Cellular localization of neuronal nitric oxide synthase (NOS-1) in the human and rat retina

The neuronal form of nitric oxide synthase (NOS-1) has been localized to se veral cell types in the retinas of experimental animals; however, localizat ion in the human retina has not been definitive. By using in situ hybridiza tion and immunohistochemistry, we have compared the cellular expression and localization of NOS-1 in the rat and human retinas. In both rat and human retinas, NOS-1 is expressed in the inner segments of photoreceptors, cells in the inner nuclear layer, particularly amacrine cells, and retinal gangli on cells. In human cones, NOS-1 is abundantly present in the outer segments . In the rat, optic nerve transection caused a loss of cells that were posi tive for NOS-1 in the ganglion cell layer. Although a retinal ganglion cell localization has not been reported consistently in the literature, our dat a clearly localize NOS-1 to the retinal ganglion cells of the rat and human retinas. J. Comp. Neurol. 416:269-275, 2000. (C) 2000 Wiley-Liss, Inc.