Regional distribution of nitrergic neurons in the inner retina of the chicken

Abstract

Using both NADPH diaphorase and anti-nNOS antibodies, we have identified-from retinal flatmounts-neuronal types in the inner retina of the chicken that are likely to be nitrergic. The two methods gave similar results and yielded a total of 15 types of neurons, comprising 9 amacrine cells, 5 ganglion cells, and 1 centrifugal midbrain neuron. Six of these 15 cell types are ubiquitously distributed, comprising 3 amacrine cells, 2 displaced ganglion cells, and a presumed orthotopic ganglion cell. The remaining nine cell types are regionally restricted within the retina. As previously reported, efferent fibers of midbrain neurons and their postsynaptic partners, the unusual axon-bearing target amacrine cells, are entirely confined to the ventral retina. Also confined to the ventral retina, though with somewhat different distributions, are the "bullwhip" amacrine cells thought to be involved in eye growth, an orthotopic ganglion cell, and two types of large axon-bearing amacrine cells whose dendrites and axons lie in stratum 1 of the inner plexiform layer (IPL). Intracellular fills of these two cell types showed that only a minority of otherwise morphologically indistinguishable neurons are nitrergic. Two amacrine cells that branch throughout the IPL are confined to an equatorial band, and one small-field orthotopic ganglion cell that branches in the proximal IPL is entirely dorsal. These findings suggest that the retina uses different processing on different regions of the visual image, though the benefit of this is presently obscure.

Nitric Oxide (NO) Mediates the Inhibition of Form-Deprivation Myopia by Atropine in Chicks

“…NADPH-diaphorase activity and nNOS-like immunoreactivity can be found in all major cell types in the chick retina and choroid 39–41 and are co-localized consistently in approximately 15 types of retinal neurons; they may be absent from RPE and scleral chondrocytes 40 . Localization of eNOS and iNOS in ocular tissues has been reported as widespread expression in the chick retina 41 , but these results may not be conclusive, as the authors were unable to reliably co-localize endogenously generated NO signal with eNOS- and iNOS-like immunoreactivity.…”

Expression of Inducible Nitric Oxide Synthase (iNOS) in Microglia of the Developing Quail Retina

“…A previous study [72] showed that NOS activity was elevated in the retinas of E8-E9 chick embryo retinas and decreased thereafter. Various retinal neurons are known to express nNOS in developing and adult chicks [73]–[77], and eNOS has been detected in certain neuronal populations and in Müller cells [73], [78]. However, there has been no previous report of iNOS expression in any cell type of the normal retina of avian species.…”

“…The weak iNOS immunolabeling in ramified microglia of the adult quail retina implies that iNOS expression is downregulated but continues to be present, as corroborated by our RT-PCR results. The role of NO produced by microglial iNOS in the adult retina is not known and warrants further investigation, although it may contribute to the same NO functions as those of the nNOS expressed in a variety of retinal neurons [76], [77].…”

Pattern of Nitrergic Neuronal System Organization in the Brain of Two Holostean Fishes (Actinopterygii: Ginglymodi)

“…Thus, nitrergic ganglion cells and photoreceptors have been reported in the retina of teleosts Pottek et al, 1997;Ota et al, 1999;Haamedi and Djamgoz, 2002;Gaikwad et al, 2009], amphibians [Nöll et al, 1994;Kurenni et al, 1995;Blom et al, 2009], reptiles [Blute et al, 1997], birds [Fischer and Stell, 1999;Wilson et al, 2011;Tekmen-Clark and Gleason, 2013], and mammals [Blom et al, 2012], where protoreceptor cells always lack nitrergic labeling. Furthermore, nitrergic bipolar neurons have been described in the retina of chondrichthyes [Shiells and Falk, 1992], amphibians [Nöll et al, 1994;Kurenni et al, 1995;Blom et al, 2009], and reptiles [Cao and Eldred, 2001], whereas horizontal nitrergic cells have been reported only in teleosts [Ota et al, 1999;Haamedi and Djamgoz, 2002] and reptiles [Haverkamp and Eldred, 1998;Cuenca et al, 2000].…”

“…Retinal NO might modulate the neuronal communication between bipolar and ganglion cells, like the transient conversion of synaptic inhibition to excitation [Hoffpauir et al, 2006]. Amacrine cells, either NADPH-d reactive or NOSir, have been thoroughly reported in the retina of teleosts Pottek et al, 1997;Haamedi and Djamgoz, 2002], amphibians [Nöll et al, 1994;Kurenni et al, 1995;Blom et al, 2009], reptiles , birds [Fischer and Stell, 1999;Wilson et al, 2011;Tekmen-Clark and Gleason, 2013], and mammals [Vielma et al, 2012], representing a feature shared in all osteichthyes studied. Of note, holosteans, like cladistians, lack other nitrergic cells in the retina [López et al, 2016;present results].…”