title: Accumbal opioid receptors modulate cue competition in one-trial overshadowing.
abstract: The contribution of opioid receptors in the nucleus accumbens to contextual and auditory fear conditioning was examined. Impairment in contextual fear conditioning was found when training occurred under accumbal infusions of the opioid receptor agonist morphine in a dose-dependent and receptor specific fashion, only when shock onset coincided with auditory stimulus offset. Contextual fear conditioning was spared, however when the delivery of shock was not signalled by an auditory stimulus, the auditory stimulus was of low intensity (70dB), or an interval (10s or 30s) was interpolated between auditory stimulus offset and shock onset. These results provide evidence that opioid receptors in the nucleus accumbens regulate competition between contextual and discrete auditory stimuli for association formation.
authors.affiliation: School of Psychology, The University of New South Wales, Gate 9, High St, Sydney NSW 2031, Australia. iordanovam@gmail.com
authors.forename: Mihaela D
authors.initials: MD
authors.lastname: Iordanova
authors.forename: Tatiana
authors.initials: T
authors.lastname: Haralambous
authors.forename: Gavan P
authors.initials: GP
authors.lastname: McNally
authors.forename: R Frederick
authors.initials: RF
authors.lastname: Westbrook
mesh_terms: D000161:Acoustic Stimulation / Q000009:adverse effects; D000701:Analgesics, Opioid / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D003213:Conditioning, Psychological / Q000502:physiology*; D003463:Cues; D004305:Dose-Response Relationship, Drug; D004597:Electroshock / Q000009:adverse effects; D005239:Fear / Q000187:drug effects / Q000502:physiology*; D046352:Freezing Reaction, Cataleptic / Q000187:drug effects / Q000502:physiology; D007859:Learning Disabilities / Q000139:chemically induced; D008297:Male; D009020:Morphine / Q000494:pharmacology; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism*; D011571:Psychoacoustics; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects; D011957:Receptors, Opioid / Q000378:metabolism*
chemical_list: D000701:Analgesics, Opioid; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D009270:Naloxone; D009020:Morphine