endothelin-1 and Glaucoma

Glaucoma is a leading cause of irreversible blindness worldwide. While intraocular pressure (IOP) presents a major risk factor, the underlying pathophysiology still remains largely unclear. The correlation between vascular abnormalities and glaucoma has been deliberated for decades. Evidence for a role played by vascular factors in the pathogenesis of glaucomatous neurodegeneration has already been postulated. In addition, the fact that glaucoma causes both structural and functional changes to retinal blood vessels has been described. This review aims to investigate the published evidence concerning the relationship between vascular abnormalities and glaucoma, and to provide an overview of the "chicken or egg" dilemma in glaucoma. In this study, several biomarkers of glaucoma progression from a vascular perspective, including endothelin-1 (ET-1), nitric oxide, vascular endothelial growth factor (VEGF), and matrix metalloproteinases (MMPs), were identified and subsequently assessed for their potential as pharmacological intervention targets.

Topics: Blindness; Endothelin-1; Glaucoma; Humans; Intraocular Pressure; Vascular Endothelial Growth Factor A

This review article is focused on the various facets of possible endothelin's role in glaucoma; involvement of endothelin in other ocular, in particular vascular, diseases is not specifically discussed. Endothelin is an ubiquitous molecule that occurs in practically all ocular tissues. Its primary physiological function is regulation of the blood vessel diameter and hence regulation of the blood supply in tissues. It is secreted locally, and exerts its effect also predominantly locally. This limits the value of venous blood sampling for estimation of the endothelin function in a particular patient, or in study cohorts as well. Endothelin is involved in the regulation of intraocular pressure, in the regulation of blood flow and in activation of retinal and optic nerve head astrocytes. All these functions are of high importance when it comes to pathogenesis of glaucoma. Possible future directions for glaucoma treatment should encompass pharmacological antagonism to endothelin, an avenue which is at present hindered by potentially serious side-effects of available endothelin-antagonists.. Dieser Review-Artikel fokussiert sich auf verschiedene Aspekte der Endothelinrollen bei einem Glaukom; auf die Beteiligung von Endothelin bei anderen, vor allem vaskulären okulären Erkrankungen wird in diesem Artikel nicht im Detail eingegangen. Endothelin ist ein ubiquitäres Molekül, das in praktisch allen okulären Geweben vorhanden ist. Seine primäre physiologische Rolle ist die Steuerung des Gefäßdurchmessers und somit die Regulierung der Gewebedurchblutung. Sowohl die Sekretion als auch die Effekte des Endothelins finden lokal statt; ein Teil des Endothelins gelangt zwar in die systemische Zirkulation, jedoch ist dieser Teil variabel. Somit ist die Messung des Plasmaendothelinspiegels im venösen Blut nicht ideal für die Einschätzung der Endothelinfunktion, sowohl bei einzelnen Patienten als auch in Studienkohorten. Im Kontext der Glaukompathogenese lassen sich die wichtigsten Funktionen des Endothelins im Auge in Regulation des Augeninnendruckes, Regulation der Durchblutung und Aktivierung der Gliazellen/Astrozyten im hinteren Segment, in der Netzhaut und im Sehnerv einteilen. Bei so einem breiten Spektrum der Funktionen, die direkt bei der Pathogenese des Glaukoms involviert sind, liegt es auf der Hand, dass künftige therapeutische Ansätze beim Glaukom eine pharmakologische Modulation des Endothelins beinhalten sollten. Zu diesem Zweck ist derzeit die entsprechende Anwendung der zur Verfügung stehenden Endothelinantagonisten durch ihr ungünstiges Nebenwirkungsprofil beeinträchtigt.

Topics: Endothelin-1; Eye; Glaucoma; Humans; Intraocular Pressure; Regional Blood Flow

The exact pathophysiology of glaucoma is not fully understood. Understanding of the vascular pathophysiology of glaucoma requires: knowing the techniques for measuring ocular blood flow and characterizing the topography of vascular disease and the mechanisms involved in this neuropathy. A decreased mean ocular perfusion pressure and a loss of vascular autoregulation are implicated in glaucomatous disease. Early decrease in ocular blood flow has been identified in primary open-angle glaucoma and normal pressure glaucoma, contributing to the progression of optic neuropathy. The vascular damage associated with glaucoma is present in various vascular territories within the eye (from the ophthalmic artery to the retina) and is characterized by a decrease in basal blood flow associated with a dysfunction of vasoregulation.

Topics: Angiotensin II; Arterial Pressure; Blood Viscosity; Endothelin-1; Endothelium, Vascular; Eye; Glaucoma; Hemodynamics; Humans; Intraocular Pressure; Nitric Oxide; Prostaglandins I; Vascular Resistance; Vasoconstriction; Vasodilation; Vasomotor System

Increasing evidence suggests that the complex interactions among multiple cell types including neuronal, glial, and vascular cells, are critical for maintaining adequate cerebral blood flow that is necessary for normal brain function and survival. The disturbance of these interactions contributes to the pathogenesis of central nervous system disorders such as stroke and Alzheimer's disease. The retina is part of the central nervous system, and the properties of vasculature in the retina are similar to those in the brain. The interactions among multiple cell types in the retina also play an important role in the maintenance of tissue homeostasis, and the impairment of interactions can contribute to the onset and/or progression of retinal diseases. In this review, we describe the neurovascular interactions in the retina and alternations of interactions in pathological conditions such as diabetic retinopathy and glaucoma.

Topics: Angiotensin II; Catecholamines; Cell Communication; Diabetic Retinopathy; Disease Progression; Drug Discovery; Endothelin Receptor Antagonists; Endothelin-1; Glaucoma; Homeostasis; Molecular Targeted Therapy; N-Methylaspartate; Neuroglia; Neurons; Nitric Oxide; Nitric Oxide Synthase Type II; Potassium Channels, Calcium-Activated; Receptors, GABA; Retina; Retinal Diseases; Retinal Vessels

To review the role of endothelin in intraocular pressure control, its effect on the trabecular meshwork (TM) and the outflow facility, effect on ocular blood flow and vascular regulation and the potential role of endothelin-1 (ET-1) antagonism in the therapeutic paradigm of glaucoma.. A thorough review of the medical literature and a meta-analysis on the level of ET-1 in OAG patients in an attempt to demonstrate the evolving importance of endothelin in glaucoma.. ET-1 has been identified in the plasma in concentrations that are markedly increased in a number of systemic as well as ocular pathologies such as glaucoma where underlying vascular dysfunction and pathology play a role. It has been shown that ET-1 induces human TM cell contraction in culture and that it can affect the outflow facility. Evidence indicates that systemic ET-1 regulatory mechanisms and vascular responses to it are also altered in glaucoma. Recently, several endothelin antagonists have been shown to have a potential role in glaucoma therapy. In our meta-analysis, only patients with normal tension glaucoma (NTG) (as opposed to patients with high tension glaucoma (HTG)) had significantly higher plasma ET-1 levels compared to non-glaucomatous control. High tension glaucomaHTG patients had significant higher levels of ET-1 in the aqueous humor.. The potential role of ET-1 antagonism in the therapeutic paradigm of glaucoma is an exciting possible new approach in the treatment of OAG patients. In NTG, ET-1 may have both a local and systemic component of vascular dysregulation, while whereas in HTG, the role of ET-1 may be dominantly localized to ocular tissue.

Topics: Animals; Antihypertensive Agents; Aqueous Humor; Blood Flow Velocity; Disease Progression; Endothelin Receptor Antagonists; Endothelin-1; Endothelins; Glaucoma; Humans; Intraocular Pressure; Retinal Vessels

It has become increasingly clear that astrocytes may play an important role in the genesis of glaucoma. Astrogliosis occurs in response to ocular stress or the presence of noxious stimuli. Agents that appear to stimulate reactive gliosis are becoming increasingly clear. One class of agents that is emerging is the endothelins (ETs; specifically, ET-1). In this review we examine the interactions of ET-1 with astrocytes and provide examples where ET-1 appears to contribute to activation of astrocytes and play a role in the neurodegenerative effects that accompany such reactivation resulting in astrogliosis. These actions are presented in the context of glaucoma although information is also presented with respect to ET-1's role in the central nervous system and brain. While much has been learned with respect to ET-1/astrocyte interactions, there are still a number of questions concerning the potential therapeutic implications of these findings. Hopefully this review will stimulate others to examine this potential.

Topics: Animals; Astrocytes; Endothelin-1; Glaucoma; Gliosis; Humans; Optic Nerve Diseases

The need of blood flow to different organs varies rapidly over time which is why there is sophisticated local regulation of blood flow. The term dysregulation simply means that blood flow is not properly adapted to this need. Dysregulative mechanisms can lead to an over- or underperfusion. A steady overperfusion may be less critical for long-term damage. A constant underperfusion, however, can lead to some tissue atrophy or in extreme situations to infarction. Unstable perfusion (underperfusion followed by reperfusion) leads to oxidative stress. There are a number of causes that lead to local or systemic vascular dysregulation. Systemic dysregulation can be primary or secondary of nature. A secondary dysregulation is due to other autoimmune diseases such as rheumatoid arthritis, giant cell arteritis, systemic lupus erythematodes, multiple sclerosis, colitis ulcerosa, or Crohns disease. Patients with a secondary vascular dysregulation normally have a high level of circulating endothelin-1 (ET-1). This increased level of ET-1 leads to a reduction of blood flow both in the choroid and the optic nerve head but has little influence on autoregulation. In contrast, primary vascular dysregulation has little influence on baseline ocular blood flow but interferes with autoregulation. This, in turn, leads to unstable oxygen supply, which seems to be a relevant component in the pathogenesis of glaucomatous optic neuropathy.

Topics: Blood Flow Velocity; Blood Pressure; Choroid; Endothelin-1; Glaucoma; Humans; Optic Disk; Peripheral Vascular Diseases; Regional Blood Flow

Vasospasm in the vessels, supporting the optic disc, is nowadays considered one of the possible etiological factors leading to development of glaucomatous neuropathy. This article describes physiological regulatory mechanisms of blood circulation in these vessels, including influence of autonomic nervous system and blood flow autoregulation; it also explains why vasospasm may disturb autoregulation. Special attention is paid to the role of vascular endothelial mediators, which are responsible for autoregulation. Observations indicating that vasospasm may be a risk factor of glaucomatous damage are also presented. The article describes data concerning vasospastic effects of two mediators: endothelin-1 (ET-1), released by vascular endothelium, and neuropeptide Y (NPY), a sympathetic nervous system neurotransmitter, on the vessels supporting the optic disc and their possible role in producing blood flow disturbances in these vessels. Investigation results indicating that endothelial dysfunction, connected with increased ET-1 plasma levels and sympathetic nervous system disorders, may be involved in the pathogenesis of normal-tension glaucoma, are presented.

Topics: Endothelin-1; Glaucoma; Humans; Neuropeptide Y; Regional Blood Flow; Risk Factors

This prospective study aimed to compare vascular parameters (endothelin-1 [ET-1] blood levels, laser Doppler imaging [LDI] of distal phalanxes, and nailfold capillaroscopy) between open-angle glaucoma patients with low- and high-tension optic disc hemorrhages (LTDH and HTDH, respectively). The 33 enrolled patients (mean age, 62.3 ± 13 years) were classified as LTDH or HTDH if they presented at the time of DH detection an intraocular pressure (IOP) < 16 mmHg or ≥ 16 mmHg, respectively. Demographic and ophthalmological data, ET-1 concentrations, LDI (before and 1, 10, and 20 min after cold stimulation), and nailfold capillaroscopy findings were evaluated. The ET-1 blood level was 65% higher in the LTDH (2.27 ± 1.46 pg/ml) than in the HTDH (1.37 ± 0.57 pg/ml; p = 0.03) group. Moreover, there was a statistically significant negative correlation between ET-1 blood concentration and IOP at the time of DH detection (r = -0.45, p = 0.02). Blood flow measurements 10 and 20 min after cold stimulation were lower in the LTDH group than in the HTDH group (p < 0.01). Patients developing DH with lower IOPs have higher ET-1 blood levels and more peripheral vascular dysfunction as estimated by LDI than those with higher IOPs. These findings suggest that distinct underlying mechanisms may be involved in patients developing DH within different IOP ranges.

Topics: Aged; Endothelin-1; Glaucoma; Glaucoma, Open-Angle; Humans; Intraocular Pressure; Low Tension Glaucoma; Middle Aged; Optic Disk; Optic Nerve Diseases; Prospective Studies; Retinal Hemorrhage; Visual Fields

Endothelin-1 (ET-1) overactivity has been implicated as a factor contributing to glaucomatous neuropathy, and it has been utilized in animal models of retinal ischemia. The functional effects of long-term ET-1 exposure and possible compensatory mechanisms have, however, not been investigated. This was therefore the purpose of our study. ET-1 was delivered into rat eyes via a single intravitreal injection of 500 µM or via transgene delivery using an adeno-associated viral (AAV) vector. Retinal function was assessed using electroretinography (ERG) and the retinal expression of potentially compensatory genes was evaluated by means of qRT-PCR. Acute ET-1 delivery led to vasoconstriction and a significant reduction in the ERG response. AAV-ET-1 resulted in substantial transgene expression and ERG results similar to the acute ET-1 injections and comparable to other models of retinal ischemia. Compensatory changes were observed, including an increase in calcitonin gene-related peptide (CGRP) gene expression, which may both counterbalance the vasoconstrictive effects of ET-1 and provide neuroprotection. This chronic ET-1 ischemia model might be especially relevant to glaucoma research, mimicking the mild and repeated ischemic events in patients with long-term vascular dysfunction. The compensatory mechanisms, and particularly the role of vasodilatory CGRP in mitigating the retinal damage, warrant further investigation with the aim of evaluating new therapeutic strategies.

Topics: Animals; Calcitonin Gene-Related Peptide; Dependovirus; Endothelin-1; Glaucoma; Intravitreal Injections; Ischemia; Rats; Retinal Diseases; Transgenes

The purpose of this study was to ascertain whether a correlation exists between glaucoma-associated alteration of ocular vascular haemodynamics and endothelin-1 (ET-1) levels exist. Eyes of patients with cataract (n = 30) or glaucoma (n = 68) were examined with optical coherence tomography (OCT) and OCT-angiography (OCT-A; AngioVue™-RTVue-XR; Optovue, Fremont, California, USA). The peripapillary and the macular vessel density (VD) values were measured. Inferior and superior retinal nerve fibre layer (RNFL) thickness loss was used for further OCT staging. Aqueous humour of the examined eye and plasma were sampled during cataract or glaucoma surgery and analysed by means of ELISA to determine their ET-1 level. Glaucoma eyes are characterised by reductions in RNFL thickness and VD that correlate significantly with the OCT GSS score. Peripheral and ocular ET-1 level were significantly elevated in patients with glaucoma and correlate positively with the OCT-GSS score of the entire study population. Peripapillary and macula VD of glaucoma patients correlates negatively with plasma ET-1 levels. Multivariable analysis showed a subordinate role of intraocular pressure predictive factor for impaired retinal blood flow compared with plasma ET-1 level in glaucoma. Peripheral ET-1 level serves as risk factor for detection of ocular blood flow changes in the optic nerve head region of glaucomatous eyes.

Topics: Cataract; Endothelin-1; Eye; Glaucoma; Hemodynamics; Humans; Nerve Fibers; Regional Blood Flow; Retinal Vessels; Risk Factors; Tomography, Optical Coherence

Elevated intraocular pressure is primarily induced by the increased resistance of conventional outflow of aqueous humor. Dysfunction of the juxtacanalicular region of trabecular meshwork (TM) and Schlemm's canal (SC) endothelium, as the main conventional outflow tissue, have been implicated as the major reasons for the increased resistance. Integrins are widespread in these tissues, especially alpha8 integrin (ITGA8). We aim to investigate the properties of cells expressing ITGA8 in the conventional outflow tissue.. Fluorescence in situ hybridization (FISH) and immunofluorescence (IF) were performed to detect the mRNA and protein levels of ITGA8 in human conventional outflow tissue. ITGA8-positive cells were isolated from the cultured human TM cells through a magnetic bead-based approach. Flow Cytometry was used to determine the purification efficiency. The expressions of TM and SC biomarkers and dexamethasone-induced myocilin secretion capacity of ITGA8-positive cells was assessed by Real-time PCR, IF and Western blot. A gel contraction assay was performed to evaluate contractility of ITGA8-positive cells after endothelin 1 treatment.. ITGA8 was found with robust expression near the inner wall of SC endothelium. After purification, the proportion of ITGA8-positive cells were increased by about 10%. ITGA8-positive cells were identified with the properties as SC endothelial cells, such as more robust expressions of SC biomarkers, less dexamethasone-inducible myocilin expression, and stronger contractility.. This study demonstrated that cells expressing ITGA8 in SC region possess more properties as SC endothelial cells. Our data implicate a crucial role of ITGA8 in aqueous humor (AH) outflow resistance regulation.

Topics: Aqueous Humor; Biomarkers; Cell Survival; Cytoskeletal Proteins; Dexamethasone; Endothelial Cells; Endothelin-1; Endothelium; Eye Proteins; Glaucoma; Glucocorticoids; Glycoproteins; Humans; In Situ Hybridization, Fluorescence; Integrin alpha Chains; Integrins; Intraocular Pressure; Trabecular Meshwork

Endothelin-1 (ET-1) is a vasoactive peptide that is elevated in aqueous humor as well as circulation of primary open angle glaucoma (POAG) patients. ET-1 has been shown to promote degeneration of optic nerve axons and apoptosis of retinal ganglion cells (RGCs), however, the precise mechanisms are still largely unknown. In this study, RNA-seq analysis was used to assess changes in ET-1 mediated gene expression in primary RGCs, which revealed that 23 out of 156 differentially expressed genes (DEGs) had known or predicted mitochondrial function, of which oxidative phosphorylation emerged as the top-most enriched pathway. ET-1 treatment significantly decreased protein expression of key mitochondrial genes including cytochrome C oxidase copper chaperone (COX17) and ATP Synthase, H

Topics: Animals; Copper Transport Proteins; Disease Models, Animal; Endothelin-1; Energy Metabolism; Female; Gene Expression; Glaucoma; Humans; Male; Mitochondria; Mitochondrial Proton-Translocating ATPases; Nerve Degeneration; Rats; Rats, Inbred BN; Retinal Ganglion Cells

Endothelin-1 (ET-1), a potent vasoconstrictor, plays a significant role in the pathophysiology of ocular conditions like glaucoma. Glaucoma is characterized by apoptotic loss of retinal ganglion cells (RGCs) and loss of visual fields and is a leading cause of irreversible blindness. In glaucomatous eyes, retinal ischemia causes release of pro-inflammatory mediators such as interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α and promotes activation of transcription factors such as nuclear factor kappa B (NFKB) and c-Jun. Magnesium acetyltaurate (MgAT) has previously been shown to protect against ET-1 induced retinal and optic nerve damage. Current study investigated the mechanisms underlying these effects of MgAT, which so far remain unknown. Sprague dawley rats were intravitreally injected with ET-1 with or without pretreatment with MgAT. Seven days post-injection, retinal expression of IL-1β, IL-6, TNF-α, NFKB and c-Jun protein and genes was determined using multiplex assay, Western blot and PCR. Animals were subjected to retrograde labeling of RGCs to determine the extent of RGC survival. RGC survival was also examined using Brn3A staining. Furthermore, visual functions of rats were determined using Morris water maze. It was observed that pre-treatment with MgAT protects against ET-1 induced increase in the retinal expression of IL-1β, IL-6 and TNF-α proteins and genes. It also protected against ET-1 induced activation of NFKB and c-Jun. These effects of MgAT were associated with greater RGC survival and preservation of visual functions in rats. In conclusion, MgAT prevents ET-1 induced RGC loss and loss of visual functions by suppressing neuroinflammatory reaction in rat retinas.

Topics: Animals; Apoptosis; Blotting, Western; Disease Models, Animal; Endothelin-1; Female; Glaucoma; Intravitreal Injections; Male; Prognosis; Rats; Rats, Sprague-Dawley; Retinal Diseases; Retinal Ganglion Cells; Taurine; Visual Acuity

The endothelin system (ES) plays a complex role in the pathogenesis of various eye diseases as a local regulator of vascular tone as well as many other physiological processes. Components of ES - endothelins and their receptors - can be found nearly in all cellular structures of the eye, their concentration increases in the presence of many eye diseases. In glaucoma, ES is involved in the mechanisms of eye hypertension by influencing the secretion and outflow of aqueous humor. The increase of endothelin level leads to the decrease of perfusion pressure, hypoxia, astrocyte proliferation, increase of density and rigidity of lamina cribrosa, apoptosis of neural cells, and has a profibrogenic effect. In retinal pathology, increase of endothelins disturbs autoregulation of retinal blood vessels changing the neurovascular interactions, breaks intercellular contacts in the retina, promotes neoangiogenesis. In diabetic retinopathy, ES contributes to the development of microangiopathy and proliferative vitreoretinopathy. The review discusses the possibility of correcting ES activity in the eye with medications by influencing its synthesis, cleavage and receptor binding.. Эндотелиновая система (ЭС) как локальный регулятор не только сосудистого тонуса, но многих других физиологических процессов играет многогранную роль в патогенезе целого ряда глазных болезней. Компоненты ЭС - эндотелины и их рецепторы - обнаружены практически во всех клеточных структурах глаза, и их содержание возрастает при многих глазных болезнях. При глаукоме ЭС участвует в механизмах повышения уровня внутриглазного давления (ВГД) путем влияния как на отток, так и на образование внутриглазной жидкости. Увеличение содержания эндотелина приводит к снижению перфузионного давления, гипоксии, пролиферации астроцитов, повышению плотности и ригидности решетчатой пластинки, апоптозу нервных клеток, оказывает профиброгенное действие. При патологии сетчатки увеличение содержания эндотелина нарушает процессы ауторегуляции сосудов сетчатки путем влияния на нейроваскулярные взаимодействия, нарушает межклеточные контакты в сетчатке, способствует ангиогенезу. При диабетической ретинопатии ЭС участвует в развитии микроангиопатий и пролиферативной витреоретинопатии. Обсуждается возможность медикаментозной коррекции активности ЭС в глазу путем воздействия на синтез, распад и взаимодействие эндотелинов с различными рецепторами.

Topics: Diabetic Retinopathy; Endothelin-1; Endothelins; Glaucoma; Humans; Retina; Retinal Vessels

Glaucoma is a neurodegenerative disease characterized by loss of retinal ganglion cells (RGCs), the output neurons of the retina. Multiple lines of evidence show the endothelin (EDN, also known as ET) system is important in glaucomatous neurodegeneration. To date, the molecular mechanisms within RGCs driving EDN-induced RGC death have not been clarified. The pro-apoptotic transcription factor JUN (the canonical target of JNK signaling) and the endoplasmic reticulum stress effector and transcription factor DNA damage inducible transcript 3 (DDIT3, also known as CHOP) have been shown to act downstream of EDN receptors. Previous studies demonstrated that JUN and DDIT3 were important regulators of RGC death after glaucoma-relevant injures. Here, we characterized EDN insult in vivo and investigated the role of JUN and DDIT3 in EDN-induced RGC death. To accomplish this, EDN1 ligand was intravitreally injected into the eyes of wildtype, Six3-cre

Topics: Animals; Cell Death; Disease Models, Animal; Endothelin-1; Genes, jun; Glaucoma; Humans; Mice; Mice, Inbred C57BL; Retinal Ganglion Cells

The aim of the study was to investigate the endothelin-1 (ET-1) plasma level and its age dependence in patients with normal tension glaucoma (NTG), high tension glaucoma (HTG), and healthy controls. In blood samples from 35 NTG patients, 34 HTG patients, and 36 controls, ET-1 plasma levels were determined by enzyme-linked immunosorbent assay (ELISA). After adjustment for age and gender, the mean ET-1 levels were found to be similar in all three study groups. The age dependency however was highest in NTGs and significantly different from that of the controls. For the HTGs, this dependence was weaker and not significantly different from that of the controls. Our findings suggest that age had a significantly greater influence on ET plasma level in the NTG patients than in the HTG patients and controls. This supports previous reports indicating that ET plays a role in the pathogenesis of glaucoma, and in particular normal NTG.

Topics: Age Factors; Aged; Case-Control Studies; Endothelin-1; Female; Glaucoma; Humans; Intraocular Pressure; Low Tension Glaucoma; Male; Middle Aged

To discover novel therapies that lower IOP by increasing aqueous humor outflow facility, ex vivo ocular perfusion systems provide a valuable tool. However, currently available designs are limited by their throughput. Here we report the development of a compact, scalable perfusion system with improved throughput and its validation using bovine and porcine eyes.. At a fixed IOP of 6 mm Hg, flow rate was measured by flow sensors. We validated the system by measuring the outflow responses to Y-39983 (a Rho kinase inhibitor), endothelin-1 (ET-1), ambrisentan (an antagonist for endothelin receptor A [ETA]), sphigosine-1-phosphate (S1P), JTE-013 (antagonist for S1P receptor 2 [S1P2]), S-nitroso-N-acetylpenicillamine (SNAP, a nitric oxide [NO] donor), and 3-Morpholino-sydnonimine (SIN-1, another NO donor).. The instrument design enabled simultaneous measurements of 20 eyes with a footprint of 1 m2. Relative to vehicle control, Y-39983 increased outflow by up to 31% in calf eyes. On the contrary, ET-1 decreased outflow by up to 79%, a response that could be blocked by pretreatment with ambrisentan, indicating a role for ETA receptors. Interestingly, the effect of ET-1 was also inhibited by up to 70% to 80% by pretreatment with NO donors, SNAP and SIN-1. In addition to testing in calf eyes, similar effects of ET-1 and ambrisentan were observed in adult bovine and porcine eyes.. The compact eye perfusion platform provides an opportunity to efficiently identify compounds that influence outflow facility and may lead to the discovery of new glaucoma therapies.

Topics: Animals; Aqueous Humor; Cattle; Computer-Aided Design; Disease Models, Animal; Endothelin-1; Equipment Design; Glaucoma; Intraocular Pressure; Perfusion; Pyrazoles; Pyridines; Swine; Trabecular Meshwork

We investigated the feasibility and efficacy of using a specific sphingosine 1-phosphate (S1P1) receptor agonist, CYM-5442, to slow or block retinal ganglion cell (RGC) loss in endothelin-1 (ET-1) induced RGC loss. A single intravitreal injection of ET-1 (20pmol/ul), a potent vasoactive peptide that produces retinal vessels vasoconstriction, was used to induce and characterize RGC-specific cell death. CYM-5442 (1 mgr/kg) or vehicle was administered intraperitoneally for five consecutive days after ET-1-induced RGC loss. The functional extent of RGC loss injury was evaluated with pattern visual evoked potentials (VEP) and electroretinography. RGCs and retinal nerve fiber layer (RNFL) thickness were assessed in vivo using optical coherence tomography and ex vivo using Brn3a immunohistochemistry in flat-mounted retinas. ET-1 caused significant RGC loss and function loss one week after intravitreal injection. VEP showed preserved visual function after CYM-5442 administration compared to vehicle-treated animals (11.95 ± 0.86 μV vs 3.47 ± 1.20 μV, n = 12) (p < 0.05). RNFL was significantly thicker in the CYM treated-animals compared to the vehicle (93.62 ± 3.22 μm vs 77.72 ± 0.35 μm, n = 12) (p < 0.05). Furthermore, Brn3a immunohistochemistry validated this observation, showing significantly higher RGCs numbers in CYM treated rats than in the vehicle group (76,540 ± 303 vs 52,426 ± 1,932 cells/retina, n = 9) (p = 0.05). CYM-5442 administration was associated with significant retinal cleaved caspase-3 deactivation, indicating reduced apoptotic levels. The results of the present study further demonstrate the important role of S1P1 receptor agonists to lessen intravitreal ET-1 induced RGC loss.

Topics: Animals; Disease Models, Animal; Electroretinography; Endothelin-1; Evoked Potentials, Visual; Feasibility Studies; Glaucoma; Immunohistochemistry; Indans; Intravitreal Injections; Ischemia; Nerve Fibers; Neuroprotective Agents; Optic Nerve Diseases; Oxadiazoles; Rats; Rats, Wistar; Receptors, Lysosphingolipid; Retinal Diseases; Retinal Ganglion Cells; Transcription Factor Brn-3A

Klotho is a newly discovered protein that presumably has an important role in the aging process. The goal of this research is to compare the levels of Klotho and Endothelin-1 (ET-1) in the serum and aqueous humor of patients with pseudoexfoliation syndrome (PES) and pseudoexfoliative glaucoma (PEG).. Aqueous humor and serum samples were obtained at the time of cataract surgery from 15 patients with PES, 15 patients with PEG, and 15 control patients. All of the samples were analyzed using enzyme-linked immunosorbent assay to evaluate the levels of ET-1 and Klotho protein.. Aqueous and serum levels of Klotho in PES patients (49.02±10.97, 56.32±10.25 ng/mL) and PEG patients (34.53±4.87, 50.49±2.63 ng/mL) were lower than in control patients (56.31±7.68, 65.06±12.32 ng/mL). Both aqueous and serum levels of Klotho in the PEG group were lower than in the PES group (P=0.001). Mean aqueous and serum levels of ET-1 in the PES (1.28±0.09, 1.65±0.75 pg/mL) and the PEG groups (1.45±0.07, 1.58±0.58 pg/mL) were significantly higher than that measured in the control group (1.17±0.09, 1.16±0.34 pg/mL). Aqueous levels of ET-1 in the PEG group were higher than the PES group (P=0.04), but there were no significant difference in serum levels of ET-1 between the PES and the PEG groups (P=0.83).. Aqueous and serum levels of Klotho decreased both in PES and PEG patients, and this decrease in the PEG group was more significant. In contrast, aqueous and serum levels of ET-1 increased in the PES and the PEG patients, and the increase in the aqueous level of ET-1 in PEG patients was more significant.

Topics: Adult; Aged; Aging; Aqueous Humor; Biomarkers; Cross-Sectional Studies; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Exfoliation Syndrome; Female; Glaucoma; Glucuronidase; Humans; Intraocular Pressure; Klotho Proteins; Male; Middle Aged

To investigate the levels of endothelin-1 (ET-1), homocysteine (Hcy), vitamins A, E, B12 and folic acid in plasma of patients with different types of glaucoma: primary open-angle glaucoma (POAG) and normotensive glaucoma (NTG). Patients were classified into 3 groups: group POAG comprised 48 patients, group NTG comprised 15 patients, and control group that comprised 75 healthy subjects. ET-1 levels were measured by ELISA, Vitamins A and E by HPLC, and Vitamin B12, homocysteine, and folic acid levels were determined by chemiluminescent immunoassay. The ET-1 and Hcy levels were significantly higher (p = 0.002) in the POAG group compared to NTG and control group. Vitamin E levels were significantly lower (p = 0.001) in the NTG group compared to POAG and control group. The increase of Hcy and ET-1 in POAG patients is related to vascular endothelial dysfunction. Thus results may play a key role in the development of this disease. Lower levels of Vitamin E in the NTG group suggest that oxidative process plays an early role in the development of this type of glaucoma.

Topics: Adult; Analysis of Variance; Antioxidants; Biomarkers; Blood Pressure; Case-Control Studies; Endothelin-1; Female; Folic Acid; Glaucoma; Homocysteine; Humans; Intraocular Pressure; Male; Middle Aged; Oxidative Stress; Vitamins

To evaluate the concentration of endothelin-1, vascular endothelial growth factor, and cyclooxygenase-2 in aqueous humor from normal and glaucomatous human patients.. Concentrations of these proteins were measured using ELISA kits in 83 patients (30 presenting for cataract surgery and 53 with glaucoma).. Endothelin-1, vascular endothelial growth factor, and cyclooxygenase-2 were detected in all samples. The ages of the patients with glaucoma (64.51 +/- 17.51 years) and cataracts subjects (59.30 +/- 19.15 years) were similar. The endothelin-1 concentration in cataracts patients (48.55 +/- 9.50 pg/ml) was statistically different when compared to endothelin-1 concentration in aqueous humor from primary open-angle glaucoma (107.94 +/- 12.20 pg/ml) and neovascular glaucoma (114.68 +/- 25.50 pg/ml) (p < 0.05). No statistical difference was observed in normal tension glaucoma group (69.14 +/- 52.80 pg/ml) (p > 0.05). Vascular endothelial growth factor concentration was higher in neovascular glaucoma (81.84 +/- 6.40 pg/ml), being the difference statistically significant when compared with the other groups (p < 0.0001). Cyclooxygenase-2 levels showed no statistical difference between cataract groups and any other glaucoma group (p > 0.05). No effect of age, gender, or previously medication of aqueous humor concentration of these proteins could be detected (p > 0.05).. In this study we observed increased levels of endothelin-1 in aqueous humor from patients with primary open-angle glaucoma and neovascular glaucoma, and increased levels of vascular endothelial growth factor only in neovascular glaucoma patients, raising a possible connection between endothelin-1 and vascular endothelial growth factor in the role of some types of glaucoma. Regarding cyclooxygenase-2 levels detected, perhaps indicate that low values of cyclooxygenase-2 are necessary for normal functions of the eye.

Topics: Aged; Aqueous Humor; Cataract; Cyclooxygenase 2; Endothelin-1; Enzyme-Linked Immunosorbent Assay; Female; Glaucoma; Humans; Male; Mexico; Middle Aged; Vascular Endothelial Growth Factor A

Recent observations suggest that the vasoactive peptide endothelin-1 (ET-1) may be an important contributor to the etiology of glaucoma. ET-1 administration has been shown to produce optic nerve axonal loss and apoptosis of retinal ganglion cells. Ocular ET-1 levels are elevated in aqueous humor in response to elevated intraocular pressure both in glaucoma patients and in animal models of glaucoma; however, the precise mechanisms by which ET-1 mediates glaucomatous optic neuropathy are not clear. Presently we report that ET-1-mediated apoptosis was markedly attenuated in ETB receptor-deficient rats, suggesting a key role for ETB receptors in apoptosis of retinal ganglion cells by ET-1 treatment. Using virally transformed rat retinal ganglion cells (RGC-5 cells), we found that ET-1 (100 nmol/L) treatment produced apoptotic changes in these cells that was determined by flow cytometric analyses, release of mitochondrial cytochrome c to the cytosol, and increased phosphorylation of c-Jun N-terminal kinase. Pretreatment with the ETB-receptor antagonist BQ788 (1 micromol/L) was able to significantly attenuate ET-1-mediated apoptosis in RGC-5 cells. ET-1-mediated apoptotic changes in RGC-5 cells were associated with ETB-receptor activation and were accompanied by a significant upregulation of ETB-receptor expression. These studies suggest that ocular ET-1 acts through ETB receptors to mediate apoptosis of retinal ganglion cells, a key event in glaucoma and related optic neuropathies.

Topics: Animals; Animals, Genetically Modified; Apoptosis; Base Sequence; Cell Line, Transformed; DNA Primers; Endothelin-1; Glaucoma; Humans; JNK Mitogen-Activated Protein Kinases; Mitochondria; Models, Biological; Promoter Regions, Genetic; Rats; Receptor, Endothelin B; Retinal Ganglion Cells; Transcription Factor AP-1; Up-Regulation

Changes in the expression of water channels or aquaporins (AQP) have been reported in several diseases. However, such changes and mechanisms remain to be evaluated for retinal injury. This study was designed to analyze changes in the expression of AQP4 following elevation of intraocular pressure (IOP) and after intravitreal endothelin-1 injection and the potential involvement of the ubiquitin-dependent proteasome.. Retinal injuries were induced by the elevation of intraocular pressure in rat eyes using the Morrison model or following endothelin-1 intravitreal injection. Immunohistochemistry using a combination of glial fibrillary acidic protein (GFAP) and aquaporin-4 antibodies were employed to follow changes in the optic nerve head astrocytes. Real-time quantitative PCR (Q-PCR) was used for measuring changes in AQP4, ubiquitin hydrolase L1 (UCH-L1), and beta-actin messages. Changes in AQP4, caspase-3, thy-1, ubiquitination, and GFAP expression were also followed in total retinal extracts using western blotting. An S5a column was used to purify ubiquitinated proteins.. In retinas of both injury models, there was an upregulation of GFAP (a marker of astrogliosis), caspase-3, and downregulation of thy-1, a marker for retinal ganglion cell stress, and decreased retinal AQP4 mRNA and protein levels as determined by Q-PCR, and western blotting, respectively. By contrast, IOP enhanced expression and co-localization of GFAP and AQP4 in optic nerve astrocytes. AQP4 was detected in affinity-purified ubiquitinated proteins using S5a column, suggesting that AQP4 is a target for degradation by the ubiquitin-dependent proteasome. While elevation of IOP induced an increase in ubiquitination in retinal extracts, it decreased ubiquitination in optic nerve extracts as detected by western blotting. Enhanced ubiquitination and decreased ubiquitination appear to correlate with AQP4 expression. IOP decreased UCH-L1 (or protein gene protein [PGP9.5]) in retinal extracts as judged by Q-PCR.. The enhanced expression of AQP4 in optic nerve astrocytes following elevation of IOP may explain the astrocytic hypertrophy normally seen in glaucoma patients and may involve alteration in the activity of ubiquitin-dependent proteasomal degradation system. The decreased ubiquitination in the optic nerve may lead to increased levels of proapoptotic proteins known to be degraded by the proteasome, and thus to axonal degeneration in glaucoma.

Topics: Animals; Aquaporin 4; Caspase 3; Disease Models, Animal; Endothelin-1; Gene Expression Regulation; Glaucoma; Glial Fibrillary Acidic Protein; Immunohistochemistry; Intraocular Pressure; Male; Mice; Rabbits; Rats; Rats, Inbred BN; Retina; Retinal Diseases; RNA, Messenger; Thy-1 Antigens; Tissue Extracts; Ubiquitin Thiolesterase; Ubiquitination

Endothelin (ET)-1 levels are increased in aqueous and vitreous humor in patients with glaucoma and animal models of glaucoma. Whether the elevated ET-1 induces extracellular matrix (ECM) remodeling in the optic nerve head is still unknown. In the present study, the regulation of matrix metalloproteinases/tissue inhibitors of matrix metalloproteinases (MMPs/TIMPs) and ECM remodeling in ET-1-activated human optic nerve head astrocytes (hONAs) were determined.. Primary hONAs were exposed to ET-1 for 1 day and 4 days. Incubation media were subjected to zymography and Western blot to detect activity and expression of MMPs and TIMPs. Fibronectin (FN) was monitored by Western blot and immunofluorescent staining.. ET-1 increased the activity of MMP-2 and the expression of TIMP-1 and -2 in hONAs. The expression of TIMP-1 and -2 induced by ET-1 was abolished by application of inhibitors of mitogen-activated protein kinase (MAPK) or PKC, leading to enhanced activity of MMP-2. Knockdown of MMP-2, by using small interfering (si)RNA, not only decreased the activity of MMP-2 but also decreased the expression of TIMP-1 and -2. ET-1 increased the soluble (s)FN expression as well as FN matrix formation. However, the accumulation of sFN did not enhance FN matrix formation. Unlike ET-1's effects on MMP-2, blockade of MAPK and PKC did not alter the expression and deposition pattern of FN in hONAs.. ET-1 increased the expression and activity of MMP-2 and TIMP-1 and -2. The ERK-MAPK and PKC pathways are involved in the regulation of expression of MMP-2 and TIMP-1 and -2. ET-1's effects on MMPs/TIMPs may be important, not only in regulating the expression of MMPs and TIMPs, but also in influencing ECM remodeling.

Topics: Aged; Astrocytes; Cells, Cultured; Endothelin-1; Enzyme Inhibitors; Fibronectins; Gene Expression Regulation, Enzymologic; Glaucoma; Humans; MAP Kinase Signaling System; Matrix Metalloproteinase 2; Middle Aged; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Optic Disk; Phosphorylation; Protein Kinase C; Protein Kinase C beta; Protein Kinase C-delta; RNA, Small Interfering; Solubility; Tissue Inhibitor of Metalloproteinase-1; Tissue Inhibitor of Metalloproteinase-2

The optic neuropathy in multiple sclerosis and glaucoma neuropathy are very common ophthalmological diseases. Multiple sclerosis /MS/ is the chronic inflammatory central nervous system demyelinisation disease with an autoimmunological ethiology. The last investigation of multiple sclerosis indicate the molecular and cellular autoimmunisation aspects. Te role of vasoactive factors is underlines in its pathogenesis which also suggests the common elements of glaucoma and MS pathogenesis. The over expressed vasoconstrictive mechanisms in both diseases can conduct to optic nerve injury. The aim of this study is evaluation of the optic disc morphological changes in sclerosis multiplex patients /MS/ with or without neuritis optica in anamnesis in glaucoma "remodeling" aspects.. We present two patients with coexsist sclerosis multiplex and glaucoma neuropathy, which underwent retrobulbar neuritis.. Coexistance of glaucoma neuropathy and multiple sclerosis neuropathy may indicate common elements of glaucoma and SM pathogenesis. The authors recommend precise morphological optic disc evaluation in multiple sclerosis patients because glaucoma neuropathy may appear.

Topics: Adolescent; Adult; Aged; Endothelin-1; Glaucoma; Humans; Magnetic Resonance Imaging; Male; Multiple Sclerosis; Optic Disk; Optic Neuritis; Radiography; Sensitivity and Specificity; Ultrasonography, Doppler, Color; Vasoconstriction; Vasodilation; Vision Disorders; Visual Acuity; Visual Fields

The vasoconstrictive peptide, Endothelin-1 (ET-1) has been found at elevated levels in glaucomatous eyes. In this study, a single 5mul intraocular injection of ET-1 was injected into the rat eye in order to characterize an in vivo retinal ganglion cell (RGC)-specific cell death model. The most effective concentration of ET-1 at inducing RGC loss at 2 weeks post-injection was determined using 5, 50 and 500mum concentrations of ET-1. The density of surviving RGCs was determined by counting Fluorogold labelled RGCs. A significant loss (25%) of RGCs was observed using only the 500mum concentration when compared to PBS-injected controls. GFAP immunohistochemistry revealed an increase in GFAP expression in Müller cell end-feet, as well as a total increase in GFAP expression (80%), following ET-1 treatment. These changes in GFAP expression are indicative of glial hyperactivity in response to stress. The specificity of ET-1 mediated cell death for RGCs was determined by measuring the changes in retinal thickness and TUNEL labeling. Retinal thickness was quantified using confocal and light microscopy. In confocal measurements, Yo Pro-1 was used to stain nuclear layers and the thickness of retinal layers determined from reconstructions. No significant loss in thickness was observed in any retinal layers. The same observations were seen in semi-thin sections when viewed by conventional transmitted light microscopy. The lack of significant thickness changes in the outer nuclear, outer plexiform or inner nuclear layer suggests that there was no significant cell loss in the retina other than in the RGC layer. Exclusive co-localization of TUNEL-labelled nuclei with Fluorogold-labelled cytoplasm provided additional evidence for RGC-specific death that most likely occurs via an apoptotic mechanism. A cell death time course was performed to determine RGC loss over time. RGC losses of 25, 25, 36 and 44% were observed at 1, 2, 3 and 4 weeks post-ET-1 injection, compared to PBS-injected controls. The total number of remaining RGC axons was determined by multiplying the number of optic nerve (ON) axons per unit area, by the cross-sectional area. There was a 31% loss in total ON axons in ET-1 treated eyes at 3 weeks post injection. Functional integrity of the visual system was determined by observing changes in the pupillary light reflex. ET-1 treatment resulted in a slowing of the pupil velocity by 31% and an average increase in the duration of contraction of 1.85sec (32% incr

Topics: Animals; Axons; Cell Death; Dose-Response Relationship, Drug; Endothelin-1; Female; Glaucoma; In Situ Nick-End Labeling; Injections; Kainic Acid; Microscopy, Confocal; Models, Animal; Neuroglia; Optic Nerve; Photic Stimulation; Rats; Rats, Sprague-Dawley; Reflex, Pupillary; Retinal Ganglion Cells; Time Factors

In normal tension glaucoma (NTG), intraocular pressure is within normal the range; thus, some mechanism other than increased pressure contributes to the optic neuropathy. Endothelin may be an important contributor to the development of the optic neuropathy characteristic of glaucoma. We investigated whether polymorphisms of the endothelin-1, endothelin receptor type A, and endothelin receptor type B genes were associated with NTG.. Sixty-seven Korean NTG patients and 100 healthy Korean subjects were enrolled. DNA from peripheral blood leukocytes was extracted and genotype distributions of six polymorphisms in genes encoding endothelin-1 (EDN1:c.-131dupA, EDN1:c.594G > T), endothelin receptor type A (EDNRA:c.-231G > A, EDNRA:c.*70C > G, EDNRA:c.*1222C > T), and endothelin receptor type B (EDNRB:c.831A > G) were determined. Genotype and allele distributions were compared between patients and controls. In NTG subjects, untreated baseline intraocular pressure and age at the time of diagnosis, as well as the mean deviation and pattern standard deviation values of automated static perimetry were examined for an association with these genetic polymorphisms.. The polymorphism of EDNRA:c.*1222C > T was significantly associated with NTG (p = 0.028, OR = 3.33, 95% CI 1.05-10.24). In addition, the AA genotype of the EDNRA:c.-231G > A polymorphism was associated with a lower baseline intraocular pressure than in the GG+GA genotype group (14.0 +/- 2.8 mm Hg versus 16.2 +/- 2.3 mm Hg, p = 0.047). No polymorphism was associated with visual field parameters.. A polymorphism of the endothelin receptor type A gene is associated with NTG.

Topics: Adult; Asian People; Endothelin-1; Female; Genotype; Glaucoma; Humans; Intraocular Pressure; Male; Middle Aged; Polymorphism, Single Nucleotide; Receptors, Endothelin

The role of endothelin-1 (ET-1) a potent vasoactive peptide, in glaucoma pathogenesis is receiving increasing attention, particularly in astroglial activation in optic nerve damage. Our laboratory has also shown that ET-1 treatment causes proliferation of cultured human optic nerve head astrocytes to possibly initiate astrogliosis. ET-1 is distributed in retina, optic nerve, and ciliary epithelium, however the effects of elevated intraocular pressure (IOP) (as seen in glaucoma) on ET-1 and ET(B) receptors are not clearly understood. In the present study, the levels of immunoreactive ET-1 (ir-ET-1) in aqueous humour (AH) and optic nerve head (ONH) were determined in the Morrison elevated IOP model of glaucoma. Additionally in the ONH of these rats, immunohistochemical analyses of ET(B) receptors and glial fibrillary acidic protein (GFAP; a marker for astroglial cells and for astrogliosis) were performed. There was 2- to 2.5-fold increase in AH ir-ET-1 levels for rats subjected to elevated IOP, compared to their respective controls. In the Morrison rat model of glaucoma, elevated IOP increased optic nerve ir-ET-1 with concomitant increases in ir-ET(B) and ir-GFAP labelling (possibly indicative of astrogliosis and hypertrophy). As seen in brain astrocytes subjected to neurotrauma, the present findings are suggestive of ET-1's role in astroglial activation, particularly in response to elevated IOP in glaucoma.

Topics: Animals; Disease Models, Animal; Endothelin-1; Glaucoma; Intraocular Pressure; Male; Rats; Rats, Inbred BN; Saline Solution, Hypertonic

It is proposed that the anterior optic nerve is specifically susceptible to microcirculatory compromise contributing to the development of glaucomatous optic neuropathy.. Ischemic optic neuropathy was induced by delivering endothelin-1 (ET-1) to the retrobulbar space in one eye of 12 primates for 6 to 12 months. Regional ganglion cell axonal sizes and densities were compared with the normal, contralateral eyes.. Without changes of intraocular pressure, mean axonal density was significantly decreased in ET-1 eyes compared to controls (P = .03, paired t test). Two-way matched-pair analysis of variance showed a significant effect of ET-1 on overall axonal density (P < .0001). Among the animals with significant axonal loss, the mean axonal loss was 11.6%, and loss varied from 4% to 21%. Axonal loss was commonly localized within specific quadrants. Five animals were examined for preferential axonal size loss. As a group, there appears to be a tendency toward preferential large axonal loss, but the mean axonal loss of large and small axons did not meet significant differences (P = .1) However, examination of individual animals with significant loss shows significantly greater loss of large axons as compared to the small axons in three of the animals.. Chronic optic nerve ischemia causes demonstrable and localized damage of the optic nerve, without intraocular pressure elevation. There is preferential loss of large retinal ganglion cell axons in animals with significant axonal loss. Ischemia-induced focal axonal loss is similar to human glaucoma and may represent a differential regional vulnerability.

Topics: Analysis of Variance; Animals; Axons; Drug Administration Schedule; Endothelin-1; Eye; Female; Glaucoma; Infusion Pumps; Intraocular Pressure; Macaca mulatta; Optic Nerve; Optic Neuropathy, Ischemic; Retinal Ganglion Cells

Glaucoma is a progressive optic neuropathy with characteristic optic disc changes, retinal ganglion cell loss and progressive visual field defects. Elevated intraocular pressure is considered to be a major risk factor in glaucomatous neuropathy. This study aimed to characterize and document a new chronic glaucoma model in the rat with respect to the effect of elevated intraocular pressure on overall retinal dysfunction and retinal ganglion cell loss, and to elucidate the possible mechanisms underlying this cell loss. Intraocular pressure (IOP) was measured in rats using a Tonopen. RGCs were retrogradely labeled with the fluorescent dye, 4-[didecylaminostyryl]-N-methyl-pyridinium-iodide (4-Di-10 ASP) and quantified on retinal flat mounts using fluorescence microscopy. The optic nerve head was examined fundoscopically. Changes in the histological appearance of the whole eyes was studied in paraffin sections, and immunohistochemistry was carried out on cryostat sections. The levels of mRNA for several genes were compared between control and glaucomatous retinae using semi-quantitative RT-PCR. Mutant animals are affected with either a unilateral or bilateral enlargement of the globes having an IOP that ranged from 25 to 45 mmHg, as compared to control values of 12-16 mmHg. The IOP of glaucomatous eyes increased significantly with age to attain a value of 35+/-7.3 at 1.5 years. Concomitant with the rise in IOP, the number of labeled RGCs continued to decrease in number with age. A total of 1887+/-117RGC mm(-2) could be labeled in wild-type control and juvenile mutant pre-glaucomatous retinas, whereas this number dropped to 92+/-26RGC mm(-2) at 1.5 years. Ophthalmoscopy revealed atrophied optic nerve heads in the affected eyes. The pars plicata and the pars plana of the ciliary body of glaucomatous eyes were hypertrophied and elongated, respectively. The anterior chamber was narrow and the irido-corneal angle open in glaucoma eyes. The mRNA of glial-fibrillary-acidic protein, endothelin-1, STAT-3 and STAT-6 increased in the retinas correlating with the severity and duration of the disease. Changes in the expression of GFAP and endothelin-1 could be confirmed using immunohistochemistry. This model may help to address several fundamental issues in the pathogenesis of glaucoma and aid in the development of neuroprotective strategies.

Topics: Animals; Cell Count; Chronic Disease; Ciliary Body; DNA-Binding Proteins; Endothelin-1; Female; Glaucoma; Glial Fibrillary Acidic Protein; Immunohistochemistry; Male; Models, Animal; Optic Nerve; Phenotype; Rats; Rats, Mutant Strains; Retina; Retinal Ganglion Cells; RNA, Messenger; STAT3 Transcription Factor; STAT6 Transcription Factor; Trans-Activators

Over contraction of vascular smooth muscle may result in ischemia to ocular neuronal cells and deteriorate the glaucoma. The purpose of this study was to investigate the inhibitory effects of various commercial antiglaucoma drugs including brimonidine, dipivefrin, betaxolol, timolol, levobunolol, carteolol, brinzolamide, dorzolamide, unoprostone, latanoprost, pilocarpine, and preservative benzalkonium chloride on endothelin-1(ET-1) and KCl-induced increase of intracellular free Ca2+ ([Ca2+]i) in cultured rat A7r5 vascular smooth muscle cells. These drugs were diluted from original concentrations to 1/100, 1/1000, and 1/10000. [Ca2+]i mobility was analyzed by spectrofluorometry after loading with fura-2-AM. Betaxolol, timolol, levobunolol, and carteolol were found to inhibit KCl-induced release of [Ca2+]i in a dose-dependent manner. High concentrations of betaxolol, timolol, levobunolol, carteolol, and unoprostone also inhibited ET-1-induced increase of [Ca2+]i in A7r5 cells. However, ET-1- and KCl-induced increase of [Ca2+]i was not diminished by other drugs including brimonidine, dipivefrin, brinzolamide, dorzolamide, latanoprost, pilocarpine, and benzalkonium chloride. These results indicate that high concentrations of unoprostone and beta-adrenergic blocking agents including betaxolol, timolol, levobunolol, and carteolol may inhibit ET-1-induced increase of [Ca2+]i. The mechanism may be mediated by inhibition of extracellular calcium influx via blocking of L-type voltage-dependent Ca2+ channel in A7r5 cells.

Topics: Animals; Antihypertensive Agents; Aorta, Thoracic; Calcium; Cell Line; Dose-Response Relationship, Drug; Endothelin-1; Glaucoma; Muscle, Smooth, Vascular; Ophthalmic Solutions; Potassium Chloride; Rats

To compare thirst, drinking behaviour, and endothelin-1 (ET-1) plasma levels between vasospastic and non-vasospastic subjects.. We compared 67 subjects with a primary vasospastic syndrome with 64 age- and sex-matched non-vasospastic control subjects. A detailed medical history was recorded, including a questionnaire containing queries about thirst and drinking behaviour, history of migraine or unspecific headache, history of episodes of low blood pressure, and smoking habits. Body mass index (BMI) was calculated and blood samples were drawn for ET-1 measurements.. Subjects with a vasospastic syndrome reported a reduced desire to drink and a lower estimated quantity of daily fluid intake, more often forgot to drink, more often had both migraine and unspecific headache, more often had episodes of low blood pressure, and had an increased plasma level of ET-1. These features differed statistically significantly between the two groups. There was also a non-significant trend among vasospastic subjects to smoke less and to have a smaller BMI.. A reduced desire to drink is found frequently among vasospastic subjects.

Topics: Adult; Aged; Aged, 80 and over; Body Mass Index; Drinking Behavior; Endothelin-1; Female; Glaucoma; Humans; Male; Middle Aged; Raynaud Disease; Surveys and Questionnaires; Syndrome; Thirst; Vasodilation

To investigate the vasoactive effect of bimatoprost (Lumigan), a new topical ocular hypotensive agent, in isolated porcine ciliary arteries.. Arteries were placed in a myograph system to measure isometric forces. Quiescent vessels as well as vessels pre-contracted with either 10 nM endothelin-1 or 100 mM potassium chloride (KCl) were exposed, in a cumulative manner, to increasing concentrations (0.1 nM - 0.1 mM) of bimatoprost (dissolved in ethanol). In quiescent vessels, results were expressed in percent of 100 mM KCl-induced contraction. In endothelin-1-pre-contracted vessels, results were expressed in percent of the maximal contraction induced by endothelin-1. In KCl-pre-contracted vessels, results were expressed in percent of the plateau contraction reached 30 minutes after 100 mM KCl application.. Bimatoprost induced a significant (p < 0.05 - 0.001) vasoconstriction at concentrations equal to or higher than 0.1 micro M in quiescent vessels (0.1 mM: 73 +/- 12 %). In KCl-pre-contracted vessels, at concentrations higher than 1 micro M, bimatoprost induced significant (p < 0.05 - 0.01) contractions (0.1 mM: 67 +/- 17 %). In endothelin-1-pre-contracted vessels, bimatoprost also induced significant (p < 0.05 - 0.001) contractions at concentrations above 10 micro M (0.1 mM: 17 +/- 8 %).. The present study indicates that bimatoprost appears to have, in vitro, some vasoactive properties in porcine ciliary arteries. The question whether Lumigan has an influence on ocular blood flow needs to be further investigated.

Topics: Amides; Animals; Antihypertensive Agents; Aqueous Humor; Bimatoprost; Cloprostenol; Culture Techniques; Dose-Response Relationship, Drug; Endothelin-1; Glaucoma; Intraocular Pressure; Lipids; Optic Neuropathy, Ischemic; Potassium Chloride; Prostaglandins F, Synthetic; Regional Blood Flow; Swine; Vasoconstriction

Topics: Clinical Trials as Topic; Endothelin-1; Endothelium, Vascular; Glaucoma; Humans; Intraocular Pressure

Topics: Antioxidants; DNA Damage; Endothelin-1; Free Radicals; Glaucoma; Humans; Intraocular Pressure; Nitric Oxide; Oxidants; Oxidative Stress; Retinal Ganglion Cells

Vascular risk factors, and particularly vasospasm, are thought to play a part in the pathogenesis of normal pressure glaucoma (NPG). This study aimed to determine whether the function of systemic resistance arteries was altered in patients with NPG.. Contractile and relaxant function was assessed in arteries dissected from gluteal fat biopsies (11 NPG, 12 control) using small vessel myography.. Responses to K(+) and noradrenaline were similar in patients and controls and were unaffected by endothelial removal. In contrast, responses to 5-hydroxytryptamine (5-HT; pD(2); 7.29 (SD 0.16) v 6.66 (0.19); p=0.03) and endothelin-1 (ET-1; pD(2), 9.12 (0.10) v 8.72 (0.13); p=0.03) were enhanced in arteries from patients with NPG. Removal of the endothelium enhanced responses to 5-HT (pD(2), 6.66 (0.19) v. 7.66 (0.08); p=0.003) and ET-1 (pD(2), 8.72 (0.13) v. 9.66 (0.39); p=0.02) in control arteries but not in those from patients. ET-1 mediated contraction in control and patient arteries was reduced in the presence of (10(-5) M) nifedipine. Endothelium dependent and independent relaxation was not impaired in arteries from patients.. This study has identified dysfunction of the systemic vascular endothelial cell in patients with normal pressure glaucoma. The vascular endothelium modulates contractile responses to 5-HT and ET-1 in human subcutaneous resistance arteries but this effect is lost in patients with NPG, indicating a selective defect in agonist mediated release of endothelium derived vasodilators. Selective antagonists of 5-HT and ET-1 may, therefore, help to prevent vasospasm in patients with NPG.

Topics: Adult; Arteries; Dose-Response Relationship, Drug; Endothelin-1; Endothelium, Vascular; Female; Glaucoma; Humans; In Vitro Techniques; Male; Middle Aged; Serotonin; Vasoconstrictor Agents; Vasodilator Agents

Endothelin 1 is a small peptide that is involved in regulation of intraocular pressure and modulation of ocular circulation. To investigate the role of endothelin 1 in canine glaucoma, the authors measured aqueous humor levels of endothelin 1 in healthy dogs and in dogs with hypertensive glaucoma.. Aqueous humor samples were obtained with general anesthesia from the eyes of healthy dogs (n = 5) and dogs with hypertensive glaucoma (n = 10). Measurements were made by enzyme immunoassay for endothelin 1.. The endothelin 1 aqueous humor range was 1.12 - 3.63 pg/mL for healthy dogs and 1.97 - 14.97 pg/mL for glaucomatous dogs. The healthy and glaucomatous canine endothelin 1 aqueous levels (mean +/- SD) were 2.33 +/- 0.90 and 8.11 +/- 5.03 pg/mL, respectively. A two-way analysis of variance indicated that this difference was significant (P = 0.0084). The effect of age on endothelin 1 levels was not significant (P = 0.6283). The large variability found within the glaucomatous group could be explained by the degree of damage of the retina (P = 0.0006). There was no significant correlation between intraocular pressure and endothelin 1 aqueous humor levels within the glaucomatous group (P = 0.29).. The aqueous humor of dogs with hypertensive glaucoma contains significantly higher levels of endothelin 1 than that of healthy dogs.

Topics: Animals; Aqueous Humor; Dog Diseases; Dogs; Endothelin-1; Female; Glaucoma; Intraocular Pressure; Male; Tonometry, Ocular

Visual field defects caused by vasospasm are often encountered in ophthalmology as a feature of glaucoma with poor response to conventional treatment. Combination therapy with drugs acting via different mechanisms might be more effective. Therefore, the effects of the calcium antagonist amlodipine and the angiotensin converting enzyme (ACE) inhibitor benazeprilat at low and high dose combination on contractions to endothelin-1 and endothelium-dependent relaxations to bradykinin were examined in porcine ciliary arteries.. Segments of the arteries were suspended in myographs for isometric tension recording.. Pretreatment of the vessels with either amlodipine, the low or high dose combination significantly reduced the sensitivity to endothelin-1 as compared to control (concentration shift 18.3-fold, 14.2-fold, 23.3-fold respectively; p < 0.05), while benazeprilat was ineffective. The maximal response to endothelin-1 (10(-7) M) was most inhibited by the high dose combination which reduced the contractions by 49% as compared to control (p < 0.05). The low dose combination and amlodipine alone were less effective (reduction: 25%; p < 0.05 and 20%; n.s., respectively). On the other hand, benazeprilat enhanced the sensitivity (concentration shift 73-fold; p < 0.05) and maximal relaxation to bradykinin (by 27%; p < 0.01), whereas amlodipine or the low or high dose combination were ineffective.. These findings indicate that amlodipine and benazeprilat differently affect vascular function of ciliary arteries. A high dose combination of both substances was most effective in inhibiting contractions to endothelin-1, suggesting a potentiating effect of the two compounds. In contrast, endothelium-dependent relaxations to bradykinin were enhanced by benazeprilat alone, but not when combined with amlodipine.

Topics: Amlodipine; Angiotensin-Converting Enzyme Inhibitors; Animals; Arteries; Benzazepines; Bradykinin; Calcium Channel Blockers; Ciliary Body; Endothelin-1; Glaucoma; Swine