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Aberrant mesolimbic dopamine-opiate interaction in obesity
Lauri Tuominen1, Jetro Tuulari2, Henry Karlsson2
1Turku PET Centre, University of Turku, Kiinamyllynkatu 4-8, 20520 Turku, Finland; Department of Psychiatry, University of Turku, Kunnallissairaalantie 20, 20700 Turku, Finland.
Neuroimage
|August 12, 2015
Summary
In healthy individuals, dopamine and opioid receptors are linked in the brain's reward system. Obesity disrupts this crucial connection, potentially explaining altered reward processing.
Area of Science:
- Neuroscience
- Neuroimaging
- Metabolic Disorders
Background:
- Dopamine and opioid systems regulate reward and pleasure.
- μ-Opioid receptors (MOR) influence the mesolimbic dopamine system in reward-related brain areas.
- Obesity is associated with altered reward processing.
Purpose of the Study:
- To investigate the in vivo correlation between dopamine D2 receptor (DRD2) and MOR availability.
- To determine if this correlation is altered in morbid obesity.
Main Methods:
- Positron emission tomography (PET) scans using [(11)C]carfentanil (MOR) and [(11)C]raclopride (DRD2).
- Scans performed on 20 lean and 25 morbidly obese females.
- Analysis of receptor availability in key reward circuitry regions.
Main Results:
- In lean subjects, significant positive correlations were found between MOR and DRD2 availability in the ventral striatum and dorsal caudate nucleus.
- DRD2 availability in the ventral striatum correlated with MOR availability in the ventral tegmental area.
- In morbidly obese subjects, this interaction was weaker in the ventral striatum and abolished between the ventral striatum and ventral tegmental area.
Conclusions:
- A direct link exists between DRD2 and MOR availability in the human brain.
- This interaction is selectively disrupted in the mesolimbic dopamine system in morbid obesity.
- Disrupted dopamine-opioid cross-talk may underlie altered reward processing in obesity.
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