title: Both α1- and β1-adrenoceptors in the bed nucleus of the stria terminalis are involved in the expression of conditioned contextual fear.
abstract: OBJECTIVE
  The bed nucleus of the stria terminalis (BNST) is a limbic structure that is involved in the expression of conditioned contextual fear. Among the numerous neural inputs to the BNST, noradrenergic synaptic terminals are prominent and some evidence suggests an activation of this noradrenergic neurotransmission in the BNST during aversive situations. Here, we have investigated the involvement of the BNST noradrenergic system in the modulation of behavioural and autonomic responses induced by conditioned contextual fear in rats.
  
  
  METHODS
  Male Wistar rats with cannulae bilaterally implanted into the BNST were submitted to a 10 min conditioning session (6 footshocks, 1.5 ma/ 3 s). Twenty-four hours later freezing and autonomic responses (mean arterial pressure, heart rate and cutaneous temperature) to the conditioning box were measured for 10 min. The adrenoceptor antagonists were administered 10 min before the re-exposure to the aversive context.
  
  
  RESULTS
  L-propranolol, a non-selective β-adrenoceptor antagonist, and phentolamine, a non-selective α-adrenoceptor antagonist, reduced both freezing and autonomic responses induced by aversive context. Similar results were observed with CGP20712, a selective β(1) -adrenoceptor antagonist, and WB4101, a selective α(1) -antagonist, but not with ICI118,551, a selective β(2) -adrenoceptor antagonist or RX821002, a selective α(2) -antagonist.
  
  
  CONCLUSIONS
  These findings support the idea that noradrenergic neurotransmission in the BNST via α(1) - and β(1) -adrenoceptors is involved in the expression of conditioned contextual fear.
authors.affiliation: Department of Pharmacology, School of Medicine, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
authors.forename: Sara C
authors.initials: SC
authors.lastname: Hott
authors.forename: Felipe V
authors.initials: FV
authors.lastname: Gomes
authors.forename: Denise R S
authors.initials: DR
authors.lastname: Fabri
authors.forename: Daniel G
authors.initials: DG
authors.lastname: Reis
authors.forename: Carlos C
authors.initials: CC
authors.lastname: Crestani
authors.forename: Fernando M A
authors.initials: FM
authors.lastname: Côrrea
authors.forename: Leonardo B M
authors.initials: LB
authors.lastname: Resstel
mesh_terms: D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D003213:Conditioning, Psychological / Q000502:physiology*; D004146:Dioxanes / Q000494:pharmacology; D004597:Electroshock; D005239:Fear / Q000502:physiology*; D019329:Idazoxan / Q000031:analogs & derivatives / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D010646:Phentolamine / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000502:physiology*; D018342:Receptors, Adrenergic, beta-1 / Q000502:physiology*; D012686:Septal Nuclei / Q000187:drug effects / Q000502:physiology*
chemical_list: D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D004146:Dioxanes; D007093:Imidazoles; D011412:Propanolamines; D018340:Receptors, Adrenergic, alpha-1; D018342:Receptors, Adrenergic, beta-1; C026777:ICI 118551; D011433:Propranolol; C049763:CGP 20712A; C058525:2-methoxyidazoxan; C010654:(2-(2',6'-dimethoxy)phenoxyethylamino)methylbenzo-1,4-dioxane; D019329:Idazoxan; D010646:Phentolamine