Persistence of one-trial cocaine-induced behavioral sensitization in young rats: regional differences in Fos immunoreactivity.

Academic Article


  • RATIONALE: Unlike adult rats, young rats exhibit context-dependent and context-independent behavioral sensitization when assessed after a single pretreatment injection of cocaine. OBJECTIVE: The purpose of this study was to determine whether: (1) the context-dependent and context-independent sensitization of young rats can be dissociated based on the persistence of the sensitized response and (2) the expression of behavioral sensitization is associated with region-specific increases in Fos immunoreactivity (Fos-IR). MATERIALS AND METHODS: On postnatal day (PD) 19, rats were injected with either saline or cocaine (30 mg/kg) in a novel test chamber or the home cage. After 1, 3, 5, 7, 14, or 61 abstinence days, rats were challenged with 20 mg/kg cocaine and locomotor activity was measured for 60 min. In a separate experiment, rats pretreated on PD 19 were challenged with cocaine (10-30 mg/kg) on PD 80. RESULTS: The sensitized responding of young rats persisted for the same length of time (5 days) regardless of whether cocaine pretreatment occurred in a novel environment or the home cage. Behavioral sensitization did not reemerge in adulthood. When assessed after three abstinence days (i.e., on PD 22), acute treatment with cocaine increased Fos-IR in various brain regions, but sensitized responding was associated with elevated Fos expression in only the caudate-putamen (CP) and prefrontal cortex (PFC). CONCLUSIONS: Persistence of the sensitized response cannot be used to dissociate the one-trial context-dependent and context-independent sensitization of young rats. Fos data indicate that the CP and PFC may be involved in the mediation of short-term behavioral sensitization on PD 22.
  • Authors

  • McDougall, Sanders A
  • Charntikov, Sergios
  • Cortez, Anthony M
  • Amodeo, Dionisio A
  • Martinez, Cynthia E
  • Crawford, Cynthia A
  • Status

    Publication Date

  • April 2009
  • Published In

  • Psychopharmacology  Journal
  • Keywords

  • Aging
  • Animals
  • Behavior, Animal
  • Brain
  • Central Nervous System Stimulants
  • Cocaine
  • Female
  • Immunohistochemistry
  • Male
  • Motor Activity
  • Proto-Oncogene Proteins c-fos
  • Rats
  • Rats, Sprague-Dawley
  • Digital Object Identifier (doi)

    Pubmed Id

  • 19020866
  • Start Page

  • 617
  • End Page

  • 628
  • Volume

  • 203
  • Issue

  • 3