Glial inhibition of nerve regeneration in the mature mammalian CNS.

The lack of axonal regeneration in the adult mammalian CNS is due to both unfavorable environmental glial factors and the intrinsic neuronal state. Inhibitors associated with myelin and the glial scar have been extensively studies and it has been shown that neutralizing at least some of the inhibitors can lead to improved growth. Meanwhile, important advances have also been made towards our understanding of the neuronal intrinsic state, particularly the intracellular levels of cyclic nucleotide, that influence the capacity of mature CNS neurons to initiate and maintain a regrowth response. It is well recognized that successful regeneration may only be achieved by application of a combination of strategies that both block glial inhibitors and enhance the intrinsic neuronal growth capacity.