[show abstract][hide abstract] ABSTRACT: Approximately 30% of current drinkers in the United States drink excessively, and are referred to as problem/hazardous drinkers. These individuals, who may not meet criteria for alcohol abuse or dependence, comprise binge, heavy drinkers, or both. Given their high prevalence, interventions that reduce the risk of binge and heavy drinking have important public health implications. Impulsivity has been repeatedly associated with excessive drinking in the clinical literature. As impulsivity is correlated with, and may play a critical role in, the initiation and maintenance of excessive drinking, this behavior may be an important target for therapeutic intervention. Hence, a better understanding of pharmacological treatments capable of attenuating excessive drinking and impulsivity may markedly improve clinical outcomes. The high-alcohol-preferring (HAP) mice represent a strong rodent model to study the relationship between impulsivity and excessive alcohol drinking, as recent evidence indicates they consume high levels of alcohol throughout their active cycle and are innately impulsive. Using this model, the present study demonstrates that the triple monoamine uptake inhibitors (TUIs) amitifadine and DOV 102, 677 effectively attenuate binge drinking, heavy drinking assessed via a 24-hour free-choice assay, and impulsivity measured by the delay discounting procedure. In contrast, 3-PBC, a GABA-A α1 preferring ligand with mixed agonist-antagonist properties, attenuates excessive drinking without affecting impulsivity. These findings suggest that in HAP mice, monoamine pathways may predominate as a common mechanism underlying impulsivity and excessive drinking, while the GABAergic system may be more salient in regulating excessive drinking. We further propose that TUIs such as amitifadine and DOV 102, 677 may be used to treat the co-occurrence of impulsivity and excessive drinking.
[show abstract][hide abstract] ABSTRACT: Crossed high-alcohol-preferring (cHAP) mice were selectively bred from a cross of the HAP1 × HAP2 replicate lines and demonstrate blood ethanol concentrations (BECs) during free-choice drinking reminiscent of those observed in alcohol-dependent humans. In this report, we investigated the relationship between free-choice drinking, intoxication, tolerance, and sensitization in cHAP mice. We hypothesized that initially mice would become ataxic after drinking alcohol, but that increased drinking over days would be accompanied by increasing tolerance to the ataxic effects of ethanol (EtOH).
Male and female cHAP mice had free-choice access to 10% EtOH and water (E), while Water mice (W) had access to water alone. In experiment 1, the first drinking experience was monitored during the dark portion of the cycle. Once E mice reached an average intake rate of ≥1.5 g/kg/h, they, along with W mice, were tested for footslips on a balance beam, and BECs were assessed. In experiments 2, 3, and 4, after varying durations of free-choice 10% EtOH access (0, 3, 14, or 21 days), mice were challenged with 20% EtOH and tested for number of footslips on a balance beam or locomotor stimulant response. Blood was sampled for BEC determination.
We found that cHAP mice rapidly acquire alcohol intakes that lead to ataxia. Over time, cHAP mice developed behavioral tolerance to the ataxic effects of alcohol, paralleled by escalating alcohol consumption. However, locomotor sensitization did not develop following 14 days of free-choice EtOH access.
Overall, we observed increases in free-choice drinking with extended alcohol access paralleled by increases in functional tolerance, but not locomotor sensitization. These data support our hypothesis that escalating free-choice drinking over days in cHAP mice is driven by tolerance to alcohol's behavioral effects. These data are the first to demonstrate that escalating free-choice consumption is accompanied by increasing alcohol tolerance. In addition to buttressing the hypothesized importance of tolerance in drinking, our findings suggest that cHAP mice may be a unique, translational resource for studying tolerance as a contributor to and consequence of chronic, excessive EtOH consumption.
Alcoholism Clinical and Experimental Research 08/2013; · 3.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: Both lithium and valproate are well-established treatments for bipolar disorder. Studies have also found that lithium is effective at reducing suicidal behaviors in patients with mood disorders. Impulsivity is a validated endophenotype of both bipolar disorder and suicidal behavior. We assessed effects of treatment with lithium or valproate on cognitive impulsivity in selectively bred mice previously shown to manifest relatively high levels of cognitive impulsivity. Mice were trained in the delay-discounting (DD) paradigm, a measure of cognitive impulsivity reflecting a behavioral bias towards immediacy, and then treated with lithium, valproate, or control chow. After three weeks of drug treatment, mice were tested at various delays to a large, delayed reward. Drug treatment continued during this time. Lithium reduced impulsivity, while valproate had no effect on choice behavior. Both drugs increased the number of choice trials and reinforcer intake, but effects on choice behavior did not depend on these motivational changes. To our knowledge, this is the first study demonstrating lithium's effects to reduce cognitive impulsivity. Future studies may focus on the ability of putative pharmacotherapies for patients at risk for bipolar disorder or suicide to modify the impulsive choice dimension of thes diseases.Neuropsychopharmacology accepted article preview online, 12 April 2013; doi:10.1038/npp.2013.89.
Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology 04/2013; · 6.99 Impact Factor
[show abstract][hide abstract] ABSTRACT: BACKGROUND: Crossed high alcohol preferring (cHAP) mice were selectively bred from a cross of the HAP1 × HAP2 replicate lines, and we demonstrate blood ethanol concentrations (BECs) during free-choice drinking that are reminiscent of those observed in alcohol-dependent humans. Therefore, this line may provide an unprecedented opportunity to learn about the consequences of excessive voluntary ethanol (EtOH) consumption, including metabolic tolerance and liver pathology. Cytochrome p450 2E1 (CYP2E1) induction plays a prominent role in driving both metabolic tolerance and EtOH-induced liver injury. In this report, we sought to characterize cHAP drinking by assessing whether pharmacologically relevant BEC levels are sustained throughout the active portion of the light-dark cycle. Given that cHAP intakes and BECs are similar to those observed in mice given an EtOH liquid diet, we assessed whether free-choice exposure results in metabolic tolerance, hepatic enzyme induction, and hepatic steatosis. METHODS: In experiment 1, blood samples were taken across the dark portion of a 12:12 light-dark cycle to examine the pattern of EtOH accumulation in these mice. In experiments 1 and 2, mice were injected with EtOH following 3 to 4 weeks of access to water or 10% EtOH and water, and blood samples were taken to assess metabolic tolerance. In experiment 3, 24 mice had 4 weeks of access to 10% EtOH and water or water alone, followed by necropsy and hepatological assessment. RESULTS: In experiment 1, cHAP mice mean BEC values exceeded 80 mg/dl at all sampling points and approached 200 mg/dl during the middle of the dark cycle. In experiments 1 and 2, EtOH-exposed mice metabolized EtOH faster than EtOH-naïve mice, demonstrating metabolic tolerance (p < 0.05). In experiment 3, EtOH-drinking mice showed greater expression of hepatic CYP2E1 than water controls, consistent with the development of metabolic tolerance (p < 0.05). EtOH access altered neither hepatic histology nor levels of alcohol dehydrogenase and aldehyde dehydrogenase. CONCLUSIONS: These results demonstrate that excessive intake by cHAP mice results in sustained BECs throughout the active period, leading to the development of metabolic tolerance and evidence of CYP2E1 induction. Together, these results provide additional support for the cHAP mice as a highly translational rodent model of alcoholism.
Alcoholism Clinical and Experimental Research 07/2012; · 3.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: BACKGROUND: Abuse of alcohol during adolescence continues to be a problem, and it has been shown that earlier onset of drinking predicts increased alcohol abuse problems later in life. High levels of impulsivity have been demonstrated to be characteristic of alcoholics, and impulsivity has also been shown to predict later alcohol use in teenage subjects, showing that impulsivity may precede the development of alcohol use disorders. These experiments examined adolescent drinking in a high-drinking, relatively impulsive mouse population and assessed its effects on adult drinking and adult impulsivity. METHODS: Experiment 1: Selectively bred high-alcohol preferring (HAPII) mice were given either alcohol (free-choice access) or water only for 2 weeks during middle adolescence or adulthood. All mice were given free-choice access to alcohol 30 days later, in adulthood. Experiment 2: Adolescent HAPII mice drank alcohol and water, or water alone, for 2 weeks, and were then trained to perform a delay discounting task as adults to measure impulsivity. In each experiment, effects of volitional ethanol (EtOH) consumption on later behavior were assessed. We expected adolescent alcohol exposure to increase subsequent drinking and impulsivity. RESULTS: Mice consumed significant quantities of EtOH, reaching average blood ethanol concentrations (BECs) of 142 mg/dl (adolescent) or 154 mg/dl (adult) in Experiment 1. Adolescent mice in Experiment 2 reached an average of 108 mg/dl. Mice exposed to alcohol in either adolescence or adulthood showed a transient increase in EtOH consumption, but we observed no differences in impulsivity in adult mice as a function of whether mice drank alcohol during adolescence. CONCLUSIONS: These findings indicate that HAPII mice drink intoxicating levels of alcohol during both adolescence and adulthood and that this volitional intake has long-term effects on subsequent drinking behavior. Nonetheless, this profound exposure to alcohol during adolescence does not increase impulsivity in adulthood, indicating that long-term changes in drinking are mediated by mechanisms other than impulsivity.
Alcoholism Clinical and Experimental Research 06/2012; · 3.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: There is considerable evidence for the existence of comorbidity between alcohol-use disorders and depression in humans. One strategy to elucidate hereditary factors affecting the comorbidity of these disorders is to use genetic animal models, such as mouse lines selectively bred for voluntary ethanol consumption. We hypothesized that mice from lines that were bred for high-alcohol preference would manifest increased depression-like phenotypes compared to low-alcohol preferring mice. Mice that were bi-directionally selected and bred on the basis of their High- (HAP) or Low-Alcohol Preference (LAP) were tested in the open-field (OFT), dark-light box (DLB), forced swim (FST), and learned helplessness tests (LH). The study was conducted in two independently derived replicates. In the OFT, both HAP2 and HAP3 mice showed higher levels of general locomotion compared to LAP mice. However, only HAP2 mice spent more time in the center compared to LAP2 mice. In the DLB, there was a slightly higher anxiety-like phenotype in HAP mice. In both FST and LH, we observed higher depression-like behaviors in HAP mice compared to LAP mice, but this was limited to the Replicate 2 mice. Overall, we identified affect-related behavioral changes in mouse lines bred for high-alcohol preference. Notably, the Replicate 3 lines that showed fewer depression-like behaviors also manifest smaller differences in alcohol intake. These data suggest that there may be overlap between genes that predispose to excessive alcohol intake and those underlying affect-related behaviors in the mouse.
[show abstract][hide abstract] ABSTRACT: Multiple lines of high alcohol-preferring (HAP) mice were selectively bred for their intake of 10% ethanol (v/v) during 24-hour daily access over a 4-week period, with the highest drinking lines exhibiting intakes in excess of 20 g/kg/day. We observed circadian drinking patterns and resulting blood ethanol concentrations (BECs) in the HAP lines. We also compared the drinking rhythms and corresponding BECs of the highest drinking HAP lines to those of the C57BL/6J (B6) inbred strain. Adult male and female crossed HAP (cHAP), HAP replicate lines 1, 2, 3 and B6 mice had free-choice access to 10% ethanol and water for 3 weeks prior to bi-hourly assessments of intake throughout the dark portion of the light-dark cycle. All HAP lines reached and maintained a rate of alcohol intake above the rate at which HAP1 mice metabolize alcohol, and BECs were consistent with this finding. Further, cHAP and HAP1 mice maintained an excessive level of intake throughout the dark portion of the cycle, accumulating mean BEC levels of 261.5 ± 18.09 and 217.9 ± 25.02 mg/dl, respectively. B6 mice drank comparatively modestly, and did not accumulate high BEC levels (53.63 + 8.15 mg/dl). Free-choice drinking demonstrated by the HAP1 and cHAP lines may provide a unique opportunity for modeling the excessive intake that often occurs in alcohol-dependent individuals, and allow for exploration of predisposing factors for excessive consumption, as well as the development of physiological, behavioral and toxicological outcomes following alcohol exposure.
[show abstract][hide abstract] ABSTRACT: Individuals learn associations between alcohol's sensory properties and intoxication, with such conditioned stimuli (CS) becoming involved in craving and relapse. However, these CS also carry idiosyncratic associations.
This study aimed to test brain responses to novel CS conditioned with alcohol intoxication.
Fourteen heavy drinkers (age 24.9 ± 3.2) performed a reaction time task with embedded novel geometric CS and were told only that the task was to measure alcohol's effect on speed. Rapid intravenous alcohol infusion (the unconditioned stimulus; UCS) began with the appearance of a CS+, using pharmacokinetic modeling to increment breath alcohol by ~18 mg% in 200 s per each of six CS-UCS pairings. Placebo-saline infusion with CS- used the same infusion parameters in same-day randomized/counterbalanced sessions. The next morning subjects, connected to inactive intravenous pumps, underwent functional magnetic resonance imaging (fMRI) of the same task with mixed brief presentations of CS+, CS-, and irrelevant CS and were told that alcohol could be infused at any time during imaging.
CS- responses were significantly greater than those of CS+ in medial frontal cortex. Notably, CS+ responses were negative, suggesting reduced neural activity. Negative activity was most pronounced in early scans, extinguishing with time. As subjects were told that alcohol could be administered in fMRI, a CS+ without alcohol is similar to a negative prediction error, with associated reduced frontal activity during withheld reward.
Novel stimuli relatively free of demand characteristics can be classically conditioned to intermittent brain exposure of even low alcohol concentrations, permitting imaging studies of conditioned alcohol expectancies.
[show abstract][hide abstract] ABSTRACT: Genetic aspects of alcoholism have been modeled using rats selectively bred for extremes of alcohol preference and voluntary alcohol intake. These lines show similar alcohol drinking phenotypes but have different genetic and environmental backgrounds and may therefore display diverse behavioral traits as seen in human alcoholics. The multivariate concentric square field™ (MCSF) test is designed to provoke exploration and behaviors associated with risk assessment, risk taking and shelter seeking in a novel environment. The aim was to use the MCSF to characterize behavioral profiles in rat lines from selective breeding programs in the United States (P/NP, HAD1/LAD1, HAD2/LAD2), Italy (sP/sNP) and Finland (AA/ANA). The open field and elevated plus maze tests were used as reference tests. There were substantial differences within some of the pairs of selectively bred rat lines as well as between all alcohol-preferring rats. The most pronounced differences within the pairs of lines were between AA and ANA rats and between sP and sNP rats followed by intermediate differences between P and NP rats and minor differences comparing HAD and LAD rats. Among all preferring lines, P, HAD1 and HAD2 rats shared similar behavioral profiles, while AA and sP rats were quite different from each other and the others. No single trait appeared to form a common 'pathway' associated with a high alcohol drinking phenotype among all of the alcohol-preferring lines of rats. The marked behavioral differences found in the different alcohol-preferring lines may mimic the heterogeneity observed among human alcoholic subtypes.
[show abstract][hide abstract] ABSTRACT: Selectively breeding lines of mice and rats to differ in alcohol intake has proven useful for defining which traits correlate with high alcohol drinking behavior, as well as for creating animal models of alcoholism. This study reports the derivation of two novel sets of selected lines, High Alcohol Preferring (HAP) and Low Alcohol Preferring (LAP) replicate 2 and 3 lines. Mice were mass-selected using the same procedure as in the replicate 1 lines: using HS/Ibg as a progenitor, mice were selected for differences in 2-bottle choice intake of 10% alcohol during a 4-week testing period. In addition, another high-drinking line, the crossed HAP (cHAP) line was selectively bred from a progenitors that were a cross of replicate 1 (S27) × replicate 2 (S21) HAP lines. All lines were characterized for saccharin intake. Overall, the response to selection of the HAP and LAP replicate 2 and 3 lines was quite similar. As anticipated, following selection, the cHAP line drank more than either parent HAP line (consuming 26.0 g/kg per day of alcohol by S11), suggesting that this method of crossing replicate lines and selecting from that cross captures more alleles than any single selected line, as well as producing a line with exceptionally high voluntary alcohol intake. As expected, saccharin consumption was highly associated with alcohol consumption; data from 7 lines (HAP 1, 2, and 3, LAP 1, 2, and 3, and cHAP) indicated a genetic correlation between 10% alcohol and 0.32% saccharin intake of 0.91. Overall, these findings show the practicality of developing replicate lines divergent in alcohol preference, and validate a novel procedure for generating very high-drinking mouse populations.
[show abstract][hide abstract] ABSTRACT: Previous studies have shown that high alcohol consumption is associated with low withdrawal susceptibility, while at the same time, other studies have shown that exposure to ethanol vapor increases alcohol drinking in rats and mice. In the present studies, we sought to shed light on this seeming contradiction using mice selectively bred for High- (HAP) and Low- (LAP) Alcohol Preference, first, assessing these lines for differences in signs of ethanol withdrawal and second, for differences in the efficacy of intermittent alcohol vapor exposure on elevating subsequent ethanol intake.
Experiment 1 examined whether these lines of mice differed in ethanol withdrawal-induced CNS hyperexcitability and the development of sensitization to this effect following intermittent ethanol vapor exposure. Adult HAP and LAP lines (replicates 1 and 2), and the C3H/HeNcr inbred strain (included as a control genotype for comparison purposes) received intermittent exposure to ethanol vapor and were evaluated for ethanol withdrawal-induced seizures assessed by scoring handling-induced convulsions (HIC). Experiment 2 examined the influence of chronic intermittent ethanol exposure on voluntary ethanol drinking. Adult male and female HAP-2 and LAP-2 mice, along with male C57BL/6J (included as comparative controls) were trained to drink 10% ethanol using a limited access (2 h/d) 2-bottle choice paradigm. After stable baseline daily intake was established, mice received chronic intermittent ethanol vapor exposure in inhalation chambers. Ethanol intake sessions resumed 72 hours after final ethanol (or air) exposure for 5 consecutive days.
Following chronic ethanol treatment, LAP mice exhibited overall greater withdrawal seizure activity compared with HAP mice. In Experiment 2, chronic ethanol exposure/withdrawal resulted in a significant increase in ethanol intake in male C57BL/6J, and modestly elevated intake in HAP-2 male mice. Ethanol intake for male control mice did not change from baseline levels of intake. In contrast, HAP-2 female and LAP-2 mice of both sexes did not show changes in ethanol intake as a consequence of intermittent ethanol exposure.
Overall, these results indicate that the magnitude of ethanol withdrawal-related seizures is inversely related to inherited ethanol intake preference. Additionally, intermittent ethanol vapor exposure appears more likely to affect high-drinking mice (C57BL/6J and HAP-2) than low drinkers, although these animals are less affected by ethanol withdrawal.
Alcoholism Clinical and Experimental Research 02/2011; 35(5):953-62. · 3.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: CP-866,087 (compound 15) is a novel, potent and selective mu opioid receptor antagonist. The design rationale, synthesis, in vitro and in vivo biological evaluation are reported herein. Preclinical efficacy data in disease relevant models measuring reduction of alcohol intake are presented, along with preclinical pharmacokinetic properties which supported the selection of the title compound for clinical evaluation.
Medicinal Chemistry Communication 01/2011; 2:1001. · 2.72 Impact Factor
[show abstract][hide abstract] ABSTRACT: A functional connection between the circadian timing system and alcohol consumption is suggested by multiple lines of converging evidence. Ethanol consumption perturbs physiological rhythms in hormone secretion, sleep, and body temperature; and conversely, genetic and environmental perturbations of the circadian system can alter alcohol intake. A fundamental property of the circadian pacemaker, the endogenous period of its cycle under free-running conditions, was previously shown to differ between selectively bred high- (HAP) and low- (LAP) alcohol preferring replicate 1 mice. To test whether there is a causal relationship between circadian period and ethanol intake, we induced experimental, rather than genetic, variations in free-running period. Male inbred C57Bl/6J mice and replicate 2 male and female HAP2 and LAP2 mice were entrained to light:dark cycles of 26 or 22 h or remained in a standard 24 h cycle. On discontinuation of the light:dark cycle, experimental animals exhibited longer and shorter free-running periods, respectively. Despite robust effects on circadian period and clear circadian rhythms in drinking, these manipulations failed to alter the daily ethanol intake of the inbred strain or selected lines. Likewise, driving the circadian system at long and short periods produced no change in alcohol intake. In contrast with replicate 1 HAP and LAP lines, there was no difference in free-running period between ethanol naïve HAP2 and LAP2 mice. HAP2 mice, however, were significantly more active than LAP2 mice as measured by general home-cage movement and wheel running, a motivated behavior implicating a selection effect on reward systems. Despite a marked circadian regulation of drinking behavior, the free-running and entrained period of the circadian clock does not determine daily ethanol intake.
[show abstract][hide abstract] ABSTRACT: Impulsivity is genetically correlated with, and precedes, addictive behaviors and alcoholism. If impulsivity or attention is causally related to addiction, certain pharmacological manipulations of impulsivity and/or attention may affect alcohol drinking, and vice versa. The current studies were designed to explore the relationship among impulsivity, drinking, and vigilance in selectively bred High Alcohol Preferring (HAP) mice, a line that has previously demonstrated both high impulsivity and high alcohol consumption. Amphetamine, naltrexone, and memantine were tested in a delay discounting (DD) task for their effects on impulsivity and vigilance. The same drugs and doses were also assessed for effects on alcohol drinking in a 2-bottle choice test.
HAP mice were subjected to a modified version of adjusting amount DD using 0.5-second and 10-second delays to detect decreases and increases, respectively, in impulsive responding. In 2 experiments, mice were given amphetamine (0.4, 0.8, or 1.2 mg/kg), naltrexone (3 and 10 mg/kg), and memantine (1 and 5 mg/kg) before DD testing. Another pair of studies used scheduled access, 2-bottle choice drinking to assess effects of amphetamine (0.4, 1.2, or 3.0 mg/kg), naltrexone (3 and 10 mg/kg), and memantine (1 and 5 mg/kg) on alcohol consumption.
Amphetamine dose-dependently reduced impulsivity and vigilance decrement in DD, but similar doses left alcohol drinking unaffected. Naltrexone and memantine decreased alcohol intake at doses that did not affect water drinking but had no effects on impulsivity or vigilance decrement in the DD task.
Contrary to our hypothesis, none of the drugs tested here, while effective on either alcohol drinking or impulsivity, decreased both behaviors. These findings suggest that the genetic association between drinking and impulsivity observed in this population is mediated by mechanisms other than those targeted by the drugs tested in these studies.
Alcoholism Clinical and Experimental Research 08/2010; 34(8):1363-75. · 3.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: Repeated studies have shown that high impulsivity, when defined as the tendency to choose small immediate rewards over larger delayed rewards, is more prevalent in drug addicts and alcoholics when compared with nonaddicts. Assessing whether impulsivity precedes and potentially causes addiction disorders is difficult in humans because they all share a history of drug use. In this study, we address this question by testing alcohol-naïve mice from lines showing heritable differences in alcohol intake.
Replicated selected lines of outbred high-alcohol preferring (HAP) mice were compared to a low-alcohol preferring (LAP) line as well as the low-drinking progenitor line (HS/Ibg) on an adjusting amount delay discounting (DD) task. The DD task employs 2 levers to present subjects with a choice between a small, immediate and a large, delayed saccharin reward. By adjusting the quantity of the immediate reward up and down based on choice behavior, the task allows an estimate of how the subjective value of the delayed reinforcer decreases as delays increase. Latency to respond was also measured for each trial.
Both HAP2 and HAP1 lines of mice were more impulsive than the LAP2 and HS/Ibg lines, respectively. Hyperbolic curve-fitting confirmed steeper discounting in the high-alcohol drinking lines. In addition, the high-alcohol drinking lines demonstrated greater within-session increases in reaction times relative to the low-alcohol drinking lines. No other differences (consumption of saccharin, total trials completed) consistently mapped onto genetic differences in alcohol drinking.
Alcohol-naïve outbred mice selected for high-alcohol drinking were more impulsive with saccharin reinforcers than low-alcohol drinkers. These data are consistent with results seen using inbred strain descendents of high-alcohol drinking and low-alcohol drinking rat lines, and suggest that impulsivity is a heritable difference that precedes alcoholism.
Alcoholism Clinical and Experimental Research 05/2009; 33(7):1294-303. · 3.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: The high and low alcohol preferring (HAP1 and LAP1) mouse lines were selectively bred for differences in alcohol intake. The HAP1 and LAP1 mice are essentially noninbred lines that originated from the outbred colony of HS/Ibg mice, a heterogeneous stock developed from intercrossing 8 inbred strains of mice.
A total of 867 informative SNPs were genotyped in 989 HAP1 x LAP1 F2, 68 F1s, 14 parents (6 LAP1, 8 HAP1), as well as the 8 inbred strains of mice crossed to generate the HS/Ibg colony. Multipoint genome wide analyses were performed to simultaneously detect linked QTLs and also fine map these regions using the ancestral haplotypes.
QTL analysis detected significant evidence of association on 4 chromosomes: 1, 3, 5, and 9. The region on chromosome 9 was previously found linked in a subset of these F2 animals using a whole genome microsatellite screen.
We have detected strong evidence of association to multiple chromosomal regions in the mouse. Several of these regions include candidate genes previously associated with alcohol dependence in humans or other animal models.
Alcoholism Clinical and Experimental Research 01/2009; 33(3):531-7. · 3.42 Impact Factor
[show abstract][hide abstract] ABSTRACT: Searches for the identity of genes that influence the levels of alcohol consumption by humans and other animals have often been driven by presupposition of the importance of particular gene products in determining positively or negatively reinforcing effects of ethanol. We have taken an unbiased approach and performed a meta-analysis across three types of mouse populations to correlate brain gene expression with levels of alcohol intake. Our studies, using filtering procedures based on QTL analysis, produced a list of eight candidate genes with highly heritable expression, which could explain a significant amount of the variance in alcohol preference in mice. Using the Allen Brain Atlas for gene expression, we noted that the candidate genes' expression was localized to the olfactory and limbic areas as well as to the orbitofrontal cortex. Informatics techniques and pathway analysis illustrated the role of the candidate genes in neuronal migration, differentiation, and synaptic remodeling. The importance of olfactory cues, learning and memory formation (Pavlovian conditioning), and cortical executive function, for regulating alcohol intake by animals (including humans), is discussed.
[show abstract][hide abstract] ABSTRACT: Many studies have used voluntary ethanol consumption by animals to assess the influence of genetic and environmental manipulations on ethanol drinking. However, the relationship between home cage ethanol consumption and more formal assessments of ethanol-reinforced behavior using operant and instrumental conditioning procedures is not always clear. The present review attempted to evaluate whether there are consistent correlations between mouse and rat home cage ethanol drinking on the one hand, and either operant oral self-administration (OSA), conditioned taste aversion (CTA), or conditioned place preference (CPP) with ethanol on the other. We also review literature on intravenous ethanol self-administration (IVSA). To collect data, we evaluated a range of genetic manipulations that can change both genes and ethanol drinking behavior including selective breeding, transgenic and knockout models, and inbred and recombinant inbred strain panels. For a genetic model to be included in the analysis, there had to be published data resulting in differences on home cage drinking and data for at least one of the other behavioral measures. A consistent, positive correlation was observed between ethanol drinking and OSA, suggesting that instrumental behavior is closely genetically related to consummatory and ingestive behavior directed at ethanol. A negative correlation was observed between CTA and drinking, suggesting that ethanol's aversive actions may limit oral consumption of ethanol. A more modest, positive relationship was observed between drinking and CPP, and there were not enough studies available to determine a relationship with IVSA. That some consistent outcomes were observed between widely disparate behavioral procedures and genetic populations may increase confidence in the validity of findings from these assays. These findings may also have important implications when researchers decide which phenotypes to use in measuring alcohol-reward relevant behaviors in novel animal models.
[show abstract][hide abstract] ABSTRACT: QTL analysis of behavioral traits and mouse brain gene expression studies were combined to identify candidate genes involved in the traits of alcohol preference and acute functional alcohol tolerance. The systematic application of normalization and statistical analysis of differential gene expression, behavioral and expression QTL location, and informatics methodologies resulted in identification of 8 candidate genes for the trait of alcohol preference and 22 candidate genes for acute functional tolerance. Pathway analysis, combined with clustering by ontology, indicated the importance of transcriptional regulation and DNA and protein binding elements in the acute functional tolerance trait, and protein kinases and intracellular signal transduction elements in the alcohol preference trait. A rudimentary search for transcription control elements that could indicate coregulation of the panels of candidate genes produced modest results, implicating SMAD-3 in the regulation of four of the eight candidate genes for alcohol preference. However, the realization of the many caveats related to transcription factor binding site analysis, and attempts to correlate between transcription factor binding and function, forestalled any definitive global analysis of transcriptional control of differentially expressed candidate genes.
[show abstract][hide abstract] ABSTRACT: Much evidence from studies in humans and animals supports the hypothesis that alcohol addiction is a complex disease with both hereditary and environmental influences. Molecular determinants of excessive alcohol consumption are difficult to study in humans. However, several rodent models show a high or low degree of alcohol preference, which provides a unique opportunity to approach the molecular complexities underlying the genetic predisposition to drink alcohol. Microarray analyses of brain gene expression in three selected lines, and six isogenic strains of mice known to differ markedly in voluntary alcohol consumption provided >4.5 million data points for a meta-analysis. A total of 107 arrays were obtained and arranged into six experimental data sets, allowing the identification of 3,800 unique genes significantly and consistently changed between all models of high or low amounts of alcohol consumption. Several functional groups, including mitogen-activated protein kinase signaling and transcription regulation pathways, were found to be significantly overrepresented and may play an important role in establishing a high level of voluntary alcohol drinking in these mouse models. Data from the general meta-analysis was further filtered by a congenic strain microarray set, from which cis-regulated candidate genes for an alcohol preference quantitative trait locus on chromosome 9 were identified: Arhgef12, Carm1, Cryab, Cox5a, Dlat, Fxyd6, Limd1, Nicn1, Nmnat3, Pknox2, Rbp1, Sc5d, Scn4b, Tcf12, Vps11, and Zfp291 and four ESTs. The present study demonstrates the use of (i) a microarray meta-analysis to analyze a behavioral phenotype (in this case, alcohol preference) and (ii) a congenic strain for identification of cis regulation.
Proceedings of the National Academy of Sciences 05/2006; 103(16):6368-73. · 9.74 Impact Factor