Effects of Nociceptin/Orphanin FQ in the Acquisition of Contextual and Tone Fear Conditioning in Rats

Nociceptin, or orphanin FQ (N/OFQ), the endogenous ligand of NOP receptors, is known to regulate learning and memory processes. To verify the role of N/OFQ in the acquisition of contextual (CFC) and tone fear conditioning (TFC), Wistar male rats received intracerebroventricular injections of N/OFQ (...

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Bibliographic Details
Published in:Behavioral neuroscience 2008-02, Vol.122 (1), p.98-106
Main Authors: Fornari, Raquel V, Soares, Juliana C. K, Ferreira, Tatiana L, Moreira, Karin M, Oliveira, Maria G. M
Format: Article
Language:English
Subjects:
Acoustic Stimulation
Analysis of Variance
Animal
Animal Learning
Animals
Aversive Stimulation
Behavior, Animal - drug effects
Behavior, Animal - physiology
Behavioral psychophysiology
Biological and medical sciences
Conditioned Emotional Responses
Conditioned Fear
Conditioning, Psychological - drug effects
Dose-Response Relationship, Drug
Electroshock - adverse effects
Fear
Fear & phobias
Freezing Reaction, Cataleptic - drug effects
Fundamental and applied biological sciences. Psychology
Hippocampus
Injections, Intraventricular - methods
Male
Memory
Neurons
Neuropsychology
Neurotransmitters
Nociceptin
Opioid Peptides - pharmacology
Psychology. Psychoanalysis. Psychiatry
Psychology. Psychophysiology
Rats
Rats, Wistar
Rodents
Time Factors
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Summary:Nociceptin, or orphanin FQ (N/OFQ), the endogenous ligand of NOP receptors, is known to regulate learning and memory processes. To verify the role of N/OFQ in the acquisition of contextual (CFC) and tone fear conditioning (TFC), Wistar male rats received intracerebroventricular injections of N/OFQ (0.1-5.0 nmol) before training, and were tested 24 and 48 hr later to access the freezing response to context and tone, respectively. The intermediate doses (1.0 and 2.5 nmol) impaired the CFC test, sparing TFC. The highest dose (5.0 nmol) reduced freezing during both tests, a result that may be due to nonspecific effects. The posttraining injection of N/OFQ (1 or 5 nmol) did not interfere with CFC and TFC, suggesting a specific effect of the peptide in acquisition processes. Moreover, the impairment observed with N/OFQ (1 nmol) in CFC cannot be attributed to a state-dependent learning because it was not reversed by its pretest administration. The data support the negative role of N/OFQ in the acquisition of aversively motivated tasks, which encompass a spatial component and depend on the hippocampus.
ISSN:0735-7044
1939-0084
DOI:10.1037/0735-7044.122.1.98