Cell Metabolism
Volume 25, Issue 2, 7 February 2017, Pages 312-321
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Article
Basal Ganglia Dysfunction Contributes to Physical Inactivity in Obesity

https://doi.org/10.1016/j.cmet.2016.12.001Get rights and content
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Highlights

  • Obesity is associated with physical inactivity

  • Obese mice have less striatal D2R binding, which may explain their inactivity

  • Restoring Gi signaling in iMSNs rescues physical activity levels of obese mice

  • Physical inactivity is more a consequence than a cause of weight gain

Summary

Obesity is associated with physical inactivity, which exacerbates the health consequences of weight gain. However, the mechanisms that mediate this association are unknown. We hypothesized that deficits in dopamine signaling contribute to physical inactivity in obesity. To investigate this, we quantified multiple aspects of dopamine signaling in lean and obese mice. We found that D2-type receptor (D2R) binding in the striatum, but not D1-type receptor binding or dopamine levels, was reduced in obese mice. Genetically removing D2Rs from striatal medium spiny neurons was sufficient to reduce motor activity in lean mice, whereas restoring Gi signaling in these neurons increased activity in obese mice. Surprisingly, although mice with low D2Rs were less active, they were not more vulnerable to diet-induced weight gain than control mice. We conclude that deficits in striatal D2R signaling contribute to physical inactivity in obesity, but inactivity is more a consequence than a cause of obesity.

Keywords

obesity
dopamine
physical activity
exercise
D2
striatum
obese
weight loss

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