Format

Send to

Choose Destination
J Neurosci. 2017 Aug 23;37(34):8284-8291. doi: 10.1523/JNEUROSCI.0976-17.2017. Epub 2017 Jul 26.

Feeding Releases Endogenous Opioids in Humans.

Author information

1
Turku PET Centre.
2
Department of Psychiatry, Institute of Clinical Medicine.
3
Turku Brain and Mind Center, and.
4
Department of Psychiatry, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02215, and.
5
Departments of Radiology and.
6
Endocrinology, Turku University Hospital, 20521 Turku, Finland.
7
Turku PET Centre, latanu@utu.fi.
8
Department of Psychology, University of Turku, 20520 Turku, Finland.

Abstract

The endogenous opioid system supports a multitude of functions related to appetitive behavior in humans and animals, and it has been proposed to govern hedonic aspects of feeding thus contributing to the development of obesity. Here we used positron emission tomography to investigate whether feeding results in hedonia-dependent endogenous opioid release in humans. Ten healthy males were recruited for the study. They were scanned with the μ-opioid-specific ligand [11C]carfentanil three times, as follows: after a palatable meal, a nonpalatable meal, and after an overnight fast. Subjective mood, satiety, and circulating hormone levels were measured. Feeding induced significant endogenous opioid release throughout the brain. This response was more pronounced following a nonpalatable meal versus a palatable meal, and independent of the subjective hedonic responses to feeding. We conclude that feeding consistently triggers cerebral opioid release even in the absence of subjective pleasure associated with feeding, suggesting that metabolic and homeostatic rather than exclusively hedonic responses play a role in the feeding-triggered cerebral opioid release.SIGNIFICANCE STATEMENT The endogenous opioid system supports both hedonic and homeostatic functions. It has been proposed that overeating and concomitant opioid release could downregulate opioid receptors and promote the development of obesity. However, it remains unresolved whether feeding leads to endogenous opioid release in humans. We used in vivo positron emission tomography to test whether feeding triggers cerebral opioid release and whether this response is associated with pleasurable sensations. We scanned volunteers using the μ-opioid receptor-specific radioligand [11C]carfentanil three times, as follows: after an overnight fast, after consuming a palatable meal, and after consuming a nonpalatable meal. Feeding led to significant endogenous opioid release, and this occurred also in the absence of feeding-triggered hedonia. Feeding-triggered opioid release thus also reflects metabolic and homeostatic responses rather than hedonic responses exclusively.

KEYWORDS:

carfentanil; emotion; feeding; neuroreceptors; opioids; positron emission tomography

PMID:
28747384
DOI:
10.1523/JNEUROSCI.0976-17.2017
[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for HighWire
Loading ...
Support Center