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Retinal axon regeneration in the lizard Gallotia galloti in the presence of CNS myelin and oligodendrocytes
Author(s) -
Lang Dirk M.,
MonzónMayor Maximina,
Bandtlow Christine E.,
Stuermer Claudia A. O.
Publication year - 1998
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/(sici)1098-1136(199805)23:1<61::aid-glia6>3.0.co;2-7
Subject(s) - biology , neurite , growth cone , myelin , optic nerve , retinal ganglion cell , oligodendrocyte , neuroscience , axon , central nervous system , dorsal root ganglion , regeneration (biology) , microbiology and biotechnology , retina , anatomy , spinal cord , in vitro , biochemistry
Retinal ganglion cell (RGC) axons in lizards (reptiles) were found to regenerate after optic nerve injury. To determine whether regeneration occurs because the visual pathway has growth‐supporting glia cells or whether RGC axons regrow despite the presence of neurite growth‐inhibitory components, the substrate properties of lizard optic nerve myelin and of oligodendrocytes were analyzed in vitro, using rat dorsal root ganglion (DRG) neurons. In addition, the response of lizard RGC axons upon contact with rat and reptilian oligodendrocytes or with myelin proteins from the mammalian central nervous system (CNS) was monitored. Lizard optic nerve myelin inhibited extension of rat DRG neurites, and lizard oligodendrocytes elicited DRG growth cone collapse. Both effects were partially reversed by antibody IN‐1 against mammalian 35/250 kD neurite growth inhibitors, and IN‐1 stained myelinated fiber tracts in the lizard CNS. However, lizard RGC growth cones grew freely across oligodendrocytes from the rat and the reptilian CNS. Mammalian CNS myelin proteins reconstituted into liposomes and added to elongating lizard RGC axons caused at most a transient collapse reaction. Growth cones always recovered within an hour and regrew. Thus, lizard CNS myelin and oligodendrocytes possess nonpermissive substrate properties for DRG neurons—like corresponding structures and cells in the mammalian CNS, including mammalian‐like neurite growth inhibitors. Lizard RGC axons, however, appear to be far less sensitive to these inhibitory substrate components and therefore may be able to regenerate through the visual pathway despite the presence of myelin and oligodendrocytes that block growth of DRG neurites. GLIA 22:61–74, 1998. © 1998 Wiley‐Liss, Inc.