Expression of nitric oxide synthase during the development of RCS rat retinas

Nitric oxide (NO) has been reported to be both neurodestructive and neuropr otective in the central nervous system and could possibly play an important role in neurodegenerative disorders. On the assumption that NO synthesis m ay influence degenerative processes in the retina, we have examined the dev elopment and distribution of nitric-oxide-synthase(NOS)-immunoreactive cell s in developing Royal College of Surgeons (RCS) rat retinas, which is an an imal model for retinal degeneration. An antibody against constitutive neuro nal NOS was used for immunocytochemistry on RCS rat retinas from postnatal (PN) days 3, 7, 10, 14, 35, 70 and 281 and compared with that in the normal rats of PN days 3, 7, 10, 14, 54 and adults. Immunoreactive cells were not seen in PN 3 retinas but were distinctly seen in the PN 7 retina along wit h a plexus in the inner plexiform layer. In both groups (normal and RCS rat s) a distinct sublayering of the plexus in the inner plexiform layer could be seen at PN 10, which became more distinct at PN 14. The immunoreactive c ells were detected also in the oldest retina examined, which was PN 281 in the case of RCS rats. In both groups, certain amacrine cells, certain bipol ar cells and certain horizontal cells were found to be immunoreactive. In c onclusion, the developmental timetable of the NOS immunoreactivity was iden tical in the normal and the RCS rat retinas. The NOS-immunoreactive cells p ersisted in the RCS retinas even when the retina had degenerated extensivel y. Abnormalities with the inducible isoforms of NOS cannot be ruled out fro m this study. We conclude that the chronological and qualitative developmen t of the constitutive neuronal NOS immunoreactivity is normal in RCS rat re tinas. Copyright (C) 2001 S.Karger AG, Basel.