LAMININ OVERRIDES THE INHIBITORY EFFECTS OF PERIPHERAL NERVOUS-SYSTEMAND CENTRAL-NERVOUS-SYSTEM MYELIN-DERIVED INHIBITORS OF NEURITE GROWTH

Axon growth inhibitory proteins associated with central nervous system (CNS) myelin are responsible in part for the absence of long distance axon regeneration in the adult mammalian CNS. We have recently report ed that myelin-associated glycoprotein (MAG), which is also present in peripheral nerves, is a potent inhibitor of neurite growth. This was surprising given the robust regenerative capacity of peripheral nerves . We now provide evidence that myelin purified from peripheral nerve a lso has neurite growth inhibitory activity. However, this activity can be masked by laminin, which is a constituent of the Schwann cell basa l lamina. We also report that laminin, which is largely absent from th e normal adult mammalian CNS, when added to purified CNS myelin, can o verride the neurite growth inhibitory activity in CNS myelin. These re sults have important implications for the development of strategies to foster axon regeneration in the adult mammalian CNS where multiple gr owth inhibitors exist. (C) 1995 Wiley-Liss, Inc.