title: Role of prefrontal 5-HT in the strain-dependent variation in sign-tracking behavior of C57BL/6 and DBA/2 mice.
abstract: BACKGROUND
  The expression of sign-tracking (ST) phenotype over goal-tracking (GT) phenotype has been associated to different aspects of impulsive behavior, and depletions of brain serotonin (5-HT) have been shown to selectively increase impulsive action as well as ST.
  
  
  OBJECTIVE
  The present study aimed at testing the relationship between reduced brain 5-HT availability and expression of ST phenotype in a genetic model of individual variation in brain 5-HT functionality. Inbred DBA/2J (DBA) mice are homozygous for the allelic variant of the TPH-2 gene causing lower brain 5-HT function in comparison with C57BL/6J (C57) inbred mice.
  
  
  METHODS
  Young adult (10 weeks) and adult (14 weeks) C57 and DBA mice were trained in a Pavlovian conditioned approach (PCA) paradigm. Lever-directed (ST) and magazine-directed (GT) responses were measured in 12 daily conditioning sessions. In a second experiment, effect of the medial prefrontal cortex (mPFC) 5-HT depletion by the neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) was assessed on acquisition of ST phenotype in adult C57 mice, according to their higher 5-HT functionality compared to DBA mice.
  
  
  RESULTS
  Young adult mice of both strains developed ST phenotype, but only adult DBA mice developed ST phenotype. 5-HT depletion in the mPFC of adult C57 mice completely changed their phenotype, as shown by their increased ST.
  
  
  CONCLUSIONS
  These findings indicate that ST phenotype can be the expression of a transitory late developmental stage and that genetic factors determine persistence of this phenotype in adulthood. These findings also support a role of 5-HT transmission in PFC in constraining development of ST phenotype.
authors.affiliation: Department of Psychology, University of Rome "Sapienza", Roma, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Campus
authors.affiliation: Department of Psychology, University of Rome "Sapienza", Roma, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Accoto
authors.affiliation: Department of Psychology, University of Rome "Sapienza", Roma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Maiolati
authors.affiliation: Fondazione Santa Lucia IRCSS, European Center for Brain Research, Rome, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Latagliata
authors.affiliation: Department of Psychology, University of Rome "Sapienza", Roma, Italy. cristina.orsini@uniroma1.it.|Center for Research in Neurobiology "Daniel Bovet", University of Rome "Sapienza", Roma, Italy. cristina.orsini@uniroma1.it.|Fondazione Santa Lucia IRCSS, European Center for Brain Research, Rome, Italy. cristina.orsini@uniroma1.it.
authors.forename: C
authors.initials: C
authors.lastname: Orsini
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D017397:Prefrontal Cortex / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*; D014365:Tryptophan Hydroxylase / Q000235:genetics / Q000378:metabolism
chemical_list: D012701:Serotonin; C487802:Tph2 protein, mouse; D014365:Tryptophan Hydroxylase
keywords: Autoshaping; Development; Goal tracking; Inbred strain; Individual differences; Pavlovian approach; Serotonin; Sign tracking