Axon regeneration capacity often declines with age. One might assume that loss of regeneration is an obvious consequence of organismai aging. However, in the latest issue of Neuron, Byrne et al. (2014) demonstrate that regeneration ability and aging are regulated cell-autonomously within neurons, and can be decoupled.In animals, the juvenile state is often associated with better tissue-repair ability. Ample evidence suggests that this is also the case for axon regeneration, an essential step of neural repair after brain and spinal cord injury. For example, in contrast to immature neurons with robust growth ability, the terminally differentiated neurons in the adult mammalian central nervous system possess limited regenerative regrowth after injury. Such aging-associated decline of regenerative growth has also been observed in the mammalian peripheral nervous system and other species.
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