Circulating Triglycerides Gate Dopamine-Associated Behaviors through DRD2-Expressing Neurons.

Area of Science:

• Neuroscience
• Metabolic research
• Nutritional science

Background:

• Energy-dense foods disrupt dopamine (DA) signaling in the mesocorticolimbic (MCL) system, potentially causing reward dysfunction, compulsive eating, and weight gain.
• The precise mechanisms by which nutrients influence MCL circuitry remain unclear.

Purpose of the Study:

• To investigate how nutritional triglycerides (TGs) affect the MCL system and associated behaviors.
• To elucidate the role of TGs in modulating dopamine receptor subtype 2 (DRD2)-expressing neurons.

Main Methods:

• Investigated the metabolism of TGs within the MCL system.
• Examined the effects of TGs on DA-associated behaviors, focusing on the action of lipoprotein lipase (LPL).
• Assessed human brain responses to food cues following post-prandial TG changes in individuals with genetic risk for reduced DRD2 signaling.

Main Results:

• Nutritional TGs are metabolized within the MCL system and modulate DA-associated behaviors.
• Lipoprotein lipase (LPL) mediates the gating of DRD2-expressing neurons by TGs.
• In humans, post-prandial TG levels influence brain responses to food cues, particularly in those with genetic predispositions affecting DRD2 signaling.

Conclusions:

• Dietary TGs directly alter reward circuit signaling to regulate behavior.
• This reveals a novel mechanism linking dietary fat intake to reward system function and behavior.
• Provides a mechanistic basis for how energy-rich diets may contribute to reward deficits and compulsive behaviors via altered DA signaling.