Ethanol consumption: how should we measure it? Achieving consilience between human and animal phenotypes

Maternal, paternal, and dual-parental alcohol exposures result in both overlapping and distinct impacts on behavior in adolescent offspring

Emerging research reveals that alcohol use by fathers before conception can affect the growth and development of their offspring. Here, we used a C57BL/6J mouse model to study the effects of alcohol exposure on the behavior of the first-generation (F1) offspring, comparing the impacts of alcohol exposure by mothers, fathers, and both parents. Our goal was to determine how alcohol exposure by each parent or both parents influences the behavior of the offspring. We found that adolescent male offspring of alcohol-exposed fathers showed reduced anxiety-like behaviors as they spent more time in the center of the testing arena during the open field test. Both maternal and paternal alcohol exposure caused sex-specific increases in the nestlet shredding test while decreasing the number of buried marbles in the marble burying test. Interestingly, dual-parental alcohol exposure did not produce any significant changes in these same tests. However, during novel object recognition testing, we found that dual-parental male and female offspring exhibit an increased preference for novel objects, suggesting an increased risk preference. Finally, at sixteen weeks, male offspring of dual-exposed parents exhibited decreased voluntary physical activity on running wheels during the active phase, suggesting alterations in their circadian rhythms. Although differences in parental exposure histories between treatment groups make interpretation challenging, our findings suggest that exposure to alcohol by both parents may have unique effects on behavior and that studying both maternal and paternal alcohol use is essential for understanding the full range of factors influencing the penetrance and severity of alcohol-related phenotypes.

Apremilast reduces co-occurring alcohol drinking and mechanical allodynia and regulates central amygdala GABAergic transmission

The FDA-approved phosphodiesterase type 4 (PDE4) inhibitor, apremilast, has been recently investigated as a pharmacotherapy for alcohol use disorder (AUD) with promising efficacy in rodent models and humans. However, apremilast's effects on mechanical allodynia associated with AUD as well as distinct responses of this drug between males and females are understudied. The present study examined the behavioral and electrophysiological effects of apremilast in Marchigian Sardinian alcohol-preferring (msP) rats and their Wistar counterparts. We used a 2-bottle choice (2-BC) alcohol drinking procedure and tested mechanical sensitivity across our drinking regimen. Spontaneous inhibitory GABA-mediated postsynaptic currents from the central nucleus of the amygdala (CeA) following apremilast application were tested in a subset of rats using ex vivo electrophysiology. Transcript levels for Pde4a or -4b subtypes were assessed for their modulation by alcohol. Apremilast reduced alcohol drinking in both strains of rats. Apremilast reduced mechanical allodynia immediately after drinking, persisting into early and late abstinence. Apremilast increased GABAergic transmission in CeA slices of alcohol-exposed Wistars but not msP rats, suggesting neuroadaptations in msPs by excessive drinking and mechanical allodynia. Pde4 subtype transcript levels were increased in CeA by alcohol. These results suggest that apremilast alleviates co-occurring excessive drinking and pain sensitivity, and they further confirm PDE4's role in pain-associated AUD.

Pace of alcohol drinking during in natural-environment drinking is associated with heightened alcohol-related reward and negative consequences in risky drinkers

BACKGROUND

Sensitivity to alcohol's stimulating and rewarding properties is associated with increased risk for future heavy drinking and the development and maintenance of alcohol use disorder (AUD). Further, pace of alcohol consumption varies across individuals and affects level of intoxication and subjective alcohol responses. The present study used smartphone-based high-resolution ecological momentary assessment (HR-EMA) of a heavy drinking episode in young adult risky drinkers' natural environments to examine associations between pace of drinking and subjective responses to alcohol.

METHOD

Young adult risky drinkers (N = 248; 42% female) completed a 3-hour HR-EMA of alcohol use and subjective responses to alcohol (stimulation, sedation, feeling, liking, and wanting more) during a drinking episode in their natural environment. Analyses examined associations between drinking pace trajectories and subjective responses to alcohol, accounting for drinking context (location/presence of others) and depression.

RESULTS

Trajectory analysis revealed three drinking pace subgroups based on total drinks consumed during the 3-hour monitoring period: fast risers (~ 4 standard drinks/hour), moderate risers (~ 2.6 standard drinks/hour), and slow risers (~ 1.4 standard drinks/hour). Overall, faster pace of drinking was associated with greater alcohol stimulation and reward (liking and wanting more) and more alcohol-related negative consequences during and after the episode.

CONCLUSIONS

Results further underscore the heterogeneous nature of young adult risky drinkers and suggest the possibility that these individuals may drink rapidly to experience the stimulating and rewarding effects of alcohol sooner. Resulting increases in the positive effects of alcohol may reinforce future rapid drinking behavior.

Excessive alcohol intake produces persistent mechanical allodynia and dysregulates the endocannabinoid system in the lumbar dorsal root ganglia of genetically-selected Marchigian Sardinian alcohol-preferring rats

Epidemiological data indicate a strong association between alcohol use disorder (AUD) and neuropathic pain. Genetically-selected Marchigian Sardinian alcohol-preferring (msP) rats exhibit a high preference for alcohol compared with their background strain (Wistar rats), but their sensitivity to mechanical allodynia after chronic alcohol exposure is unknown. The present study compared the development of mechanical allodynia between "low, non-pathological drinker" Wistar rats and "high drinker" msP rats using the two-bottle choice (2BC) free-access procedure. Several studies reported the involvement of endocannabinoids (eCBs) in modulating mechanical allodynia, but there are no data on their role in alcohol-related allodynia. Thus, the present study assessed eCBs and their related lipid species in lumbar dorsal root ganglia (DRG) and correlated them with mechanical allodynia in our model. We found that male and female msP rats developed persistent mechanical allodynia during protracted abstinence from alcohol, presenting no sign of recovery, as opposed to Wistar rats. This effect directly correlated with their total alcohol intake. Notably, we found a correlation between lower lumbar DRG 2-arachidonoylglycerol (2-AG) levels and the development of higher mechanical allodynia during abstinence in msP rats of both sexes but not in Wistar rats. Moreover, alcohol-exposed and abstinent msP and Wistar females but not males exhibited significant alterations of thromboxane B2 and prostaglandin E2/prostaglandin D2 compared with naive rats. These findings demonstrate that DRG 2-AG metabolism is altered in msP rats during prolonged abstinence and represents a potentially interesting pharmacological target for the treatment of mechanical allodynia during alcohol abstinence.

Parental Alcohol Exposures Associate with Lasting Mitochondrial Dysfunction and Accelerated Aging in a Mouse Model

Although detrimental changes in mitochondrial morphology and function are widely described symptoms of fetal alcohol exposure, no studies have followed these mitochondrial deficits into adult life or determined if they predispose individuals with fetal alcohol spectrum disorders (FASDs) to accelerated biological aging. Here, we used a multiplex preclinical mouse model to compare markers of cellular senescence and age-related outcomes induced by maternal, paternal, and dual-parental alcohol exposures. We find that even in middle life (postnatal day 300), the adult offspring of alcohol-exposed parents exhibited significant increases in markers of stress-induced premature cellular senescence in the brain and liver, including an upregulation of cell cycle inhibitory proteins and increased senescence-associated β-galactosidase activity. Strikingly, in the male offspring, we observe an interaction between maternal and paternal alcohol use, with histological indicators of accelerated age-related liver disease in the dual-parental offspring exceeding those induced by either maternal or paternal alcohol use alone. Our studies indicate that chronic parental alcohol use causes enduring mitochondrial dysfunction in offspring, resulting in a reduced NAD+/NAHD ratio and altered expression of the NAD+-dependent deacetylases SIRT1 and SIRT3. These observations suggest that some aspects of FASDs may be linked to accelerated aging due to programmed changes in the regulation of mitochondrial function and cellular bioenergetics.

Chronic paternal alcohol exposures induce dose-dependent changes in offspring craniofacial shape and symmetry

Although dose-response analyses are a fundamental tool in developmental toxicology, few studies have examined the impacts of toxicant dose on the non-genetic paternal inheritance of offspring disease and dysgenesis. In this study, we used geometric morphometric analyses to examine the impacts of different levels of preconception paternal alcohol exposure on offspring craniofacial shape and symmetry in a mouse model. Procrustes ANOVA followed by canonical variant analysis of geometric facial relationships revealed that Low-, Medium-, and High-dose treatments each induced distinct changes in craniofacial shape and symmetry. Our analyses identified a dose threshold between 1.543 and 2.321 g/kg/day. Below this threshold, preconception paternal alcohol exposure induced changes in facial shape, including a right shift in facial features. In contrast, above this threshold, paternal exposures caused shifts in both shape and center, disrupting facial symmetry. Consistent with previous clinical studies, changes in craniofacial shape predominantly mapped to regions in the lower portion of the face, including the mandible (lower jaw) and maxilla (upper jaw). Notably, high-dose exposures also impacted the positioning of the right eye. Our studies reveal that paternal alcohol use may be an unrecognized factor contributing to the incidence and severity of alcohol-related craniofacial defects, complicating diagnostics of fetal alcohol spectrum disorders.

Maternal 129S1/SvImJ background attenuates the placental phenotypes induced by chronic paternal alcohol exposure

Paternal alcohol use is emerging as a plausible driver of alcohol-related growth and patterning defects. Studies from our lab using an inbred C57Bl/6 J mouse model suggest that these paternally-inherited phenotypes result from paternally programmed deficits in the formation and function of the placenta. The 129S1/SvImJ genetic background is typically more susceptible to fetoplacental growth defects due to strain-specific differences in placental morphology. We hypothesized that these placental differences would sensitize 129S1/SvImJ-C57Bl/6 J hybrid offspring to paternally-inherited fetoplacental growth phenotypes induced by paternal alcohol exposure. Using a limited access model, we exposed C57Bl/6 J males to alcohol and bred them to naïve 129S1/SvImJ dams. We then assayed F1 hybrid offspring for alterations in fetoplacental growth and used micro-CT imaging to contrast placental histological patterning between the preconception treatments. F1 hybrid placentae exhibit larger placental weights than pure C57Bl/6 J offspring but display a proportionally smaller junctional zone with increased glycogen content. The male F1 hybrid offspring of alcohol-exposed sires exhibit modest placental hyperplasia but, unlike pure C57Bl/6 J offspring, do not display observable changes in placental histology, glycogen content, or measurable impacts on fetal growth. Although F1 hybrid female offspring do not exhibit any measurable alterations in fetoplacental growth, RT-qPCR analysis of placental gene expression reveals increased expression of genes participating in the antioxidant response. The reduced placental junctional zone but increased glycogen stores of 129S1/SvImJ-C57Bl/6 J F1 hybrid placentae ostensibly attenuate the previously observed placental patterning defects and fetal growth restriction induced by paternal alcohol use in the C57Bl/6 J strain.

Sexually dimorphic effects of monoacylglycerol lipase inhibitor MJN110 on stress-related behaviour and drinking in Marchigian Sardinian alcohol-preferring rats

BACKGROUND AND PURPOSE

The endocannabinoid (eCB) system plays an important homeostatic role in the regulation of stress circuits and has emerged as a therapeutic target to treat stress disorders and alcohol use disorder (AUD). Extensive research has elucidated a role for the eCB anandamide (AEA), but less is known about 2-arachidonoylglycerol (2-AG) mediated signalling.

EXPERIMENTAL APPROACH

We pharmacologically enhanced eCB signalling by inhibiting the 2-AG metabolizing enzyme, monoacylglycerol lipase (MAGL), in male and female Marchigian Sardinian alcohol-preferring (msP) rats, a model of innate alcohol preference and stress hypersensitivity, and in control Wistar rats. We tested the acute effect of the selective MAGL inhibitor MJN110 in alleviating symptoms of alcohol drinking, anxiety, irritability and fear.

KEY RESULTS

A single systemic administration of MJN110 increased 2-AG levels in the central amygdala, prelimbic and infralimbic cortex but did not acutely alter alcohol drinking. MAGL inhibition reduced aggressive behaviours in female msPs, and increased defensive behaviours in male msPs, during the irritability test. Moreover, in the novelty-induced hypophagia test, MJN110 selectively enhanced palatable food consumption in females, mitigating stress-induced food suppression. Lastly, msP rats showed increased conditioned fear behaviour compared with Wistar rats, and MJN110 reduced context-associated conditioned fear responses, but not cue-probed fear expression, in male msPs.

CONCLUSIONS AND IMPLICATIONS

Acute inhibition of MAGL attenuated some stress-related responses in msP rats but not voluntary alcohol drinking. Our results provide new insights into the sex dimorphism documented in stress-induced responses. Sex-specific eCB-based approaches should be considered in the clinical development of therapeutics.

High-intensity drinking and hours spent drinking

BACKGROUND

High-intensity drinking (HID) is associated with negative consequences, but it remains unclear whether a time qualifier (i.e., time spent drinking) is needed to identify individuals at highest risk. To improve the measurement and conceptualization of HID, we examined the utility of adding a time qualifier to define what constitutes an occasion of HID using repeated daily surveys in a sample of young adults.

METHODS

Participants were selected from a nationally representative sample of 12th-grade students in the United States who participated in the Monitoring the Future (MTF) study in Spring 2018. In 2019 and 2020, young adults (at modal ages 19-20) responded to annual and daily (14 consecutive days per year) online surveys about their alcohol use.

RESULTS

When we compared moderate drinking days (less than 4/5 drinks for women/men), binge drinking days (4-7/5-9 drinks), and HID days (8+/10+ drinks), HID days had the longest duration of drinking (5.2 h), highest peak estimated blood alcohol concentration (eBAC, 0.30%), and greatest drinking pace (2.58 drinks/h). HID was associated with a greater number of negative consequences than either moderate or binge drinking; adjusting for time spent drinking did not impact this interpretation. HID was reported on 10.9% of days; when defined as 8/10+ drinks in 4 h or 2 h, HID was reported on 4.8% and 1.0% of days, respectively. Nearly all differences in eBAC and negative consequences persisted across drinking intensity despite the introduction of time constraints.

CONCLUSIONS

HID days were characterized by both a longer time spent drinking and a more rapid pace of drinking. Adding a time qualifier to the definition of HID would restrict variability by only describing the minority of days and does not improve the distinctions among levels of risk.

A novel monobactam lacking antimicrobial activity, MC-100093, reduces sex-specific ethanol preference and depressive-like behaviors in mice

Several β-lactam derivatives upregulate astrocytic glutamate transporter type 1expression and are known to improve measures in models of mood and alcohol use disorders (AUD) through normalizing glutamatergic states. However, long-term, and high doses of β-lactams may cause adverse side effects for treating mood disorders and AUD. Studies suggest that MC-100093, a novel β-lactam lacking antimicrobial activity, rescues GLT1 expression. Thus, we sought to investigate whether MC-100093 improves affective behaviors and reduces voluntary ethanol drinking. We intraperitoneally administered MC-100093 (50 mg/kg) or vehicle once per day to C57BL/6J male and female mice (8-10 weeks old) over 6 days. We employed the open field test and the elevated plus maze to examine the effect of MC-100093 on anxiety-like behaviors. We assayed MC-100093's effects on depressive-like behaviors using the tail suspension and forced swim tests. Next, utilizing a separate cohort of male and female C57BL6 mice, we assessed the effects MC100093 treatment on voluntary ethanol drinking utilizing the 2-bottle choice continuous access drinking paradigm. After screening and selecting high-drinking mice, we systematically administered MC-100093 (50 mg/kg) or vehicle to the high-drinking mice over 6 days. Overall, we found that MC-100093 treatment resulted in sex-specific pharmacological effects with female mice displaying reduced innate depressive-like behaviors during the tail suspension and force swim testing juxtaposed with male treated mice who displayed no changes in tail suspension and a paradoxical increased depressive-like behavior during the forced swim testing. Additionally, we found that MC100093 treatment reduced female preference for 10% EtOH during the 2-bottle choice continuous access drinking with no effects of MC100093 treatment detected in male mice. Overall, this data suggests sex-specific regulation of innate depressive-like behavior and voluntary EtOH drinking by MC100093 treatment. Western blot analysis of the medial prefrontal cortex and hippocampus revealed no changes in male or female GLT1 protein abundance relative to GAPDH.

Predictive risk markers in alcoholism

The medical disorders of alcoholism rank among the leading public health problems worldwide and the need for predictive and prognostic risk markers for assessing alcohol use disorders (AUD) has been widely acknowledged. Early-phase detection of problem drinking and associated tissue toxicity are important prerequisites for timely initiations of appropriate treatments and improving patient's committing to the objective of reducing drinking. Recent advances in clinical chemistry have provided novel approaches for a specific detection of heavy drinking through assays of unique ethanol metabolites, phosphatidylethanol (PEth) or ethyl glucuronide (EtG). Carbohydrate-deficient transferrin (CDT) measurements can be used to indicate severe alcohol problems. Hazardous drinking frequently manifests as heavy episodic drinking or in combinations with other unfavorable lifestyle factors, such as smoking, physical inactivity, poor diet or adiposity, which aggravate the metabolic consequences of alcohol intake in a supra-additive manner. Such interactions are also reflected in multiple disease outcomes and distinct abnormalities in biomarkers of liver function, inflammation and oxidative stress. Use of predictive biomarkers either alone or as part of specifically designed biological algorithms helps to predict both hepatic and extrahepatic morbidity in individuals with such risk factors. Novel approaches for assessing progression of fibrosis, a major determinant of prognosis in AUD, have also been made available. Predictive algorithms based on the combined use of biomarkers and clinical observations may prove to have a major impact on clinical decisions to detect AUD in early pre-symptomatic stages, stratify patients according to their substantially different disease risks and predict individual responses to treatment.

Sex-specific differences in alcohol-induced pain sensitization

Pain sensitization is a phenomenon that occurs to protect tissues from damage and recent studies have shown how a variety of non-noxious stimuli included in our everyday lives can lead to pain sensitization. Consumption of large amounts of alcohol over a long period of time invokes alcohol use disorder (AUD), a complex pathological state that has many manifestations, including alcohol peripheral neuropathy (neuropathic pain). We asked if 'non-pathological' alcohol consumption can cause pain sensitization in the absence of other pathology? Studies have pointed to glia and other immune cells and their role in pain sensitization that results in cell and sex-specific responses. Using a low-dose and short-term ethanol exposure model, we investigated whether this exposure would sensitize mice to a subthreshold dose of an inflammatory mediator that normally does not induce pain. We observed female mice exhibited specific mechanical and higher thermal sensitivity than males. We also observed an increase in CD68⁺ macrophages in the ipsilateral dorsal root ganglia (DRG) and Iba1⁺ microglia in the ipsilateral spinal dorsal horn of animals that were exposed to ethanol and injected with subthreshold inflammatory prostaglandin E2. Our findings suggest that short-term ethanol exposure stimulates peripheral and central, immune and glial activation, respectively to induce pain sensitization. This work begins to reveal a possible mechanism behind the development of alcoholic peripheral neuropathy.

Choline Supplementation Alters Hippocampal Cytokine Levels in Adolescence and Adulthood in an Animal Model of Fetal Alcohol Spectrum Disorders

Alcohol (ethanol) exposure during pregnancy can adversely affect development, with long-lasting consequences that include neuroimmune, cognitive, and behavioral dysfunction. Alcohol-induced alterations in cytokine levels in the hippocampus may contribute to abnormal cognitive and behavioral outcomes in individuals with fetal alcohol spectrum disorders (FASD). Nutritional intervention with the essential nutrient choline can improve hippocampal-dependent behavioral impairments and may also influence neuroimmune function. Thus, we examined the effects of choline supplementation on hippocampal cytokine levels in adolescent and adult rats exposed to alcohol early in development. From postnatal day (PD) 4-9 (third trimester-equivalent), Sprague-Dawley rat pups received ethanol (5.25 g/kg/day) or sham intubations and were treated with choline chloride (100 mg/kg/day) or saline from PD 10-30; hippocampi were collected at PD 35 or PD 60. Age-specific ethanol-induced increases in interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), and keratinocyte chemoattractant/human growth-regulated oncogene (KC/GRO) were identified in adulthood, but not adolescence, whereas persistent ethanol-induced increases of interleukin-6 (IL-6) levels were present at both ages. Interestingly, choline supplementation reduced age-related changes in interleukin-1 beta (IL-1β) and interleukin-5 (IL-5) as well as mitigating the long-lasting increase in IFN-γ in ethanol-exposed adults. Moreover, choline influenced inflammatory tone by modulating ratios of pro- to -anti-inflammatory cytokines. These results suggest that ethanol-induced changes in hippocampal cytokine levels are more evident during adulthood than adolescence, and that choline can mitigate some effects of ethanol exposure on long-lasting inflammatory tone.

Alcoholic neuropathy associated with chronic alcohol intake

Alcoholic neuropathy (AN), a debilitating condition that mainly affects chronic alcohol drinkers, is thought to cause lesions in the peripheral nervous system leading to sensory, autonomic, and motor dysfunctions. Despite many studies, the pathogenesis of these lesions is still not completely understood. We investigated few aspects on the development of alcohol-induced peripheral neuropathy, by assessing sensory, motor and autonomic functions, as well as stereological analysis of axonal fibers and myelin sheath of the sciatic nerve. Twelve male Wistar rats were divided into Control group and Alcohol group that was submitted to Two Bottle-Choice Paradigm of intermittent and voluntary alcohol solution intake (20%; v/v) during eight weeks. At the end of treatment, three different sensorium-motor tests were applied - Tactile Sensitivity, Thermal Sensitivity, and Functional Observational Battery (FOB). Quantitative morphometric analysis of sciatic nerve structures was performed by stereological method. Alcohol concentration in the blood was measured to analyze possible correlation between availability of alcohol in the blood and the magnitude of the peripheral nerve lesion. Our data showed a peripheral effect of chronic alcohol intake associated with hyperalgesia and a process of demyelination with a strong correlation with alcohol consumption. This process was associated with increased tactile sensitivity, with behavioral reflexes such as locomotor hyperactivity, changes in gait and balance, and autonomic reflexes such as piloerection.

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Alcoholic neuropathy and its consequences.

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Neuropathy and sensitive and motor alterations.

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Alcoholic neuropathy and thinner myelin sheath thickness.

Paternal alcohol exposures program intergenerational hormetic effects on offspring fetoplacental growth

Hormesis refers to graded adaptive responses to harmful environmental stimuli where low-level toxicant exposures stimulate tissue growth and responsiveness while, in contrast, higher-level exposures induce toxicity. Although the intergenerational inheritance of programmed hormetic growth responses is described in plants and insects, researchers have yet to observe this phenomenon in mammals. Using a physiologically relevant mouse model, we demonstrate that chronic preconception paternal alcohol exposures program nonlinear, dose-dependent changes in offspring fetoplacental growth. Our studies identify an inverse j-shaped curve with a threshold of 2.4 g/Kg per day; below this threshold, paternal ethanol exposures induce programmed increases in placental growth, while doses exceeding this point yield comparative decreases in placental growth. In male offspring, higher paternal exposures induce dose-dependent increases in the placental labyrinth layer but do not impact fetal growth. In contrast, the placental hypertrophy induced by low-level paternal ethanol exposures associate with increased offspring crown-rump length, particularly in male offspring. Finally, alterations in placental physiology correlate with disruptions in both mitochondrial-encoded and imprinted gene expression. Understanding the influence of ethanol on the paternally-inherited epigenetic program and downstream hormetic responses in offspring growth may help explain the enormous variation observed in fetal alcohol spectrum disorder (FASD) phenotypes and incidence.

Effects of moderate alcohol consumption on behavior and neural systems of Wistar rats

Chronic alcohol consumption affects various neurotransmitters, especially those implicated in the transitioning to alcohol use disorders (particularly dopaminergic and CRFergic systems). Few studies have investigated moderate alcohol consumption and its harmful consequences. The objective of this work was to analyze behavioral and neurochemical (dopaminergic and CRFergic systems) alterations during chronic moderate alcohol consumption. Twelve male Wistar rats were submitted to an intermittent alcohol ingestion protocol (alcohol group) for four weeks. The control group consisted of six rats. Open Field and Elevated Plus Maze tests were used for analysis of motor and anxiety-like behaviors. Immunohistochemistry analysis was performed in dopaminergic and CRFergic systems. Animals exposed to alcohol consumed moderate doses, chronic and intermittently. Behavioral tests detected fewer fecal boli in the alcohol exposed group, and immunohistochemical analysis indicated fewer dopamine-immunoreactive cells in the ventral tegmental area, and more CRF-immunoreactive cells in the anterior cingulate cortex and dorsolateral septum in this group. Thus we concluded that Wistar rats that consumed moderate doses of alcohol voluntarily and chronically showed a discreet anxiolytic effect in behavior, and a hypodopaminergic and hyperCRFergic neurochemical condition, which together are strong inducers of alcohol consumption predisposing to the development of alcohol use disorder (AUD).

Choline Supplementation Modifies the Effects of Developmental Alcohol Exposure on Immune Responses in Adult Rats

Prenatal alcohol exposure can disrupt the development of numerous systems, including the immune system. Indeed, alterations in cytokine levels may contribute to the neuropathological, behavioral, and cognitive problems, and other adverse outcomes observed in individuals with fetal alcohol spectrum disorders. Importantly, supplementation with the essential nutrient choline can improve performance in hippocampal-dependent behaviors; thus, the present study examined the effects of choline on plasma and hippocampal cytokines in adult rats exposed to ethanol in early development. From postnatal day (PD) 4–9 (third trimester equivalent), pups received ethanol (5.25 g/kg/day) or Sham intubations. Subjects were treated with choline chloride (100 mg/kg/day) or saline from PD10–30. On PD60, plasma and hippocampal tissue was collected before and after an immune challenge (lipopolysaccharide (LPS); 50 ug/kg). Prior to the immune challenge, ethanol-exposed subjects showed an overall increase in hippocampal pro-inflammatory cytokines, an effect mitigated by choline supplementation. In contrast, in the plasma, choline reduced LPS-related increases in pro-inflammatory markers, particularly in ethanol-exposed subjects. Thus, early choline supplementation may modify both brain and peripheral inflammation. These results suggest that early choline can mitigate some long-term effects of ethanol exposure on hippocampal inflammation, which may contribute to improved hippocampal function, and could also influence peripheral immune responses that may impact overall health.

Caffeine and alcohol - Friends or foes of human iron stores?

BACKGROUND & AIMS

There is clear evidence that lifestyle factors affect iron bioavailability. However, information regarding the effect of alcohol and caffeine consumption on iron metabolism is limited. The aim of the current study was to evaluate the effect of caffeine and alcohol consumption on iron metabolism in healthy men, regarding their everyday physical activity level.

METHODS

The study enrolled 83 men (59 physically active and 24 sedentary men) aged 18-32 years. Fasting blood samples were collected. ELISA kits were used to determine levels of ferritin, soluble transferrin receptor, hepcidin, hemojuvelin, and C-reactive protein (hsCRP). Level of physical activity was assessed using the International Physical Activity Questionnaire (IPAQ). Caffeine and alcohol intake was assessed using a food frequency questionnaire. A general linear model was performed to evaluate the relationship between caffeine intake and levels of serum ferritin, ferritin, soluble transferrin receptor, hepcidin, hemojuvelin, and hsCRP.

RESULTS

Physically active men (but not sedentary men) who consumed alcohol in excess presented higher ferritin levels when compared to moderate drinkers and abstainers (R2 = 0.35, p = 0.0001). Heavy drinkers presented the highest hepcidin levels when compared to both abstainers and moderate drinkers (p < 0.0001 for physically active, and p = 0.0267 for sedentary men). However, moderate drinkers showed significantly lower hsCRP levels when compared to heavy drinkers and abstainers drinkers (p < 0.0001 for physically active, and p = 0.0116 for sedentary men). Greater caffeine intake was generally associated with greater serum hepcidin levels, with the strongest effect on moderate drinkers. A significant influence of caffeine intake on hsCRP was shown for physically active men but not for sedentary men - greater caffeine intake was connected with higher hsCRP levels for participants who drank alcohol.

CONCLUSION

Based on the presented results it can be assumed that high caffeine consumption may lead to suppression of iron bioavailability through increased inflammation. Furthermore, physical activity and moderate alcohol consumption seemed to benefit reduction of inflammatory response, at least as represented by hsCRP levels.

Long-term consequences of alcohol use in early adolescent mice: Focus on neuroadaptations in GR, CRF and BDNF

Our aim was to assess the cognitive and emotional state, as well as related-changes in the glucocorticoid receptor (GR), the corticotropin-releasing factor (CRF) and the brain-derived neurotrophic factor (BDNF) expression of adolescent C57BL/6J male mice after a 5-week two-bottle choice protocol (postnatal day [pd]21 to pd52). Additionally, we wanted to analyse whether the behavioural and neurobiological effects observed in late adolescence (pd62) lasted until adulthood (pd84). Behavioural testing revealed that alcohol during early adolescence increased anxiety-like and compulsive-related behaviours, which was maintained in adulthood. Concerning cognition, working memory was only altered in late adolescent mice, whereas object location test performance was impaired in both ages. In contrast, novel object recognition remained unaltered. Immunohistochemical analysis showed that alcohol during adolescence diminished BDNF+ cells in the cingulate cortex, the hippocampal CA1 layer and the central amygdala. Regarding hypothalamic-pituitary-adrenal axis (HPA) functioning, alcohol abuse increased the GR and CRF expression in the hypothalamic paraventricular nucleus and the central amygdala. Besides this, GR density was also higher in the prelimbic cortex and the basolateral amygdala, regardless of the animals' age. Our findings suggest that adolescent alcohol exposure led to long-term behavioural alterations, along with changes in BDNF, GR and CRF expression in limbic brain areas involved in stress response, emotional regulation and cognition.

Transcranial direct current stimulation (tDCS) reduces motivation to drink ethanol and reacquisition of ethanol self-administration in female mice

Transcranial direct current stimulation (tDCS) is an emerging noninvasive brain neuromodulation technique aimed at relieving symptoms associated with psychiatric disorders, including addiction. The goal of the present study was to better identify which phase of alcohol-related behavior (hedonic effect, behavioral sensitization, self-administration, or motivation to obtain the drug) might be modulated by repeated anodal tDCS over the frontal cortex (0.2 mA, 20 min, twice a day for 5 consecutive days), using female mice as a model. Our data showed that tDCS did not modulate the hedonic effects of ethanol as assessed by a conditioned place preference test (CPP) or the expression of ethanol-induced behavioral sensitization. Interestingly, tDCS robustly reduced reacquisition of ethanol consumption (50% decrease) following extinction of self-administration in an operant paradigm. Furthermore, tDCS significantly decreased motivation to drink ethanol on a progressive ratio schedule (30% decrease). Taken together, our results show a dissociation between the effects of tDCS on “liking” (hedonic aspect; no effect in the CPP) and “wanting” (motivation; decreased consumption on a progressive ratio schedule). Our tDCS procedure in rodents will allow us to better understand its mechanisms of action in order to accelerate its use as a complementary and innovative tool to help alcohol-dependent patients maintain abstinence or reduce ethanol intake.

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.

Orexin receptor blockers: A tool for lowering alcohol intake and alcohol addictive behavior in the light of preclinical studies

Alcohol use disorder (AUD) is a severe and globally widespread neurological and psychiatric problem. The treatment with currently used drugs often does not bring the expected effect. New optimization methods or directions in pharmacotherapy are still being sought. The group of bioactive ligands, targeted at neuropeptides called orexins (OXs) and their receptors (OXRs), affects a number of functions including ingestion, sleep-wake regulation, as well as the brain reward system which is the basis of addiction.

The purpose of this paper is to systematize the knowledge in the field of preclinical behavioral studies on rodents (rats and mice) in several models of alcohol consumption using the OXRs antagonists.

The results of the experiments indicated a potential efficacy of particular OXRs antagonists in the AUD treatment, especially those selectively blocking the OX1R. Among them, SB-334867 in the lowest effective dose of 3 mg/kg i.p. was most studied, as shown in the model of two-bottle choice using C57BL/6 mice. Moreover, this compound did not affect the reduction of cognitive functions. GSK1059865 was also involved in the selective reduction of ethanol intake, and simultaneously did not alter the consumption of sugar solution. The other group of selective OX2R antagonists, such as TCS-OX2-29 and LSN2424100, was less efficient.

In summary, the OX1R antagonists proved to have the potential in AUD therapy, not only through the reduction of ethanol consumption but also in the treatment of coexisting behavioral and physiological disorders, such as insomnia and anxiety.

Blood Biomarkers of Alcohol Use: A Scoping Review

Purpose of Review

Understanding whether a person has consumed alcohol or not, as well as quantitative assessment of alcohol use, are often based on self-reported measures, which may be subject to recall bias, among other challenges. Although not without limitations, blood biomarkers may complement self-reported assessments to provide a more accurate determination of the presence and quantity of alcohol use. The aim of this review is to provide a critical overview of the current knowledge and research on biomarkers of alcohol use, with a particular focus on blood tests.

Recent Findings

This scoping review summarizes the published work on blood tests currently used in clinical practice, including phosphatidyl ethanol (PEth), fatty acid ethyl ester (FAEE), carbohydrate-deficient transferrin (CDT), total serum sialic acid (TSA), mean corpuscular volume (MCV), alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma glutamyl transpeptidase (GGT), and cholesteryl ester transfer protein (CETP). Emerging blood biomarkers with a potential use to assess alcohol drinking are also briefly reviewed, including N-Acetyl-β-Hexosaminidase (Beta-Hex), macrophage migration inhibitory factor (MIF), and D-dopachrome tautomerase (DDT). We discuss the aforementioned biomarkers in the context of their clinical implications, characteristics, strengths, and limitations.

Summary

The available blood biomarkers considerably vary in the time period in which they detect alcohol use and the amount of alcohol they are sensitive to. While currently available biomarkers provide useful information, especially in combination with self-reported measures, future work is needed to identify more sensitive and specific blood biomarkers for different levels and patterns of alcohol use. Integration of such biomarkers into clinical practice and research will increase the accuracy and richness of the data and may guide more effective and targeted strategies for prevention, diagnosis, and treatment of excessive alcohol use.

Translational opportunities in animal and human models to study alcohol use disorder

Animal and human laboratory paradigms offer invaluable approaches to study the complex etiologies and mechanisms of alcohol use disorder (AUD). We contend that human laboratory models provide a "bridge" between preclinical and clinical studies of AUD by allowing for well-controlled experimental manipulations in humans with AUD. As such, examining the consilience between experimental models in animals and humans in the laboratory provides unique opportunities to refine the translational utility of such models. The overall goal of the present review is to provide a systematic description and contrast of commonly used animal paradigms for the study of AUD, as well as their human laboratory analogs if applicable. While there is a wide breadth of animal species in AUD research, the paradigms discussed in this review rely predominately on rodent research. The overarching goal of this effort is to provide critical analysis of these animal models and to link them to human laboratory models of AUD. By systematically contrasting preclinical and controlled human laboratory models, we seek to identify opportunities to enhance their translational value through forward and reverse translation. We provide future directions to reconcile differences between animal and human work and to improve translational research for AUD.

N-acylethanolamine acid amidase (NAAA) inhibition decreases the motivation for alcohol in Marchigian Sardinian alcohol-preferring rats

RATIONALE

N-acylethanolamine acid amidase (NAAA) is an intracellular cysteine hydrolase that terminates the biological actions of oleoylethanolamide (OEA) and palmitoylethanolamide (PEA), two endogenous lipid-derived agonists of the nuclear receptor, and peroxisome proliferator-activated receptor-α. OEA and PEA are important regulators of energy balance, pain, and inflammation, but recent evidence suggests that they might also contribute to the control of reward-related behaviors.

OBJECTIVES AND METHODS

In the present study, we investigated the effects of systemic and intracerebral NAAA inhibition in the two-bottle choice model of voluntary alcohol drinking and on operant alcohol self-administration.

RESULTS

Intraperitoneal injections of the systemically active NAAA inhibitor ARN19702 (3 and 10 mg/kg) lowered voluntary alcohol intake in a dose-dependent manner, achieving ≈ 47% reduction at the 10 mg/kg dose (p < 0.001). Water, food, or saccharin consumption was not affected by the inhibitor. Similarly, ARN19702 dose-dependently attenuated alcohol self-administration under both fixed ratio 1 (FR-1) and progressive ratio schedules of reinforcement. Furthermore, microinjection of ARN19702 (1, 3 and 10 μg/μl) or of two chemically different NAAA inhibitors, ARN077 and ARN726 (both at 3 and 10 μg/μl), into the midbrain ventral tegmental area produced dose-dependent decreases in alcohol self-administration under FR-1 schedule. Microinjection of ARN19702 into the nucleus accumbens had no such effect.

CONCLUSION

Collectively, the results point to NAAA as a possible molecular target for the treatment of alcohol use disorder.

Alcohol as friend or foe in autoimmune diseases: a role for gut microbiome?

Alcohol is well known for promoting systemic inflammation and aggravating multiple chronic health conditions. Thus, alcohol may also be expected to serve as a risk factor in autoimmune diseases. However, emerging data from human and animal studies suggest that alcohol may in fact be protective in autoimmune diseases. These studies point toward alcohol's complex dose-dependent relationship in autoimmune diseases as well as potential modulation by duration and type of alcohol consumption, cultural background and sex. In this review, we will explore alcohol's pro- and anti-inflammatory properties in human and animal autoimmune diseases, including autoimmune diabetes, thyroid disease, systemic lupus erythematosus, rheumatoid arthritis, experimental autoimmune encephalomyelitis and multiple sclerosis. We will also discuss potential mechanisms of alcohol's anti-inflammatory effects mediated by the gut microbiome.

How much and how fast: Alcohol consumption patterns, drinking-episode affect, and next-day consequences in the daily life of underage heavy drinkers

BACKGROUND

Understanding how alcohol consumption patterns are associated with negative and positive outcomes can inform efforts to reduce negative consequences through modification of those patterns. This is important in underage drinkers, many of whom drink heavily despite negative consequences. Most work has focused on the amount of alcohol consumed, but amount provides limited information about consumption patterns compared to rate of consumption, or how fast individuals drink. We therefore examined associations of both amount and rate of consumption with negative and positive outcomes (immediate affective states and next-morning consequences) in daily life.

METHOD

Ninety-five college students aged 18-20 years completed ecological momentary assessment over 28 days. Participants reported number of standard drinks consumed and positive and negative affect hourly within drinking episodes. Estimated blood alcohol concentration (eBAC) values were used to create amount and rate of consumption indicators. Each morning after drinking, participants reported negative (e.g., blackout, hangover) and positive (e.g., new friend, making others laugh) consequences.

RESULTS

Within drinking episodes, multilevel models showed faster consumption was associated with reduced negative affect and both larger amount and faster consumption were associated with greater positive affect. Further, amount and rate were both associated with greater likelihood of a negative consequence the next morning. Rate, but not amount, was associated with more positive consequences.

CONCLUSIONS

Not only how much but also how fast individuals drink may be important for the positive and negative outcomes they experience. Interventions to reduce negative alcohol-related outcomes should consider not only amount, but also rate of consumption.

Glucagon-Like Peptide-1 Receptor Signaling in the Ventral Tegmental Area Reduces Alcohol Self-Administration in Male Rats

BACKGROUND

The misuse and abuse of alcohol is a major public health issue. However, available treatments are limited with variable efficacy. Recently, preclinical studies show that glucagon-like-peptide-1 (GLP-1) and its analogue Exendin-4 (Ex4) potently reduce a range of alcohol intake behaviors, thus highlighting its potential as a treatment for alcohol use disorders. However, the neural mechanisms and sites of action mediating the effects of Ex4 on alcohol intake behaviors remain to be characterized. This study examined the ventral tegmental area (VTA) as a site of action for the effects of GLP-1 on alcohol intake.

METHODS

Male Long-Evans rats were given intermittent access to 20% alcohol and trained to nose poke for 20% alcohol. Rats received intra-VTA injections of Ex4 (vehicle, 0.01, 0.05 μg), and the effects of VTA Ex4 on alcohol self-administration, motivation, and relapse were assessed.

RESULTS

When compared to vehicle treatment, intra-VTA Ex4 (0.01, 0.05 μg) delivery significantly reduced alcohol self-administration, an effect that was particularly prominent in high alcohol drinkers. However, VTA Ex4 did not reduce reacquisition of alcohol self-administration after extinction nor the motivation to obtain alcohol. Importantly, the lower dose of Ex4 (0.01 μg) used had no effect on food intake or locomotor activity, suggesting that the reduction in alcohol self-administration observed was not secondary to caloric intake or motor deficits.

CONCLUSIONS

Together, these findings provide support for the VTA as a key site of action for GLP-1 on alcohol self-administration but not the reacquisition of alcohol self-administration or motivation to work for alcohol.

Sex-dependent effects of chronic intermittent voluntary alcohol consumption on attentional, not motivational, measures during probabilistic learning and reversal

Background

Forced alcohol (ethanol, EtOH) exposure has been shown to cause significant impairments on reversal learning, a widely-used assay of cognitive flexibility, specifically on fully-predictive, deterministic versions of this task. However, previous studies have not adequately considered voluntary EtOH consumption and sex effects on probabilistic reversal learning. The present study aimed to fill this gap in the literature.

Methods

Male and female Long-Evans rats underwent either 10 weeks of voluntary intermittent 20% EtOH access or water only (H2O) access. Rats were then pretrained to initiate trials and learn stimulus-reward associations via touchscreen response, and subsequently required to select between two visual stimuli, rewarded with probability 0.70 or 0.30. In the final phase, reinforcement contingencies were reversed.

Results

We found significant sex differences on several EtOH-drinking variables, with females reaching a higher maximum EtOH consumption, exhibiting more high-drinking days, and escalating their EtOH at a quicker rate compared to males. During early abstinence, EtOH drinkers (and particularly EtOH-drinking females) made more initiation omissions and were slower to initiate trials than H2O drinking controls, especially during pretraining. A similar pattern in trial initiations was also observed in discrimination, but not in reversal learning. EtOH drinking rats were unaffected in their reward collection and stimulus response times, indicating intact motivation and motor responding. Although there were sex differences in discrimination and reversal phases, performance improved over time. We also observed sex-independent drinking group differences in win-stay and lose-shift strategies specific to the reversal phase.

Conclusions

Females exhibit increased vulnerability to EtOH effects in early learning: there were sex-dependent EtOH effects on attentional measures during pretraining and discrimination phases. We also found sex-independent EtOH effects on exploration strategies during reversal. Future studies should aim to uncover the neural mechanisms for changes in attention and exploration in both acute and prolonged EtOH withdrawal.

An update on the role of common genetic variation underlying substance use disorders

PURPOSE OF THE REVIEW

Sample size increases have resulted in novel and replicable loci for substance use disorders (SUDs). We summarize some of the latest insights into SUD genetics and discuss some next steps in addiction genetics.

RECENT FINDINGS

Genome-wide association studies have substantiated the role of previously known variants (e.g., rs1229984 in ADH1B for alcohol) and identified several novel loci for alcohol, tobacco, cannabis, opioid and cocaine use disorders. SUDs are genetically correlated with psychiatric outcomes, while liability to substance use is inconsistently associated with these outcomes and more closely associated with lifestyle factors. Specific variant associations appear to differ somewhat across populations, although similar genes and systems are implicated.

SUMMARY

The next decade of human genetic studies of addiction should focus on expanding to non-European populations, consider pleiotropy across SUD and with other psychiatric disorders, and leverage human and cross-species functional data to elucidate the biological mechanisms underlying SUDs.

Platelet to lymphocyte ratio (PLR) in alcohol use disorder

Lymphocyte-related parameters in Alcohol Use Disorder (AUD) have recently been investigated. However, knowledge of platelet to lymphocyte ratio (PLR) in AUD is limited. In this study, we compared complete blood count values of 31 AUD male patients and 31 healthy male controls. There was no significant difference between the two groups in terms of PLR (p = .123). When the age was controlled, there was a negative correlation between the duration of alcohol use and PLR (r = -0.567; p = .005). The significance of the parameters in the AUD group was found to be related to the duration of alcohol use.

Magnetic Resonance Imaging and Micro-Computed Tomography reveal brain morphological abnormalities in a mouse model of early moderate prenatal ethanol exposure

BACKGROUND

This study investigated the effects of early moderate prenatal ethanol exposure (PEE) on the brain in a mouse model that mimics a scenario in humans, whereby moderate daily drinking ceases after a woman becomes aware of her pregnancy.

METHODS

C57BL/6J pregnant mice were given 10% v/v ethanol from gestational day 0-8 in the drinking water. The male offspring were used for imaging. Anatomical and diffusion Magnetic Resonance Imaging were performed in vivo at postnatal day 28 (P28, adolescence) and P80 (adulthood). Micro-Computed Tomography was performed on fixed whole heads at P80. Tensor-based morphometry (TBM) was applied to detect alterations in brain structure and voxel-based morphometry (VBM) for skull morphology. Diffusion tensor and neurite orientation dispersion and density imaging models were used to detect microstructural changes. Neurofilament (NF) immunohistochemistry was used to validate findings by in vivo diffusion MRI.

RESULTS

TBM showed that PEE mice exhibited a significantly smaller third ventricle at P28 (family-wise error rate (FWE), p < 0.05). All other macro-structural alterations did not survive FWE corrections but when displayed with an uncorrected p < 0.005 showed multiple regional volume reductions and expansions, more prominently in the right hemisphere. PEE-induced gross volume changes included a bigger thalamus, hypothalamus and ventricles at P28, and bigger total brain volumes at both P28 and P80 (2-sample t-tests). Disproportionately smaller olfactory bulbs following PEE were revealed at both time-points. No alterations in diffusion parameters were detected, but PEE animals exhibited reduced NF positive staining in the thalamus and striatum and greater bone density in various skull regions.

CONCLUSION

Our results show that early moderate PEE can cause alterations in the brain that are detectable during development and adulthood.

Rate of alcohol consumption in the daily life of adolescents and emerging adults

RATIONALE

Alcohol consumption in adolescents and emerging adults is a significant issue. However, our understanding of the topography of alcohol use within drinking episodes in this population is at a nascent stage.

OBJECTIVES

This study characterized rate of alcohol consumption in the daily lives of problem drinkers ages 16-24 years (N = 75). We examined whether AUD symptoms and the presence of peers, factors relevant to alcohol consumption in youth, were associated with rate of consumption.

METHODS

Ecological momentary assessment (EMA) was used (N_observations = 799). Rate of consumption was defined as change in estimated blood alcohol concentration (eBAC) relative to the start of the drinking episode. Piecewise multi-level modeling was used to test hypotheses. As a comparison, we examined whether indicators of quantity and frequency (Q-F) were associated with AUD symptoms and presence of peers.

RESULTS

For all participants, eBAC increased sharply early in the episode, then plateaued. Participants with more AUD symptoms or who were in the presence of peers had significantly steeper increases in eBAC over the early part of the episode. Participants with more AUD symptoms were also more likely to engage in binge-like behavior. For Q-F, only peak eBAC and peak number of standard drinks were associated with AUD symptoms, and not presence of peers.

CONCLUSIONS

Findings highlight the value of rate of consumption as an indicator of use in youth, one sensitive to the influence of relevant person-level and situational factors. Intervention efforts may benefit from targeting the speed at which youth drink.

Novel Adenosine Analog, N6-(4-Hydroxybenzyl)-Adenosine, Dampens Alcohol Drinking and Seeking Behaviors

Adenosine signaling is associated with ethanol-related behaviors. We previously found that adenosine A2A receptor (A2AR) activation dampens ethanol drinking behaviors in equilibrative nucleoside transporter 1 (ENT1) knockout mice, and A2AR inhibition augments reward-seeking behavior in wild-type mice. The novel adenosine analog N6-(4-hydroxybenzyl)-adenosine (NHBA), which is isolated from the rhizomes of Gastrodia elata, activates A2AR and inhibits ENT1. Here, we examined the effects of NHBA on ethanol drinking in the two-bottle choice test and operant ethanol seeking behaviors. We selected mice exhibiting high ethanol drinking behavior in the two-bottle choice test. NHBA (0.1 mg/kg, i.p.) reduced ethanol drinking behavior in a limited-access 3-hour drinking session in high-consumption ethanol drinking mice, and NHBA (0.1 mg/kg, i.p.) did not alter locomotor activity in the open-field test. Operant conditioning with 10% ethanol and 10% sucrose (10E10S) reward increased zone entries and time spent in the ethanol zone, while NHBA (0.1 mg/kg, i.p.) dampened ethanol zone preference in the Y-maze. Furthermore, NHBA (0.1 mg/kg, i.p.) devalued 10E10S and 10% ethanol (10E) reward after operant conditioning with 10E10S and 10E. Taken together, NHBA through A2AR activation and ENT1 modulation may dampen ethanol drinking and seeking behaviors, suggesting that NHBA is a potential therapeutic agent for treating alcohol use disorder. SIGNIFICANCE STATEMENT: Our work highlights that A2AR activation and ENT1 inhibition by a novel adenosine analog isolated from Gastrodia elata, N6-(4-hydroxybenzyl)-adenosine, decreases ethanol drinking and seeking behaviors. We suggest that NHBA is a potential therapeutic agent to treat alcohol use disorder.

Nicotine and alcohol: the role of midbrain dopaminergic neurons in drug reinforcement

Nicotine and alcohol addiction are leading causes of preventable death worldwide and continue to constitute a huge socio-economic burden. Both nicotine and alcohol perturb the brain's mesocorticolimbic system. Dopamine (DA) neurons projecting from the ventral tegmental area (VTA) to multiple downstream structures, including the nucleus accumbens, prefrontal cortex, and amygdala, are highly involved in the maintenance of healthy brain function. VTA DA neurons play a crucial role in associative learning and reinforcement. Nicotine and alcohol usurp these functions, promoting reinforcement of drug taking behaviors. In this review, we will first describe how nicotine and alcohol individually affect VTA DA neurons by examining how drug exposure alters the heterogeneous VTA microcircuit and network-wide projections. We will also examine how coadministration or previous exposure to nicotine or alcohol may augment the reinforcing effects of the other. Additionally, this review briefly summarizes the role of VTA DA neurons in nicotine, alcohol, and their synergistic effects in reinforcement and also addresses the remaining questions related to the circuit-function specificity of the dopaminergic system in mediating nicotine/alcohol reinforcement and comorbidity.

Adverse reproductive outcomes associated with fetal alcohol exposure: a systematic review

Fetal alcohol exposure results in well-characterised neurobehavioural deficits in offspring, which form the basis for diagnosing fetal alcohol spectrum disorder. However, there is increasing interest in the full range of health complications that can arise in children and adults with this disorder. We used a systematic review approach to locate all clinical and preclinical studies across a broad range of health outcomes in offspring exposed to prenatal alcohol. Our search encompassed four databases (PubMed, CINAHL, EMBASE and Web of Science) and titles/abstracts from retrieved studies were screened against strict inclusion/exclusion criteria. This review specifically evaluated studies reporting on reproductive outcomes in both males and females. A total of 23 studies were included, 5 clinical and 18 preclinical. Although there was a wide range in the quality of reporting across both clinical and preclinical studies, and variable results, trends emerged amongst the reproductive measures that were investigated. In females, most studies focussed on age at first menarche/puberty onset, with evidence for a significant delay in alcohol-exposed offspring. In males, offspring exposed to prenatal alcohol had altered testosterone levels, reduced testes and accessory gland weights and reduced sperm concentration and semen volume. However, further studies are required due to the paucity of clinical studies, the narrow scope of female reproductive outcomes examined and inconsistencies in outcomes across preclinical studies. We recommend that adolescents and individuals of reproductive age diagnosed with f-etal alcohol spectrum disorder be assessed for reproductive dysfunction to allow appropriate management of their reproductive health and fertility.

What Is Addiction? How Can Animal and Human Research Be Used to Advance Research, Diagnosis, and Treatment of Alcohol and Other Substance Use Disorders?

The current article highlights key issues in defining, studying, and treating addiction, a concept related to but distinct from substance use disorders. The discussion is based upon a roundtable discussion at the 2017 annual meeting of the Research Society on Alcoholism where Warren K. Bickel and John C. Crabbe were charged with answering a range of questions posed by Kenneth J. Sher. All the presenters highlighted a number of central concerns for those interested in assessing and treating addiction as well as those seeking to conduct basic preclinical research that is amenable to meaningful translation to the human condition. In addition, the discussion illustrated both the power and limitations of using any single theory to explain multiple phenomena subsumed under the rubric of addiction. Among the major issues examined were the important differences between traditional diagnostic approaches and current concepts of addiction, the difficulty of modeling key aspects of human addiction in nonhuman animals, key aspects of addiction that have, to date, received little empirical attention, and the importance of thinking of recovery as a phenomenon that possibly involves processes distinct from those undergirding the development and maintenance of addiction.

Central administration of galanin N-terminal fragment 1-15 decreases the voluntary alcohol intake in rats

Alcohol consumption is considered a major risk factor for disease and mortality worldwide. In the absence of effective treatments in alcohol use disorders, it is important to find new biological targets that could modulate alcohol consumption. We tested the role of the N-terminal galanin fragment (1-15) [GAL(1-15)] in voluntary ethanol consumption in rats using the two-bottle choice paradigm as well as compare the effects of GAL(1-15) with the whole molecule of GAL. We describe for the first time that GAL(1-15), via central mechanisms, induces a strong reduction in preference and ethanol consumption in rats. These effects were significantly different than GAL. GAL receptor (GALR) 2 was involved in these effects, because the specific GALR2 antagonist M871 blocked GAL(1-15) mediated actions in preference and ethanol intake. Importantly, the mechanism of this action involves changes in GALR expression and also in immediate-early gene C-Fos and receptors-internalization-related gene Rab5 in the striatum. The relevance of the striatum as a target for GAL(1-15) was supported by the effect of GAL(1-15) on the locomotor activity of rats after ethanol administration. These results may give the basis for the development of novel therapeutics strategies using GAL(1-15) analogues for the treatment of alcohol use disorders in humans.

Chronic ethanol forced administration from adolescence to adulthood reduces cell density in the rat spinal cord

Ethanol (EtOH) consumption is a risk factor for central nervous system damage, especially during adolescence. This study aimed to investigate the possible effects of chronic EtOH forced administration on gray and white matter of the spinal cord, from adolescence to adulthood. For this, male Wistar rats were administered EtOH by gavage (6.5 g/kg/day; 22.5% w/v) from the 35th to the 90th day of life, while control animals received only distilled water. After exposure, animals were euthanized and their spinal cords processed to obtain cervical and thoracic segments for histological analyses. Quantitative analyses of total cell density and motor neurons of white and gray matter from the ventral horns were evaluated. Forced EtOH administration model showed a decrease in the motoneuron density in the spinal cord in both segments evaluated. Analyses of total cell density showed that the cervical segment was more susceptible to damages promoted by EtOH, with a significant decrease in cell density. Our results showed that chronic EtOH exposure during adolescence could promote injuries to the spinal cord, with neurodegeneration of motoneurons and other cell types present in neural parenchyma.

LSD Administered as a Single Dose Reduces Alcohol Consumption in C57BL/6J Mice

There is a substantive clinical literature on classical hallucinogens, most commonly lysergic acid diethylamide (LSD) for the treatment of alcohol use disorder. However, there has been no published research on the effect of LSD on alcohol consumption in animals. This study evaluated the effect of LSD in mice using a two-bottle choice alcohol drinking paradigm. Adult male C57BL/6J mice were exposed to ethanol to develop preference and divided into three groups of equal ethanol consumption, and then treated with single intraperitoneal injection of saline or 25 or 50 μg/kg LSD and offered water and 20% ethanol. The respective LSD-treated groups were compared to the control group utilizing a multilevel model for repeated measures. In mice treated with 50 μg/kg LSD ethanol consumption was reduced relative to controls (p = 0.0035), as was ethanol preference (p = 0.0024), with a group mean reduction of ethanol consumption of 17.9% sustained over an interval of 46 days following LSD administration. No significant effects on ethanol consumption or preference were observed in mice treated with 25 μg/kg LSD. Neither total fluid intake nor locomotor activity in the LSD-treated groups differed significantly from controls. These results suggest that classical hallucinogens in the animal model merit further study as a potential approach to the identification of targets for drug discovery and investigation of the neurobiology of addiction.

Assessment of alcohol intake: Retrospective measures versus a smartphone application

INTRODUCTION

Research investigating problem drinking often relies on retrospective measures to assess alcohol consumption behaviour. Limitations associated with such instruments can, however, distort actual consumption levels and patterns. We developed the smartphone application (app), CNLab-A, to assess alcohol intake behaviour in real-time.

METHODS

Healthy individuals (N=671, M age 23.12) completed demographic questions plus the Alcohol Use Questionnaire and a 21-day Timeline Followback before using CNLab-A for 21days. The app asked participants to record alcohol consumption details in real time. We compared data reported via retrospective measures with that captured using CNLab-A.

RESULTS

On average, participants submitted data on 20.27days using CNLab-A. Compared to Timeline Followback, a significantly greater percentage of drinking days (24.79% vs. 26.44%) and significantly higher total intake (20.30 vs. 24.26 standard drinks) was recorded via the app. CNLab-A captured a substantially greater number of high intake occasions at all levels from 8 or more drinks than Timeline Followback. Additionally, relative to the Alcohol Use Questionnaire, a significantly faster rate of consumption was recorded via the app.

CONCLUSIONS

CNLab-A provided more nuanced information regarding quantity and pattern of alcohol intake than the retrospective measures. In particular, it revealed higher levels of drinking than retrospective reporting. This will have implications for how particular at-risk alcohol consumption patterns are identified in future and might enable a more sophisticated exploration of the causes and consequences of drinking behaviour.

A longitudinal event-level investigation of alcohol intoxication, alcohol-related blackouts, childhood sexual abuse, and sexual victimization among college students

Sexual assault is a troubling epidemic that plagues college campuses across the United States, and is often proceeded by drinking by the perpetrator and/or victim. The goal of this study was to examine the effect of level of intoxication, history of alcohol-related blackouts, and childhood sexual abuse (CSA) on the likelihood of being a victim or perpetrator of coercive sexual activities. Participants (N = 2,244) were part of a 6-year longitudinal study which explored alcohol use and associated behavioral risks during college. A subsample (N = 1,423) completed 30 days of daily diary surveys across four years of college. Participants provided daily reports of their alcohol consumption, sexual coercion perpetration, and sexual coercion victimization. Using hierarchical linear models, results indicated that increases in daily estimated blood alcohol concentration (eBAC) were associated with a greater likelihood of being a victim and a perpetrator of sexual coercion. In addition, main effects of CSA and history of blackouts predicted a greater likelihood of being coerced into sexual activity, but blackouts were not associated with being a perpetrator. A significant interaction between blackouts and event-level eBAC indicated that individuals with a history of blackouts had a greater likelihood of sexual coercion victimization relative to those without prior blackouts. Finally, having a history of blackouts and CSA was predictive of a lower likelihood of being a perpetrator of sexual coercion at higher eBACs relative to those without a history of blackouts. Thus, prevention efforts should integrate the impact of blackouts and CSA on sexual coercion victimization and perpetration. (PsycINFO Database Record

Maternal care-related differences in males and females rats' sensitivity to ethanol and the associations between the GABAergic system and steroids in males

This study investigated the effect of maternal care on adolescent ethanol consumption, sensitivity to ethanol-induced hypnosis, as well as gonadal hormones and γ-aminobutyric acid type-A (GABA_A ) systems. Long Evans rat dams were categorized by maternal licking/grooming (LG) frequency into High- and Low-LG mothers. Both female and male offspring from Low-LG rats demonstrated a greater sensitivity to ethanol-induced hypnosis in the loss-of-righting-reflex test at ethanol doses of 3.0 and 3.5 g/kg during late-adolescence (postnatal Day 50) but not at mid-adolescence (postnatal Day 42). However, we found no effect of maternal care on consumption of a 5% ethanol solution in a two-bottle choice test. We further investigated the association between the observed variations in sensitivity to ethanol-induced hypnosis and baseline hormonal levels in males. In male offspring from Low-LG mothers compared to High-LG mothers, baseline plasma corticosterone and progesterone levels were higher. GABA_A α1 and δ subunit expressions were also higher in the cerebral cortex of Low-LG males but lower in the cerebellar synaptosomal fraction. Early environmental influences on adolescent sensitivity to ethanol-induced hypnosis, consumption, and preference may be mediated by gonadal hormones and possibly through GABAergic functions.

GABRA2, alcohol, and illicit drug use: An event-level model of genetic risk for polysubstance use

GABRA2, the gene encoding the α2 subunit of the GABAA receptor, potentially plays a role in the etiology of problematic drinking, as GABRA2 genotype has been associated with subjective response to alcohol and other alcohol-related reward processes. The GABRA2 gene has also been associated with illicit drug use, but the extent to which associations with drug use are independent of associations with alcohol use remains unclear, partly because most previous research has used a cross-sectional design that cannot discriminate comorbidity at the between-person level and co-occurrence within-persons. The present study used a daily monitoring method that assessed the effects of GABRA2 variation on substance use as it occurred in the natural environment during emerging adulthood. Non-Hispanic European participants provided DNA samples and completed daily reports of alcohol and drug use for 1 month per year across 4 years (N = 28,263 unique observations of N = 318 participants). GABRA2 variants were associated with illicit drug use in both sober and intoxicated conditions. Moreover, the effect of GABRA2 variation on drug use was moderated by an individual's degree of intoxication. These findings are consistent with recent genetic and neuroscience research, and they suggest GABRA2 variation influences drug-seeking behavior through both alcohol-related and alcohol-independent pathways. (PsycINFO Database Record

Voluntary alcohol intake after noise exposure in adolescent rats: Hippocampal-related behavioral alterations

Different physical or chemical agents, such as noise or alcohol, can induce diverse behavioral and biochemical alterations. Considering the high probability of young people to undergo consecutive or simultaneous exposures, the aim of the present work was to investigate in an animal model if noise exposure at early adolescence could induce hippocampal-related behavioral changes that might be modified after alcohol intake. Male Wistar rats (28-days-old) were exposed to noise (95-97 dB, 2 h). Afterwards, animals were allowed to voluntarily drink alcohol (10% ethanol in tap water) for three consecutive days, using the two-bottle free choice paradigm. After that, hippocampal-related memory and anxiety-like behavior tests were performed. Results show that whereas noise-exposed rats presented deficits in habituation memory, those who drank alcohol exhibited impairments in associative memory and anxiety-like behaviors. In contrast, exposure to noise followed by alcohol intake showed increases in exploratory and locomotor activities as well as in anxiety-like behaviors, unlike what was observed using each agent separately. Finally, lower levels of alcohol intake were measured in these animals when compared with those that drank alcohol and were not exposed to noise. Present findings demonstrate that exposure to physical and chemical challenges during early adolescence might induce behavioral alterations that could differ depending on the schedule used, suggesting a high vulnerability of rat developing brain to these socially relevant agents.

Elevated rate of alcohol consumption in borderline personality disorder patients in daily life

RATIONALE

Borderline personality disorder (BPD) is highly associated with alcohol use disorder, but little is known about how BPD individuals consume alcohol or the immediate effects of their consumption. There is therefore a need for research investigating drinking behavior in BPD.

OBJECTIVES

The current study examined rate of alcohol consumption in BPD (N = 54) and community individuals (COM; N = 59) within ecologically valid drinking episodes. We hypothesized that rate of consumption would be elevated in BPD individuals. We further hypothesized that rate of consumption would be positively associated with subjective stimulation, but not sedation, and that stimulation would be associated with increased positive affect (PA) and reduced negative affect (NA).

METHODS

Ambulatory assessment was used to assess rate of consumption, subjective alcohol response, and affect in the moment (N observations = 3444). Rate of consumption was defined as change in estimated blood alcohol concentration (eBAC) relative to drinking episode start. Multilevel modeling was used to test hypotheses.

RESULTS

As hypothesized, BPD individuals demonstrated a faster increase in eBAC than COM individuals. Rate of consumption was associated with subjective stimulation, but not sedation, in both groups. Stimulation was associated with increased PA in both groups and reduced NA in the BPD group.

CONCLUSIONS

BPD individuals consumed alcohol more rapidly than COM individuals. Faster consumption may serve as a means for BPD individuals to maximize the rewarding pharmacological effects of alcohol and to increase positive and reduce negative affect.

A prospective study of genetic factors, human laboratory phenotypes, and heavy drinking in late adolescence

Subjective responses to alcohol are considered candidate endophenotypes for alcohol use disorder and appear to anticipate future consumption. However, prospective studies have been rare, and laboratory research has typically examined subjective responses absent measures of self-administration. This study examined the association of subjective responses with subsequent laboratory self-administration, also evaluating laboratory phenotypes in relation to putative genetic risk factors [family history (FH) of alcohol dependence and OPRM1 genotype] and subsequent heavy drinking. Participants (N = 61, M = 19.89 years, SD = 0.86) completed laboratory sessions involving intravenous alcohol challenge (Session 1) and free-access intravenous self-administration (Session 2), followed by prospective assessments. Multilevel modeling showed that higher reported stimulation and lower sedation during Session 1 independently predicted greater alcohol self-administration during Session 2. Although self-administration did not differ by FH group, participants with the OPRM1 118G allele evidenced steeper breath alcohol concentration (BrAC) trajectories and greater peak BrAC relative to 118A homozygous participants. Prospective analyses supported significant indirect associations between Session 1 subjective responses and 6-month heavy drinking via peak BrAC in Session 2. Additionally, significant indirect associations of FH (via Session 1 stimulation and Session 2 peak BrAC) and OPRM1 (via peak BrAC) with follow-up heavy drinking were observed. These results further support the utility of human laboratory phenotypes in prospective studies of alcohol use disorder risk and highlight the potential role of self-administration phenotypes in longitudinal research.