title: Higher sensitivity to the conditioned rewarding effects of cocaine and MDMA in High-Novelty-Seekers mice exposed to a cocaine binge during adolescence.
abstract: BACKGROUND
  Exposure to drugs during adolescence can induce alterations in the central nervous system. The novelty-seeking personality trait influences differences observed among individuals exposed to drugs of abuse.
  
  
  OBJECTIVE
  Long-term effects of intensive pre-treatment with cocaine during adolescence or adulthood were evaluated in High- and Low-Novelty Seeker (HNS and LNS) mice. It was hypothesized that a cocaine binge during adolescence would increase sensitivity to the rewarding effects of cocaine and MDMA, especially in HNS animals, and modify the spontaneous behaviour of adult animals.
  
  
  METHODS
  Adolescent (PND 33) and adult (PND 60) mice were identified as HNS or LNS according to their performance in the hole-board test. Subsequently, they received pre-treatment with cocaine (three injections per day of an increasing dose for 10 days) or saline. Three weeks later, the mice performed the hole-board, elevated plus maze, spontaneous locomotor activity and cocaine- (1 mg/kg) or MDMA- (1.25 mg/kg) induced conditioning place preference (CPP) tests. In another set of mice, the effects of pre-treatment of cocaine during adulthood on MDMA- or cocaine-induced CPP were also evaluated 3 weeks later.
  
  
  RESULTS
  Only HNS mice treated with cocaine during adolescence acquired MDMA- or cocaine-induced CPP in adulthood. Moreover, pre-exposure to cocaine during adolescence caused subsequent behavioural alterations, including reduced exploratory behaviour and increased locomotor reactivity.
  
  
  CONCLUSIONS
  Cocaine binge administration during adolescence induces a higher sensitivity to the rewarding effects of MDMA and cocaine in HNS mice in adulthood. This may explain the greater vulnerability often seen among individuals exposed early in life to drugs of abuse.
authors.affiliation: Unidad de investigación Psicobiología de las Drogodependencias, Departamento de Psicobiología, Facultad de Psicología, Universitat de València, Avda. Blasco Ibañez, 21, 46010, Valencia, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Mateos-García
authors.forename: C
authors.initials: C
authors.lastname: Roger-Sánchez
authors.forename: M
authors.initials: M
authors.lastname: Rodriguez-Arias
authors.forename: J
authors.initials: J
authors.lastname: Miñarro
authors.forename: M A
authors.initials: MA
authors.lastname: Aguilar
authors.forename: C
authors.initials: C
authors.lastname: Manzanedo
authors.forename: M C
authors.initials: MC
authors.lastname: Arenas
mesh_terms: D000367:Age Factors; D000818:Animals; D003042:Cocaine / Q000008:administration & dosage*; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D005106:Exploratory Behavior / Q000187:drug effects* / Q000502:physiology; D008297:Male; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D051379:Mice; D018817:N-Methyl-3,4-methylenedioxyamphetamine / Q000008:administration & dosage*; D012201:Reward
chemical_list: D003042:Cocaine; D018817:N-Methyl-3,4-methylenedioxyamphetamine