Environmental enrichment-dependent neuronal activity pathways for axonal regeneration and recovery after spinal cord injury

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Injury to the adult mammalian nervous system leads to permanent deficits in sensory and motor function. This is partly due the inability of neurons to initiate an effective molecular regenerative response, resulting in failed axon regeneration. Sensory neurons in the dorsal root ganglia (DRG) are vital for physiological and post-injury sensorimotor function as they receive and convey sensory information from the environment to motor circuits in the spinal cord and brain. We have recently found that exposing mice to environmental enrichment (EE) prior to an injury induces a long-lasting increase in the regenerative potential of DRG neurons. Moreover, prior exposure to EE augmented sensory axon regeneration and functional improvements after spinal cord injury, which were further enhanced when combined with a conditioning injury. Mechanistic experiments suggest that an enhancement in neuronal activity and histone acetylation may be responsible for the observed regenerative phenotype. Here we will investigate whether an EE-dependent increase in sensory axon regeneration depends upon enhancing neuronal activity and calcium signalling, leading to activation of CREB-binding protein (CBP)-dependent histone acetylation and regenerative gene reprogramming. Secondly, we will explore whether the use of a small molecule activator of CBP promotes axonal regeneration and recovery after spinal cord injury. Overall this proposal will clarify (i) the mechanisms supporting this novel EE-dependent conditioning model for regenerative priming of sensory neurons and (ii) will test a recently developed small molecular activator of CBP for functionally relevant axon regeneration after spinal injury.This research will be important as it will set the groundwork for a novel translational opportunity to promote regeneration and recovery after spinal injury by using a regenerative small molecule amenable for use in patients.