Reward Processing by the Opioid System in the Brain

Institut de Génétique et de Biologie Moléculaire et Cellulaire, Département Neurobiologie et Génétique, Illkirch, France.
Physiological Reviews (Impact Factor: 27.32). 10/2009; 89(4):1379-412. DOI: 10.1152/physrev.00005.2009
Source: PubMed


The opioid system consists of three receptors, mu, delta, and kappa, which are activated by endogenous opioid peptides processed from three protein precursors, proopiomelanocortin, proenkephalin, and prodynorphin. Opioid receptors are recruited in response to natural rewarding stimuli and drugs of abuse, and both endogenous opioids and their receptors are modified as addiction develops. Mechanisms whereby aberrant activation and modifications of the opioid system contribute to drug craving and relapse remain to be clarified. This review summarizes our present knowledge on brain sites where the endogenous opioid system controls hedonic responses and is modified in response to drugs of abuse in the rodent brain. We review 1) the latest data on the anatomy of the opioid system, 2) the consequences of local intracerebral pharmacological manipulation of the opioid system on reinforced behaviors, 3) the consequences of gene knockout on reinforced behaviors and drug dependence, and 4) the consequences of chronic exposure to drugs of abuse on expression levels of opioid system genes. Future studies will establish key molecular actors of the system and neural sites where opioid peptides and receptors contribute to the onset of addictive disorders. Combined with data from human and nonhuman primate (not reviewed here), research in this extremely active field has implications both for our understanding of the biology of addiction and for therapeutic interventions to treat the disorder.

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    • "In these studies manipulating the opioid system, the expected outcome (i.e., the predicted pain signal) did not match the actual outcome (i.e., the actually perceived nociceptive stimulus) – which describes exactly the discrepancy between expected and received outcomes as reflected by prediction error signals. Although previous research assumed that endogenous opioids are primarily involved in nociception and analgesia, but also in hedonic control and reward processing (Le Merrer, et al., 2009), the mentioned Contents lists available at ScienceDirect journal homepage: Neuropsychologia 0028-3932/& 2015 The Authors. "
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    ABSTRACT: Recent research suggests that not only the dopamine neurotransmitter system but also the endogenous opioid system is involved in performance monitoring and the generation of prediction error signals. Therefore, the current study investigated the potential link between the functional opioid peptide prodynorphin (PDYN) 68bp VNTR genetic polymorphism and neuronal correlates of performance monitoring. To this end, forty-seven healthy participants genotyped for this polymorphism, related to high-, intermediate-, and low-expression levels of PDYN, performed a choice-reaction task while their electroencephalogram (EEG) was recorded. On the ehavioural level, no differences between the three PDYN groups could be observed. EEG data, however, showed significant differences. High PDYN expression individuals showed heightened neural error processing indicated by higher ERN amplitudes, compared to intermediate and low expression individuals. Later stages of error processing, indexed by late Pe amplitudes, and stimulus-driven conflict processing, indexed by N2 amplitudes, were not affected by PDYN genotype. The current results corroborate the notion of an indirect effect of endogenous opioids on performance monitoring, probably mediated by the mesencephalic dopamine system. Overall, enhanced ERN amplitudes suggest a hyper-active performance monitoring system in high PDYN expression individuals, and this might also be an indicator of a higher risk for internalizing disorders. Copyright © 2015. Published by Elsevier Ltd.
    Neuropsychologia 09/2015; 77. DOI:10.1016/j.neuropsychologia.2015.08.028 · 3.30 Impact Factor
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    • "Feeding behavior is modulated in several parts of the brain, such as striatum, hypothalamus, amygdala, orbitofrontal cortex (OFC), nucleus ventral tegmental area (VTA), nucleus accumbens (NAcc), tractus solitaries (NTS) and arcuate nucleus (ARC) (Parker et al. 2014). Several neurotransmitters, including DA, cannabinoids, opioids, GABA and serotonin are implicated in the rewarding effect of food (Chen et al. 2006; Le Merrer et al. 2009). DA is a key anorexigenic neurotransmitter modulating reward which acts mainly through its projections from the VTA into the NAcc and ARC (Volkow et al. 2011). "
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    International Journal of Peptide Research and Therapeutics 08/2015; 21(4). DOI:10.1007/s10989-015-9486-4 · 0.91 Impact Factor
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    • "and parahippocampal cortex (a region with a high-density of µ-opioid receptors that is involved in scene processing) in the ventral visual pathway (Biederman & Vessel, 2006; Yue, Vessel & Biederman., 2007). Opioid reward systems such as these have been linked to natural reinforcement, and regulation of pain, stress, and emotion (Merrer et al., 2009). When reviewing the restorative effects of nature, there is a striking similarity between responses to nature scenes and activation of opioid reward systems: similar to other stimuli that can activate opioid reward systems (food and sex for example), viewing nature scenes has been shown to reduce perception of pain (Lechtzin et al., 2010), improve affect, and reduce physiological and perceived stress (Valtchanov & Ellard, 2010). "
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    ABSTRACT: Research has shown that humans have a preference for images of nature over images of built environments, and that eye-movement behaviour and attention are significantly different across these categories. To build on these findings, we investigated the influence of low-level visual properties on scene preference, cognitive load, and eye-movements. In the present study, participants viewed a mixture of unaltered and altered photographs of nature and urban scenes to determine if low-level visual properties influenced responses to scenes. Altered versions included photographs with only low or mid-to-high visual spatial frequency information, and photographs where the phase or amplitude of visual spatial frequencies had been scrambled. We replicated past findings, demonstrating preference and longer fixation-time for nature scenes versus urban cities. We then demonstrated that the visual spatial frequencies and power spectra contained in images significantly influenced preference, cognitive load, and eye-movements, and can partially explain the restoration response to natural environments.
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