A major challenge for achieving nerve regeneration following an injury to the adult brain and spine is the presence of numerous proteins that block the growth of axons across the injury site. In tomorrow's Nature, James Fawcett and colleagues at the University of Cambridge report that one class of inhibitory proteins is modified by the addition of sugars known as chondroitin sulfates, and that removing these sugar groups also lifts the inhibitory effect of the proteins and permits axonal regrowth. The researchers used a rat model in which they lesioned the nigrostriatal system, which degenerates in Parkinson's disease. The injury resulted in scarring and an increase in the expression of chondroitin sulfate proteins at the injured site. In control animals, virtually no axons were seen to grow across this scar, but in animals treated with chondroitinase ABC, an enzyme that removes the inhibitory sugar groups, axons grew across the injured site and reconnected with their original target. Future studies will address whether this regrowth results in recovery of motor function in these animals. This work does suggest that enzymes such as chondroitinase ABC are promising candidates for therapy in cases of traumatic injury to the adult brain and spine.—June Kinoshita
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- Moon LD, Asher RA, Rhodes KE, Fawcett JW. Regeneration of CNS axons back to their target following treatment of adult rat brain with chondroitinase ABC. Nat Neurosci. 2001 May;4(5):465-6. PubMed.