Low Drinkers Research Articles

Sex differences in sensitivity to the social consequences of acute ethanol and social drinking during adolescence

In human adolescents, sociable males frequently drink to enhance positive emotional states, whereas anxious females often drink to avoid negative affective states. This study used a rat model of adolescence to provide information regarding possible sex differences in contributors to social drinking. The effects of ethanol (0, 0.5, and 0.75g/kg) on play fighting and social preference were assessed on P30, P32, and P34 using a within-subject design. Then animals were tested in a social drinking paradigm (P37–P40), with this testing revealing high drinkers and low drinkers. Sex differences in sensitivity to ethanol emerged among high and low drinkers. High socially drinking males, but not females, when tested prior to drinking sessions, showed significant increases in play fighting at both doses. In low drinking males, play fighting was increased by 0.5g/kg ethanol, whereas the higher dose of 0.75g/kg produced significant decreases in play fighting. High drinking females initially showed low levels of social preference than high drinking males and low drinking females and were extremely sensitive to ethanol-induced enhancement of this social measure. Low social drinkers, both males and females, were more sensitive to the suppressing effects of ethanol on social preference following 0.75g/kg ethanol. These findings indicate that during adolescence enhanced sensitivity to the facilitating effects of ethanol on play fighting is associated with heavy drinking among males, whereas low social preference together with high sensitivity to ethanol-induced enhancement of social preference is related to high social drinking in females.

Association of daily coffee and tea consumption and metabolic syndrome: results from the Polish arm of the HAPIEE study.

PurposeThe aim of this study was to evaluate whether daily consumption of coffee and tea was associated with components and prevalence of metabolic syndrome (MetS) in the Polish arm of the Health, Alcohol and Psychosocial factors In Eastern Europe cohort study.MethodsA cross-sectional population-based survey including 8,821 adults (51.4 % female) was conducted in Krakow, Poland. Coffee and tea consumption was evaluated using food frequency questionnaires. MetS was defined according to the International Diabetes Federation definition. Linear and logistic regression models were performed to estimate odds ratios and confidence intervals.ResultsAmong high coffee and tea consumers (3 or more cups/day), high prevalence of female gender, young age, medium–high educational and occupational level, high total energy intake, and smoking habit were found. High coffee drinkers had lower BMI, waist circumference, systolic and diastolic blood pressure, triglycerides, and higher HDL cholesterol than those drinking less than 1 cup/day. In contrast, high tea consumers had lower BMI, waist circumference, but not diastolic blood pressure, which was higher than low drinkers. After adjusting for potential confounding factors, both higher coffee and tea consumption were negatively associated with MetS (OR 0.75, 95 % CI 0.66, 0.86 and OR 0.79, 95 % CI 0.67, 0.92, respectively). Among specific components of MetS, high coffee consumption was negatively associated with waist circumference, hypertension, and triglycerides, whereas tea consumption with central obesity and fasting plasma glucose in women, but not in men.ConclusionsCoffee and tea consumption was negatively associated with MetS and some of its components.

Chronic alcohol self-administration in monkeys shows long-term quantity/frequency categorical stability.

The current criteria for alcohol use disorders (AUDs) do not include consumption (quantity/frequency) measures of alcohol intake, in part due to the difficulty of these measures in humans. Animal models of ethanol (EtOH) self-administration have been fundamental in advancing our understanding of the neurobiological basis of AUD and can address quantity/frequency measures with accurate measurements over prolonged periods of time. The nonhuman primate model of voluntary oral alcohol self-administration has documented both binge drinking and drinking to dependence and can be used to test the stability of consumption measures over time. Here, an extensive set of alcohol intakes (g/kg/d) was analyzed from a large multi-cohort population of Rhesus (Macaca mulatta) monkeys (n=31). Daily EtOH intake was uniformly distributed over chronic (12months) access for all animals. Underlying this distribution of intakes were subpopulations of monkeys that exhibited distinctive clustering of drinking patterns, allowing us to categorically define very heavy drinking (VHD), heavy drinking (HD), binge drinking (BD), and low drinking (LD). These categories were stable across the 12months assessed by the protocol, but exhibited fluctuations when examined at shorter intervals. The establishment of persistent drinking categories based on quantity/frequency suggests that consumption variables can be used to track long-term changes in behavioral, molecular, or physiochemical mechanisms related to our understanding of diagnosis, prevention, intervention, and treatment efficacies.

New frontiers in the neuropsychopharmacology of mental illness.

New frontiers in the neuropsychopharmacology of mental illness.

Effects of changes in water intake on mood of high and low drinkers.

ObjectiveTo evaluate the effects of a change in water intake on mood and sensation in 22 habitual high-volume (HIGH; 2-4 L/d) and 30 low-volume (LOW; <1.2 L/d) drinkers who were asked to respectively decrease and increase their daily water intake.MethodDuring baseline HIGH consumed 2.5 L and LOW 1 L of water/day. During 3 controlled intervention days HIGH's water intake was restricted to 1 L/day whereas LOW's was increased to 2.5 L water/day. Several mood scales (Bond & Lader Visual Analog Scale (VAS), Profile of Mood States, Karolinska Sleepiness Scale, Thirst & Emotional VAS) were administered at different time points during the study. ANOVA including intervention, time point and intervention by time point as fixed effects on mean values (i.e.; baseline data vs. mean of 3 intervention days) for each mood scale was performed.ResultsAt baseline HIGH and LOW were comparable in mood state, except for thirst scores (estimate = 17.16, p<0.001) and POMS depression-dejection scores (estimate = 0.55, p<0.05) which were both higher in the HIGH vs. LOW. In HIGH the restricted water intake resulted in a significant increase in thirst (p<0.001) and a decrease in contentedness (p<0.05), calmness (p<0.01), positive emotions (p<0.05) and vigor/activity (p<0.001). In LOW, increased water consumption resulted in a significant decrease in fatigue/inertia (p<0.001), confusion/bewilderment (p = 0.05) and thirst (p<0.001) and a trend to lower sleepiness (p = 0.07) compared to baseline.ConclusionIncreasing water intake has beneficial effects in LOW, especially sleep/wake feelings, whereas decreasing water intake has detrimental effects on HIGH's mood. These deleterious effects in HIGH were observed in some sleep/wake moods as well as calmness, satisfaction and positive emotions.

중년여성의 생활습관에 따른 체력과 골밀도 비교 연구

본 연구는 중년 여성을 대상으로 생활습관에 따라 골밀도와 체력에 미치는 영향을 분석하여 운동프로그램에 관련된 유용한 정보를 제공하는데 목적이 있다. 연구를 수행하기 위하여 C보건소를 내원한 여성 331명을 대상으로 운동습관에 따라 비운동군, 저빈도운동군(주당 2회 이하 운동), 중정도운동군(주당 3회 이상)으로, 음주습관에 따라서는 비음주군과 저음주군(주당 2회 이하 음주), 고음주군(주당 3회 이상), 염분섭취수준에 따라 저염식이군, 중염식이군, 고염식이군으로 각각 분류하였다. 측정변인은 골밀도와 최대산소섭취량, 체지방률, 악력, 유연성, 민첩성, 평형성으로 하였으며, 집단간 차이를 검증하기 위하여 운동습관에 따라서 one-way ANOVA를 각각 실시하였다. 운동습관이 많을수록 골밀도는 유의하게 높았으며, 체지방률은 유의하게 낮게 나타났다. 음주습관과 염분섭취수준에 따른 골밀도 및 체력은 유의한 차이를 보이지 않았지만, 염분섭취가 많을수록 체중과 체지방이 증가하는 경향을 보였다. 결론적으로 규칙적인 운동은 골밀도와 체력유지에 도움을 주며, 고염식이는 체중증가의 요인이 될 수 있을 것으로 사료된다. The purpose of the this study was to examine the comparison of bone mineral density and health related physical fitness induced exercise habits, drinking habits and salt consumption habits on middle-age women. Using a cross-sectional approach, we studied 331 middle-age women who visited the C health center. Subjects were divided into 3 groups depended on exercise habits(sedentary, exercise less than twice a week and more than three time a week), 3 groups depended on drinking habits(non-drinker, low drinker, high drinker), also 3 groups depended on salt consumption habits(low, middle, high), respectively. We measured bone mineral density and health related physical fitness. One-way ANOVA were used to assess differences among 3 groups divided on life habits. Significance was accepted at p<.05. Exercise habits showed significant difference in BMD & % body fat. But another variables showed no significant difference. Also, drinking and salt consumption habits showed no significant differences among the groups. This study suggests that regular exercise can improve bone health and body fat.

Pretreatment changes in drinking: relationship to treatment outcomes.

Pretreatment changes in alcohol use challenges the assumption that the major portion of the change process occurs after treatment entry. Greater understanding of the behavior change process prior to treatment has the potential to improve our understanding of behavioral changes during treatment. In this study, participants (N = 45) were recruited for a clinical trial examining multiple mechanisms of change in cognitive-behavioral treatment for alcohol dependence. Using data from both baseline and end of treatment assessments, several pretreatment intervals were created (e.g., a 2-week pre-phone call interval, phone call to baseline assessment, baseline assessment to first treatment). To examine pretreatment changes in drinking, percent days abstinent and drinks per drinking day were analyzed using multilevel growth curve modeling and repeated-measures ANOVAs. Initial examination of the data revealed significant increases in percent days abstinent and decreases in drinks per drinking day during the pretreatment intervals. Follow-up analyses also suggested that the majority of change in drinking occurs between the phone call and baseline assessment. Further examination of the data revealed two distinct patterns of pretreatment change: (a) rapid changers who maintained changes during the course of treatment and (b) gradual changers who changed more gradually during the course of treatment. Analyses revealed that rapid changers had significantly higher rates of abstinence and lower drinks per drinking day at 90 days posttreatment compared with gradual changers. Overall, the data suggest that a more systematic investigation of pretreatment changes in alcohol use is warranted. Future studies may yield insights resulting in more efficient treatment delivery and adaptations to treatment based on an individual's pretreatment change status.

Domain-Specific Consumer Involvement in the U.S. Wine Market

An 18-item multidimensional scale was developed to measure wine consumer involvement level impact on behavior and consumption dynamics. Data were collected at wine tasting events in Portland, Oregon, U.S., yielding a final sample size of 101 respondents. Male wine consumers do not display a higher level of involvement with wine as a product than females, and neither do consumers 45 years and older in comparison with younger consumers. Consumers with high education and income levels do not use these as a basis of their involvement level with wine. Price is not more frequently used by low involvement wine drinkers in the wine purchasing decision.

The relationship between parental alcohol use and college students' alcohol-related cognitions

This study examined how parental and cognitive factors are structurally related to college students' intention to drink alcohol as well as possible gender differences in these relationships. Multiple-group comparison was used in structural equation modeling to assess data-to-model fit of the hypothesized model. Perceived parental alcohol use, positive expectancies, abstinence self-efficacy in social situations, and intent to drink alcohol were structurally modeled and examined in 714 college students based on self-report measures. Results showed good fit of the hypothesized model in both men and women. Invariance of model fit was found across genders, although a more detailed analysis of the results suggested gender-specific influence of parental alcohol use over students' cognitions. Perceptions of greater parental alcohol use were associated with higher positive expectancies for alcohol use, which, in turn, were significantly related to lower drink refusal self-efficacy. Both higher expectancies and lower refusal self-efficacy were related to the intention for future use. Results of the study shed light on the development of alcohol-related cognitions in male and female college students and contribute to our understanding of the structural relationship between expectancies and self-efficacy in alcohol use.

A Water Intervention Program to Improve Fluid Intakes Among French Women

This research aimed at assessing the impact of a water intervention program on fluid intake over a 12-month period in free-living conditions. A total of 178 French women with low fluid intake habits were enrolled in a short-term program from 4 weeks’ to 4 months’ duration including home deliveries of bottled water and educational content on water and health. Fluid intakes were assessed at baseline and at 2, 6, and 12 months. Results show a significant improvement in total fluid intake mainly from water intake over 12 months. An intervention program combining bottled water supply and educational information is efficient to increased sustainably water intake among low drinkers in free-living conditions.

Circadian variation and responsiveness of hydration biomarkers to changes in daily water intake

Biomarkers of hydration change in response to acute dehydration; however, their responsiveness to changes in fluid intake volume, without exercise or heat exposure, has not been adequately described. Moreover, patterns of circadian variation in hydration biomarkers have not been established. The study aims were to (1) assess the response of hydration biomarkers to changes in daily water intake; and (2) evaluate circadian variation in urinary and salivary biomarkers. Fifty-two adults (24.8 ± 3.1 years; 22.3 ± 1.6 kg/m2; 79 % female), grouped based on habitual fluid intake (low drinkers, n = 30, <1.2 L/day; high drinkers, n = 22, >2.0 L/day), completed a 5-day inpatient crossover trial. On days 1 and 2, low drinkers received 1.0 L/day of water while high drinkers received 2.5 L/day. On days 3 through 5, intake was reversed between groups. Plasma and saliva osmolality were assessed daily at predetermined times, and all urine produced over 24 h was collected in timed intervals. ANOVA with intake (1.0 vs. 2.5 L/day), day, and time revealed that (1) urine concentration (osmolality, specific gravity, color) and volume, but not plasma nor saliva osmolality, responded to changes in water intake; (2) urinary hydration biomarkers and saliva osmolality vary as a function of the time of day; and (3) urine osmolality measured in samples collected during the afternoon most closely reflects the corresponding 24 h value. Overall, urinary hydration biomarkers are responsive to changes in water intake, and stabilize within 24 h of modifying intake volume. Moreover, short afternoon urine collections may be able to replace 24 h collections for more convenience in hydration assessment.

Changes in daily water intake impact mood of high and low drinkers

PurposeThe effect of dehydration on cognition has been examined in fluid deprivation studies. However, such study conditions are far from real life conditions. This inpatient crossover trial evaluated the effect of mild changes in water intake on subjective cognitive performance (i.e. mood) in 22 high volume (HIGH; 2–4L/d; 25 ± 1 y) and 30 low volume drinkers (LOW; &lt;1.2L/d; 25 ± 3 y).MethodDuring days 1 and 2 HIGH consumed 2.5L of water/day and LOW 1L/day. On Days 3 through 5, HIGH restricted water intake to 1L/d and LOW increased to 2.5L/d. Several mood scales (Bond &amp; Lader VAS, Profile of mood states, Karolinska Sleepiness Scale, Thirst &amp; Emotional VAS) were administered at different time points. An ANOVA model including treatment, time point and treatment × time as fixed effects on mean values (i.e.; baseline data vs mean of 3 intervention days) for each mood scale was performed.ResultsIn LOW increased water consumption resulted in a significant decrease in fatigue (p&lt;0.001), confusion (p=0.05) and thirst (p&lt;0.001) and a trend to lower sleepiness (p=0.07) compared to baseline. In HIGH the restricted water intake lead to a significant increase in thirst (p&lt;0.001) and a decrease in contentedness (p&lt;0.05), calmness (p&lt;0.01), positive emotions (p&lt;0.05) and vigor (p&lt;0.001).ConclusionIncreasing water intake has a beneficial mood effect, especially on sleep/wake feelings, whereas restricting water intake can deteriorate mood. Even though the results were observed in young adults, they can still be of importance to the healthy aging population. The link between water increase and decrease in confusion is also of interest for diagnosis and treatment of delirium.

Identification of subpopulations of prairie voles differentially susceptible to peer influence to decrease high alcohol intake

Peer influences are critical in the decrease of alcohol (ethanol) abuse and maintenance of abstinence. We previously developed an animal model of inhibitory peer influences on ethanol drinking using prairie voles and here sought to understand whether this influential behavior was due to specific changes in drinking patterns and to variation in a microsatellite sequence in the regulatory region of the vasopressin receptor 1a gene (avpr1a). Adult prairie voles’ drinking patterns were monitored in a lickometer apparatus that recorded each lick a subject exhibited during continuous access to water and 10% ethanol during periods of isolation, pair housing of high and low drinkers, and subsequent isolation. Analysis of fluid consumption confirmed previous results that high drinkers typically decrease ethanol intake when paired with low drinkers, but that a subset of voles do not decrease. Analysis of bout structure revealed differences in the number of ethanol drinking bouts in the subpopulations of high drinkers when paired with low drinkers. Lickometer drinking patterns analyzed by visual and by cross-correlation analyses demonstrated that pair housing did not increase the rate of subjects drinking in bouts occurring at the same time. The length of the avpr1a microsatellite did not predict susceptibility to peer influence or any other drinking behaviors. In summary, subpopulations of high drinkers were identified, by fluid intake and number of drinking bouts, which did or did not lower their ethanol intake when paired with a low drinking peer, and these subpopulations should be explored for testing the efficacy of treatments to decrease ethanol use in groups that are likely to be responsive to different types of therapy.

Standardized ileal amino acid digestibility in egg from hyperimmunized hens fed to weaned pigs

The study was conducted to determine the apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of AA in egg from hens hyperimmunized with Escherichia coli K88 antigens (EGG) fed to weaned pigs. Spray dried porcine plasma (SDPP) was included for comparison. Eight barrows (Yorkshire-Landrace × Duroc; initial BW of 17 ± 1 kg) were fitted with a T-cannula at the distal ileum and fed 2 diets in a completely randomized design to give 4 replicates per diet. The diets were corn (Zea mays) starch based with either EGG or SDPP as the sole source of protein and were formulated to contain 130 g/kg CP. At the end of the study, a 50 g/kg casein diet was fed to all pigs (n = 8) to quantify endogenous N and AA losses to determine SID. Titanium dioxide (3 g/kg) was included in the diets as an indigestible maker. Each period lasted for 7 d. Pigs were adapted to their respective diets for 5 d followed by 12 h of continuous ileal digesta collection on days 6 and 7. Daily feed allowance was set at 4% BW at the beginning of each period and offered in 2 equal portions at 0800 and 1600 h as a dry mash. Pigs had unlimited access to water via low pressure nipple drinkers. The AID (%) of CP and indispensable AA were lower (P < 0.05) in EGG compared with SDPP. The SID (%) of CP (82 vs. 96) and indispensable AA were lower (P < 0.05) in pigs fed EGG compared with SDPP. In conclusion, the average AID and SID of N and indispensable AA in EGG are lower than in SDPP when fed at high levels.

Hydration biomarkers in free-living adults with different levels of habitual fluid consumption

Little is known about the impact of habitual fluid intake on physiology. Specifically, biomarkers of hydration status and body water regulation have not been adequately explored in adults who consume different fluid volumes in everyday conditions, without prolonged exercise or environmental exposure. The purpose of the present study was to compare adults with habitually different fluid intakes with respect to biomarkers implicated in the assessment of hydration status, the regulation of total body water and the risk of kidney pathologies. In the present cross-sectional study, seventy-one adults (thirty-two men, thirty-nine women, age 25–40 years) were classified according to daily fluid intake: thirty-nine low drinkers (LD; ≤ 1·2 litres/d) and thirty-two high drinkers (HD; 2–4 litres/d). During four consecutive days, urinary parameters (first morning urine (FMU) on day 1 and subsequent 24 h urine (24hU) collections), blood parameters, and food and beverage intake were assessed. ANOVA and non-parametric comparisons revealed significant differences between the LD and HD groups in 24hU volume (1·0 (se 0·1) v. 2·4 (se 0·1) litres), specific gravity (median 1·023 v. 1·010), osmolality (767 (se 27) v. 371 (se 33) mOsm/kg) and colour (3·1 (se 0·2) v. 1·8 (se 0·2)). Similarly, in the FMU, the LD group produced a smaller amount of more concentrated urine. Plasma cortisol, creatinine and arginine vasopressin concentrations were significantly higher among the LD. Plasma osmolality was similar between the groups, suggesting physiological adaptations to preserve plasma osmolality despite low fluid intake. The long-term impact of adaptations to preserve plasma osmolality must be examined, particularly in the context of renal health.

Disturbances in behavior and cortical enkephalin gene expression during the anticipation of ethanol in rats characterized as high drinkers

The process of ethanol anticipation is a particularly important phenomenon that can determine subsequent drug-taking behavior. Recent studies suggest that systems within the medial prefrontal cortex (mPFC), during anticipation, may contribute to the goal-directed seeking of ethanol. The current investigation examined the possibility that the opioid peptide enkephalin (ENK), known to mediate some of the reinforcing properties of ethanol, may function in the mPFC during the anticipation of ethanol access. Using a limited access (3 h/d) paradigm for 10 days with 20% ethanol, Sprague-Dawley rats were first identified either as low drinkers (LD, <1.0 g/kg/3 h) or as high drinkers (HD, >2.0 g/kg/3 h) that exhibited a long-term phenotype of high ethanol consumption and a significant ethanol deprivation effect. During the anticipation period immediately preceding daily ethanol access, the HD rats compared to LD or Control animals with ad libitum ethanol access exhibited increased anticipatory behaviors, including greater exploratory behavior in a novel open field as revealed by significantly more time spent in the rearing position (+53–65%, p < 0.05) and increased number of rears made (+33–44%, p < 0.05) and greater novelty-seeking behavior in a hole-board apparatus revealed by an increase in total (+50–52%, p < 0.05) and novel nose pokes (+45–48%, p < 0.05). In the HD rats, analysis of the mPFC using real-time quantitative PCR showed significantly greater mRNA levels of ENK (p < 0.05) and the mu-opioid receptor (MOR) (p < 0.05), but not delta-opioid receptor (DOR), and this increase in ENK expression was found, using in situ hybridization, to occur specifically in the prelimbic (PrL) subregion of the mPFC. When injected into the PrL during the anticipation period, a MOR agonist but not DOR agonist significantly increased consumption of 20% ethanol (p < 0.05). These findings support the role of ENK, acting through MOR within the PrL to promote the anticipation and excessive consumption of ethanol.

Poor inhibitory control and neurochemical differences in high compulsive drinker rats selected by schedule-induced polydipsia

Schedule-induced polydipsia (SIP), characterized by the development of excessive drinking under intermittent food reinforcement schedules, has been proposed as a model for obsessive-compulsive disorder, schizophrenia and drug abuse. The purpose of this study is to investigate if individual differences in SIP reflect psychopathological behavioural traits related to lack of inhibitory control and reactivity to novelty, and if these differences have neurochemical correlates. Outbred Wistar rats were selected for being either high (HD) or low (LD) drinkers according to their SIP behaviour. We tested locomotor reactivity to a novel environment and inhibitory control on the five-choice serial reaction time task (5-CSRTT), under baseline vs. extinction conditions and following challenge with D: -amphetamine (saline, 0.5 or 1 mg/kg). Post-mortem analyses of the monoaminergic levels in different brain regions were also analysed. Compared to LD animals, HD rats exhibiting SIP acquisition showed no differences in spontaneous locomotor reactivity to novelty. On the 5-CSRTT, HD rats showed a greater increase in perseverative responses under extinction, a trend towards elevated premature responses on baseline, and a significantly greater elevation of premature responses to D: -amphetamine 0.5 mg/kg. The HD animals also exhibited increased serotonin activity in the amygdala, and correlational analyses between the rate of drinking on SIP and monoamine levels also revealed altered dopaminergic mesolimbic function. These findings show that HD rats selected by SIP exhibit compulsive and impulsive behaviour based on measures of performance on the five-choice serial reaction time task and associated with changes in monoaminergic systems in limbic-striatal circuitry.

Meta‐analysis of alcohol consumption and risk of extrahepatic bile system cancer

Alcohol consumption increases the risk of liver cancer. However, there is still controversy regarding alcohol consumption and the risk of extrahepatic bile system cancer (EBSC). We performed a meta-analysis to provide an overview of the relevant studies and gain more robust estimates of the relationship between alcohol consumption and risk of EBSC. Relevant studies published between January 1966 and October 2010 were identified by searching Medline, Embase and the Cochrane Library. Studies were selected using a priori defined criteria. The strength of the relationship between alcohol consumption and risk of EBSC was assessed by adjusted odds ratio (OR). A total of 113 767 participants from 10 studies (nine case-control studies and one cohort study) were identified in this meta-analysis. The studies provided adjusted overall OR estimates for drinkers versus non-/low drinkers, leading to a pooled adjusted OR of 0.82 (95% confidence interval [CI] = 0.72-0.94, P for heterogeneity = 0.194, I(2) = 27.2%). The overall adjusted OR of hospital-based studies and population-based studies were 0.80 (95% CI = 0.65-0.99, P = 0.260) and 0.79 (95% CI = 0.64-0.98, P = 0.119), respectively. For the heavy drinkers, the adjusted OR significance increased to 1.58 (95% CI = 0.97-2.57, P for heterogeneity = 0.055, I(2) = 65.4%), but it had no statistical significance. There is evidence that moderate alcohol consumption lowers the risk of EBSC compared with non-/low alcohol consumption, but not heavy alcohol consumption. Further multicenter and better controlled studies are required to confirm these findings.

Associations of corticosterone and testosterone with alcohol drinking in F2 populations derived from AA and ANA rat lines

In our previous studies on alcohol-preferring AA (Alko alcohol) and nonpreferring ANA (Alko nonalcohol) rats, we have observed that the AA rats exhibit lower endogenous levels of corticosterone, higher testosterone levels, and more frequent alcohol-induced testosterone elevations when compared with ANA rats. The objective of the present study was to get more conclusive evidence for the potential role of the hypothalamus–pituitary–adrenal and hypothalamus–pituitary–gonadal axes in alcohol drinking by using the F2 experimental design. Alcohol-preferring AA and alcohol-nonpreferring ANA rat lines were crossbred to form a F1 population from which the final F2 population was derived. Male animals were challenged with a priming alcohol dose after which a 3 weeks’ voluntary alcohol drinking period took place. After a washout period of 1 week, one-half of the 40 highest and 40 lowest alcohol drinkers were challenged with a second dose of alcohol and the other half with saline. Serum testosterone and corticosterone levels were measured before and during the test. Higher endogenous testosterone levels were detected in the rats of the high alcohol consumption group compared with the low consumption group. Also supporting the original AA/ANA line differences, a trend for lower endogenous corticosterone levels were measured in the high alcohol consumption group compared with the low consumption group. The alcohol challenge test after the drinking period resulted in a higher frequency (38%) of testosterone elevations in the high drinkers compared with the low drinkers (5%). The present data confirms the validity of the positive connections between testosterone elevation and increased alcohol drinking, as well as between testosterone reduction and decreased alcohol drinking, in AA and ANA rats.

Alcohol Intake in Prairie Voles is Influenced by the Drinking Level of a Peer

Peer interactions can have important effects on alcohol-drinking levels, in some cases increasing use, and in other cases preventing it. In a previous study, we have established the prairie vole as a model animal for the effects of social relationships on alcohol intake and have observed a correlation of alcohol intake between individual voles housed together as pairs. Here, we investigated this correlated drinking behavior, hypothesizing that 1 animal alters its alcohol intake to match the drinking of its partner. Adult prairie voles were tested for baseline drinking levels with continuous access to 10% alcohol and water for 4 days. In Experiment 1, high alcohol drinkers (>9 g/kg/d) were paired with low alcohol drinkers (<5 g/kg/d) of the same sex on either side of a mesh divider for 4 days with continuous access to the same 2-bottle choice test. In Experiment 2, high drinkers were paired with high drinkers and low drinkers paired with low drinkers. In both experiments, animals were again separated following pairing, and drinking was retested in isolation. In Experiment 3, alcohol-naïve animals were tested for saccharin consumption (0.05%) first in isolation and then in high saccharin drinkers paired with low saccharin drinkers, and then in another isolation period. In Experiment 1, high drinkers paired with low drinkers significantly decreased their alcohol intake and preference from baseline drinking in isolation, and drinking levels remained significantly lower during isolation following pairing. Interestingly, there was variability between pairs in whether the high drinker decreased or the low drinker increased intake. In Experiment 2, high drinkers paired with high drinkers did not significantly change their intake level or preference, nor did low drinkers paired with low drinkers, and no changes occurred during the subsequent isolation. In Experiment 3, there was no change in saccharin intake or preference when high drinkers were paired with high drinkers or low paired with low, or in the subsequent isolation. Alcohol drinking of prairie voles can be altered under social conditions, such that 1 animal changes its alcohol intake to more closely match the intake of the other animal, helping to explain previous findings of correlated alcohol drinking. The effect does not extend to saccharin, a naturally rewarding sweet substance. This behavior can be used to model the peer pressure that can often affect alcohol intake in humans.