A new animal model of placebo analgesia: involvement of the dopaminergic system in reward learning
Open Access
- 25 November 2015
- journal article
- Published by Springer Science and Business Media LLC in Scientific Reports
- Vol. 5 (1), 17140
- https://doi.org/10.1038/srep17140
Abstract
We suggest a new placebo analgesia animal model and investigated the role of the dopamine and opioid systems in placebo analgesia. Before and after the conditioning, we conducted a conditioned place preference (CPP) test to measure preferences for the cues (Rooms 1 and 2) and a hot plate test (HPT) to measure the pain responses to high level-pain after the cues. In addition, we quantified the expression of tyrosine hydroxylase (TH) in the ventral tegmental area (VTA) and c-Fos in the anterior cingulate cortex (ACC) as a response to reward learning and pain response. We found an enhanced preference for the low level-pain paired cue and enhanced TH expression in the VTA of the Placebo and Placebo + Naloxone groups. Haloperidol, a dopamine antagonist, blocked these effects in the Placebo + Haloperidol group. An increased pain threshold to high-heat pain and reduced c-Fos expression in the ACC were observed in the Placebo group only. Haloperidol blocked the place preference effect and naloxone and haloperidol blocked the placebo analgesia. Cue preference is mediated by reward learning via the dopamine system, whereas the expression of placebo analgesia is mediated by the dopamine and opioid systems.Keywords
This publication has 45 references indexed in Scilit:
- Placebo analgesia: Psychological and neurobiological mechanismsPain, 2013
- The Effect of Treatment Expectation on Drug Efficacy: Imaging the Analgesic Benefit of the Opioid RemifentanilScience Translational Medicine, 2011
- A selective role for dopamine in stimulus–reward learningNature, 2010
- Disruption of morphine‐conditioned place preference by a δ2‐opioid receptor antagonist: study of μ‐opioid and δ‐opioid receptor expression at the synapseEuropean Journal of Neuroscience, 2010
- A prefrontal non-opioid mechanism in placebo analgesiaPain, 2010
- Placebo conditioning and placebo analgesia modulate a common brain network during pain anticipation and perceptionPain, 2009
- Pavlovian conditioning of multiple opioid-like responses in miceDrug and Alcohol Dependence, 2009
- How prior experience shapes placebo analgesiaPain, 2006
- Placebo-Induced Changes in fMRI in the Anticipation and Experience of PainScience, 2004
- THE MECHANISM OF PLACEBO ANALGESIAThe Lancet, 1978