Widespread drastic reduction in brain myelin content upon marathon running

Abstract

Recent evidence suggests that myelin lipids may act as glial energy reserves when glucose is lacking, a hypothesis yet to be solidly proven. Hereby, we examined the effects of running a marathon on myelin content by MRI. Our findings show that marathon runners undergo widespread robust myelin decrease at completion of the effort. This reduction involves white and gray matter and includes primary motor and sensory cortical areas and pathways, as well as the entire corpus callosum and internal capsule. Notably, myelin levels partially recover within two weeks after the marathon. These results reveal that myelin use and replenishment is an unprecedented form of metabolic plasticity aimed at maintaining brain function during extreme conditions.

Forelimb motor learning and memory consolidation drives distinct oligodendrocyte plasticity to fine-tune task-related neural activity

“…The metabolic demands of producing and maintaining vast myelin sheath make OLs highly vulnerable to energy challenges and environmental changes. In a model of white matter injury caused by chronic hypoxia, hypomyelination is associated with synaptic deficits and functional impairment 67,68 . Myelin lipid depletion also occurs in marathon runners who require high levels of glucose 68 .…”

“…In a model of white matter injury caused by chronic hypoxia, hypomyelination is associated with synaptic deficits and functional impairment 67,68 . Myelin lipid depletion also occurs in marathon runners who require high levels of glucose 68 . Thus, there may be a competition in energy consumption/distribution between type 1 and type 2 OL plasticity, and the transient suppression of OL generation may appear to be a tradeoff of node elongation for motor skill acquisition during online phase, since when suppression of OL generation was artificially achieved by Myrf deletion, the learning ability of Myrf-cKO mice was also improved (Fig.…”