Molecular-biological Research for Neuron-Glial Interaction during retinal regeneration.

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The cytotoxic effects of hypoxia and excitatory amino acids on cultured retinal ganglion cells (RGCs) were studied. And the influence of coculture with retinal Muller glia and cortical astrocytes on cell survival was evaluated. The results from our culture model demonstrate the importance of the neuron-glial interaction in determining cellular viability. Glial cells seem to play an important role in the response to hypoxia and excitotoxicity.Nitric oxide may mediate hypoxic and excitotoxic effects on central neurons. In this culture, the glial cell monolayer is bNOS positive and iNOS negative immunohistochemically. The effect of a nitric oxide synthase (NOS) inhibitor, Nω-nitro-L-arginine (NA), on survival of culture rat retinal ganglion cells subjected to hypoxia and excitotoxicity were investigated. The survival rate of cultured RGCs exposed to hypoxia and excitatory amino acids increased in a dose-dependent fashion with NA. The time course of the survival rate of RGC cultures pretreated with NA showed a better survival rate. A NOS inhibitor provides partial protection of RGCs against hypoxia and excitotoxicity in cell culture.In this culture, the glial cell monolayer express immunocytochemically nerve growth factor (NGF) and brain-derived neuritrophic factor (BDNF), vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), transforming growth factor β1 (TGF β1).The ciliary marginal zone (CMZ) of the vertebrate retina contains undifferentiated progenitor cells that continue to proliferate and differentiate into retinal-specific cell types. With this culture system, cells from the CMZ of neonatal rat retina identified as various retinal cell types. To investigate whether conditioned medium with NGF and BDNF can induce differentiation of the cells from the CMZ, however, cells cultured in the conditioned medium showed very little retinal cell differentiation.