title: Binge-like acquisition of 3,4-methylenedioxypyrovalerone (MDPV) self-administration and wheel activity in rats.
abstract: BACKGROUND
  Lack of access to conventional sources of reinforcement has been proposed as a risk factor for substance abuse in lower socioeconomic populations. There is laboratory evidence that behavioral alternatives (enrichment or exercise) and alternative reinforcers (e.g., sweetened solutions) can reduce self-administration of a variety of drugs.
  
  
  OBJECTIVE
  The objective of this study is to determine if drug self-administration could devalue wheel activity in an animal model.
  
  
  METHODS
  Male Wistar rats were trained to self-administer 3,4-methylenedioxypyrovalerone (MDPV; "bath salts"), 0.05 mg/kg/infusion, i.v., with concurrent access to a running wheel that was either locked (LW) or unlocked (UW).
  
  
  RESULTS
  MDPV intake steadily increased across the 20-session acquisition interval but did not differ significantly between UW and LW groups. Mean wheel rotations declined significantly across the acquisition interval in the UW group. Of the rats that acquired self-administration, 60 % engaged in a binge-like behavior at the initiation of acquisition; intake was limited only by post-reinforcement time-out. The binge rats had higher post-acquisition levels of drug intake (even after excluding the binge session), and the UW binge rats showed a precipitous post-acquisition drop in wheel activity that was not observed in the UW no-binge rats.
  
  
  CONCLUSIONS
  These data confirm that MDPV is a powerful reward/reinforcer and show that a relatively high rate of intake at the onset of drug taking can devalue natural rewards (wheel activity) and can predict higher subsequent drug intake levels. Thus, limiting the intensity of initial drug exposure may attenuate subsequent drug abuse/addiction by preventing the devaluation of natural alternative rewards/reinforcers.
authors.affiliation: Committee on the Neurobiology of Addictive Disorders, The Scripps Research Institute, SP30-2400, 10550 North Torrey Pines Road, La Jolla, CA, 92037, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Aarde
authors.forename: P K
authors.initials: PK
authors.lastname: Huang
authors.forename: T J
authors.initials: TJ
authors.lastname: Dickerson
authors.forename: M A
authors.initials: MA
authors.lastname: Taffe
mesh_terms: D000818:Animals; D052117:Benzodioxoles / Q000008:administration & dosage* / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D007262:Infusions, Intravenous; D008297:Male; D009042:Motivation / Q000187:drug effects; D009043:Motor Activity / Q000187:drug effects*; D011759:Pyrrolidines / Q000008:administration & dosage* / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012201:Reward; D012646:Self Administration / Q000523:psychology*; D019966:Substance-Related Disorders / Q000523:psychology*; D000094982:Synthetic Cathinone
chemical_list: D052117:Benzodioxoles; D011759:Pyrrolidines; D000094982:Synthetic Cathinone