title: Individual Variation in Alcohol Intake Predicts Reinforcement, Motivation, and Compulsive Alcohol Use in Rats.
abstract: BACKGROUND
  Alcohol is one of the most commonly used psychoactive substances. Prolonged alcohol use can result in alcohol use disorder (AUD), characterized by excessive and compulsive alcohol consumption. Importantly, however, the development of AUD only happens in a minority of individuals who consume alcohol. To understand the individual vulnerability for AUD, models that capture both the individual variability in alcohol consumption and the transition from casual to compulsive alcohol use are essential.
  
  
  METHODS
  Individual variability in voluntary alcohol intake and the preference for alcohol were assessed under continuous alcohol access (CAA) and intermittent-every-other-day alcohol access (IAA) schedules in the home cage using outbred Lister Hooded rats. Subsequently, the reinforcing properties of alcohol were tested in an operant setting. In subsequent experiments, we performed a quinine adulteration experiment to assess inflexible alcohol consumption and blood alcohol levels (BALs) were assessed after voluntary alcohol consumption.
  
  
  RESULTS
  We found marked individual differences in alcohol consumption and preference under both access schedules, whereby subgroups of high- and low-alcohol-drinking rats (HD and LD) could be identified. HD with IAA increased their alcohol intake over days in the first month, whereas LD did not. Moreover, when alcohol access time was extended from 7 to 24 h/d for rats with IAA, alcohol intake profoundly increased in HD with IAA, whereas LD with IAA maintained low levels of alcohol intake. Furthermore, HD earned more alcohol than LD under both fixed ratio and progressive ratio schedules of reinforcement. We further found that HD continued their intake of a quinine-adulterated alcohol solution to a larger extent than LD and HD showed higher BALs after 30 minutes of alcohol consumption.
  
  
  CONCLUSIONS
  These profound individual differences in alcohol intake, reinforcement, motivation, and AUD-like behavior provide a promising tool to unravel the neurobehavioral underpinnings of individual vulnerability for AUD.
authors.affiliation: Faculty of Veterinary Medicine, Department of Animals in Science and Society, Division of Behavioural Neuroscience, Utrecht University, Utrecht, the Netherlands.
authors.forename: Marcia
authors.initials: M
authors.lastname: Spoelder
authors.affiliation: Faculty of Veterinary Medicine, Department of Animals in Science and Society, Division of Behavioural Neuroscience, Utrecht University, Utrecht, the Netherlands.
authors.forename: Peter
authors.initials: P
authors.lastname: Hesseling
authors.affiliation: Faculty of Veterinary Medicine, Department of Animals in Science and Society, Division of Behavioural Neuroscience, Utrecht University, Utrecht, the Netherlands.
authors.forename: Annemarie M
authors.initials: AM
authors.lastname: Baars
authors.affiliation: Faculty of Veterinary Medicine, Department of Animals in Science and Society, Division of Behavioural Neuroscience, Utrecht University, Utrecht, the Netherlands.
authors.forename: José G
authors.initials: JG
authors.lastname: Lozeman-van 't Klooster
authors.affiliation: Faculty of Veterinary Medicine, Department of Animals in Science and Society, Division of Behavioural Neuroscience, Utrecht University, Utrecht, the Netherlands.
authors.forename: Marthe D
authors.initials: MD
authors.lastname: Rotte
authors.affiliation: Faculty of Veterinary Medicine, Department of Animals in Science and Society, Division of Behavioural Neuroscience, Utrecht University, Utrecht, the Netherlands.|Department of Translational Neuroscience (LJMJV), Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, the Netherlands.
authors.forename: Louk J M J
authors.initials: LJ
authors.lastname: Vanderschuren
authors.affiliation: Faculty of Veterinary Medicine, Department of Animals in Science and Society, Division of Behavioural Neuroscience, Utrecht University, Utrecht, the Netherlands.
authors.forename: Heidi M B
authors.initials: HM
authors.lastname: Lesscher
mesh_terms: D000428:Alcohol Drinking / Q000097:blood* / Q000523:psychology*; D000818:Animals; D003192:Compulsive Behavior / Q000097:blood* / Q000523:psychology*; D003216:Conditioning, Operant / Q000187:drug effects / Q000502:physiology; D008297:Male; D009042:Motivation / Q000187:drug effects / Q000502:physiology*; D011237:Predictive Value of Tests; D051381:Rats; D012054:Reinforcement, Psychology; D012646:Self Administration
keywords: Addiction-Like Behavior; Alcohol Intake; Individual Differences; Rats; Reinforcement