title: Metoprolol, but not atenolol, reduces stress induced neuropeptide Y release in pigs.
abstract: OBJECTIVE
  To explore if β-adrenergic receptors in the brain are involved in acute and delayed cardiovascular responses to a brief emotional stress, by comparing the effects of the β1-blockers metoprolol (lipophilic) and atenolol (hydrophilic).
  
  
  METHODS
  Male dominant pigs, singleliving, freely moving, with telemetric recordings of intra-arterial pressure and ECG and assay of plasma levels of the adrenergic cotransmitter neuropeptide Y (NPY), were confronted with four alien pigs for three minutes at weekly intervals. Weeks 1 and 4 were controls, in weeks 2 and 3 randomized crossover treatment with metoprolol or atenolol were given.
  
  
  RESULTS
  The confrontation caused instant and transient tachycardia and more prolonged effects in terms of increased plasma NPY levels, increased arterial pressure and reduced cardiac vagal activation. The two β-blockers inhibited the tachycardia equally, but only metoprolol reduced the prolonged effects.
  
  
  CONCLUSIONS
  Emotionally induced sympathetic activation involves peripheral release of NPY causing a prolonged increase of arterial pressure and a reduction of cardiac vagal activity. These effects are prevented by central nervous β-adrenoceptor blockade.
authors.affiliation: AstraZeneca R&D, Mölndal, Sweden. bengtablad@hotmail.com
authors.forename: Bengt
authors.initials: B
authors.lastname: Åblad
authors.forename: Thorvald
authors.initials: T
authors.lastname: Bjurö
authors.forename: Jan-Arne
authors.initials: JA
authors.lastname: Björkman
authors.forename: Owe
authors.initials: O
authors.lastname: Brax
authors.forename: Lars
authors.initials: L
authors.lastname: Ewaldsson
authors.forename: Eva
authors.initials: E
authors.lastname: Forshult
authors.forename: Lena
authors.initials: L
authors.lastname: Lidfors
authors.forename: Jan M
authors.initials: JM
authors.lastname: Lundberg
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001262:Atenolol / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D001921:Brain / Q000378:metabolism; D006321:Heart / Q000294:innervation; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D008790:Metoprolol / Q000494:pharmacology*; D009478:Neuropeptide Y / Q000097:blood*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism; D013315:Stress, Psychological / Q000503:physiopathology*; D013552:Swine; D014630:Vagus Nerve / Q000502:physiology
chemical_list: D000319:Adrenergic beta-Antagonists; D009478:Neuropeptide Y; D011943:Receptors, Adrenergic, beta; D001262:Atenolol; D008790:Metoprolol