Correlation of nitric oxide synthase expression with changing patterns of axonal projections in the developing visual system

Abstract

A precise pattern of connections between the retina and central visual nuclei in the brain is established during development. Activity-dependent presynaptic mechanisms and NMDA receptor-mediated postsynaptic mechanisms are thought to play important roles in this developmental process. A model proposed for production of the newly described neurotransmitter, nitric oxide, involves presynaptic activity and activation of postsynaptic NMDA receptors. If present in the developing visual system, nitric oxide could represent a form of retrograde communication from postsynaptic to presynaptic cells that mediates the formation of the proper pattern of connections. This study used the diaphorase histochemical technique to detect the presence of nitric oxide synthase (NOS), the enzyme responsible for the production of nitric oxide, in the developing chick optic tecturn. Results from this study showed that NOS is present in the developing tectum and that its expression coincides temporally with innervation by retinal axons. NOS expression reaches a peak at the time that refinement of the initial pattern of connections is occurring. WGA/HRP labeling of retinal axons confirmed that processes of NOS-positive cells in the tectum extend well into the area of the ingrowing retinal axons. Histochemical results from eyeless chick embryos indicate that NOS expression is dependent on the presence of retinal axons, which suggests that retinal axons synapse on cells that express nitric oxide. Northern blot analysis using a cDNA probe to NOS from rat brain verified the histochemical results. These results are consistent with nitric oxide having a role in development of the proper pattern of connections in the chick retinotectal system.

NADPH-Diaphorase activity changes during gangliogenesis and metamorphosis in the gastropod molluscIlyanassa obsoleta

“…In the abalone Haliotis rufescens, cerebral serotonergic neurons that innervate the velum are most likely lost by cell death (Barlow and Truman, 1992). In mammals, changes in NOS activity correlate with synaptogenesis and cell death (Bredt and Snyder, 1994;Williams et al, 1994;Ogilvie et al, 1995), two processes common to developing nervous systems. Edelman and Gally (1992) have suggested that NO could function to coordinate the development of groups of interactive neurons, but further experiments would be necessary to document this phenomenon in developing Ilyanassa.…”

Transient and continuous expression of NADPH diaphorase in different neuronal populations of developing rat spinal cord

“…On the other hand, there is no evidence to support the hypothesis that the cells adjacent to the AMNs undergo cell death. Therefore, an equally valid alternative is that this group of diaphorase-positive cells, like SMNs, DRG, and a number of other neurons (Bruning, 1993;Cramer et al, 1993;Gonzalez-Hernandez et al, 1993Kalb and Agostini, 1993;Ward et al, 1994;Williams et al, 1994), may express diaphorase activity only transiently during development.…”

Differential expression of nadph diaphorase in functionally distinct prefrontal cortices in the rhesus monkey

“…1°2. 122 It should be noted that the distribution of diaphorase-positive neurons in several neural structures had been described, albeit not quantitatively, prior to its association with NOS had been established. 2° '27"34"6°'61,l°9 '117'l18 1987).…”