Changes in NADPH-diaphorase expression induced by excitotoxicity in the goldfish retina: relation with some...

We report alterations in the pattern of NADPH-diaphorase staining, a marker of nitric oxide, in the goldfish retina after kainic acid administration. The heavily stained ellipsoids of the photoreceptors, the heavily stained neurons of the inner plexiform layer and the labeled neurons of the ganglion cell layer are spared by excitotoxic insult, while the faintly medium sized neurons of the inner plexiform layer disappear after kainic acid administration. Furthermore, in the bipolar and in the horizontal retinal neurons we observe an induction of NADPH-diaphorase expression. The kainic acid-induced neurotoxicity evaluated by morphological observations and by measuring the levels of choline acetyltranferase in retinal homogenates, is not prevented by the administration of a nitric oxide synthase inhibitor.