivity whole brain maps were generated for three subgroups: those with strong (∆ σ max $$ \Delta {\sigma}_{\mathrm{max}} $$  > 0.1 S/m; N = 33), weak (0.02 S/m ≤ ∆ σ max $$ \Delta {\sigma}_{\mathrm{max}} $$  ≤ 0.1 S/m; N = 9) conductivity decrease, and no significant response (∆ σ max $$ \Delta {\sigma}_{\mathrm{max}} $$  < 0.02 S/m, N = 10). Maps were compared in the strong response group where breath alcohol rose between scans, vs. those where it fell.

STATISTICAL TESTS

Average breath alcohol levels were compared to the differential conductivity maps using linear regression. T-maps were generated (threshold P < 0.05 and P < 0.001; minimum cluster 48 mm3). Differential conductivity maps were compared with ANOVA.

RESULTS

Whole-group analysis showed decreased conductivity that did not survive statistical thresholding. Strong responders (N = 33) showed a consistent pattern of significantly decreased conductivity (∆ σ max $$ \Delta {\sigma}_{\mathrm{max}} $$  > 0.1 S/m) in frontal/occipital and cerebellar white matter. The weak response group (N = 9) showed a similar pattern of conductivity decrease (0.02 S/m ≤ ∆ σ max $$ \Delta {\sigma}_{\mathrm{max}} $$  ≤ 0.1 S/m). There was no significant relationship with breath alcohol levels, alcohol use, age, ethnicity, or sex. The strong responders' regional response was different between ascending (N = 12) or descending (N = 20) alcohol during the scan.

DATA CONCLUSION

Ethanol reduces brain tissue conductivity in a participant-dependent and spatially dependent fashion.

EVIDENCE LEVEL

1 TECHNICAL EFFICACY: Stage 2.

The Dopamine System in Mediating Alcohol Effects in Humans

Brain-imaging studies show that the development and maintenance of alcohol use disorder (AUD) is determined by a complex interaction of different neurotransmitter systems and multiple psychological factors. In this context, the dopaminergic reinforcement system appears to be of fundamental importance. We focus on the excitatory and depressant effects of acute versus chronic alcohol intake and its impact on dopaminergic neurotransmission. Furthermore, we describe alterations in dopaminergic neurotransmission as associated with symptoms of alcohol dependence. We specifically focus on neuroadaptations to chronic alcohol consumption and their effect on central processing of alcohol-associated and reward-related stimuli. Altered reward processing, complex conditioning processes, impaired reinforcement learning, and increased salience attribution to alcohol-associated stimuli enable alcohol cues to drive alcohol seeking and consumption. Finally, we will discuss how the neurobiological and neurochemical mechanisms of alcohol-associated alterations in reward processing and learning can interact with stress, cognition, and emotion processing.

Hazardous drinking and alcohol use disorders

Alcohol is one of the most widely consumed psychoactive drugs globally. Hazardous drinking, defined by quantity and frequency of consumption, is associated with acute and chronic morbidity. Alcohol use disorders (AUDs) are psychiatric syndromes characterized by impaired control over drinking and other symptoms. Contemporary aetiological perspectives on AUDs apply a biopsychosocial framework that emphasizes the interplay of genetics, neurobiology, psychology, and an individual's social and societal context. There is strong evidence that AUDs are genetically influenced, but with a complex polygenic architecture. Likewise, there is robust evidence for environmental influences, such as adverse childhood exposures and maladaptive developmental trajectories. Well-established biological and psychological determinants of AUDs include neuroadaptive changes following persistent use, differences in brain structure and function, and motivational determinants including overvaluation of alcohol reinforcement, acute effects of environmental triggers and stress, elevations in multiple facets of impulsivity, and lack of alternative reinforcers. Social factors include bidirectional roles of social networks and sociocultural influences, such as public health control strategies and social determinants of health. An array of evidence-based approaches for reducing alcohol harms are available, including screening, pharmacotherapies, psychological interventions and policy strategies, but are substantially underused. Priorities for the field include translating advances in basic biobehavioural research into novel clinical applications and, in turn, promoting widespread implementation of evidence-based clinical approaches in practice and health-care systems.

The intertwining between lead and ethanol in the model organism Caenorhabditis elegans

Caenorhabditis elegans (C. elegans) is a model organism widely used to evaluate the mechanistic aspects of toxicants with the potential to predict responses comparable to those of mammals. We report here the consequences of developmental lead (Pb) exposure on behavioral responses to ethanol (EtOH) in C. elegans. In addition, we present data on morphological alterations in the dopamine (DA) synapse and DA-dependent behaviors aimed to dissect the neurobiological mechanisms that underlie the relationship between these neurotoxicants. Finally, the escalation to superior animals that parallels the observed effects in both experimental models with references to EtOH metabolism and oxidative stress is also discussed. Overall, the literature revised here underpins the usefulness of C. elegans to evidence behavioral responses to a combination of neurotoxicants in mechanistic-orientated studies.

Sex-Specific Effects of Acute Ethanol Exposure on Locomotory Activity and Exploratory Behavior in Adult Zebrafish (Danio rerio)

The zebrafish (Danio rerio) is an established model organism in pharmacology and biomedicine, including in research on alcohol use disorders and alcohol-related disease. In the past 2 decades, zebrafish has been used to study the complex effects of ethanol on the vertebrate brain and behavior in both acute, chronic and developmental exposure paradigms. Sex differences in the neurobehavioral response to ethanol are well documented for humans and rodents, yet no consensus has been reached for zebrafish. Here, we show for the first time that male zebrafish of the AB strain display more severe behavioral impairments than females for equal exposure concentrations. Adult zebrafish were immersed in 0, 1 or 2% (v/v) ethanol for 30 min, after which behavior was individually assessed in the zebrafish Multivariate Concentric Square Field™ (zMCSF) arena. Males exposed to 2% ethanol showed clear signs of sedation, including reduced activity, increased shelter seeking and reduced exploration of shallow zones. The 1% male group displayed effects in the same direction but of smaller magnitude; this group also explored the shallow areas less, but did not show a general reduction in activity nor an increase in shelter seeking. By contrast, 1 and 2% exposed females showed no alterations in explorative behavior. Females exposed to 2% ethanol did not display a general reduction in activity, rather activity gradually increased from hypoactivity to hyperactivity over the course of the test. This mixed stimulatory/depressant effect was only quantifiable when locomotory variables were analyzed over time and was not apparent from averages of the whole 30-min test, which may explain why previous studies failed to detect sex-specific effects on locomotion. Our results emphasize the importance of explicitly including sex and time as factors in pharmacological studies of zebrafish behavior. We hypothesize that the lower sensitivity of female zebrafish to ethanol may be explained by their greater body weight and associated larger distribution volume for ethanol, which may render lower brain ethanol concentrations in females.

GABAB Receptors and Alcohol Use Disorders: Preclinical Studies

Preclinical research over the past several decades has demonstrated a role for the γ-aminobutyric acid_B (GABA_B) receptor in alcohol use disorder (AUD). This chapter offers an examination of preclinical evidence on the role of the GABA_B receptor on alcohol-related behaviors with a particular focus on the GABA_B receptor agonist baclofen, for which effects have been most extensively studied, and positive allosteric modulators (PAMs) of the GABA_B receptor. Studies employing rodent and non-human primate models have shown that activation of the GABA_B receptor can reduce (1) stimulating and rewarding effects of alcohol; (2) signs of alcohol withdrawal in rats made physically dependent on alcohol; (3) acquisition and maintenance of alcohol drinking under a two-bottle alcohol versus water choice procedure; (4) alcohol intake under oral operant self-administration procedures; (5) motivational properties of alcohol measured using extinction and progressive ratio procedures; (6) the increase in alcohol intake after a period of alcohol abstinence (the alcohol deprivation effect or ADE); and (7) the ability of alcohol cues and stress to reinstate alcohol seeking when alcohol is no longer available. Baclofen and GABA_B PAMs reduce the abovementioned behaviors across different preclinical models, which provides strong evidence for a significant role of the GABA_B receptor in alcohol-related behaviors and supports development of medications targeting GABA_B receptors for the treatment of AUD. This chapter highlights the value of examining mechanisms of alcohol-related behaviors across multiple animal models to increase the confidence in identification of new therapeutic targets.

Acute alcohol does not impair attentional inhibition as measured with Stroop interference scores but impairs Stroop performance

RATIONALE

Inhibition is a core executive function and refers to the ability to deliberately suppress attention, behavior, thoughts, and/or emotions and instead act in a specific manner. While acute alcohol exposure has been shown to impair response inhibition in the stop-signal and Go/NoGo tasks, reported alcohol effects on attentional inhibition in the Stroop task are inconsistent. Notably, studies have operationalized attentional inhibition variably and there has been intra- and inter-individual variability in alcohol exposure.

OBJECTIVE

This study aimed to examine the acute effects of alcohol on attentional inhibition, considering previous limitations.

METHODS

In a single-blind, cross-over design, 40 non-dependent participants with a medium-to-high risk drinking behavior performed a Counting Stroop task (CST) under a baseline and an arterial blood alcohol concentration (aBAC) clamp at 80 mg%. Attentional inhibition was assessed as the alteration of reaction times (RT), error rates (ER), and inverse efficiency scores (IES) between incongruent and congruent trials (interference score). Stroop performance was also assessed regardless of trial-type.

RESULTS

Compared to saline, acute alcohol exposure via an aBAC clamp did not affect CST interference scores but increased RTs and IES in both incongruent and congruent trials.

CONCLUSIONS

Attentional inhibition (Stroop interference score) was not impaired by clamped moderate alcohol exposure. Acute alcohol impaired Stroop performance evidenced by a general increase in response times. Our findings suggest that response and attentional inhibition do not share the same neurocognitive mechanisms and are affected differently by alcohol. Results could also be explained by automated behaviors known to be relatively unaffected by acute alcohol.

Experimental tasks of behavioral risk taking in alcohol administration studies: A systematic review

Research on emerging adults shows this population exhibits the highest rates of alcohol use and engages in the riskiest of behaviors (Boyer, 2006; Fromme, Corbin, & Kruse, 2008). Among experimental paradigms, prior reviews have established an increase in behavioral risk taking while under the influence of alcohol (Moskowitz & Robinson, 1988; Martin et al., 2013; Weafer & Fillmore, 2016). Previous research highlighted the importance of alcohol dose on behavioral risk taking and the lack of agreement on which psychometric tools are most accurate in assessing behavioral risk taking (Beulow & Blaine, 2015; King, Toule, De Wit, & Holdstock, 2002). This systematic review of experimental paradigms assessing the effects of the dose of alcohol on various behavioral risk taking tasks suggest that higher alcohol doses (0.6 g/kg and above) produces the most robust increase in behavioral risk taking across tasks, compared to lower doses of alcohol (<0.6 g/kg). Results suggest the BART is the most sensitive behavioral risk task used to detect increases in risk taking in moderate/higher doses compared to lower doses of alcohol. This review also highlights the difficulty in measuring behavioral risk taking, as behavioral risk taking is a complex, multifaceted phenomenon that may involve multiple constructs and means to capture it. Future research is needed to standardize experimental administration protocols, to aid in advancing the field of alcohol administration experiments, and to determine the most accurate measurement of behavioral risk taking. PUBLIC HEALTH SIGNIFICANCE: Past experimental paradigms measuring behavioral risk taking under the influence of alcohol in emerging adults have used various alcohol administration paradigms, experimental protocols, and behavioral risk tasks. Key to examining behavioral risk taking via experimental paradigms should use at higher alcohol doses. Future interventions need to assess for levels of blood alcohol concentration when assessing for at-risk populations for alchol use disorders.

The Neurotransmitters Involved in Drosophila Alcohol-Induced Behaviors

Alcohol is a widely used and abused substance with numerous negative consequences for human health and safety. Historically, alcohol's widespread, non-specific neurobiological effects have made it a challenge to study in humans. Therefore, model organisms are a critical tool for unraveling the mechanisms of alcohol action and subsequent effects on behavior. Drosophila melanogaster is genetically tractable and displays a vast behavioral repertoire, making it a particularly good candidate for examining the neurobiology of alcohol responses. In addition to being experimentally amenable, Drosophila have high face and mechanistic validity: their alcohol-related behaviors are remarkably consistent with humans and other mammalian species, and they share numerous conserved neurotransmitters and signaling pathways. Flies have a long history in alcohol research, which has been enhanced in recent years by the development of tools that allow for manipulating individual Drosophila neurotransmitters. Through advancements such as the GAL4/UAS system and CRISPR/Cas9 mutagenesis, investigation of specific neurotransmitters in small subsets of neurons has become ever more achievable. In this review, we describe recent progress in understanding the contribution of seven neurotransmitters to fly behavior, focusing on their roles in alcohol response: dopamine, octopamine, tyramine, serotonin, glutamate, GABA, and acetylcholine. We chose these small-molecule neurotransmitters due to their conservation in mammals and their importance for behavior. While neurotransmitters like dopamine and octopamine have received significant research emphasis regarding their contributions to behavior, others, like glutamate, GABA, and acetylcholine, remain relatively unexplored. Here, we summarize recent genetic and behavioral findings concerning these seven neurotransmitters and their roles in the behavioral response to alcohol, highlighting the fitness of the fly as a model for human alcohol use.

Changes in behavioral and neuronal parameters by alcohol, cigarette, or their combined use in rats

Few studies have explored the effects of the combined use of alcohol and cigarette in humans, despite its prevalence. Here we evaluated the effect of isolated and combined use on behaviors and neuronal parameters in rats. Male adult rats were divided into alcohol (AL, 2 g/kg, by oral gavage), cigarette smoke (TB, six cigarettes, by inhalation), combined use (ALTB), or control (CT, water by oral gavage and environmental air) groups, treated twice a day (09.00 and 14.00 h). After 4 weeks, the rats were tested in the open field for behavioral analysis and euthanized for brain volume estimation and counting of neurons in the hippocampus. All treatments increased locomotion, and this behavior was higher in the ALTB than TB group. Latency to exit from the central area was lower in the ALTB than in the AL or CT groups. Rearing behavior increased in TB and decreased in AL and ALTB rats. Combined ALTB rats significantly increased their grooming behavior. Only the AL group showed decreased neuron counts and increased brain volume. Our results show that the isolated and combined uses of alcohol and cigarette smoke have diverse effects on behavioral and neuronal parameters in rats after long-term treatment.

Experimental and observational studies on alcohol use and dietary intake: a systematic review

The scientific literature on links among alcohol use, total energy intake, cardiometabolic disease and obesity is conflicting. To clarify the link between alcohol use and cardiometabolic health, this systematic review (PROSPERO CRD42016039308A) uses PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines to synthesize how alcohol use affects dietary intake (carbohydrate, fat and protein intake) in humans. A search of Google Scholar, PsycINFO and PubMed from June 2016-March 2019 yielded 30 qualified studies. Experimental and observational studies allowed for inferences about effects of a single drinking occasion and of frequent drinking, respectively. Alcohol quantities were standardized according to the 2015-2020 Dietary Guidelines for Americans. On average, methodological quality of the studies was medium strength. Results indicated that a single occasion of light and moderate drinking as well as frequent light and moderate drinking were linked to greater fat and protein intake, albeit the majority of studies did not detect differences in dietary intake due to these drinking behaviours. Frequent heavy drinking, on the other hand, was linked to less carbohydrate intake in the majority of studies. Overall, alcohol use does not appear to uniformly affect diet but instead appears to affect intake of specific macronutrients in a dose-dependent manner, most consistently decreasing carbohydrate intake with heavier use.

A Mechanism Linking Two Known Vulnerability Factors for Alcohol Abuse: Heightened Alcohol Stimulation and Low Striatal Dopamine D2 Receptors

Alcohol produces both stimulant and sedative effects in humans and rodents. In humans, alcohol abuse disorder is associated with a higher stimulant and lower sedative responses to alcohol. Here, we show that this association is conserved in mice and demonstrate a causal link with another liability factor: low expression of striatal dopamine D2 receptors (D2Rs). Using transgenic mouse lines, we find that the selective loss of D2Rs on striatal medium spiny neurons enhances sensitivity to ethanol stimulation and generates resilience to ethanol sedation. These mice also display higher preference and escalation of ethanol drinking, which continues despite adverse outcomes. We find that striatal D1R activation is required for ethanol stimulation and that this signaling is enhanced in mice with low striatal D2Rs. These data demonstrate a link between two vulnerability factors for alcohol abuse and offer evidence for a mechanism in which low striatal D2Rs trigger D1R hypersensitivity, ultimately leading to compulsive-like drinking.

Oxidative stress and DNA damage in the mechanism of fetal alcohol spectrum disorders

This review covers molecular mechanisms involving oxidative stress and DNA damage that may contribute to morphological and functional developmental disorders in animal models resulting from exposure to alcohol (ethanol, EtOH) in utero or in embryo culture. Components covered include: (a) a brief overview of EtOH metabolism and embryopathic mechanisms other than oxidative stress; (b) mechanisms within the embryo and fetal brain by which EtOH increases the formation of reactive oxygen species (ROS); (c) critical embryonic/fetal antioxidative enzymes and substrates that detoxify ROS; (d) mechanisms by which ROS can alter development, including ROS-mediated signal transduction and oxidative DNA damage, the latter of which leads to pathogenic genetic (mutations) and epigenetic changes; (e) pathways of DNA repair that mitigate the pathogenic effects of DNA damage; (f) related indirect mechanisms by which EtOH enhances risk, for example by enhancing the degradation of some DNA repair proteins; and, (g) embryonic/fetal pathways like NRF2 that regulate the levels of many of the above components. Particular attention is paid to studies in which chemical and/or genetic manipulation of the above mechanisms has been shown to alter the ability of EtOH to adversely affect development. Alterations in the above components are also discussed in terms of: (a) individual embryonic and fetal determinants of risk and (b) potential risk biomarkers and mitigating strategies. FASD risk is likely increased in progeny which/who are biochemically predisposed via genetic and/or environmental mechanisms, including enhanced pathways for ROS formation and/or deficient pathways for ROS detoxification or DNA repair.

Studying alcohol use disorder using Drosophila melanogaster in the era of 'Big Data'

Our understanding of the networks of genes and protein functions involved in Alcohol Use Disorder (AUD) remains incomplete, as do the mechanisms by which these networks lead to AUD phenotypes. The fruit fly (Drosophila melanogaster) is an efficient model for functional and mechanistic characterization of the genes involved in alcohol behavior. The fly offers many advantages as a model organism for investigating the molecular and cellular mechanisms of alcohol-related behaviors, and for understanding the underlying neural circuitry driving behaviors, such as locomotor stimulation, sedation, tolerance, and appetitive (reward) learning and memory. Fly researchers are able to use an extensive variety of tools for functional characterization of gene products. To understand how the fly can guide our understanding of AUD in the era of Big Data we will explore these tools, and review some of the gene networks identified in the fly through their use, including chromatin-remodeling, glial, cellular stress, and innate immunity genes. These networks hold great potential as translational drug targets, making it prudent to conduct further research into how these gene mechanisms are involved in alcohol behavior.

Comparison of Subjective Responses to Oral and Intravenous Alcohol Administration Under Similar Systemic Exposures

BACKGROUND

Individuals perceive the effects of alcohol differently, and the variation is commonly used in research assessing the risk for developing an alcohol use disorder. Such research is supported by both oral and intravenous (IV) alcohol administration techniques, and any differences attributable to the route employed should be understood. Our objective was to test whether an individual's subjective responses to alcohol are similar when the breath alcohol concentration (BrAC) trajectory resulting from oral administration is matched by IV administration.

METHODS

We conducted a 2-session, within-subject study in 44 young adult, healthy, nondependent drinkers (22 females and 22 males). In the first session, subjects ingested a dose of alcohol which was individually calculated, on the basis of total body water, to yield a peak BrAC near 80 mg/dl, and the resulting BrAC trajectory was recorded. A few days later, subjects received an IV alcohol infusion rate profile, precomputed to replicate each individual's oral alcohol BrAC trajectory. In both sessions, we assessed 4 subjective responses to alcohol: SEDATION, SIMULATION, INTOXICATION, and HIGH; at baseline and frequently for 4 hours. We compared the individuals' baseline-corrected responses at peak BrAC and at half-peak BrAC on both the ascending and descending limbs. We also computed and compared Pearson-product moment correlations of responses by route of administration, the Mellanby measure of acute adaptation to alcohol, and the area under the entire response curve for each subjective response.

RESULTS

No significant differences in any measure could be attributed to the route of alcohol administration. Eleven of 12 response comparisons were significantly correlated across the routes of alcohol administration, with 9 surviving correction for multiple measures, as did the Mellanby effect and area under the response curve correlations.

CONCLUSIONS

The route of alcohol administration has a minimal effect on subjective responses to alcohol when an individual's BrAC exposure profiles are similar.

Effects of a low dose of ethanol on mating success of Drosophila melanogaster males: implications for the evolution of ethanol resistance?

Ethanol occurs naturally in the decaying fruit in which many species of Drosophila (Diptera: Drosophilidae) breed, potentially generating selection for resistance to its toxic and sedating effects. Studies measuring mortality of flies exposed to a range of ethanol concentrations have shown that within Drosophila melanogaster Meigen, populations from temperate regions are more ethanol resistant than ancestral tropical African populations. The high ethanol resistance of temperate D. melanogaster presents a puzzle, however, because breeding and feeding sites in the wild seldom contain enough ethanol to kill even more ethanol-sensitive Afrotropical genotypes. We hypothesize that the ethanol concentrations encountered by temperate populations, though usually sub-lethal, are nonetheless high enough to reduce fitness in other ways, potentially generating indirect selection for genotypes that can survive exposure to unnaturally high ethanol concentrations. As a first step in testing this hypothesis, we compared the effects of a sub-lethal dose of ethanol, comparable to that obtainable from fermenting fruit, on the mating success of males from one European and one Afrotropical population. Ethanol significantly reduced mating success of males from the Afrotropical population, but had no effect on that of males from the European population. We also show that when flies are placed on medium with a realistic concentration of ethanol, considerably more ethanol is absorbed through vapor than through feeding, suggesting that courting males may be unable to avoid being exposed to ethanol. We hypothesize that the higher resistance of temperate populations to being killed by high, unnatural ethanol concentrations may have evolved in part as a correlated response to selection for behavioral insensitivity to natural concentrations.

Effect of different alcohol levels on take-over performance in conditionally automated driving

Automated driving systems are getting pushed into the consumer market, with varying degrees of automation. Most often the driver's task will consist of being available as a fall-back level when the automation reaches its limits. These so-called take-over situations have attracted a great body of research, focusing on various human factors aspects (e.g., sleepiness) that could undermine the safety of control transitions between automated and manual driving. However, a major source of accidents in manual driving, alcohol consumption, has been a non-issue so far, although a false understanding of the driver's responsibility (i.e., being available as a fallback level) might promote driving under its influence. In this experiment, N = 36 drivers were exposed to different levels of blood alcohol concentrations (BACs: placebo vs. 0.05% vs. 0.08%) in a high fidelity driving simulator, and the effect on take-over time and quality was assessed. The results point out that a 0.08% BAC increases the time needed to re-engage in the driving task and impairs several aspects of longitudinal and lateral vehicle control, whereas 0.05% BAC did only go along with descriptive impairments in fewer parameters.

Effects of ethanol on cocaine self-administration in monkeys responding under a second-order schedule of reinforcement

BACKGROUND

Concurrent alcohol use among cocaine abusers is common but the behavioral variables that promote co-abuse are not well understood. The present study examined the effects of intragastric (i.g.) ethanol (EtOH) administration in monkeys responding under a schedule of cocaine reinforcement in which extensive drug seeking was maintained by conditioned stimuli.

METHODS

Four adult male cynomolgus monkeys (Macaca fascicularis) were trained to respond under a second-order fixed-interval (FI) 600s (fixed-ratio (FR) 30:S) schedule of cocaine (0.003-0.56mg/kg/injection) presentation. Sessions ended after 5 injections or 90min had elapsed. Different EtOH doses (0.5-2.0g/kg, i.g.) were administered 30min before the session, typically on Tuesdays and Fridays. Blood ethanol concentrations (BECs) were also assessed. Pattern of FI responding was assessed by determining quarter-life (QL) values.

RESULTS

Cocaine self-administration was characterized as an inverted U-shaped function of dose; QL values increased monotonically with dose. EtOH pretreatments dose-dependently decreased self-administration at several cocaine doses in 3 of 4 monkeys. In one animal, EtOH increased low-dose cocaine-maintained responding. For all monkeys, QL values were increased by EtOH when low- and high-cocaine doses were self-administered, suggesting additive effects of EtOH and cocaine. Furthermore, BECs were not altered following cocaine self-administration.

CONCLUSIONS

The reductions in cocaine self-administration and the increases in QL values following EtOH, suggest that EtOH was enhancing cocaine-related conditioned reinforcement. A better understanding of the behavioral mechanisms that mediate the co-abuse of alcohol and cocaine will lead to improved treatments for both drugs.

Acute subjective response to alcohol as a function of reward and punishment sensitivity

Individual differences in subjective response to alcohol play a crucial role in the development of heavy drinking and related problems. In light of this, a growing focus of research has been identifying factors that contribute to differences in response. The aim of the present study was to determine whether individual differences in the subjective experience of rewarding and aversive effects of alcohol are a specific manifestation of general differences in reward and punishment sensitivity. Eighty-nine participants (M age=22.4, SD=1.9; 47.2% women) consumed a moderate dose of alcohol, i.e., peak breath alcohol concentration (BrAC)≈0.080g%, and rated their level of stimulation and sedation at seven timepoints over the BrAC curve. Sensitivity to reward and punishment were assessed by a self-report questionnaire prior to consumption. Multilevel growth models showed that post-consumption changes in stimulation ratings varied as a function of participants' level of reward and punishment sensitivity. Drinkers more sensitive to reward reported feeling more stimulated shortly after drinking and exhibited an attenuated rate of decline in stimulation over the blood alcohol curve, relative to drinkers with less strong reward sensitivity. Reward sensitivity was not related to subjective ratings of sedation, and punishment sensitivity was not related to either stimulation or sedation ratings. Findings suggest that reward sensitivity may increase risk for alcohol misuse among young adult social drinkers by increasing their subjective feelings of stimulation while drinking.

Dose-dependent effects of alcohol administration on behavioral profiles in the MCSF test

The acute effects of alcohol administration are age-, dose-, time- and task-dependent. Although generally considered to be a sedative drug, alcohol has both stimulatory and depressant effects on behavior, depending on dose and time. Alcohol-induced motor activating effects are consistently shown in mice but rarely demonstrated in adult, outbred rats using conventional behavioral tests. The aim of the present experiment was to study acute alcohol-induced effects on behavioral profiles in a more complex environment using the novel multivariate concentric square field™ (MCSF) test, designed for assessing different behaviors in the same trial including locomotor activity. Adult male Wistar rats (Sca:WI) were administered one intraperitoneal (i.p.) injection of alcohol (0.0 g/kg, 0.5 g/kg, 1.0 g/kg, or 1.5 g/kg) 5 min prior to the 30-min MCSF test. The two highest doses induced marked motor-suppressing effects. A significant interaction between group and time was found in general activity when comparing rats exposed to alcohol at 0.0 g/kg and 0.5 g/kg. In contrast to the 0.0 g/kg dose that increased the activity over time, animals administered the low dose (0.5 g/kg) demonstrated an initial high activity followed by a decline over time. No indications for acute alcohol-induced anxiolytic-like effects were found. The multivariate setting in the MCSF test appears to be sensitive for detecting motor-activating effects of low doses of alcohol as well as reduced locomotion at doses lower than in other behavioral tasks. The detection of subtle changes in behavior across time and dose is important for understanding alcohol-induced effects. This approach may be useful in evaluating alcohol doses that correspond to different degrees of intoxication in humans.

Explicit and Implicit Positive Alcohol Expectancies in Problem and Non-Problem Drinkers: Differences Across Age Groups from Young Adolescence to Adulthood

Aims: Recent studies with animal models showed that the stimulant and sedative effects of alcohol change during the adolescent period. In humans, the stimulant effects of ethanol are most often indirectly recorded through the measurement of explicit and implicit alcohol effect expectancies. However, it is unknown how such implicit and explicit expectancies evolve with age in humans during adolescence.

Methods: Adolescent (13–16 year old), young adult (17–18 year old), and adult (35–55 year old) participants were recruited. On the basis of their score on the Alcohol Use Disorder Identification Test (AUDIT), they were classified as non-problem (AUDIT ≤ 7) or problem (AUDIT ≥ 11) drinkers. The participants completed the Alcohol Expectancy Questionnaire (AEQ) and performed two unipolar Implicit Association Test (IAT) to assess implicit associations between alcohol and the concepts of “stimulation” and “sedation”.

Results: Problem drinkers from the three age groups reported significantly higher positive alcohol expectancies than non-problem drinkers on all AEQ subscales. Positive alcohol explicit expectancies also gradually decreased with age, with adolescent problem drinkers reporting especially high positive expectancies. This effect was statistically significant for all positive expectancies, with the exception of relaxation expectancies that were only close to statistical significance. In contrast, stimulation and sedation alcohol implicit associations were not significantly different between problem and non-problem drinkers and did not change with age.

Conclusion: These results indicate that explicit positive alcohol effect expectancies predict current alcohol consumption levels, especially in adolescents. Positive alcohol expectancies also gradually decrease with age in the three cross-sectional groups of adolescents, young adults, and adults. This effect might be related to changes in the physiological response to alcohol.

Alcohol and violence: neuropeptidergic modulation of monoamine systems

Neurobiological processes underlying the epidemiologically established link between alcohol and several types of social, aggressive, and violent behavior remain poorly understood. Acute low doses of alcohol, as well as withdrawal from long-term alcohol use, may lead to escalated aggressive behavior in a subset of individuals. An urgent task will be to disentangle the host of interacting genetic and environmental risk factors in individuals who are predisposed to engage in escalated aggressive behavior. The modulation of 5-hydroxytryptamine impulse flow by gamma-aminobutyric acid (GABA) and glutamate, acting via distinct ionotropic and metabotropic receptor subtypes in the dorsal raphe nucleus during alcohol consumption, is of critical significance in the suppression and escalation of aggressive behavior. In anticipation and reaction to aggressive behavior, neuropeptides such as corticotropin-releasing factor, neuropeptide Y, opioid peptides, and vasopressin interact with monoamines, GABA, and glutamate to attenuate and amplify aggressive behavior in alcohol-consuming individuals. These neuromodulators represent novel molecular targets for intervention that await clinical validation. Intermittent episodes of brief social defeat during aggressive confrontations are sufficient to cause long-lasting neuroadaptations that can lead to the escalation of alcohol consumption.

Modulation of neural circuit actvity by ethanol in basolateral amygdala

Ethanol actions in the amygdala formation may underlie in part the reinforcing effects of ethanol consumption. Previously a physiological phenomenon in the basolateral amygdala (BLA) that is dependent on neuronal network activity, compound postsynaptic potentials (cPSPs) were characterized. Effects of acute ethanol application on the frequency of cPSPs were subsequently investigated. Whole cell patch clamp recordings were performed from identified projection neurons in a rat brain slice preparation containing the amygdala formation. Acute ethanol exposure had complex effects on cPSP frequency, with both increases and decreases dependent on concentration, duration of exposure and age of the animal. Ethanol produces complex biphasic effects on synaptically-driven network activity in the BLA. These findings may relate to subjective effects of ethanol on arousal and anxiolysis in humans.

Alcohol and sleep restriction combined reduces vigilant attention, whereas sleep restriction alone enhances distractibility

STUDY OBJECTIVES

Alcohol and sleep loss are leading causes of motor vehicle crashes, whereby attention failure is a core causal factor. Despite a plethora of data describing the effect of alcohol and sleep loss on vigilant attention, little is known about their effect on voluntary and involuntary visual attention processes.

DESIGN

Repeated-measures, counterbalanced design.

SETTING

Controlled laboratory setting.

PARTICIPANTS

Sixteen young (18-27 y; M = 21.90 ± 0.60 y) healthy males.

INTERVENTIONS

Participants completed an attention test battery during the afternoon (13:00-14:00) under four counterbalanced conditions: (1) baseline; (2) alcohol (0.05% breath alcohol concentration); (3) sleep restriction (02:00-07:00); and (4) alcohol/sleep restriction combined. This test battery included a Psychomotor Vigilance Task (PVT) as a measure of vigilant attention, and two ocular motor tasks-visually guided and antisaccade-to measure the involuntary and voluntary allocation of visual attention.

MEASUREMENTS AND RESULTS

Only the combined condition led to reductions in vigilant attention characterized by slower mean reaction time, fastest 10% responses, and increased number of lapses (P < 0.05) on the PVT. In addition, the combined condition led to a slowing in the voluntary allocation of attention as reflected by increased antisaccade latencies (P < 0.05). Sleep restriction alone however increased both antisaccade inhibitory errors [45.8% errors versus < 28.4% all others; P < 0.001] and the involuntary allocation of attention, as reflected by faster visually guided latencies (177.7 msec versus > 185.0 msec all others) to a peripheral target (P < 0.05).

CONCLUSIONS

Our data reveal specific signatures for sleep related attention failure: the voluntary allocation of attention is impaired, whereas the involuntary allocation of attention is enhanced. This provides key evidence for the role of distraction in attention failure during sleep loss.

Acetaldehyde self-administration by a two-bottle choice paradigm: consequences on emotional reactivity, spatial learning, and memory

Acetaldehyde, the first alcohol metabolite, is responsible for many pharmacological effects that are not clearly distinguishable from those exerted by its parent compound. It alters motor performance, induces reinforced learning and motivated behavior, and produces different reactions according to the route of administration and the relative accumulation in the brain or in the periphery. The effective activity of oral acetaldehyde represents an unresolved field of inquiry that deserves further investigation. Thus, this study explores the acquisition and maintenance of acetaldehyde drinking behavior in adult male rats, employing a two-bottle choice paradigm for water and acetaldehyde solution (from 0.9% to 3.2% v/v), over 8 weeks. The behavioral consequences exerted by chronic acetaldehyde intake are assessed by a set of different tests: trials in an open-field arena and elevated-plus maze provided information on both general motor and explorative activity, and anxiety-driven behavioral responses. The Morris water maze allowed the exploration of cognitive processes such as spatial learning and memory. Determination of acetaldehyde levels in the brain was carried out at the end of the drinking paradigm. Our results indicate that rats exposed for the first time to acetaldehyde at 0.9% displayed a regular and stable daily drinking pattern that reached higher values and a "peaks and drops" shaped-trend when acetaldehyde concentration was increased to 3.2%. Accordingly, an increase in acetaldehyde levels in the brain was determined compared to non-acetaldehyde drinking rats. Acetaldehyde intake during the free-choice paradigm exerted an anxiogenic response in the open-field arena and elevated-plus maze, which in turn correlates with an enhancement in cognitive flexibility and spatial orientation skills, when an adaptive response to a stressful environmental challenge was required. These findings further support the idea that acetaldehyde is indeed a centrally active and behaviorally relevant metabolite of alcohol.

Conservation of the Ethanol-Induced Locomotor Stimulant Response among Arthropods

Ethanol-induced locomotor stimulation has been variously described as reflective of the disinhibitory, euphoric, or reinforcing effects of ethanol and is commonly used as an index of acute ethanol sensitivity in rodents. The fruit fly Drosophila melanogaster also shows a locomotor stimulant response to ethanol that is believed to occur via conserved, ethanol-sensitive neurobiological mechanisms, but it is currently unknown whether this response is conserved among arthropod species or is idiosyncratic to D. melanogaster. The current experiments surveyed locomotor responses to ethanol in a phylogenetically diverse panel of insects and other arthropod species. A clear ethanol-induced locomotor stimulant response was seen in 9 of 13 Drosophilidae species tested, in 8 of 10 other species of insects, and in an arachnid (wolf spider) and a myriapod (millipede) species. Given the diverse phylogenies of the species that showed the response, these experiments support the hypothesis that locomotor stimulation is a conserved behavioral response to ethanol among arthropod species. Further comparative studies are needed to determine whether the specific neurobiological mechanisms known to underlie the stimulant response in D. melanogaster are conserved among arthropod and vertebrate species.

Altered performance in a rat gambling task after acute and repeated alcohol exposure

RATIONALE

A bidirectional relationship between alcohol use disorder (AUD) and deficits in impulse control and decision making has been suggested. However, the mechanisms by which neurocognitive impairments predispose to, or result from AUD remain incompletely understood.

OBJECTIVES

The aim of this study is to gain more insight in the effects of alcohol exposure on decision making and impulse control. We used two modified versions of the rat gambling task (rGT) that differ in the net gain and the punishment magnitude associated with the different response options.

METHODS

In experiment 1, we assessed the effects of acute alcohol treatment (0-0.8 g/kg) on rGT performance. In experiment 2, we determined the effects of alcohol on rGT acquisition (15 sessions, 0.6 g/kg). Next, these animals were challenged with alcohol (0-1.0 g/kg) prior to rGT sessions.

RESULTS

Acute alcohol treatment suppressed baseline performance in both rGT versions but only modestly altered decision making. Treatment with alcohol during acquisition increased risky choices in the rGT version that involved larger punishment and blunted the reduction in win-shift behavior during acquisition in both rGT versions. Moreover, rats treated with alcohol during acquisition showed an increase in premature and perseverative responding upon subsequent alcohol challenges (0-1.0 g/kg) and were less sensitive to the behavioral suppressant effects of alcohol.

CONCLUSIONS

Our results show that repeated alcohol exposure alters decision making during rGT acquisition and reduces the ability to adjust choice behavior on the basis of feedback. In addition, repeated alcohol exposure unmasks its behavioral disinhibitory effects in the rGT. Impaired responsiveness to choice feedback and behavioral disinhibition may contribute to the development of AUD.

Disinhibition of olfaction: human olfactory performance improves following low levels of alcohol

We hypothesize that true human olfactory abilities are obscured by cortical inhibition. Alcohol reduces inhibition. We therefore tested the hypothesis that olfactory abilities will improve following alcohol consumption. We measured olfaction in 85 subjects, 45 in a between-subjects design, and 40 in a repeated-measures within-subjects design before and after consumption of alcoholic or non-alcoholic beverages. Subjects were also assessed using neurocognitive measures of inhibition. Following alcohol consumption, blood alcohol levels ranged from 0.005% to 0.11%. Across subjects, before any consumption of alcohol, we found that individuals who were less inhibited had lower (better) olfactory detection thresholds (r=0.68, p<0.005). Moreover, after alcohol consumption, subjects with low alcohol levels could make olfactory discriminations that subjects with 0% alcohol could not make (chance=33%, alcohol=51.3±22.7%, control=34.7±31.6%, t(43)=2.03, p<0.05). Within subjects, we found correlations between levels of alcohol and olfactory detection (r=0.63, p<0.005) and discrimination (r=-0.50, p<0.05), such that performance was improved at low levels of alcohol (significantly better than baseline for detection) and deteriorated at higher levels of alcohol. Finally, levels of alcohol-induced improved olfactory discrimination were correlated with levels of alcohol-induced cognitive disinhibition (r=0.48, p<0.05). Although we cannot rule out alternative non-inhibitory alcohol-induced routes of influence, we conclude that improved olfaction at low levels of alcohol supports the notion of an inhibitory mechanism obscuring true olfactory abilities.

Early ethanol and water consumption: accumulating experience differentially regulates drinking pattern and bout parameters in male alcohol preferring (P) vs. Wistar and Sprague Dawley rats

Alcohol-preferring (P) rats develop high ethanol intake over several weeks of water/10% ethanol (10E) choice drinking. However, it is not yet clear precisely what components of drinking behavior undergo modification to achieve higher intake. Our concurrent report compared precisely measured daily intake in P vs. non-selected Wistar and Sprague Dawley (SD) rats. Here we analyze their drinking patterns and bouts to clarify microbehavioral components that are common to rats of different genetic backgrounds, vs. features that are unique to each. Under sole-fluid conditions P, Wistar and SD rats all consumed water at a high initial rate followed by a slow maintenance phase, but 10E - in a distinctly different step-like pattern of evenly distributed bouts. During choice period, 10E vs. water patterns for P rat appeared as an overlap of sole-fluid patterns. The SD rat choice patterns resembled sole-fluid patterns but were less regular. Choice patterns in Wistar differed from both P and SD rats, by consisting of intermixed small frequent episodes of drinking both 10E and water. Wistar and SD rats increased choice ethanol intake by elevating the number of bouts. A key finding was that P rat increased choice ethanol intake through a gradual increase of the bout size and duration, but kept bout number constant. This supports the hypothesis that genetic selection modifies microbehavioral machinery controlling drinking bout initiation, duration, and other pattern features. Precision analysis of drinking patterns and bouts allows differentiation between genetic lines, and provides a venue for study of localized circuit and transmitter influences mediating mesolimbic control over ethanol consumption.

Ethanol, not detectably metabolized in brain, significantly reduces brain metabolism, probably via action at specific GABA(A) receptors and has measureable metabolic effects at very low concentrations

Ethanol is a known neuromodulatory agent with reported actions at a range of neurotransmitter receptors. Here, we measured the effect of alcohol on metabolism of [3-¹³C]pyruvate in the adult Guinea pig brain cortical tissue slice and compared the outcomes to those from a library of ligands active in the GABAergic system as well as studying the metabolic fate of [1,2-¹³C]ethanol. Analyses of metabolic profile clusters suggest that the significant reductions in metabolism induced by ethanol (10, 30 and 60 mM) are via action at neurotransmitter receptors, particularly α4β3δ receptors, whereas very low concentrations of ethanol may produce metabolic responses owing to release of GABA via GABA transporter 1 (GAT1) and the subsequent interaction of this GABA with local α5- or α1-containing GABA(A)R. There was no measureable metabolism of [1,2-¹³C]ethanol with no significant incorporation of ¹³C from [1,2-¹³C]ethanol into any measured metabolite above natural abundance, although there were measurable effects on total metabolite sizes similar to those seen with unlabelled ethanol.

The evolution of Drosophila melanogaster as a model for alcohol research

Animal models have been widely used to gain insight into the mechanisms underlying the acute and long-term effects of alcohol exposure. The fruit fly Drosophila melanogaster encounters ethanol in its natural habitat and possesses many adaptations that allow it to survive and thrive in ethanol-rich environments. Several assays to study ethanol-related behaviors in flies, ranging from acute intoxication to self-administration and reward, have been developed in the past 20 years. These assays have provided the basis for studying the physiological and behavioral effects of ethanol and for identifying genes mediating these effects. In this review we describe the ecological relationship between flies and ethanol, the effects of ethanol on fly development and behavior, the use of flies as a model for alcohol addiction, and the interaction between ethanol and social behavior. We discuss these advances in the context of their utility to help decipher the mechanisms underlying the diverse effects of ethanol, including those that mediate ethanol dependence and addiction in humans.

Relations among stress, coping strategies, coping motives, alcohol consumption and related problems: a mediated moderation model

Although prominent models of alcohol use and abuse implicate stress as an important motivator of alcohol consumption, research has not consistently identified a relationship between stress and drinking outcomes. Presumably stress leads to heavier alcohol consumption and related problems primarily for individuals who lack other adaptive methods for coping effectively with stressful experiences. To test this hypothesis, we examined four adaptive coping approaches (active coping, planning, suppression of competing activities, and restraint), as predictors of alcohol use and related problems as well as moderators of relations between stress and drinking outcomes in an undergraduate population (N=225). Further, we examined coping motives for drinking as potential mediators of the effects of coping strategies as well as stress by coping strategy interactions. Analyses supported both restraint and suppression of competing activities as moderators of the influence of stress on alcohol use but not problems. The stress by restraint interaction was also evident in the prediction of coping motives, and coping motives were related to higher levels of both weekly drinking and alcohol-related problems. Finally, coping motives for drinking served to mediate the stress by restraint interaction on weekly drinking. Overall, these results suggest that efforts to suppress competing activities and restrain impulsive responses in the face of stress may reduce the risk for heavy drinking during the transition from high school to college.

The Impact of Caffeine on the Behavioral Effects of Ethanol Related to Abuse and Addiction: A Review of Animal Studies

The impact of caffeine on the behavioral effects of ethanol, including ethanol consumption and abuse, has become a topic of great interest due to the rise in popularity of the so-called energy drinks. Energy drinks high in caffeine are frequently taken in combination with ethanol under the popular belief that caffeine can offset some of the intoxicating effects of ethanol. However, scientific research has not universally supported the idea that caffeine can reduce the effects of ethanol in humans or in rodents, and the mechanisms mediating the caffeine-ethanol interactions are not well understood. Caffeine and ethanol have a common biological substrate; both act on neurochemical processes related to the neuromodulator adenosine. Caffeine acts as a nonselective adenosine A1 and A2A receptor antagonist, while ethanol has been demonstrated to increase the basal adenosinergic tone via multiple mechanisms. Since adenosine transmission modulates multiple behavioral processes, the interaction of both drugs can regulate a wide range of effects related to alcohol consumption and the development of ethanol addiction. In the present review, we discuss the relatively small number of animal studies that have assessed the interactions between caffeine and ethanol, as well as the interactions between ethanol and subtype-selective adenosine receptor antagonists, to understand the basic findings and determine the possible mechanisms of action underlying the caffeine-ethanol interactions.

Ethanol concentration-dependent alterations in gene expression during acute binge drinking in the HIV-1 transgenic rat

BACKGROUND

Binge drinking of high ethanol (EtOH) concentration beverages is common among young adults and can be a risk factor for exposure to sexually transmitted diseases, including HIV-1. We used a novel noninfectious HIV-1 transgenic (HIV-1Tg) rat model that mimics HIV-1 patients in terms of altered immune responses and deficits in cognitive learning and memory to investigate EtOH concentration-dependent effects on 48 alcohol-modulated genes during binge EtOH administration.

METHODS

HIV-1Tg and control F344 rats were administered water, 8% EtOH, or 52% EtOH by gavage (i.g.) for 3 days (2.0 g/kg/d). Two hours after final treatment, blood, liver, and spleen were collected from each animal. Serum blood EtOH concentration (BEC) was measured, and gene expression in the liver and spleen was determined using a specifically designed PCR array.

RESULTS

The BEC was significantly higher in the 52% EtOH-treated HIV-1Tg rats compared with the 8% EtOH group; however, the BEC was higher in the 8% EtOH-treated control rats compared with the 52% EtOH group. There was no change in expression of the EtOH metabolism-related genes, Adh1, Adh4, and Cyp2e1, in either the 8 or 52% EtOH-treated HIV-1Tg rats, whereas expression of those genes was significantly higher in the liver of the 52% EtOH control rats, but not in the 8% EtOH group. In the HIV-1Tg rats, expression of the GABAA , metabotropic glutamate, and dopamine neurotransmitter receptor genes was significantly increased in the spleen of the 52% EtOH group, but not in the 8% EtOH group, whereas no change was observed in those genes in either of the control groups.

CONCLUSIONS

Our data indicate that, in the presence of HIV-1 infection, EtOH concentration-dependent binge drinking can have significantly different molecular effects.

Acute ethanol responses in Drosophila are sexually dimorphic

In mammalian and insect models of ethanol intoxication, low doses of ethanol stimulate locomotor activity whereas high doses induce sedation. Sex differences in acute ethanol responses, which occur in humans, have not been characterized in Drosophila. In this study, we find that male flies show increased ethanol hyperactivity and greater resistance to ethanol sedation compared with females. We show that the sex determination gene transformer (tra) acts in the developing nervous system, likely through regulation of fruitless (fru), to at least partially mediate the sexual dimorphism in ethanol sedation. Although pharmacokinetic differences may contribute to the increased sedation sensitivity of females, neuronal tra expression regulates ethanol sedation independently of ethanol pharmacokinetics. We also show that acute activation of fru-expressing neurons affects ethanol sedation, further supporting a role for fru in regulating this behavior. Thus, we have characterized previously undescribed sex differences in behavioral responses to ethanol, and implicated fru in mediating a subset of these differences.

Validation of the brief Biphasic Alcohol Effects Scale (B-BAES)

BACKGROUND

The Biphasic Alcohol Effects Scale (BAES) is a reliable and valid 14-item measure of alcohol's acute stimulant and sedative effects, but its length may preclude use in research paradigms with time constraints on assessment. Here, we report further psychometric support for the 6-item Brief BAES (B-BAES) originally developed by our group in 2009.

METHODS

Two studies are included: the first study tested the B-BAES in an independent sample of young adult heavy social drinkers administered 0.8 g/kg alcohol in a laboratory challenge study (N = 104) to confirm the reliability and validity of the 6-item B-BAES. The second study compared the predictive validity of the B-BAES versus the BAES in a separate sample of 104 heavy drinkers who took part in a prospective laboratory alcohol challenge and follow-up study of drinking behaviors.

RESULTS

An item analysis demonstrated strong support across several intervals on the breath alcohol curve for the same 6 B-BAES items (energized, excited, up, sedated, slow thoughts, sluggish). Confirmatory factor analysis with the B-BAES demonstrated strong support for the same underlying structure as with the full BAES, and tests of internal consistency reliability were very strong to excellent. B-BAES subscale scores correlated highly with corresponding scores of the BAES and predicted binge-drinking frequency during a 2-year follow-up.

CONCLUSIONS

These results provide strong psychometric support to confirm use of the B-BAES in studies assessing alcohol's stimulant and sedative properties. The B-BAES may be a useful new tool to enhance the scope of future research assessing alcohol's biphasic effects, particularly in paradigms when time and concise measurement are priorities.

The relationship between placebo alcohol and affect: motives for drinking

INTRODUCTION AND AIMS

Although alcohol is often used in an attempt to alleviate negative affect, alcohol oftentimes exacerbates depressive symptoms. Therefore the relationship between alcohol and affect, and the role of motives for drinking remain unclear. The present study hypothesised that placebo alcohol would blunt affective responding and that desire to drink would increase in individuals who expected alcohol to help them cope after a negative experience. The present study also explored whether motives and reasons for drinking altered after a negative experience.

DESIGN AND METHODS

Participants (36 first-year psychology students and 41 community members) were randomly assigned to one of four experimental groups, being soft drink or placebo alcohol, neutral or negative mood induction.

RESULTS

Two repeated measures analyses indicated that placebo alcohol did not significantly blunt affective responding after the negative mood induction. T-tests showed that desire to drink did not significantly increase post negative mood induction for participants who endorsed coping motives for drinking. However, interestingly coping-depression and enhancement motives decreased after negative mood induction, and participants misattributed the majority of their mood to other life events.

DISCUSSION AND CONCLUSIONS

The findings indicate that motives for drinking are amendable with prior learning, providing support for expectancy challenge procedures. The study also provides some evidence for alcohol's effect on emotional lability.

Chronic tolerance to the locomotor stimulating effect of ethanol in preweanling rats as a function of social stress

During early stages of development rats are highly sensitive to the locomotor stimulating effect of relatively high ethanol doses, an effect strongly modulated by social stress. This ethanol effect can be modulated by pharmacological treatments that also can attenuate the development of ethanol-induced locomotor sensitization in mice. By the end of the preweanling period the mechanisms underlying sensitization induced by psychostimulants are functional. The aim of the present study was to analyze the locomotor response to ethanol in preweanling rats as a function of repeated exposure to the drug under two different social conditions. Subjects were treated with ethanol between postnatal days 15 and 18 after being isolated for four hours (Experiment 1a) or simply residing in their home-cage (Experiment 1b). After two days of withdrawal locomotor response to ethanol was assessed in both social conditions. In Experiment 2 naïve rats were tested in terms of ethanol-induced activation of the locomotor response in both social conditions. Results from the present study showed no evidence of locomotor sensitization in preweanling rats in any of the social conditions. Instead we observed behavioral tolerance to the stimulating effect of ethanol in animals trained in the home-cage condition, in which subjects trained with ethanol showed sedation in response to ethanol at testing. Overall these results contribute to the understanding of the sensitivity of rats to the acute and chronic locomotor response to ethanol in an ontogenetic period characterized by high sensitivity to ethanol.

Alcohol exposure rate control through physiologically based pharmacokinetic modeling

BACKGROUND

The instantaneous rate of change of alcohol exposure (slope) may contribute to changes in measures of brain function following administration of alcohol that are usually attributed to breath alcohol concentration (BrAC) acting alone. To test this proposition, a 2-session experiment was designed in which carefully prescribed, constant-slope trajectories of BrAC intersected at the same exposure level and time since the exposure began. This paper presents the methods and limitations of the experimental design.

METHODS

Individualized intravenous infusion rate profiles of 6% ethanol (EtOH) that achieved the constant-slope trajectories for an individual were precomputed using a physiologically based pharmacokinetic model. Adjusting the parameters of the model allowed each infusion profile to account for the subject's EtOH distribution and elimination kinetics. Sessions were conducted in randomized order and made no use of feedback of BrAC measurements obtained during the session to modify the precalculated infusion profiles. In one session, an individual's time course of exposure, BrAC(t), was prescribed to rise at a constant rate of 6.0 mg% per minute until it reached 68 mg% and then descend at -1.0 mg% per minute; in the other, to rise at a rate of 3.0 mg% per minute. The 2 exposure trajectories were designed to intersect at a BrAC (t = 20 minutes) = 60 mg% at an experimental time of 20 minutes.

RESULTS

Intersection points for 54 of 61 subjects were within prescribed deviations (range of ± 3 mg% and ± 4 minutes from the nominal intersection point).

CONCLUSIONS

Results confirmed the feasibility of applying the novel methods for achieving the intended time courses of the BrAC, with technical problems limiting success to 90% of the individuals tested.

Mood and implicit alcohol expectancy processes: predicting alcohol consumption in the laboratory

BACKGROUND

Implicit positive alcohol expectancy (PAE) processes are thought to respond phasically to external and internal stimuli-including mood states-and so they may exert powerful proximal influences over drinking behavior. Although social learning theory contends that mood states activate mood-congruent implicit PAEs, which in turn lead to alcohol use, there is a dearth of experimental research examining this mediation model relative to observable drinking. Moreover, an expectancy theory perspective might suggest that, rather than influencing PAEs directly, mood may moderate the association between PAEs and drinking. To test these models, this study examined the role of mood in the association between implicitly measured PAE processes (i.e., latency to endorse PAEs) and immediate alcohol consumption in the laboratory. Gender differences in these processes also were examined.

METHOD

College students (N = 146) were exposed to either a positive, negative, or neutral mood induction procedure, completed a computerized PAE reaction time (RT) task, and subsequently consumed alcohol ad libitum.

RESULTS

The mood manipulation had no direct effects on drinking in the laboratory, making the mediation hypothesis irrelevant. Instead, gender and mood condition moderated the association between RT to endorse PAEs and drinking in the laboratory. For males, RT to tension reduction PAEs was a stronger predictor of volume of beer consumed and peak blood alcohol concentration in the context of general arousal (i.e., positive and negative mood) relative to neutral mood. RT to PAEs did not predict drinking in the laboratory for females.

CONCLUSIONS

The results show that PAE processes are important determinants of immediate drinking behavior in men, suggesting that biased attention to mood-relevant PAEs-as indicated by longer RTs-predicts greater alcohol consumption in the appropriate mood context. The findings also highlight the need to consider gender differences in PAE processes. This study underscores the need for interventions that target automatic cognitive processes related to alcohol use.

Effects of removing food on maintenance of drinking initiated by pairings of sipper and food

Two experiments evaluated the effects of removing food presentations on the maintenance of drinking induced by experience with sipper - food pairings. In Exp 1, ethanol drinking was induced in non-deprived Long-Evans rats by Pavlovian conditioning procedures employing an ethanol sipper as conditioned stimulus (CS) and food pellet as unconditioned stimulus (US). The Paired/Ethanol group received presentations of the ethanol sipper CS followed immediately by the response-independent presentation of the food pellet US. The Random/Ethanol group received the ethanol sipper CS and food US randomly with respect to one another. For both groups, the concentration of ethanol in the sipper CS [(3%, 4%, 6%, 8% (vol./vol.)] was increased across sessions, and, as in previous studies employing low concentrations of ethanol in non-deprived rats (i.e., maintained with free access to food in their home cages), the two procedures induced comparable levels of sipper CS-directed ethanol drinking. Removing food US presentations had no effect on sipper CS-directed ethanol drinking in either group. In Exp 2, groups of non-deprived Long-Evans rats were trained either with water or ethanol in the sipper CS paired with food US. Removing food US presentations had no effect on ethanol drinking in the Paired/Ethanol group, but water drinking in the Paired/Water group declined systematically across sessions. Results indicate that food US presentations contribute to the maintenance of water drinking but not to the maintenance of ethanol drinking. Implications for accounts of ethanol drinking based on Pavlovian sign-tracking, behavioral economics and intermittent sipper procedures are considered.

Commentary on ‘Resveratrol commonly displays hormesis: Occurrence and biomedical significance’

The plan of attack for this Commentary is threefold. First: to consider, place in perspective and judge some of the claims that have been advanced for resveratrol’s utility. Second: to evaluate and judge the scientific basis and validity of the paper being commented upon. The judgment is very positive. Third: to place in perspective the importance of hormesis in being a major factor determining resveratrol’s ultimate efficacy.

Should mood during intravenous alcohol administration be studied as a bi- or unipolar phenomenon? a pilot study

In this study, alcohol was administered intravenously to study whether its effects on mood should preferably be studied as a bi- or unipolar phenomenon. This was studied in a double-blind, placebo-balanced, design on six healthy male volunteers. Of the three bipolar aspects of mood (calmness, activity, and pleasantness), only calmness was significantly affected by intravenous alcohol. In contrast, there were significant differences between alcohol and placebo for five of the six unipolar indexes. This support the hypothesis that subjective effects of alcohol on mood are preferably studied with self-ratings that allows positive and negative aspects to be analyzed separately. Further, our data suggest that the effects of alcohol are primarily on negative aspects of mood rather than on positive.

Effects of ethanol on the shoaling behavior of zebrafish (danio rerio)

Ethanol (EtOH) often has stimulatory effects at low doses and inhibitory effects at high doses, affecting behavior and physiology of many organisms in a non-linear manner suggestive of hormesis. Zebrafish (Danio rerio) shoaling was studied in adult fish exposed to one of five different EtOH concentrations (v/v): 0.0% control, 0.125%, 0.25%, 0.5%, and 1.0%. Digital photographs of groups of four fish were taken every 2 min, with each trial lasting a total of 12 min. The median nearest neighbor distance and shoal area were calculated for each photograph. Exposure to 1.0% EtOH inhibited shoaling. In contrast, as predicted from hormesis, shoaling was significantly tighter (as measured by nearest neighbor distance) at low concentrations (0.125%, 0.25%) compared to the control, and a J-shaped dose-response curve was present. A similar pattern occurred for shoal area, but in this case the only statistically significant differences were between the high concentration and all others.