title: The sensitivity of light-evoked responses of retinal ganglion cells is decreased in nitric oxide synthase gene knockout mice.
abstract: We have shown previously that increasing the production of nitric oxide (NO) results in a dampening of visual responses of retinal ganglion cells (G. Y. Wang, L. C. Liets, & L. M. Chalupa, 2003). To gain further insights into the role of NO in retinal function, we made whole-cell patch clamp recordings from ganglion cells of neural type nitric oxide synthase (nNOS) gene knockout mice. Here we show that in the dark-adapted state, the sensitivity of retinal ganglion cell to light stimulation is decreased in nNOS knockout animals. The lowest light intensities required to evoke optimal responses and the average intensities that evoked half-maximal responses were significantly higher in nNOS knockouts than in normal mice. Retinal histology and other features of light-evoked responses of ganglion cells in nNOS mice appeared to be indistinguishable from those of normal mice. Collectively, these results, in conjunction with our previous work, provide evidence that increasing levels of NO dampen visual responses of ganglion cells, while a lack of nNOS decreases the sensitivity of these neurons to light. Thus, NO levels in the retina are capable of modulating the information that ganglion cells convey to the visual centers of the brain.
authors.affiliation: Department of Structural and Cellular Biology, School of Medicine, Tulane University, New Orleans, LA 70112, USA. gwang@tulane.edu
authors.forename: Guo-Yong
authors.initials: GY
authors.lastname: Wang
authors.forename: Deborah A
authors.initials: DA
authors.lastname: van der List
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Nemargut
authors.forename: Julie L
authors.initials: JL
authors.lastname: Coombs
authors.forename: Leo M
authors.initials: LM
authors.lastname: Chalupa
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D025042:Amacrine Cells / Q000166:cytology / Q000201:enzymology; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D003623:Dark Adaptation / Q000502:physiology; D004307:Dose-Response Relationship, Radiation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007158:Immunologic Techniques; D066298:In Vitro Techniques; D008027:Light; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008959:Models, Neurological; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D052248:Nitric Oxide Synthase Type I / Q000172:deficiency* / Q000378:metabolism; D018408:Patch-Clamp Techniques; D012160:Retina / Q000166:cytology / Q000378:metabolism; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects*; D015398:Signal Transduction / Q000502:physiology; D013194:Staining and Labeling
chemical_list: D004791:Enzyme Inhibitors; D001120:Arginine; D052248:Nitric Oxide Synthase Type I; D019331:NG-Nitroarginine Methyl Ester