NEURITE OUTGROWTH INHIBITORS ASSOCIATED WITH GLIAL-CELLS AND GLIAL-CELL LINES

'REACTIVE' astrocytes and 'activated' microglial cells are the major c ellular components of gliotic tissue, one of the most serious obstacle s to axonal regeneration in mammalian central nervous system grey and white matter. The appearance of reactive glial cells after a lesion in the CNS correlates with the expression of molecules, like proteoglyca ns, capable of preventing neurite outgrowth. Co-cultures of embryonic neurones with glial cells and glial cell lines, that might share chara cteristics with reactive astrocytes and microglial cells, show that wh ile cultured astrocytes promote neurite outgrowth, plasma membranes of C6 glioma and microglial cells express neurite inhibitory activities with proteoglycan-like characteristics, similar to those expressed by the gliotic tissue associated inhibitors. These results suggest that i n vivo microglial cells might be at least one of the sources of proteo glycans with neurite outgrowth inhibitory properties,