Sweet taste pleasantness is modulated by morphine and naltrexone

Eikemo, Marie; Løseth, Guro Engvig; Johnstone, Tom; Gjerstad, Johannes; Willoch, Frode; Leknes, Siri

doi:10.1007/s00213-016-4403-x

Cited by 64 publications

(95 citation statements)

References 69 publications

(91 reference statements)

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“…Human data largely corroborates the animal literature, and show decreased appetite and food intake following MOR antagonism (e.g. Bertino, Beauchamp, & Engelman, 1991;Eikemo et al, 2016;Yeomans & Gray, 2002;Ziauddeen et al, 2013).…”

Section: Direct µ-Opioid Modulation Of Reward Motivation?supporting

confidence: 67%

“…The few that exist (Drewnowski, Krahn, Demitrack, Nairn, & Gosnell, 1992;Eikemo et al, 2016;Morley, Parker, & Levine, 1985) do not provide consistent results regarding agonistic effects. For instance, Morley et al (1985) found increased food consumption, while Drewnowski et al (1992) and Eikemo et al (2016) did not. Notably, the two former studies had quite limited sample sizes and used the mixed MOR agonist and antagonist butorphanol, which complicates inferences from these results.…”

Section: Direct µ-Opioid Modulation Of Reward Motivation?mentioning

confidence: 96%

“…Behavioral studies from our own lab already provide support for this hypothesis (Chelnokova et al, 2014;Eikemo et al, 2017;Eikemo et al, 2016), but brain mechanisms underlying opioid modulation of non-pathologic wanting in healthy humans remains poorly understood.…”

Section: Direct µ-Opioid Modulation Of Reward Motivation?mentioning

confidence: 98%

“…In conclusion, based on multiple lines of evidence there is good reason to suspect that the MOR system is intricately involved human wanting. We hypothesize that since opioid mechanisms in general appears to be highly conserved across species (Berridge, 2003;Chelnokova et al, 2014;Eikemo et al, 2016;Fields & Margolis, 2015;Mahler & Berridge, 2012) opioids should modulate wanting in healthy humans in a way comparable to rodents.…”

Section: Direct µ-Opioid Modulation Of Reward Motivation?mentioning

confidence: 99%

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μ-Opioid Modulation of Reported Wanting of Palatable Food Images: A pharmacological fMRI study in healthy humans

Isager¹

2017

Preprint

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Type: Master's thesisSupervisors: Siri Leknes, Marie Eikemo, Tom JohnstoneFinal grade: B (Norwegian grade system). See supplemental materials for grader evaluation document.The endogenous μ-opioid receptor (MOR) system in the brain is central to reward behaviors across species, and brain areas implicated in reward are dense with μ-opioid receptors. The MOR system has received the most interest through its involvement in pleasure mediation (‘liking’), but there is much evidence to suggest a role for the MOR system in motivated ‘wanting’ as well. Nevertheless, we still know very little about the mechanisms of MOR modulation in reward motivation in healthy humans. Further, it is unclear to what extent the animal research on MOR modulation of reward-processing in the brain can be extended to humans, as very few studies have explored this relationship directly in the human brain. We examined the effects of a low dose (10mg) of per oral morphine (a μ-opioid agonist) on reported food wanting, and of applying a cognitive regulation task to downregulate this wanting, in healthy human participants. We also measured neural activity as approximated by functional magnetic resonance imaging. The study was designed to minimize the risk of potential confound effects of the drug manipulation. In a within-subject, counterbalanced, placebo-controlled, double-blind design, 63 participants (31 male, mean age 27 ±5) were tested in a morphine and placebo session on two separate days. In line with our expectations, morphine did not significantly affect subjective mood or state, respiration- or heart rate, or motor coordination. Morphine also did not appear to alter global BOLD, measured by a simple visual control task. The food wanting task elicited significant activation in reward related regions compared to baseline, and cognitive regulation produced the expected decrease in food wanting, together with increased activity in ventral prefrontal regions. Activation in extrastriate occipital regions was observed across tasks. Preliminary analyses confirmed our hypothesis that MOR agonism would increase food wanting, but did not confirm our hypothesis of associated activity increase in the striatum and medial prefrontal areas. Instead, increased activity in regulation-related regions may be required for successful downregulation of wanting after morphine treatment. In summary, we have now validated the paradigm and task design of this study. Thus, a complete analysis of the drug effects of interest can be conducted and the results interpreted to draw meaningful conclusions regarding the effects of MOR stimulation with morphine on BOLD signals relating to ‘wanting’ for palatable food images.

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Section: Direct µ-Opioid Modulation Of Reward Motivation?supporting

confidence: 67%

Section: Direct µ-Opioid Modulation Of Reward Motivation?mentioning

confidence: 96%

Section: Direct µ-Opioid Modulation Of Reward Motivation?mentioning

confidence: 98%

Section: Direct µ-Opioid Modulation Of Reward Motivation?mentioning

confidence: 99%

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μ-Opioid Modulation of Reported Wanting of Palatable Food Images: A pharmacological fMRI study in healthy humans

Isager¹

2017

Preprint

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“…Indeed, injections of µ and δ opioid receptor agonists have been shown to increase food approach and feeding behavior, especially for palatable and high-energy foods [20], which shows that opioids primarily affect wanting through liking. Similar evidence in humans suggest that µ opioid receptor agonists increase the subjective pleasantness of the most palatable food option available [21], and both subjective feelings of wanting and liking of the most attractive opposite sex faces [22]. In contrast, the non-selective opioid receptor antagonist naloxone decreases subjective pleasure (liking) associated with viewing erotic pictures and reduces the activation of reward related brain regions such as the ventral striatum [23].…”

Section: Introductionmentioning

confidence: 77%

Dopaminergic and opioidergic regulation of implicit hedonic facial reactions during anticipation and consumption of social and nonsocial rewards

Korb

Goetzendorfer

Sezen

et al. 2019

Preprint

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Rewards can be parsed into a motivational component ('wanting'), which relies mainly on the brain's dopaminergic system, and a hedonic component ('liking'), which relies on the opioidergic system. The observation of animal facial and behavioral reactions to rewards (e.g. pleasant tastes) has played a crucial role for our understanding of the neurochemical bases of reward processing. In adult humans, however, implicit facial reactions to reward anticipation and consumption are rarely reported, and the role that the dopaminergic and opioidergic systems play in human facial reactions to rewards remains largely unknown. It is also unclear, if human facial reactions to different types of rewards have the same neurochemical basis. To answer these questions, we conducted a study using a randomized, double-blind, betweensubject design in which 131 volunteers (88 females) received orally either the D2/D3 receptor antagonist amisulpride (400 mg), the non-selective opioid receptor antagonist naltrexone (50 mg), or placebo. Explicit (ratings and physical effort) and implicit (facial EMG) reactions to matched primary social and nonsocial rewards were assessed on a trial-by-trail basis. Sweet milk with different concentrations of chocolate flavor served as nonsocial food reward. Gentle caresses to the forearm, delivered by the same-sex experimenter at different speeds, served as social reward. Results suggested 1) reduced wanting of rewards after administration of both dopamine and opioid receptor antagonists, compared to placebo, as indicated by less physical effort produced to obtain the announced reward and increased negative facial reactions during reward anticipation; 2) reduced liking of rewards only after administration of the opioid receptors antagonist, compared to placebo, as indicated by reduced positive and increased negative facial reactions during and following reward consumption. Most drug effects were either stronger or restricted to food trials, suggesting that wanting and liking of both social and nonsocial rewards may only partially share the same neurochemical brain substrates. The results are in line with the distinction of wanting and liking by current theories of reward, and underline the importance of assessing implicit facial reactions when conducting research on reward processing in adult human participants.

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Effects of dopamine and opioid receptor antagonism on the neural processing of social and nonsocial rewards

Massaccesi,

Korb,

Götzendorfer

et al. 2024

Human Brain Mapping

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Rewards are a broad category of stimuli inducing approach behavior to aid survival. Extensive evidence from animal research has shown that wanting (the motivation to pursue a reward) and liking (the pleasure associated with its consumption) are mostly regulated by dopaminergic and opioidergic activity in dedicated brain areas. However, less is known about the neuroanatomy of dopaminergic and opioidergic regulation of reward processing in humans, especially when considering different types of rewards (i.e., social and nonsocial). To fill this gap of knowledge, we combined dopaminergic and opioidergic antagonism (via amisulpride and naltrexone administration) with functional neuroimaging to investigate the neurochemical and neuroanatomical bases of wanting and liking of matched nonsocial (food) and social (interpersonal touch) rewards, using a randomized, between‐subject, placebo‐controlled, double‐blind design. While no drug effect was observed at the behavioral level, brain activity was modulated by the administered compounds. In particular, opioid antagonism, compared to placebo, reduced activity in the medial orbitofrontal cortex during consumption of the most valued social and nonsocial rewards. Dopamine antagonism, however, had no clear effects on brain activity in response to reward anticipation. These findings provide insights into the neurobiology of human reward processing and suggest a similar opioidergic regulation of the neural responses to social and nonsocial reward consumption.

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Sweet taste pleasantness is modulated by morphine and naltrexone

Cited by 64 publications

References 69 publications

μ-Opioid Modulation of Reported Wanting of Palatable Food Images: A pharmacological fMRI study in healthy humans

μ-Opioid Modulation of Reported Wanting of Palatable Food Images: A pharmacological fMRI study in healthy humans

Dopaminergic and opioidergic regulation of implicit hedonic facial reactions during anticipation and consumption of social and nonsocial rewards

Effects of dopamine and opioid receptor antagonism on the neural processing of social and nonsocial rewards

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