A role for the ventral hippocampal endocannabinoid system in fear-conditioned analgesia and fear responding in the presence of nociceptive tone in rats
| Autor: | Gemma K. Ford, David P. Finn, Kenneth Dolan, Siobhan Kieran, Brendan Harhen |
|---|---|
| Přispěvatelé: | SFI |
| Rok vydání: | 2011 |
| Předmět: |
Male
Cannabinoid receptor medicine.medical_treatment Ventral hippocampus Pain Pharmacology N-Acylethanolamines Hippocampus chemistry.chemical_compound Rimonabant Receptor Cannabinoid CB1 Fatty acid amide hydrolase Cannabinoid type 1 (CB1) receptor Fatty acid amide hydrolase (FAAH) Cannabinoid Receptor Modulators Conditioning Psychological medicine Animals Palmitoylethanolamide Nociceptors Rats Inbred Strains Anandamide Fear URB597 Endocannabinoid system Rats Anesthesiology and Pain Medicine Neurology chemistry nervous system lipids (amino acids peptides and proteins) Neurology (clinical) Cannabinoid Psychology medicine.drug Endocannabinoids |
| Zdroj: | PainReferences. 152(11) |
| ISSN: | 1872-6623 |
| Popis: | The endogenous cannabinoid (endocannabinoid) system plays an important role in fear-conditioned analgesia (FCA) and expression and extinction of conditioned fear. The hippocampus has an established role in both pain and conditioned fear and is a substrate for endocannabinoid activity. This study aimed to investigate the role of the endocannabinoid system in the ventral hippocampus (vHip) in FCA and in fear responding in the presence of nociceptive tone. Fear-conditioned rats displayed significantly increased freezing and 22-kHz ultrasonic vocalisation and a reduction in formalin-evoked nociceptive behaviour (ie, FCA) upon re-exposure to a context previously paired with footshock. Tissue levels of the endocannabinoids, anandamide, and 2-arachidonoylglycerol, as well as the fatty acid amide, palmitoylethanolamide, were significantly higher in the vHip of fear-conditioned rats compared with non-fear-conditioned controls. URB597 (inhibitor of fatty acid amide hydrolase [FAAH]), administered bilaterally into the vHip, significantly enhanced FCA during the entire trial and increased fear responding in formalin-treated rats early in the trial. The URB597-induced enhancement of FCA was blocked by intra-vHip administration of the cannabinoid(1) (CB(1)) receptor antagonist/inverse agonist rimonabant. Intra-vHip rimonabant alone had no effect on the expression of FCA, and URB597 did not significantly alter formalin-evoked nociceptive behaviour in non-fear-conditioned rats. These data suggest an important role for the endocannabinoid system in the vHip in FCA, whereby levels of 2-arachidonoylglycerol and the FAAH substrates palmitoylethanolamide and anandamide are increased in rats expressing FCA, and pharmacological inhibition of FAAH in the vHip enhances this form of endogenous analgesia via a CB(1) receptor-dependent mechanism. peer-reviewed |
| Databáze: | OpenAIRE |
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