sfn2018

Exercise is neuroprotective following partial motoneuron depletion: Run for your dendrites

Chew C, Sengelaub DR (2018) Exercise is neuroprotective following partial motoneuron depletion: Run for your dendrites. Neuroscience 2018 Abstracts 761.02 / MM11. Society for Neuroscience, San Diego, CA.

Summary: We have previously demonstrated that partial depletion of motoneurons innervating the quadriceps muscles induces dendritic atrophy in remaining motoneurons. Furthermore, systemic treatment with supplemental androgens is neuroprotective and dendritic atrophy following partial motoneuron depletion is attenuated. Circulating levels of androgens have previously been shown to increase following exercise, and exercise has been demonstrated to be neuroprotective in a variety of other neurodegenerative and injury models. Thus, we hypothesized that allowing animals to exercise following partial motoneuron depletion would produce neuroprotective effects similar to treatment with supplemental androgens. Motoneurons innervating the vastus medialis muscle in adult male rats were selectively killed by intramuscular injection of cholera toxin-conjugated saporin. Following saporin injections, some animals were allowed free access to a running wheel attached to their home cages. Four weeks later, motoneurons innervating the ipsilateral vastus lateralis muscle were labeled with cholera toxin-conjugated horseradish peroxidase, and dendritic arbors were reconstructed in three dimensions. Compared with intact normal males, partial motoneuron depletion resulted in decreased dendritic length in remaining quadriceps motoneurons. Early data suggests that exercise can completely protect against this dendritic atrophy, with exercised males showing dendritic arbors lengths significantly longer than saporin and testosterone-treated animals, and of similar length to intact normal animals. These findings suggest that exercise may be a viable means of protecting against collateral dendritic atrophy. The upregulation of testosterone release following exercise combined with our previous data showing the neuroprotective effects of androgen treatment suggest that the neuroprotective following exercise may be attributable to systemic androgen upregulation.

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