title: Cocaine self-administration and reinstatement in female rats selectively bred for high and low voluntary running.
abstract: Previous research has found that rats behaviorally screened for high (vs. low) wheel running were more vulnerable to cocaine abuse. To assess the extent to which a genetic component is involved in this drug-abuse vulnerability, rats selectively bred for high or low voluntary running (HVR or LVR, respectively) were examined for differences in cocaine seeking in the present study.
  
  
  
  Female rats were trained to lever press for food and then were assessed for differences in acquisition of cocaine (0.4mg/kg; i.v.) self-administration across 10 sessions. Once acquired, rats self-administered cocaine for a 14-day maintenance phase, followed by a 14-day extinction phase when cocaine was no longer available. Subsequently, reinstatement of cocaine seeking was examined with priming injections of cocaine (5, 10 & 15mg/kg), caffeine (30mg/kg), yohimbine (2.5mg/kg) and cocaine-paired cues.
  
  
  
  A greater percentage of LVR rats met the acquisition criteria for cocaine self-administration and in fewer sessions than HVR rats. No differences in responding for cocaine were observed between phenotypes during maintenance. However, during extinction LVR rats initially responded at higher rates and persisted in cocaine seeking for a greater number of sessions. No phenotype differences were observed following drug and cue-primed reinstatement of cocaine seeking.
  
  
  
  In general, LVR rats were more sensitive to the reinforcing effects of cocaine than HVR rats during periods of transition into and out of cocaine self-administration. Thus, LVR rats sometimes showed a greater vulnerability cocaine seeking than HVR rats.
authors: Department of Psychiatry, University of Minnesota Medical School, Minneapolis, MN, United States. Electronic address: jsmethells@gmail.com.
authors: J R
authors: JR
authors: Smethells
authors: Department of Psychiatry, University of Minnesota Medical School, Minneapolis, MN, United States.
authors: N E
authors: NE
authors: Zlebnik
authors: Department of Psychological Sciences, University of Missouri, Columbia, MO, United States.
authors: D K
authors: DK
authors: Miller
authors: Department of Psychological Sciences, University of Missouri, Columbia, MO, United States.
authors: M J
authors: MJ
authors: Will
authors: Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, United States; Department of Biomedical Science, University of Missouri, Columbia, MO, United States, United States; Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, United States; Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO, United States.
authors: F
authors: F
authors: Booth
authors: Department of Psychiatry, University of Minnesota Medical School, Minneapolis, MN, United States.
authors: M E
authors: ME
authors: Carroll
mesh_terms: D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D002110:Caffeine / Q000494:pharmacology; D000697:Central Nervous System Stimulants / Q000008:administration & dosage*; D003042:Cocaine / Q000008:administration & dosage*; D019970:Cocaine-Related Disorders / Q000503:physiopathology; D003463:Cues; D005108:Extinction, Psychological / Q000187:drug effects*; D005260:Female; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D012054:Reinforcement, Psychology; D012420:Running; D012646:Self Administration; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D058669:Adrenergic alpha-2 Receptor Antagonists; D000697:Central Nervous System Stimulants; D015016:Yohimbine; D002110:Caffeine; D003042:Cocaine
keywords: Acquisition; Cocaine self-administration; Extinction; Phenotype; Rats; Wheel running