The Effect of Obesity on Muscle Sensory Neuron Function in Mice

The sense of body movement and position in a three dimensional space, known as proprioception, is largely responsible for maintaining proper balance and gait. Abnormalities in proprioception can lead to an increased risk of falling. Obese people have demonstrated balance and gait impairments and fall nearly twice as often as non-obese individuals, suggesting proprioceptive defects. Proprioception relies on integration of visual, vestibular, and somatosensory systems, but group Ia and II muscle spindle afferents are considered the most important proprioceptors. Obesity leads to chronic low level systemic inflammation, and inflammatory factors have been shown to alter the activity of group Ia and II muscle spindle afferents. The present study evaluated the effects of diet-induced obesity on group Ia and II muscle spindle afferent function in 20 mice. Muscle spindle afferent activity significantly decreased in response to static and dynamic stretch in obese mice compared to control mice. This suggests that in obesity, improper proprioceptive information is relayed to the central nervous system which could contribute to the balance and gait impairments seen in the obese population.