scholarly journals Retinal glial cells under hypoxia possibly function in mammalian myopia by responding to mechanical stimuli, affecting hormone metabolism and peptide secretion

2020 ◽  
Author(s):  
Xuhong Zhang ◽  
Yingying Wen ◽  
Le Jin ◽  
Dongyan Zhang ◽  
Liyue Zhang ◽  
...  
Keyword(s):  
Blood Vessels ◽  
Glial Cells ◽  
Müller Cells ◽  
Mechanical Stimuli ◽  
Muller Cells ◽  
Protein Fluorescence ◽  
Target Proteins ◽  
Hypoxic Conditions ◽  
The Common ◽  
Peptide Secretion

AbstractPurposeChanges in the retina and the choroid blood vessels are regularly observed in myopia. The aim of this study is to test if the retinal glial cells, which directly contact blood vessels, play a role in mammalian myopia.MethodWe adapted the common form-deprivation myopia mouse model and used the retina slice and whole-mount immunofluorescence technique to evaluate changes in the morphology, and distribution of retinal glial cells. We then searched the Gene Expression Omnibus database for series on myopia and retinal glial cells (astrocytes and Müller cells). Using review articles and the National Center for Biotechnology Information gene database, we obtained clusters of myopia-related gene lists. By searching SwissTargetPrediction, we collected information on atropine target proteins. We then used online tools to find the Gene Ontology analysis enriched clusters, pathways, and proteins that provide correlative evidence.ResultGlial fibrillary acidic protein fluorescence was observed in mice eyes that were covered and deprived of light for five days compared to uncovered eyes, and the cell morphology became more star-like. From in silico experiments, we identified several pathways and proteins that were common to both myopia and retinal glial cells in hypoxic conditions. The common pathways in human astrocytes represented response to mechanical stimuli, peptide secretion, skeletal system development, and monosaccharide binding. In mouse Müller cells, the pathways represented membrane raft and extracellular structure organisation. The proteins common to myopia and hypoxic glial cells were highly relevant to atropine target proteins.ConclusionRetinal astrocytes and Müller cells under hypoxic conditions contribute to the development of myopia, and may be a valid target for atropine.

scholarly journals A2AR Antagonists Upregulate Expression of GS and GLAST in Rat Hypoxia Model

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Jun Yu ◽  
Yan Yan ◽  
Yiye Chen ◽  
Yan Zheng ◽  
Xiaoyan Yu ◽  
...  
Keyword(s):  
Müller Cells ◽  
Muller Cells ◽  
Cell Viability Assay ◽  
Hypoxic Conditions ◽  
Viability Assay ◽  
Drug Concentrations ◽  
A Cell ◽  
Short Time

Background. The aim of this study was to research the effects of glutamine synthetase (GS) and glutamate aspartate transporter (GLAST) in rat Müller cells and the effects of an adenosine A2AR antagonist (SCH 442416) on GS and GLAST in hypoxia both in vivo and in vitro. Methods. This study used RT-PCR and Western blotting to quantify the expressions of GS and GLAST under different hypoxic conditions as well as the expressions of GS and GLAST at different drug concentrations. A cell viability assay was used to assess drug toxicity. Results. mRNA and protein expression of GS and GLAST in hypoxia Group 24 h was significantly increased. mRNA and protein expressions of GS and GLAST both increased in Group 1 μM SCH 442416 compared with other groups. One micromolar SCH 442416 could upregulate GS and GLAST’s activity in hypoxia both in vivo and in vitro. Conclusions. Hypoxia activates GS and GLAST in rat retinal Müller cells in a short time in vitro. (2) A2AR antagonists upregulate the activity of GS and GLAST in hypoxia both in vivo and in vitro.

Müller Cell Ca2+ Waves Evoked by Purinergic Receptor Agonists in Slices of Rat Retina

2001 ◽  
Vol 85 (2) ◽  
pp. 986-994 ◽  
Author(s):  
Yang Li ◽  
Lynne A. Holtzclaw ◽  
James T. Russell
Keyword(s):  
Glial Cells ◽  
Purinergic Receptor ◽  
Rank Order ◽  
Müller Cells ◽  
Uridine Diphosphate ◽  
Muller Cells ◽  
Wave Amplification ◽  
Dye Loading ◽  
Intracellular Ca ◽  
Retinal Slices

We have measured agonist evoked Ca2+ waves in Müller cells in situ within freshly isolated retinal slices. Using an eye cup dye loading procedure we were able to preferentially fill Müller glial cells in retinal slices with calcium green. Fluorescence microscopy revealed that bath perfusion of slices with purinergic agonists elicits Ca2+ waves in Müller cells, which propagate along their processes. These Ca2+ signals were insensitive to tetrodotoxin (TTX, 1.0 μM) pretreatment. Cells were readily identified as Müller cells by their unique morphology and by subsequent immunocytochemical labeling with glial fibrillary acidic protein antibodies. While cells never exhibited spontaneous Ca2+ oscillations, purinoreceptor agonists, ATP, 2 MeSATP, ADP, 2 MeSADP, and adenosine readily elicited Ca2+ waves. These waves persisted in the absence of [Ca2+]o but were abolished by thapsigargin pretreatment, suggesting that the purinergic agonists tested act by releasing Ca2+ from intracellular Ca2+ stores. The rank order of potency of different purines and pyrimidines for inducing Ca2+ signals was 2 MeSATP = 2MeSADP > ADP > ATP ≫ αβmeATP = uridine triphosphate (UTP) > uridine diphosphate (UDP). The Ca2+signals evoked by ATP, ADP, and 2 MeSATP were inhibited by reactive blue (100 μM) and suramin (200 μM), and the adenosine induced signals were abolished only by 3,7-dimethyl-1-propargylxanthine (200 μM) and not by 1,3-dipropyl-8-(2-amino-4-chlorophenyl)-xanthine) or 8-cyclopentyl-1,3-dipropylxanthine at the same concentration. Based on these pharmacological characteristics and the dose-response relationships for ATP, 2 MeSATP, 2 MeSADP, ADP, and adenosine, we concluded that Müller cells express the P1A2 and P2Y1 subtypes of purinoceptors. Analysis of Ca2+ responses showed that, similar to glial cells in culture, wave propagation occurred by regenerative amplification at specialized Ca2+ release sites (wave amplification sites), where the rate of Ca2+ release was significantly enhanced. These data suggest that Müller cells in the retina may participate in signaling, and this may serve as an extra-neuronal signaling pathway.

scholarly journals A dialogue between glia and neurons in the retina: modulation of neuronal excitability

2004 ◽  
Vol 1 (3) ◽  
pp. 245-252 ◽  
Author(s):  
ERIC A. NEWMAN
Keyword(s):  
Synaptic Transmission ◽  
Glial Cells ◽  
Neuronal Excitability ◽  
Ganglion Cells ◽  
Brain Slices ◽  
Müller Cells ◽  
Muller Cells ◽  
Signaling Mechanisms ◽  
Bidirectional Signaling ◽  
Stimulation Of

Bidirectional signaling between neurons and glial cells has been demonstrated in brain slices and is believed to mediate glial modulation of synaptic transmission in the CNS. Our laboratory has characterized similar neuron–glia signaling in the mammalian retina. We find that light-evoked neuronal activity elicits Ca2+ increases in Müller cells, which are specialized retinal glial cells. Neuron to glia signaling is likely mediated by the release of ATP from neurons and is potentiated by adenosine. Glia to neuron signaling has also been observed and is mediated by several mechanisms. Stimulation of glial cells can result in either facilitation or depression of synaptic transmission. Release of D-serine from Müller cells might also potentiate NMDA receptor transmission. Müller cells directly inhibit ganglion cells by releasing ATP, which, following hydrolysis to adenosine, activates neuronal A1 receptors. The existence of bidirectional signaling mechanisms indicates that glial cells participate in information processing in the retina.

scholarly journals Glial cell regulation of neuronal activity and blood flow in the retina by release of gliotransmitters

2015 ◽  
Vol 370 (1672) ◽  
pp. 20140195 ◽  
Author(s):  
Eric A. Newman
Keyword(s):  
Blood Flow ◽  
Arachidonic Acid ◽  
Glial Cells ◽  
Neuronal Activity ◽  
Neurovascular Coupling ◽  
Müller Cells ◽  
Future Research ◽  
Prostaglandin E ◽  
Sk Channels ◽  
Muller Cells

Astrocytes in the brain release transmitters that actively modulate neuronal excitability and synaptic efficacy. Astrocytes also release vasoactive agents that contribute to neurovascular coupling. As reviewed in this article, Müller cells, the principal retinal glial cells, modulate neuronal activity and blood flow in the retina. Stimulated Müller cells release ATP which, following its conversion to adenosine by ectoenzymes, hyperpolarizes retinal ganglion cells by activation of A1 adenosine receptors. This results in the opening of G protein-coupled inwardly rectifying potassium (GIRK) channels and small conductance Ca 2+ -activated K + (SK) channels. Tonic release of ATP also contributes to the generation of tone in the retinal vasculature by activation of P2X receptors on vascular smooth muscle cells. Vascular tone is lost when glial cells are poisoned with the gliotoxin fluorocitrate. The glial release of vasoactive metabolites of arachidonic acid, including prostaglandin E 2 (PGE 2 ) and epoxyeicosatrienoic acids (EETs), contributes to neurovascular coupling in the retina. Neurovascular coupling is reduced when neuronal stimulation of glial cells is interrupted and when the synthesis of arachidonic acid metabolites is blocked. Neurovascular coupling is compromised in diabetic retinopathy owing to the loss of glial-mediated vasodilation. This loss can be reversed by inhibiting inducible nitric oxide synthase. It is likely that future research will reveal additional important functions of the release of transmitters from glial cells.

scholarly journals 670nm photobiomodulation modulates bioenergetics and oxidative stress, in rat Müller cells challenged with high glucose

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0260968
Author(s):  
Hannah J. Nonarath ◽  
Alexandria E. Hall ◽  
Gopika SenthilKumar ◽  
Betsy Abroe ◽  
Janis T. Eells ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Glial Cells ◽  
High Glucose ◽  
Near Infrared ◽  
Müller Cells ◽  
Model System ◽  
Light Treatment ◽  
Muller Cells ◽  
Müller Glial Cells

Diabetic retinopathy (DR), the most common complication of diabetes mellitus, is associated with oxidative stress, nuclear factor-κB (NFκB) activation, and excess production of vascular endothelial growth factor (VEGF) and intracellular adhesion molecule-1 (ICAM-1). Muller glial cells, spanning the entirety of the retina, are involved in DR inflammation. Mitigation of DR pathology currently occurs via invasive, frequently ineffective therapies which can cause adverse effects. The application of far-red to near-infrared (NIR) light (630-1000nm) reduces oxidative stress and inflammation in vitro and in vivo. Thus, we hypothesize that 670nm light treatment will diminish oxidative stress preventing downstream inflammatory mechanisms associated with DR initiated by Muller cells. In this study, we used an in vitro model system of rat Müller glial cells grown under normal (5 mM) or high (25 mM) glucose conditions and treated with a 670 nm light emitting diode array (LED) (4.5 J/cm2) or no light (sham) daily. We report that a single 670 nm light treatment diminished reactive oxygen species (ROS) production and preserved mitochondrial integrity in this in vitro model of early DR. Furthermore, treatment for 3 days in culture reduced NFκB activity to levels observed in normal glucose and prevented the subsequent increase in ICAM-1. The ability of 670nm light treatment to prevent early molecular changes in this in vitro high glucose model system suggests light treatment could mitigate early deleterious effects modulating inflammatory signaling and diminishing oxidative stress.

scholarly journals Evaluation of Proteoforms of the Transmembrane Chemokines CXCL16 and CX3CL1, Their Receptors, and Their Processing Metalloproteinases ADAM10 and ADAM17 in Proliferative Diabetic Retinopathy

2021 ◽  
Vol 11 ◽  
Author(s):  
Ahmed M. Abu El-Asrar ◽  
Mohd Imtiaz Nawaz ◽  
Ajmal Ahmad ◽  
Alexandra De Zutter ◽  
Mohammad Mairaj Siddiquei ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
Blood Vessels ◽  
Proliferative Diabetic Retinopathy ◽  
Müller Cells ◽  
Intercellular Adhesion Molecule ◽  
Enzyme Linked Immunosorbent Assay ◽  
Diabetic Patients ◽  
Muller Cells ◽  
Epiretinal Membranes ◽  
Positive Correlations

The transmembrane chemokine pathways CXCL16/CXCR6 and CX3CL1/CX3CR1 are strongly implicated in inflammation and angiogenesis. We investigated the involvement of these chemokine pathways and their processing metalloproteinases ADAM10 and ADAM17 in the pathophysiology of proliferative diabetic retinopathy (PDR). Vitreous samples from 32 PDR and 24 non-diabetic patients, epiretinal membranes from 18 patients with PDR, rat retinas, human retinal Müller glial cells and human retinal microvascular endothelial cells (HRMECs) were studied by enzyme-linked immunosorbent assay, immunohistochemistry and Western blot analysis. In vitro angiogenesis assays were performed and the adherence of leukocytes to CXCL16-stimulated HRMECs was assessed. CXCL16, CX3CL1, ADAM10, ADAM17 and vascular endothelial growth factor (VEGF) levels were significantly increased in vitreous samples from PDR patients. The levels of CXCL16 were 417-fold higher than those of CX3CL1 in PDR vitreous samples. Significant positive correlations were found between the levels of VEGF and the levels of CXCL16, CX3CL1, ADAM10 and ADAM17. Significant positive correlations were detected between the numbers of blood vessels expressing CD31, reflecting the angiogenic activity of PDR epiretinal membranes, and the numbers of blood vessels and stromal cells expressing CXCL16, CXCR6, ADAM10 and ADAM17. CXCL16 induced upregulation of phospho-ERK1/2, p65 subunit of NF-κB and VEGF in cultured Müller cells and tumor necrosis factor-α induced upregulation of soluble CXCL16 and ADAM17 in Müller cells. Treatment of HRMECs with CXCL16 resulted in increased expression of intercellular adhesion molecule-1 (ICAM-1) and increased leukocyte adhesion to HRMECs. CXCL16 induced HRMEC proliferation, formation of sprouts from HRMEC spheroids and phosphorylation of ERK1/2. Intravitreal administration of CXCL16 in normal rats induced significant upregulation of the p65 subunit of NF-κB, VEGF and ICAM-1 in the retina. Our findings suggest that the chemokine axis CXCL16/CXCR6 and the processing metalloproteinases ADAM10 and ADAM17 might serve a role in the initiation and progression of PDR.

scholarly journals Metabolic Imbalance Effect on Retinal Müller Glial Cells Reprogramming Capacity: Involvement of Histone Deacetylase SIRT6

2021 ◽  
Vol 12 ◽  
Author(s):  
L Francisco Sanhueza Salas ◽  
Alfredo García-Venzor ◽  
Natalia Beltramone ◽  
Claudia Capurro ◽  
Debra Toiber ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Histone Deacetylase ◽  
Glial Cells ◽  
High Glucose ◽  
Müller Cells ◽  
Enrichment Analysis ◽  
Regulatory Elements ◽  
Muller Cells ◽  
Müller Glial Cells ◽  
And Oxidative Stress

Retinal Müller glial cells (MGs) are among the first to demonstrate metabolic changes during retinal disease and are a potential source of regenerative cells. In response to a harmful stimulus, they can dedifferentiate acquiring neural stem cells properties, proliferate and migrate to the damaged retinal layer and differentiate into lost neurons. However, it is not yet known how this reprogramming process is regulated in mammals. Since glucose and oxygen are important regulatory elements that may help directing stem cell fate, we aimed to study the effect of glucose variations and oxidative stress in Müller cells reprogramming capacity and analyze the participation the histone deacetylase SIRT6, as an epigenetic modulator of this process. We found that the combination of high glucose and oxidative stress induced a decrease in the levels of the marker glutamine synthetase, and an increase in the migration capacity of the cells suggesting that these experimental conditions could induce some degree of dedifferentiation and favor the migration ability. High glucose induced an increase in the levels of the pluripotent factor SOX9 and a decrease in SIRT6 levels accompanied by the increase in the acetylation levels of H3K9. Inhibiting SIRT6 expression by siRNA rendered an increase in SOX9 levels. We also determined SOX9 levels in retinas from mice with a conditional deletion of SIRT6 in the CNS. To further understand the mechanisms that regulate MGs response under metabolic impaired conditions, we evaluated the gene expression profile and performed Gene Ontology enrichment analysis of Müller cells from a murine model of Diabetes. We found several differentially expressed genes and observed that the transcriptomic change involved the enrichment of genes associated with glucose metabolism, cell migration, development and pluripotency. We found that many functional categories affected in cells of diabetic animals were directly related to SIRT6 function. Transcription factors enrichment analysis allowed us to predict several factors, including SOX9, that may be involved in the modulation of the differential expression program observed in diabetic MGs. Our results underline the heterogeneity of Müller cells response and the challenge that the study of metabolic impairment in vivo represents.

scholarly journals Review and Hypothesis: A Potential Common Link Between Glial Cells, Calcium Changes, Modulation of Synaptic Transmission, Spreading Depression, Migraine, and Epilepsy—H+

2021 ◽  
Vol 15 ◽  
Author(s):  
Robert Paul Malchow ◽  
Boriana K. Tchernookova ◽  
Ji-in Vivien Choi ◽  
Peter J. S. Smith ◽  
Richard H. Kramer ◽  
...  
Keyword(s):  
Synaptic Transmission ◽  
Intracellular Calcium ◽  
Glial Cells ◽  
Spreading Depression ◽  
Müller Cells ◽  
Extracellular Atp ◽  
Muller Cells ◽  
Radial Glial Cells ◽  
Synaptic Modulation ◽  
Radial Glial

There is significant evidence to support the notion that glial cells can modulate the strength of synaptic connections between nerve cells, and it has further been suggested that alterations in intracellular calcium are likely to play a key role in this process. However, the molecular mechanism(s) by which glial cells modulate neuronal signaling remains contentiously debated. Recent experiments have suggested that alterations in extracellular H+ efflux initiated by extracellular ATP may play a key role in the modulation of synaptic strength by radial glial cells in the retina and astrocytes throughout the brain. ATP-elicited alterations in H+ flux from radial glial cells were first detected from Müller cells enzymatically dissociated from the retina of tiger salamander using self-referencing H+-selective microelectrodes. The ATP-elicited alteration in H+ efflux was further found to be highly evolutionarily conserved, extending to Müller cells isolated from species as diverse as lamprey, skate, rat, mouse, monkey and human. More recently, self-referencing H+-selective electrodes have been used to detect ATP-elicited alterations in H+ efflux around individual mammalian astrocytes from the cortex and hippocampus. Tied to increases in intracellular calcium, these ATP-induced extracellular acidifications are well-positioned to be key mediators of synaptic modulation. In this article, we examine the evidence supporting H+ as a key modulator of neurotransmission, review data showing that extracellular ATP elicits an increase in H+ efflux from glial cells, and describe the potential signal transduction pathways involved in glial cell—mediated H+ efflux. We then examine the potential role that extracellular H+ released by glia might play in regulating synaptic transmission within the vertebrate retina, and then expand the focus to discuss potential roles in spreading depression, migraine, epilepsy, and alterations in brain rhythms, and suggest that alterations in extracellular H+ may be a unifying feature linking these disparate phenomena.

Retinal glucose metabolism in mice lacking the L-glutamate/aspartate transporter

2004 ◽  
Vol 21 (4) ◽  
pp. 637-643 ◽  
Author(s):  
VIJAY P. SARTHY ◽  
V. JOSEPH DUDLEY ◽  
KOHICHI TANAKA
Keyword(s):  
Glucose Metabolism ◽  
Glucose Uptake ◽  
Glial Cells ◽  
Glutamate Transporter ◽  
Lactate Production ◽  
Müller Cells ◽  
Mouse Retina ◽  
Muller Cells ◽  
Wild Type ◽  
Lactate Release

The conventional view that glucose is the substrate for neuronal energy metabolism has been recently challenged by the “lactate shuttle” hypothesis in which glutamate cycling in glial cells drives all neuronal glucose metabolism. According to this view, glutamate released by activated retinal neurons is transported into Müller (glial) cells where it triggers glycolysis. The lactate released by Müller cells serves as the energy substrate for neuronal metabolism. Because the L-Glutamate/aspartate transporter (GLAST) is the predominant, Na+-dependent, glutamate transporter expressed by Müller cells, we have used GLAST-knockout (GLAST−/−) mice to examine the relationship between lactate release and GLAST activity in the retina. We found that glucose uptake and lactate production by the GLAST−/− mouse retina was similar to that observed in the wild type mouse retina. Furthermore, addition of 1 mM glutamate and NH4Cl to the incubation medium did not further stimulate glucose uptake in either case. When lactate release was measured in the presence of the lactate uptake inhibitor, α-cyano-4-hydroxycinnamate, there was no significant change in the amount of lactate released by retinas from GLAST−/− mice compared to the wild type. Finally, lactate release was similar under both dark and light conditions. These results show that lactate production and release is not altered in retinas of GLAST−/− mice, which suggests that metabolic coupling between photoreceptors and Müller cells is not mediated by the glial glutamate transporter, GLAST.

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