title: Alcohol-Preferring P Rats Exhibit Elevated Motor Impulsivity Concomitant with Operant Responding and Self-Administration of Alcohol.
abstract: Increased levels of impulsivity are associated with increased illicit drug use and alcoholism. Previous research in our laboratory has shown that increased levels of delay discounting (a decision-making form of impulsivity) are related to appetitive processes governing alcohol self-administration as opposed to purely consummatory processes. Specifically, the high-seeking/high-drinking alcohol-preferring P rats showed increased delay discounting compared to nonselected Long Evans rats (LE) whereas the high-drinking/moderate-seeking HAD2 rats did not. The P rats also displayed a perseverative pattern of behavior such that during operant alcohol self-administration they exhibited greater resistance to extinction.
  
  
  
  One explanation for the previous findings is that P rats have a deficit in response inhibition. This study followed up on this possibility by utilizing a countermanding paradigm (stop signal reaction time [SSRT] task) followed by operant self-administration of alcohol across increasing fixed ratio requirements (FR; 1, 2, 5, 10, and 15 responses). In separate animals, 24-hour access 2-bottle choice (10% EtOH vs. water) drinking was assessed.
  
  
  
  In the SSRT task, P rats exhibited an increased SSRT compared to both LE and HAD2 rats indicating a decrease in behavioral inhibition in the P rats. Also, P rats showed increased operant self-administration across all FRs and the greatest increase in responding with increasing FR requirements. Conversely, the HAD2 and LE had shorter SSRTs and lower levels of operant alcohol self-administration. However, for 2-bottle choice drinking HAD2s and P rats consumed more EtOH and had a greater preference for EtOH compared to LE.
  
  
  
  These data extend previous findings showing the P rats to have increased delay discounting (decision-making impulsivity) and suggest that P rats also have a lack of behavioral inhibition (motor impulsivity). This supports the notion that P rats are a highly impulsive as well as "high-seeking" model of alcoholism, and that the HAD2s' elevated levels of alcohol consumption are not mediated via appetitive processes or impulsivity.
authors.affiliation: Department of Psychology (SWB, CLC), Indiana University Purdue University Indianapolis, Indianapolis, Indiana.
authors.forename: Steven Wesley
authors.initials: SW
authors.lastname: Beckwith
authors.affiliation: Department of Psychology (SWB, CLC), Indiana University Purdue University Indianapolis, Indianapolis, Indiana.
authors.forename: Cristine Lynn
authors.initials: CL
authors.lastname: Czachowski
mesh_terms: D000818:Animals; D002755:Choice Behavior; D003216:Conditioning, Operant; D000431:Ethanol / Q000008:administration & dosage; D007175:Impulsive Behavior; D007266:Inhibition, Psychological; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011930:Reaction Time; D012055:Reinforcement Schedule; D012646:Self Administration; D013045:Species Specificity
chemical_list: D000431:Ethanol
keywords: Alcohol Self-Administration; Impulsivity; Rat; Selected Line