CHARACTERIZATION OF A NEURITE OUTGROWTH INHIBITOR EXPRESSED AFTER CNSINJURY

Reactive gliosis, a general response to injury in the central nervous system grey and white matter, represents a serious obstacle to axonal regeneration in.mammals. In culture, myelin-free plasma membranes from normal rat brain tissue promoted neurite outgrowth, whereas myelin-fr ee membranes purified from injured tissue were inhibitory. The inhibit ory activity could be solubilized by detergent, was sensible to glycos aminoglycan lyase digestion and eluted with an apparent molecular weig ht of 160-220 kDa in gel filtration chromatography. When presented as a surface-bound molecule, the inhibitor prevented neurite initiation; when added in a soluble form to growing neurites, it induced their ret raction. These results provide cellular and molecular evidence support ing the classical view that, in the mammalian central nervous system, damage-evoked gliosis correlates with the expression of molecules capa ble of preventing neurite outgrowth.