title: Psychopharmacological characterisation of the successive negative contrast effect in rats.
abstract: BACKGROUND
  Successive negative contrast (SNC) describes a change in the behaviour of an animal following a downshift in the quantitative or qualitative value of an expected reward. This behavioural response has been hypothesised to be linked to affective state, with negative states associated with larger and/or prolonged shifts in behaviour.
  
  
  OBJECTIVE
  This study has investigated whether different psychopharmacological treatments have dissociable actions on the SNC effect in rats and related these findings to their actions on different neurotransmitter systems and affective state.
  
  
  METHODS
  Animals were trained to perform a nose-poke response to obtain a high-value food reward (four pellets). SNC was quantified during devalue sessions in which the reward was reduced to one pellet. Using a within-subject study design, the effects of acute treatment with anxiolytic, anxiogenic, antidepressant and dopaminergic drugs were investigated during both baseline (four pellets) or devalue sessions (one pellet).
  
  
  RESULTS
  The indirect dopamine agonist, amphetamine, attenuated the SNC effect whilst the D1/D2 antagonist, alpha-flupenthixol, potentiated it. The antidepressant citalopram, anxiolytic buspirone and anxiogenic FG7142 had no specific effects on SNC, although FG7142 induced general impairments at higher doses. The α2-adrenoceptor antagonist, yohimbine, increased premature responding but had no specific effect on SNC. Results for the anxiolytic diazepam were mixed with one group showing an attenuation of the SNC effect whilst the other showed no effect.
  
  
  CONCLUSIONS
  These data suggest that the SNC effect is mediated, at least in part, by dopamine signalling. The SNC effect may also be attenuated by benzodiazepine anxiolytics.
authors: School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol, BS8 1TD, UK.
authors: C E
authors: CE
authors: Phelps
authors: E N
authors: EN
authors: Mitchell
authors: D J
authors: DJ
authors: Nutt
authors: H M
authors: HM
authors: Marston
authors: E S J
authors: ES
authors: Robinson
mesh_terms: D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects*; D002065:Buspirone / Q000494:pharmacology; D002243:Carbolines / Q000494:pharmacology; D015283:Citalopram / Q000494:pharmacology; D003975:Diazepam; D015259:Dopamine Agents / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology*; D004644:Emotions / Q000187:drug effects; D005475:Flupenthixol / Q000494:pharmacology*; D018756:GABA Antagonists / Q000494:pharmacology; D008297:Male; D051381:Rats; D012201:Reward; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology
chemical_list: D000661:Amphetamine; D014151:Anti-Anxiety Agents; D002065:Buspirone; D002243:Carbolines; D015283:Citalopram; D003975:Diazepam; D015259:Dopamine Agents; D018492:Dopamine Antagonists; D005475:Flupenthixol; D018756:GABA Antagonists; D017366:Serotonin Receptor Agonists; D017367:Selective Serotonin Reuptake Inhibitors; C035874:FG 7142