NADPH diaphorase activity in mammalian retinas is modulated by the state of visual adaptation

• Published in: Visual neuroscience 1996-09, Vol.13 (5), p.863-871
• Main Authors: Zemel, Esther, Eyal, Orly, Lei, Bo, Perlman, Ido
• Format: Article
• Language: English
• Subjects: Adaptation, Ocular - physiology; Amacrine cells; Animals; Biological and medical sciences; Dark Adaptation - physiology; Electroretinography; Enzyme Inhibitors - pharmacology; Eye and associated structures. Visual pathways and centers. Vision; Fundamental and applied biological sciences. Psychology; Glutamic Acid - pharmacology; Histocytochemistry; Horizontal cells; Injections; Müller cells; NADPH Dehydrogenase - metabolism; NADPH diaphorase; NG-Nitroarginine Methyl Ester - pharmacology; Nitric Oxide - biosynthesis; Nitric Oxide Synthase - metabolism; Rabbit; Rabbits; Rat; Rats; Retina; Retina - drug effects; Retina - enzymology; Vertebrates: nervous system and sense organs; Visual adaptation
• ISSN: 0952-5238; 1469-8714
• DOI: 10.1017/S0952523800009111

NADPH diaphorase histochemistry is commonly used to identify cells containing nitric oxide synthase (NOS), the enzyme catalyzing the production of nitric oxide from L-arginine. NADPH diaphorase activity and NOS immunostaining was demonstrated in different cells of the vertebrate retina; photoreceptors, horizontal cells, amacrine cells, ganglion cells, and Müller cells. However, the physiological role of nitric oxide (NO) in the retina has yet to be elucidated. In this study, we tested the assumption that NADPH diaphorase activity in the retinas of rabbits and rats depended on the state of visual adaptation. In the rabbit, light adaptation enhanced NADPH diaphorase activity in amacrine cells and practically eliminated it in horizontal cells. Dark adaptation induced the opposite effects; the NADPH diaphorase activity was reduced in amacrine cells and enhanced in horizontal cells. Retinas from eyes that were injected intravitreally with L-glutamate exhibited a pattern of NADPH diaphorase activity that was similar to that seen in dark-adapted retinas. In rats, the NADPH diaphorase activity of amacrine and horizontal cells exhibited adaptation dependency similar to that of the rabbit retina. But, the most pronounced effect of dark adaptation in the rat's retina was an enhancement of NADPH diaphorase activity in Müller cells, especially of the endfoot region. Assuming that NADPH diaphorase activity is a marker for NOS, these findings suggest that NO production in the mammalian retina is modulated by the level of ambient illumination and support the notion that NO plays a physiological role in the retina.