The Opioid System and Food Intake: Homeostatic and Hedonic Mechanisms

Nogueiras, Rubén; Romero‐Picó, Amparo; Vázquez, María J.; Novelle, Marta G.; López, Miguel; Diéguez, Carlos

doi:10.1159/000338163

Cited by 123 publications

(94 citation statements)

References 121 publications

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“…The magnitude of these effects was large enough such that, under naloxone, there was no clear preference for either food type. Our experiments converge with lines of preclinical and clinical data suggesting the EOS mediates aspects of hedonic feeding [10,16,19,20,23,29,30].…”

Section: Discussionsupporting

confidence: 84%

“…It has also been suggested that opioids mediate eating that occurs outside of caloric needs, or hedonic feeding [19,29,30]. Opioid receptor agonists tend to produce increases in food intake in animals while opioid receptor antagonists mostly show inhibitory effects [31][32][33], but these affects appear to be sensitive to the overall palatability of the reinforcer.…”

Section: Introductionmentioning

confidence: 99%

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Opioidergic and dopaminergic modulation of cost/benefit decision-making in Long Evans Rats

Morales

Currie

Hackenberg

et al. 2017

Physiology & Behavior

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Highlights• We assess opioid and dopamine control of food intake with two cost/benefit decision-making tasks • Naloxone reduces operant responses for palatable food without affecting free chow intake • Haloperidol shifts behavior away from lever pressing and increases free chow feeding • Naloxone reduces preference for palatable banana pellets when no effort is involved • Dopamine antagonism reduces intake of both foods without altering preference AbstractEating disorders are associated with impaired decision-making and dysfunctional reward-related neurochemistry. The present study examined the potential contributions of dopamine and opioid signaling to these processes using two different decision-making tasks. In one task, Long Evans Rats chose between working for a preferred food (high-carbohydrate banana-flavored sucrose pellets) by lever pressing on a progressive-ratio schedule of reinforcement vs. obtaining less preferred laboratory chow that was concurrently available. In a second (effort-free) task, rats chose between the same two reinforcers when they were both available freely. Rats were trained in these tasks before receiving haloperidol (0.00, 0.05, 0.10 mg/kg, intraperitoneally (i.p.)) or naloxone (0.0, 1.5, 3.0 mg/kg, i.p.). In the first task, haloperidol decreased breakpoint, lever presses, number of reinforcers earned, and increased chow intake, whereas naloxone decreased breakpoint and number of reinforcers earned but had no effect on chow consumption. In the effort-free task, haloperidol reduced intakes of both foods without affecting preference, whereas naloxone selectively reduced the consumption of banana-pellets. The present findings support converging evidence suggesting that DA signaling affects processes more closely related to appetitive motivation, leaving other components of motivation unchanged. By contrast, opioid signaling appears to mediate aspects of hedonic feeding by selectively altering intakes of highly palatable foods. For preferred foods, both appetitive and consummatory aspects of food intake were altered by opioid receptor antagonism. Our findings argue against a general suppression of appetite by either compound, as appetite manipulations have been shown to unselectively alter intakes of both types of food regardless of the task employed.

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Section: Discussionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Opioidergic and dopaminergic modulation of cost/benefit decision-making in Long Evans Rats

Morales

Currie

Hackenberg

et al. 2017

Physiology & Behavior

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“…Despite this plausible explanation, we propose that the weight loss is not due solely to withdrawal or alterations in food/fluid consumption. 79,80 Hook and colleagues have shown that a single intrathecal administration of morphine produces lasting weight loss in rats. 39,40 This weight loss cannot result from withdrawal, and acute administration of morphine does not significantly affect food intake.…”

Section: Fig 13mentioning

confidence: 99%

Morphine Self-Administration following Spinal Cord Injury

Woller

Malik²,

Aceves³

et al. 2014

Journal of Neurotrauma

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Neuropathic pain develops in up to two-thirds of people following spinal cord injury (SCI). Opioids are among the most effective treatments for this pain and are commonly prescribed. There is concern surrounding the use of these analgesics, however, because use is often associated with the development of addiction. Previous data suggests that this concern may not be relevant in the presence of neuropathic pain. Yet, despite the common prescription of opioids for the treatment of SCI-related pain, there has been only one previous study examining the addictive potential of morphine following spinal injury. To address this, the present study used a self-administration paradigm to examine the addictive potential of morphine in a rodent model of SCI.Animals were placed into self-administration chambers 24 h, 14 d, or 35 d following a moderate spinal contusion injury. They were placed into the chambers for seven 12-hour sessions with access to 1.5 mg morphine/lever depression (up to 30 mg/d). In the acute phase of SCI, contused animals self-administered significantly less morphine than their sham counterparts, as previously shown. However, contused animals showing signs of neuropathic pain did not self-administer less morphine than their sham counterparts when administration began 14 or 35 d after injury. Instead, these animals administered nearly the full amount of morphine available each session. This amount of morphine did not affect recovery of locomotor function but did cause significant weight loss. We suggest caution is warranted when prescribing opioids for the treatment of neuropathic pain resulting from SCI, as the addictive potential is not reduced in this model.

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“…This study was conducted on healthy subjects aged 18-44 years, because this age group is active and productive and has not yet undergone the changes in β-endorphin metabolism that occur in the elderly [9]. This study also limited the consumption of foods and medications that may affect β-endorphin levels [10,11]. Subjects with a BMI of 18.5-25 were part of the inclusion criteria to reduce the likelihood of metabolic differences that may affect β-endorphin levels [12,13].…”

Section: Discussionmentioning

confidence: 99%