title: Amphetamine-induced rapid-onset sensitization: role of novelty, conditioning and behavioral parameters.
abstract: BACKGROUND
  Environmental factors may modulate sensitization to the locomotor-activating effects of psychostimulants. In addition, some parameters of locomotor activity seem to be more sensitive to detect cocaine-induced behavioral sensitization. We examined how novelty and conditioning can modulate a previously described rapid-onset type of behavioral sensitization to amphetamine (AMP) in mice, using total, peripheral and central open-field locomotion frequencies as experimental parameters.
  
  
  METHODS
  In the first experiment, mice received an ip injection of saline (SAL) or 5.0 mg/kg AMP paired or not with the open-field or in their home-cages. Four hours later, all the animals received an ip SAL challenge injection and, 15 min later, were observed in the open-field for quantification of total, peripheral and central locomotion frequencies. The second experiment had a similar protocol, except that mice received a challenge injection of 1.5 mg/kg AMP.
  
  
  RESULTS
  The priming AMP injection significantly increased all the parameters of locomotion of SAL-challenged mice firstly exposed to or previously paired (but not unpaired) with the open-field. AMP priming injection enhanced total and peripheral locomotion of all AMP-challenged mice but only increased central locomotion of mice submitted to novelty or environmental conditioning.
  
  
  CONCLUSIONS
  Our results showed: 1) the development of an AMP-induced rapid-onset sensitization to novelty and rapid-onset environmental conditioning in mice, 2) the potentiation of the AMP-induced rapid-onset sensitization to an AMP challenge injection by novelty and environmental conditioning and 3) the importance of measuring different locomotor activity parameters in behavioral sensitization experiments.
authors.affiliation: Department of Pharmacology, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Juliana do Nascimento
authors.initials: Jdo N
authors.lastname: Alvarez
authors.forename: Daniela Fukue
authors.initials: DF
authors.lastname: Fukushiro
authors.forename: Julie Anne Obara
authors.initials: JA
authors.lastname: Tatsu
authors.forename: Erika Pereira
authors.initials: EP
authors.lastname: de Carvalho
authors.forename: Ana Camila de Castro
authors.initials: AC
authors.lastname: Gandolfi
authors.forename: Joyce Borges
authors.initials: JB
authors.lastname: Tsuchiya
authors.forename: Priscila Fernandes
authors.initials: PF
authors.lastname: Carrara-Nascimento
authors.forename: Melina Lopes
authors.initials: ML
authors.lastname: Lima
authors.forename: Rogério Gentil
authors.initials: RG
authors.lastname: Bellot
authors.forename: Roberto
authors.initials: R
authors.lastname: Frussa-Filho
mesh_terms: D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003213:Conditioning, Psychological / Q000187:drug effects*; D005106:Exploratory Behavior / Q000187:drug effects*; D005260:Female; D051379:Mice; D009043:Motor Activity / Q000187:drug effects
chemical_list: D000661:Amphetamine