title: The attribution of incentive salience to an appetitive conditioned cue is not affected by knockout of the serotonin transporter in rats.
abstract: Understanding the neurobiological basis underlying individual differences in conditioned stimulus (CS) sensitivity is pertinent, given that excessive conditioned responses to CSs is a key feature of anxiety-related disorders and drug addiction. We have previously shown that behaviour of serotonin transporter knockout (5-HTT(-/-)) rats-mimicking the common 5-HTT promoter polymorphism in humans-is strongly driven by Pavlovian CSs. To investigate whether the knockout rats attribute greater incentive salience to CSs, we tested the 5-HTT(-/-) rats and their wild-type counterparts in the sucrose-reinforced sign-versus goal-tracking task. We also assessed whether motivational properties of the unconditioned stimulus (sucrose pellet) are involved in the individual differences under investigation, by testing the animals in a sucrose-reinforced progressive ratio schedule of reinforcement. We found no genotype differences in sign-versus goal-tracking behavior, despite that progressive ratio responding was increased in 5-HTT(-/-) rats. In conclusion, the high CS sensitivity in 5-HTT(-/-) rats cannot be explained by enhanced incentive salience attribution to the CS as measured by the sign- versus goal-tracking paradigm. Rather, 5-HTT(-/-) rats may be more sensitive to the motivational properties of the unconditioned stimulus.
authors.affiliation: Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, Department of Cognitive Neuroscience, Radboud University Nijmegen Medical Centre, The Netherlands. Electronic address: j.homberg@cns.umcn.nl.
authors.forename: Lourens J P
authors.initials: LJ
authors.lastname: Nonkes
authors.affiliation: Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, Department of Cognitive Neuroscience, Radboud University Nijmegen Medical Centre, The Netherlands.
authors.forename: Ilse I G M
authors.initials: II
authors.lastname: van de Vondervoort
authors.affiliation: Donders Institute for Brain, Cognition, and Behaviour, Centre for Neuroscience, Department of Cognitive Neuroscience, Radboud University Nijmegen Medical Centre, The Netherlands.
authors.forename: Judith R
authors.initials: JR
authors.lastname: Homberg
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001070:Appetitive Behavior / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D003463:Cues; D009042:Motivation / Q000235:genetics*; D051381:Rats; D055647:Rats, Transgenic; D017208:Rats, Wistar; D050486:Serotonin Plasma Membrane Transport Proteins / Q000172:deficiency* / Q000235:genetics
chemical_list: D050486:Serotonin Plasma Membrane Transport Proteins
keywords: 5-HTT; BP; CR; CS; Conditioning; FR; Goal tracking; ITI; Knockout; PR; Progressive ratio; Serotonin transporter; Sign tracking; US; breaking point; conditioned response; conditioned stimulus; fixed ratio; intertrial interval; progressive ratio; serotonin transporter; unconditioned stimulus