title: Dopamine D2-like receptors modulate unconditioned fear: role of the inferior colliculus.
abstract: BACKGROUND
  A reduction of dopamine release or D2 receptor blockade in the terminal fields of the mesolimbic system clearly reduces conditioned fear. Injections of haloperidol, a preferential D2 receptor antagonist, into the inferior colliculus (IC) enhance the processing of unconditioned aversive information. However, a clear characterization of the interplay of D2 receptors in the mediation of unconditioned and conditioned fear is still lacking.
  
  
  METHODS
  The present study investigated the effects of intra-IC injections of the D2 receptor-selective antagonist sulpiride on behavior in the elevated plus maze (EPM), auditory-evoked potentials (AEPs) to loud sounds recorded from the IC, fear-potentiated startle (FPS), and conditioned freezing.
  
  
  RESULTS
  Intra-IC injections of sulpiride caused clear proaversive effects in the EPM and enhanced AEPs induced by loud auditory stimuli. Intra-IC sulpiride administration did not affect FPS or conditioned freezing.
  
  
  CONCLUSIONS
  Dopamine D2-like receptors of the inferior colliculus play a role in the modulation of unconditioned aversive information but not in the fear-potentiated startle response.
authors.affiliation: Laboratório de Neuropsicofarmacologia, FFCLRP, Universidade de São Paulo (USP), Ribeirão Preto, São Paulo, Brazil; Instituto de Neurociências e Comportamento, INeC, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Amanda Ribeiro
authors.initials: AR
authors.lastname: de Oliveira
authors.affiliation: Laboratório de Neuropsicofarmacologia, FFCLRP, Universidade de São Paulo (USP), Ribeirão Preto, São Paulo, Brazil; Instituto de Neurociências e Comportamento, INeC, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Ana Caroline
authors.initials: AC
authors.lastname: Colombo
authors.affiliation: Laboratório de Neuropsicofarmacologia, FFCLRP, Universidade de São Paulo (USP), Ribeirão Preto, São Paulo, Brazil; Instituto de Neurociências e Comportamento, INeC, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Sangu
authors.initials: S
authors.lastname: Muthuraju
authors.affiliation: Laboratório de Neuropsicofarmacologia, FFCLRP, Universidade de São Paulo (USP), Ribeirão Preto, São Paulo, Brazil; Instituto de Neurociências e Comportamento, INeC, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Rafael Carvalho
authors.initials: RC
authors.lastname: Almada
authors.affiliation: Laboratório de Neuropsicofarmacologia, FFCLRP, Universidade de São Paulo (USP), Ribeirão Preto, São Paulo, Brazil; Instituto de Neurociências e Comportamento, INeC, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Marcus Lira
authors.initials: ML
authors.lastname: Brandão
mesh_terms: D000818:Animals; D003213:Conditioning, Psychological; D065127:Dopamine D2 Receptor Antagonists / Q000494:pharmacology; D005072:Evoked Potentials, Auditory; D005239:Fear / Q000502:physiology*; D006220:Haloperidol / Q000494:pharmacology; D007245:Inferior Colliculi / Q000378:metabolism*; D008297:Male; D017208:Rats, Wistar; D017448:Receptors, Dopamine D2 / Q000502:physiology*; D013216:Reflex, Startle
chemical_list: D065127:Dopamine D2 Receptor Antagonists; D017448:Receptors, Dopamine D2; D006220:Haloperidol