Inner Plexiform Layer Of Retina Research Articles

Tafluprost promotes axon regeneration after optic nerve crush via Zn2+-mTOR pathway

PurposeTo investigate whether Tafluprost could promote optic nerve regeneration in mice after optic nerve crush (ONC) and determine the underlying molecular mechanism. MethodsTafluprost was injected into the vitreous body immediately after ONC. The level of Zn2+ in the inner plexiform layer (IPL) of the retina was stained using autometallography (AMG). The number of survival retinal ganglion cells (RGCs) was determined via dual staining with RGC markers Tuj1 and RBPMS. Individual axons that regenerated to 0.25, 0.5, 0.75 and 1 mm were manually counted in the whole-mount optic nerve labeled by cholera toxin B fragment (CTB). Immunofluorescence and Western blot were performed to detect protein expression levels. Pattern electroretinogram was used to evaluate RGCs function. ResultsTafluprost promoted RGC survival in a dose-dependent manner with an optimal concentration of 1 μM. Tafluprost significantly decreased ZnT-3 expression and Zn2+ accumulation in the IPL of retina. Tafluprost stimulated intense axonal regeneration and maintained RGCs function compared to control. Mechanistically, Tafluprost and Zn2+ elimination treatment (TPEN or ZnT-3 deletion) can activate the mTOR pathway with an improved percentage of pS6+ RGCs in the retina. However, rapamycin, a specific inhibitor of the mTOR1, inhibited the activation of the mTOR pathway and abolished the regenerative effect mediated by Tafluprost. Tafluprost also inhibited the upregulation of p62, LC3 and Beclin-1, attenuated the overactivation of microglia/macrophages and downregulated the expression of TNFα and IL-1β. ConclusionsOur results suggest that Tafluprost promoted axon regeneration via regulation of the Zn2+-mTOR pathway, and provide novel research directions for glaucomatous optic nerve injury mechanisms.

Gestational diabetes influences retinal Muller cells in rat's offspring.

Objective(s):The Muller cell is the principal glial cell of the vertebrate retina. The expression of Glial fibrillary acidic protein (GFAP) in the Muller cells was used as a cellular marker for retinal damage. This study was done to evaluate the effect of gestational diabetes on retinal Muller cells in rat’s offspring.Materials and Methods:In this experimental study, 12 Wistar rat dams were randomly allocated in control and diabetic groups. Gestational diabetes was induced by 40 mg/kg/body weight of streptozotocin at the first day of gestation, intraperitoneally. Dams in control group received an equivalent volume normal saline. Eye of six offspring of each group were removed at postnatal day 28 (P28). The histopathological changes in retina were examined through H&E staining and ultrastructure transmission electron microscopy (TEM). The expression of GFAP was examined using Immunohisto-chemical staining of GFAP in Muller cells. Photographs of retina were taken using Olympus BX51 microscope and a digital camera DP12 and EM LEO906; Zeiss, Germany.Results:In the control rat’s offspring, GFAP expression was not significant in Muller cells. According to the optical microscope images, GFAP expression was observed in the processes of the Muller cell in the inner plexiform layer of retina in offspring of diabetic mothers. In TEM technique, nuclear fragmentation and apoptotic bodies were observed in Muller cell of diabetic offspring.Conclusion:This study showed that the uncontrolled gestational diabetes can increase GFAP expression in Muller cells and retinal thickness of retinal layer in rat offspring’s, therefore uncontrolled gestational can damage the Muller cells.

The Simulation of Retinal Inner Plexiform Layer Based on Parallel Algorithm

The final objective of retinal simulation is to construct an artificial computer retina to replace the biological retina, and to offset the vision-impaired people. Due to the complexity of the retinal structure and the great number of bipolar cells and ganglion cells in retinal (exceeding tens of millions), both the speed and accuracy of the simulation of the retinal up to date are at a low level. In this paper we present a method for the simulation of inner plexiform layer of retina based on Compute Unified Device Architecture (CUDA) parallel algorithm to achieve the maximum utilization of CPU and Graphic Processing Unit(GPU), and to improve the speed and accuracy of the retina simulation.

Inhibition of hypoxia-induced [ 3H]glycine release from chicken retina by the glycine transporter type-1 (GlyT-1) inhibitors NFPS and Org-24461

Chicken posterior eyecup lined by the retina were prepared, loaded with [ 3H]glycine and superfused in order to determine its release in various experimental conditions. Electrical field stimulation of the retina evoked [ 3H]glycine release with a voltage- and frequency-dependent manner and this release may be originated from glycinergic amacrine cell processes of the inner plexiform layer of the retina. Glycine released from an abundance of different amacrine cells may modulate retinal circuitry by activation of inhibitory glycine receptors and by acting as a coagonist on N-methyl- d-aspartate receptors on AII amacrine cells and retinal ganglion cells. The latter effect of glycine may be modulated by glycine transporter type-1. Cells with glycine transporter type-1 immunopositive staining were visualized in the inner nuclear layer and dens immunolabeling was also detected throughout the inner plexiform layer of chicken retina. Glycine and the substrate-type glycine transporter type-1 inhibitor sarcosine increased [ 3H]glycine release from glycinergic amacrine cells and/or glial cells by extrusion of glycine from cytoplasmic pools by homo- and heteroexchange mechanisms. Deprivation of oxygen and glucose from the buffer used for superfusion evoked a marked increase in [ 3H]glycine efflux, an effect probably due to reverse mode operation of glycine transporter type-1. The non-transportable glycine transporter type-1 inhibitors NFPS and Org-24461, which did not alter [ 3H]glycine efflux from isolated chicken retina by themselves in normoxic condition, inhibited oxygen and glucose deprivation-induced [ 3H]glycine release. It is concluded that reduction of the N-methyl- d-aspartate receptor coagonist glycine concentrations in hypoxic conditions by glycine transporter type-1 inhibitors may decrease N-methyl- d-aspartate receptor-mediated neuronal toxicity and cell death in retinal tissue.

Retinal ischemic injury rescued by sodium 4-phenylbutyrate in a rat model

Retinal ischemia is a common cause of visual impairment for humans and animals. Herein, the neuroprotective effects of phenylbutyrate (PBA) upon retinal ischemic injury were investigated using a rat model. Retinal ganglion cells (RGCs) were retrograde labeled with the fluorescent tracer fluorogold (FG) applied to the superior collicoli of test Sprague–Dawley rats. High intraocular pressure and retinal ischemia were induced seven days subsequent to such FG labeling. A dose of either 100 or 400 mg/kg PBA was administered intraperitoneally to test rats at two time points, namely 30 min prior to the induction of retinal ischemia and 1 h subsequent to the cessation of the procedure inducing retinal ischemia. The test-rat retinas were collected seven days subsequent to the induction of retinal ischemia, and densities of surviving RGCs were estimated by counting FG-labeled RGCs within the retina. Histological analysis revealed that ischemic injury caused the loss of retinal RGCs and a net decrease in retinal thickness. For PBA-treated groups, almost 100% of the RGCs were preserved by a pre-ischemia treatment with PBA (at a dose of either 100 or 400 mg/kg), while post-ischemia treatment of RGCs with PBA did not lead to the preservation of RGCs from ischemic injury by PBA as determined by the counting of whole-mount retinas. Pre-ischemia treatment of RGCs with PBA (at a dose of either 100 or 400 mg/kg) significantly reduced the level of ischemia-associated loss of thickness of the total retina, especially the inner retina, and the inner plexiform layer of retina. Besides, PBA treatment significantly reduced the ischemia-induced loss of cells in the ganglion-cell layer of the retina. Taken together, these results suggest that PBA demonstrates a marked neuroprotective effect upon high intraocular pressure-induced retinal ischemia when the PBA is administered prior to ischemia induction.

OFF-cholinergic-pathway-selective localization of P2X2 purinoceptors in the mouse retina.

It is known that, in the retina, extracellular adenosine triphosphate (ATP) inhibits acetylcholine (ACh) release from cholinergic neurons, but the types of purinoceptors on cholinergic neurons have not been examined. In the present work, we immunohistochemically examined the distribution of the purinoceptors P2X1, P2X2, P2X4, and P2X7 in relation to the cholinergic system of the retina in wild-type mice and transgenic mice expressing green fluorescent protein (GFP). Immunoreactivity for P2X2 was very strong in sublamina a of the inner plexiform layer but very weak in sublamina b of the inner plexiform layer of the retina. Immunoreactivity for P2X2 was colocalized with that for choline acetyltransferase (ChAT). When transgenic mice were treated with the immunotoxin-mediated cell-targeting technology to ablate cholinergic amacrine cells selectively, immunoreactivity for P2X2 and the signals for GFP disappeared in parallel and selectively in the OFF pathway. The distribution of immunoreactivity for P2X1, P2X4, and P2X7 differed from that of ChAT immunoreactivity. The selective distribution of P2X2 purinergic receptors in OFF-type cholinergic amacrine cells indicates that the P2X2 purinergic signaling systems in the ON and OFF pathways of the inner plexiform layer of the mouse retina are functionally different. The distribution of P2X2 purinoceptors may be responsible for the selective regulation of ACh release in the OFF pathway.

Immunohistochemical localization of copper-zinc and manganese superoxide dismutases in rat tissues.

Immunolocalization of both copper-zinc (CuZn) and manganese (Mn) superoxide dismutases (SODs) in various formalin-fixed rat tissues was investigated using the indirect immunoenzyme method. The optimal dilution was 1:10000 for rabbit anti-rat CuZnSOD and 1:5000 for anti-rat MnSOD antisera, respectively. The higher dilutions of the present antisera than those used in previous studies enabled a higher resolution of the present immunostaining because of a lower background staining. Neither SOD have been previously reported to be stained in eyeballs and brain. The following tissues were intensely stained for CuZnSOD: the fundic glands of the stomach, epithelium of the large intestine, tracheal and bronchial epithelia, liver parenchymal cells, proximal tubules and papillary ducts of the kidneys, pancreatic ducts and islets, zona glomerulosa of the adrenals, myocardial cells, ciliary bodies and pigment cell layers of retinas. On the other hand, the MnSOD reactivity was found to be rich in the following tissues: the gastric pits, epithelium of the small intestine, tracheal epithelium, Henle's loop and collecting ducts of the kidneys, zona fasciculata of the adrenals, ciliary bodies and inner plexiform layer of retinas, and cortical neurons. The surface epithelia of both gastrointestinal and respiratory tracts tended to have high reactivities for both SODs, suggesting that the antioxidant enzyme defense system in these tissues responded to the exposure to superoxide generated from environmental oxygen. There was a wide range of variability in the distribution of each SOD from cell to cell. The present technique is thus considered to be useful for revealing site-specific changes in SODs in various rat tissues.

An electron microscopic study on the retina of rodless mutant mice (ddN/Nagoya).

The fine structure of the retina in rodless mutant mice (ddN/Nagoya) was studied electron-microscopically. Photoreceptor cells of the retina in these mice degenerated and entirely disappeared in the course of postnatal development. Consequently in the adult mice the inner nuclear layer was contiguous with the outer limiting membrane. Small triangular plexiform areas (remnant of the outer plexiform layer) intervened between the outer limiting membrane and the outermost row of the bipolar cells. These plexiform areas were occupied by the processes and terminals classified into four types; neurotubular processes, neurofilamentous processes, terminals containing spherical vesicles and terminals containing cored vesicles. A few synaptic contacts made by these structures were observed. A small part of the neurotubular processes was assigned to be the bipolar cell dendrites, while the other profiles could not be identified in this study.In the inner plexiform layer of the retina in normal mice, large bipolar terminals which were characterized by the presence of ribbons and closely packed vesicles made diad synaptic contacts, whereas in the rodless retina of the mutant mice, the diad synaptic contacts between smaller terminals were observed packed less closely with vesicles and containing ribbons. In the inner plexiform layer of the rodless retina the ganglion dendrites, the amacrine terminals and their synaptic contacts were well preserved, though the size of components forming synapses seemed to be somewhat reduced.

Lateral interactions at inner plexiform layer of vertebrate retina: antagonistic responses to change.

Lateral interactions at the inner plexiform layer of the retina of the mudpuppy were studied intracellularly after they were isolated from interactions at the outer plexiform layer with a special stimulus. The isolation was confirmed by recording no surround effect at bipolar cells under conditions that elicited a strong surround effect at ganglion cells. It appears that amacrine cell, which respond to spatiotemporal change at one retinal region, inhibit the response to change in on-off ganglion cells at adjacent sites.