Differential vulnerability of neurochemically identified subpopulations of retinal neurons in a monkey model of glaucoma (original) (raw)
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Selective Ganglion Cell Functional Loss in Rats with Experimental Glaucoma
Investigative Ophthalmology & Visual Science, 2004
To characterize retinal functional consequences of elevated intraocular pressure (IOP) in a rat model of experimental glaucoma. Unilateral elevation of IOP was produced by hypertonic saline injection into an episcleral vein in 20 adult male Brown-Norway rats. IOP was measured in both eyes of awake animals four to five times per week. After 5 weeks, animals were dark adapted overnight (>12 hours) and full-field electroretinograms (ERGs) were obtained simultaneously from both eyes. Scotopic ERG stimuli were brief white flashes (-6.64-2.72 log cd-s/m(2)). Photopic responses were also obtained (0.97-2.72 log cd-s/m(2)) after 15 minutes of light adaptation (150 cd/m(2)). Eyes were processed the following day for histologic evaluation by light microscopy, including masked determination of optic nerve injury grade (ONIG; 1, normal; 5, severe, diffuse damage). Among experimental eyes, the group average IOP (+/-SD) was 34.5 +/- 4.1 mm Hg, whereas the average for control eyes was 28.1 +/- 0.5 mm Hg (t = 7.1, P < 0.0001). The average ONIG for experimental and control eye groups, respectively, was 3.4 +/- 1.7 and 1.0 +/- 0.02 (t = 6.3, P < 0.0001). The ONIG increased with mean IOP in experimental eyes (r(2) = 0.78, P < 0.0001) and was unrelated to mean IOP in control eyes (r(2) = 0.09, P = 0.18). In experimental eyes with relatively mild IOP elevation (mean IOP < 31 mm Hg) and no structural (histologic) damage to the optic nerve evident by light microscopy (ONIG = 1.1 +/- 0.2, n = 5), there was a selective reduction of the positive scotopic threshold response (pSTR; P < 0.001), whereas other ERG components remained unaltered. In four of the five eyes, pSTR amplitude was reduced by more than 50%, whereas all five had normal scotopic a-wave, b-wave, and OP amplitudes. Eyes with mean IOP of more than 35 mm Hg had reduced a-wave, b-wave, and oscillatory potential (OP) amplitudes. As demonstrated by prior studies, selective loss of the pSTR is indicative of selective retinal ganglion cell (RGC) injury. In this rat model of experimental glaucoma, selective RGC functional injury occurred before the onset of structural damage, as assessed by light microscopy of optic nerve tissue. The highest IOP levels resulted in nonselective functional loss. Thus, in rodent models of experimental glaucoma, lower levels of chronically elevated IOP may be more relevant to human primary chronic glaucoma.
Molecular Biology of Retinal Ganglion Cells
Cells, 2020
The main goal of this thematic issue was to bring both original research papers and reviews together to provide an insight into the rather broad topic of molecular biology of retinal ganglion cells (RGCs). The objective for such a collection of articles is given by the fact that RGCs are the output neurons of the vertebrate retina and, in addition to integrating information and passing it to target neurons in retinorecipient brain centers, they also perform a significant computation to encode signals into action potential trains. Since this mechanism requires the coordinated expression, activation, modulation, deactivation, and disintegration of molecules that partake in RGC signaling, the molecular constituents of the RGC intracellular molecular milieu play a functionally relevant role in terms of visual signaling and vision. In a review article, May [1] summarizes factors that majorly determine the diffusion efficiency of nutrients between supplying blood vessels and inner retinal neurons including RGCs. It has been put forward that three basic types of nutrition supply mechanisms exist, namely the choroidal nutrition type, a retinal nutrition type, and a mixture of these two. In addition, species-dependent differences in supply mechanisms have also been pointed out. Besides normal functioning, changes in the expression levels of certain molecules may induce pathological alterations in the retina, or their down-and upregulation is simply the consequence of a chain of molecular changes that occur during the development of a disease. One of the most common vision deficits is myopia, which is a substantial public health problem worldwide. It has been known that defocused images alter eye growth and refraction. In this issue, Feng Pan [2] shows that defocused images change the signaling of certain RGCs in the mouse eye, which may be the first step in the induction of myopia development. In addition, work from the same laboratory demonstrates that besides changes in individual RGC signals, synchronous activation is altered as well, as a result of image distortion by defocusing [3]. Another very common progressive condition is glaucoma, which is one of the leading causes of irreversible blindness in the world and remains a major public health problem. A review article in this thematic issue by Parsadaniantz and colleagues [4] collects converging experimental and clinical evidence showing that glaucomatous optic neuropathy shares common neuroinflammatory mechanisms with "classical" neurodegenerative pathologies. Therefore, new combinations of neuroprotective and immunomodulatory therapies may provide therapeutic potential to prevent blindness in glaucoma patients. Mechanical impacts or chemical changes may deteriorate the retinal tissue, even with no clear sign of any progressive retinal disease, thereby inducing disruptive changes in the retinal tissue and RGC function. One of the great challenges of modern neuroscience is to prevent such alterations via neuroprotective mechanisms and even to induce regenerative processes in the nervous tissue. Dulz and colleagues report that the combined administration of glial cell line-derived neurotrophic factor (GDNF) and ciliary neurotrophic factor (CNTF) conferred lifelong protection to injured RGCs [5]. Interestingly, the simultaneous administration of GDNF and CNTF stimulated an intraretinal axon growth that was
Comparative study of the three neurofilament subunits within pig and human retinal ganglion cells
2004
Purpose: Neurofilaments (NF) are neuronal cytoskeletal components and immunostaining against them has been used to visualize retinal ganglion cells (RGC) and their axons. Since the RGC cytoskeleton exhibits differential damage in diseases such as glaucoma, we examined the distribution of light, medium, and heavy NF subunits (NF-L, NF-M, and NF-H respectively) within normal human and porcine retinas, as a function of RGC soma size and eccentricity. Methods: NF subunits were visualized with immunofluorescence techniques using retinal sections and flatmounts from adult human and pig retinas that were incubated with specific antisera against the three NF subunits. Porcine RGCs were retrogradely labeled with fluorogold while human RGCs were identified based on their position within the inner retina and their relatively large somata. Results: NF-H and NF-M were distributed widely within all RGC somata and dendrites, whereas NF-L was more restricted to the perinuclear area. In addition, phosphorylated NF-H distribution varied with retinal eccentricity so a subpopulation of large RGCs located in the peripheral retina was intensely labeled with the antiserum recognizing the phosphorylated NF-H.
RETRACTED: Characterization of a transformed rat retinal ganglion cell line
Molecular Brain Research, 2001
The purpose of the present study was to establish a rat retinal ganglion cell line by transformation of rat retinal cells. For this investigation, retinal cells were isolated from postnatal day 1 (PN1) rats and transformed with the c2 E1A virus. In order to isolate retinal ganglion cells (RGC), single cell clones were chosen at random from the transformed cells. Expression of Thy-1 (a marker for RGC), glial fibrillary acidic protein (GFAP, a positive marker for Muller cells), HPC-1 / syntaxin (a marker for amacrine cells), 8A1 (a marker for horizontal and ganglion cells) and neurotrophins was studied using reverse transcriptase-polymerase chain reaction (RT-PCR), immunoblotting and immunocytochemistry. One of the retinal cell clones, designated RGC-5, was positive for Thy-1, Brn-3C, Neuritin, NMDA receptor, GABA-B receptor, and synaptophysin expression and negative for GFAP, HPC-1, and 8A1, suggesting that it represented a putative RGC clone. The results of RT-PCR analysis were confirmed by immunocytochemistry for Thy-1 and GFAP. Upon further characterization by immunoblotting, the RGC-5 clone was positive for Thy-1, negative for GFAP, 8A1 and syntaxin. RGC 5 cells were also positive for the expression of neurotrophins and their cognate receptors. To establish the physiological relevance of RGC-5, the effects of serum / trophic factor deprivation and glutamate toxicity were analyzed to determine if these cells would undergo apoptosis. The protective effects of neurotrophins on RGC-5 after serum deprivation was also investigated. Apoptosis was studied by terminal deoxynucleotidyl transferase-mediated fluoresceinated dUTP nick end labeling (TUNEL). Serum deprivation resulted in apoptosis and supplementation with both BDNF and NT-4 in the growth media, protected the RGC-5 cells from undergoing apoptosis. On differentiation with succinyl concanavalin A (sConA), RGC-5 cells became sensitive to glutamate toxicity, which could be reversed by inclusion of ciplizone (MK801). In conclusion, a transformed rat retinal cell line, RGC-5, has certain characteristics of retinal ganglion cells based on Thy-1 and Brn-3C expression and its sensitivity to glutamate excitotoxicity and neurotrophin withdrawal. These cells may be valuable in understanding of retinal ganglion cell biology and physiology including in vitro manipulations in experimental models of glaucoma.
Vision Research, 2009
We investigated the effect of glaucoma (GL) on nerve growth factor (NGF) presence in two brain visual areas. Rats with elevated intraocular pressure (EIOP), induced by hypertonic saline injection in the episcleral vein, were treated with eye topical application of saline or NGF. Rats were subsequently sacrificed, and brain tissues were used for immunohistochemical, biochemical, and molecular analyses. We found that GL alters the basal level of NGF and NGF receptors in brain visual centers and that NGF eye application normalized these deficits. These findings demonstrate that the reduced presence of NGF can arise due to degenerative events in retinal and brain visual areas.
Immunohistochemical Classification and Functional Morphology of Human Choroidal Ganglion Cells
Investigative Opthalmology & Visual Science, 2004
PURPOSE. To characterize human choroidal ganglion cells (CGCs) further, regarding their immunohistochemical and ultrastructural appearance and their pre-and postsynaptic connections. METHODS. Choroidal wholemounts and serial sections of human donor eyes were stained with antibodies against neuronal nitric oxide synthase (nNOS), vasoactive intestinal peptide (VIP), tyrosine hydroxylase (TH), vesicular monoaminergic transporter (VMAT)-2, vesicular acetylcholine transporter (VAChT), neuropeptide Y (NPY), substance P (SP), calcitonin gene-related peptide (CGRP), calretinin, galanin, synaptophysin, and ␣-smooth muscle actin. Ultrathin sections of glutaraldehydefixed eyes were studied with an electron microscope. RESULTS. All CGCs stained for nNOS, most for VIP, approximately 45% for calretinin, and only single neurons for NPY and galanin. Ultrastructurally, the CGCs showed an incomplete glial sheath and, in places, showed close contact to surrounding collagen fibrils. The CGCs were in close contact with numerous boutons staining for the different neuronal markers including synaptophysin, nNOS, VIP, NPY, TH, VMAT-2, VAChT, calretinin, and NPY. CONCLUSIONS. The data indicate a complex integrative function of CGCs. The immunohistochemical and ultrastructural characteristics also indicate that the CGCs may have mechanosensory properties. The complex synaptic information points to a specific regulative CGC function in parallel with ciliary muscle contraction (accommodation). Axons originating from CGCs mainly supply the choroidal vasculature, thus implicating the CGCs as vasodilative neurons, but single CGCs may also innervate other structures such as nonvascular choroidal smooth muscle cells.