Similar to humans, different lines of heterogeneous stock rats display a wide-range of ethanol-consumption levels.18 The very early work by Williams and coworkers,19 as well as Mardones and coworkers,20 resulted in the hypothesis that ethanol intake in rodents is also under substantial genetic control. From their early work and that of four other international sites, bidirectional selective breeding has resulted in at least five high alcohol–consuming versus their respective low alcohol–consuming rat lines.21 One of these selectively bred high alcohol–consuming rat lines is the alcohol-preferring P rat. Essentially, starting from a closed colony of Wistar rats, the highest alcohol drinkers were mated together and the lowest alcohol drinkers were mated together, which resulted in the P and NP lines, respectively.21,22 The selectively bred alcohol-preferring P rat meets all of the criteria put forth for a valid animal model23,24 of alcoholism.21,22 It also meets the more recently proposed criteria including relapse-like,25 binge-like,21,22,26,27 and early/adolescent-onset of excessive drinking, which results in blood alcohol concentrations (BACs) greater than the threshold (80 mg%) of NIAAA’s28 definition for binge drinking.26,29 By the nature of selective
