Basal Ganglia Dysfunction Contributes to Physical Inactivity in Obesity

Area of Science:

• Neuroscience
• Metabolic disease research
• Dopamine signaling pathways

Background:

• Obesity is linked to physical inactivity, worsening health outcomes.
• The underlying mechanisms connecting obesity and inactivity are not well understood.
• Dopamine signaling is crucial for motor control and motivation.

Purpose of the Study:

• To investigate the role of dopamine signaling deficits in mediating physical inactivity in obesity.
• To test the hypothesis that reduced dopamine signaling contributes to reduced physical activity in obese individuals.

Main Methods:

• Quantified dopamine signaling aspects, including D2 receptor binding, in lean and obese mice.
• Utilized genetic manipulation to alter D2 receptor function in specific neuron types.
• Assessed motor activity and diet-induced weight gain in experimental mouse models.

Main Results:

• Obese mice exhibited reduced D2 receptor binding in the striatum compared to lean mice.
• Genetic deletion of D2 receptors in medium spiny neurons decreased motor activity in lean mice.
• Restoring G_i signaling in these neurons increased activity in obese mice.
• Reduced D2 receptor signaling led to inactivity but did not increase vulnerability to diet-induced weight gain.

Conclusions:

• Deficits in striatal D2 receptor signaling contribute to physical inactivity observed in obesity.
• Physical inactivity in obesity is more likely a consequence of altered dopamine signaling than a primary cause of obesity.