The sensitivity of light-evoked responses of retinal ganglion cells is decreased in nitric oxide synthase gene knockout mice.

We have shown previously that increasing the production of nitric oxide (NO) results in a dampening of visual responses ofretinal ganglion cells (G. Y. Wang, L. C. Liets, & L. M. Chalupa, 2003). To gain further insights into the role of NO in retinalfunction, we made whole-cell patch clamp recordings from ganglion cells of neural type nitric oxide synthase (nNOS) geneknockout mice. Here we show that in the dark-adapted state, the sensitivity of retinal ganglion cell to light stimulation isdecreased in nNOS knockout animals. The lowest light intensities required to evoke optimal responses and the averageintensities that evoked half-maximal responses were significantly higher in nNOS knockouts than in normal mice. Retinalhistology and other features of light-evoked responses of ganglion cells in nNOS mice appeared to be indistinguishable fromthose of normal mice. Collectively, these results,in conjunction with our previous work, provide evidence that increasing levelsofNOdampenvisualresponsesofganglioncells,whilealackofnNOSdecreasesthesensitivityoftheseneuronstolight.Thus,NO levels in the retina are capable of modulating the information that ganglion cells convey to the visual centers of the brain.Keywords: retinal ganglion cell, neural type nitric oxide synthase (nNOS), visual response, nitric oxide,patch clamp recordingCitation: Wang, G., van der List, D. A., Nemargut, J. P., Coombs, J. L., & Chalupa, L. M. (2007). The sensitivity of light-evoked responses of retinal ganglion cells is decreased in nitric oxide synthase gene knockout mice. Journal of Vision,7(14):7, 1–13, http://journalofvision.org/7/14/7/, doi:10.1167/7.14.7.