Targeting but not resists an age-dependent decline in promoting axon sprouting.

Axonal repair is critical for functional recovery after injury of the CNS. We previously reported that neuronal deletion exhibits an age-dependent decline in promoting axon regeneration from the corticospinal tract (CST). How sprouting of uninjured axons, a naturally occurring form of axonal repair, is impacted by age is unknown. We assessed CST sprouting after unilateral pyramidotomy in and/or -deleted mice at different ages. While deletion enhances sprouting independently of age, deletion loses its sprouting-promoting effect with age. The synergistic effect of / co-deletion on CST sprouting is rapidly lost with increased age. Overall, promoting sprouting appears more robust across age than regeneration, yet distinct molecular pathways are differentially impacted by age. Importantly, six-week delayed deletion promotes CST sprouting across age groups, supporting a clinically relevant time frame for this neural repair strategy independently of age.