Opiate effects in the amygdala central nucleus on heart rate conditioning in rabbits

Michela Gallagher, Bruce S. Kapp, Carol L. McNall, Jeffrey P. Pascoe

Research output: Contribution to journalArticle


Opiate agents were administered into the central nucleus of the amygdala complex of rabbits prior to either classical conditioning or pseudoconditioning of heart rate responding. Compared to control groups, opiate administration into the central nucleus did not significantly alter baseline heart rate, heart rate responding during habituation trials to presentations of the conditioned stimulus alone, or heart rate responding during the pseudoconditioning procedure. However, opiate administration altered the acquisition of a conditioned bradycardia response during classical conditioning trials in which the offset of the conditioned stimulus was coincident with the presentation of an aversive unconditioned stimulus. The opiate agonist levorphanol (5.0 nmole) significantly impaired the acquisition of the conditioned bradycardia response. This effect was observed to be stereospecific and blocked by concurrent administration of the opiate antagonist naloxone (2.5 nmole). Naloxone (2.5 nmole) administration alone significantly increased the magnitude of the conditioned bradycardia response. These effects produced by opiate administration into the central nucleus were not observed following administration of the same agents into sites 1-2 mm dorsal to the central nucleus.

Original languageEnglish (US)
Pages (from-to)497-505
Number of pages9
JournalPharmacology Biochemistry and Behavior
Issue number4
Publication statusPublished - 1981
Externally publishedYes



  • Amygdala central nucleus
  • Heart rate conditioning
  • Opiate receptors
  • Rabbits

ASJC Scopus subject areas

  • Biochemistry
  • Behavioral Neuroscience
  • Pharmacology

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