Studying Nitric Oxide in the Developing Retina: Neuromodulatory Func- tions and Signaling Mechanisms

The retina is a highly organized structure responsible for transducing light stimulation into electrical responses. Retinal organization is conserved in all vertebrate species and the generation of retinal cell types is chronologically determined and fairly documented from amphibians to humans. Furthermore, the chick retina is a well-established experimental paradigm for neurochemical and developmental studies regarding the nervous system. Among many signaling molecules regulating retinal physiology, nitric oxide (NO) is likely to play a prominent role within the retina. NO is a gaseous signaling transmitter, which regulates a plethora of physiological functions within an organism, including high-order signaling events both in the developing and mature nervous system. In this review we focus on different aspects of NO signaling in regulating retinal cell neurochemistry, focusing mainly on developing chick retina as a prevalent experimental model. Based on literature and data gathered from our group we conclude that NO is a major atypical neurotransmitter in the retina, regulating signaling events associated with the development of embryonic retinal neurons and glial cells.