title: The effect of chronic amphetamine treatment on cocaine-induced facilitation of intracranial self-stimulation in rats.
abstract: BACKGROUND
  Chronic amphetamine treatment reduces cocaine self-administration in pre-clinical and clinical settings, and amphetamine has been proposed as a candidate medication for treatment of cocaine abuse.
  
  
  OBJECTIVE
  The objective of the present study was to investigate whether chronic amphetamine treatment can decrease abuse-related cocaine effects in an assay of intracranial self-stimulation (ICSS).
  
  
  METHODS
  Thirteen adult male Sprague-Dawley rats were equipped with intracranial electrodes targeting the medial forebrain bundle and trained to lever press for pulses of brain stimulation in a "frequency-rate" ICSS procedure. Cocaine (10 mg/kg) was administered before (day 0), during (days 7 and 14), and after (posttreatment days 1 and 3) 2 weeks of continuous treatment with either amphetamine (0.32 mg/kg/h, n = 7) or saline (n = 6) via osmotic pump.
  
  
  RESULTS
  Prior to treatment, cocaine facilitated ICSS in all rats. Saline treatment had no effect on baseline ICSS or cocaine-induced facilitation of ICSS at any time. Conversely, amphetamine produced a sustained though submaximal facilitation of baseline ICSS, and cocaine produced little additional facilitation of ICSS during amphetamine treatment. Termination of amphetamine treatment produced a depression of baseline ICSS and recovery of cocaine-induced facilitation of ICSS.
  
  
  CONCLUSIONS
  These data suggest that chronic amphetamine treatment blunts expression of abuse-related cocaine effects on ICSS in rats.
authors.affiliation: Department of Pharmacology and Toxicology, Virginia Commonwealth University, 410 N. 12th St., PO Box 980613, Richmond, VA, 23298, USA.
authors.forename: Clayton T
authors.initials: CT
authors.lastname: Bauer
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Banks
authors.forename: S Stevens
authors.initials: SS
authors.lastname: Negus
mesh_terms: D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D003042:Cocaine / Q000494:pharmacology*; D019970:Cocaine-Related Disorders / Q000188:drug therapy* / Q000503:physiopathology*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D058542:Implantable Neurostimulators; D008297:Male; D008474:Medial Forebrain Bundle / Q000187:drug effects / Q000503:physiopathology; D017207:Rats, Sprague-Dawley; D012646:Self Administration; D012653:Self Stimulation / Q000187:drug effects* / Q000502:physiology
chemical_list: D018765:Dopamine Uptake Inhibitors; D000661:Amphetamine; D003042:Cocaine