Role of nitric oxide in photoreceptor survival in embryonic chick retinal cell culture

The presence of nitric oxide synthase (NOS) in chick retina during developm ent has allowed us to study the role of nitric oxide (NO) during retinal di fferentiation in dissociated chick retinal cell culture from embryonic day 6, We have demonstrated the presence of nicotinamide adenine dinucleotide p hosphate diaphorase staining in these cultures after 3 days in vitro (Div), with a maximal intensity after 8 Div, corresponding to embryonic day 14, I mmunohistochemistry studies confirmed the presence of the two isoforms of N OS, NOS-I and -III, in dissociated retinal cell cultures at 8 Div, Addition of NG-monomethyl-L-arginine, a NOS inhibitor, to retinal cell cultures pre vented NO production but did not modify the appearance and the survival of ganglion and amacrine cells. However, immunohistochemical analysis with dis tinct markers for photoreceptor cells (rods and cones) showed that inhibiti on of endogenous NOS in retinal cell cultures prevented the developmental d ecrease of rod number between 5 and 8 Div, thus supporting the hypothesis t hat NO may be involved in the cell death of rods during the development of the retina. J. Neurosci. Res. 55:423-431, 1999, (C) 1999 Wiley-Liss, Inc.