NITRIC-OXIDE SYNTHASE IN THE CNS OF THE ATLANTIC SALMON

This study describes for the first time the presence and distribution of the nitric oxide (NO) synthesizing enzyme, NO synthase (NOS), in th e retina of a teleost. NADPH diaphorase (NADPHd) histochemistry and NO S immunohistochemistry revealed both NOS immunoreactive and NADPHd pos itive structures in photoreceptor outer segments, amacrine cells, hori zontal cells and ganglion cells. Since NO is known to stimulate the sy nthesis of cGMP, our results implicate an important role for NO in ret inal function, especially in cGMP related events in the photoreceptors .