Experimental Glaucoma Research Articles

Expansions of the neurovascular scleral canal and contained optic nerve occur early in the hypertonic saline rat experimental glaucoma model

PurposeTo characterize early optic nerve head (ONH) structural change in rat experimental glaucoma (EG). MethodsUnilateral intraocular pressure (IOP) elevation was induced in Brown Norway rats by hypertonic saline injection into the episcleral veins and animals were sacrificed 4 weeks later by perfusion fixation. Optic nerve cross-sections were graded from 1 (normal) to 5 (extensive injury) by 5 masked observers. ONHs with peripapillary retina and sclera were embedded, serial sectioned, 3-D reconstructed, delineated, and quantified. Overall and animal-specific EG versus Control eye ONH parameter differences were assessed globally and regionally by linear mixed effect models with significance criteria adjusted for multiple comparisons. ResultsExpansions of the optic nerve and surrounding anterior scleral canal opening achieved statistical significance overall (p < 0.0022), and in 7 of 8 EG eyes (p < 0.005). In at least 5 EG eyes, significant expansions (p < 0.005) in Bruch's membrane opening (BMO) (range 3–10%), the anterior and posterior scleral canal openings (8–21% and 5–21%, respectively), and the optic nerve at the anterior and posterior scleral canal openings (11–30% and 8–41%, respectively) were detected. Optic nerve expansion was greatest within the superior and inferior quadrants. Optic nerve expansion at the posterior scleral canal opening was significantly correlated to optic nerve damage (R = 0.768, p = 0.042). ConclusionIn the rat ONH, the optic nerve and surrounding BMO and neurovascular scleral canal expand early in their response to chronic experimental IOP elevation. These findings provide phenotypic landmarks and imaging targets for detecting the development of experimental glaucomatous optic neuropathy in the rat eye.

Anatomic, biochemical and functional evidence for cone injury in glaucoma

SummaryPurposeTo investigate outer retinal injury in glaucoma.MethodsStudies were done on human glaucomatous eyes as well as eyes from a laser trabecular meshwork destruction model of experimental glaucoma (EG) in non‐human primates (NHPs), including light microscopy and in situ hybridization (ISH) for mRNA using probes specific for rod, S‐cone and M/L‐cone opsins. Choroidal blood flow (ChBF) was measured using non‐recirculating fluorescent microspheres. Functional studies on the NHP eyes included multifocal and full‐field electroretinography (mfERG and ffERG).ResultsSwelling of M/L‐cones) was a common finding in both the glaucomatous human and NHP EG eyes. Cone loss was also observed in some of the human eyes. ISH for mRNA showed reduced levels in both the S‐ and M/L‐cones in human glaucoma and NHP EG. Supranormal mfERG waveforms were a common feature of the NHP EG eyes. ChBF was greatly reduced in eyes with EG. The ffERG in NHP eyes with advanced EG showed larger reductions in photopic than in scotopic a‐ and b‐wave single‐flash responses; particularly at higher intensities.ConclusionMultiple lines of evidence show cone injury in human glaucoma and in NHP EG. Reduced ChBF could be the cause.

OCT in animal models

SummaryDue to their accessibility, animal models are playing a major role in understanding some of the underlying causes of glaucoma. Optical Coherence Tomography (OCT) has been used extensively in these animal models giving us the advantage of longitudinal in‐vivo assessments of the natural history of this disease. Outer retina involvement has recently been demonstrated in‐vivo in experimental glaucoma. OCT segmentation software are now available as an aid for understanding the involvement of retinal layers other than the RNFL. Retinal blood flow is also currently under investigation in experimental glaucoma using ultra high resolution OCT. Furthermore, investigations of the irido‐corneal angle configuration and its structural modifications in response to anti glaucoma drugs have also been conducted in experimental models using anterior segment OCT. The talk will discuss the utility of OCT in animal models in Glaucoma.

Comparison of fMRI measurements in LGN and Primary Visual cortex with visual deficits in Glaucoma

Experimental primate glaucoma demonstrates that the retinal ganglion cell (RGC) loss is associated with atrophies in the lateral geniculate nucleus (LGN) and the primary visual cortex (V1). The purpose of our study was to determine whether, in glaucoma patients, selective behavioural deficits in the three main visual pathways (magnocellular, parvocellular, koniocellular) are associated with selective changes in the neural activity in LGN and V1. A POAG group (n=20) and a matched control group (n=20) were examined using the following tests: Visual field loss was assessed using standard automated perimetry (SAP); the Cambridge Colour Vision test (CCT) was used to assess colour deficiencies; visual thresholds along the three cardinal directions of colour space were measured (achromatic; red-greenish; lime-violet). For a subset of the participants (n=9 in either groups), functional Magnetic Resonance Imaging (fMRI) was used to obtain BOLD signals in the LGN and V1 in response to supra-threshold modulations along these three cardinal directions. We report the following results: (1) There are significant visual threshold differences between patients with Glaucoma and controls, in particular along the yellowish-violet (YV) cardinal direction. (2) The average BOLD signal in primary visual cortex (V1) is lower in the Glaucoma group compared to the control group. High thresholds along the yellowish-violet colour direction are associated with low V1 activity. (3) In contrast, the BOLD signal in the LGN is higher in Glaucoma patients compared to the controls. Within the Glaucoma group, more severe visual field defects are associated with higher LGN activity. In conclusion and contrary to our expectations, the LGN signal is increased in glaucoma patients compared to the controls. We speculate that this may reflect feedback from primary visual cortex.

α2-Adrenergic modulation of the glutamate receptor and transporter function in a chronic ocular hypertension model

Excitotoxicity, glutamate-induced toxic effects to retinal ganglion cells (RGCs), is one of several mechanisms of RGC loss suggested in glaucoma. In this study, we focused on the role of glutamate transporter of glial cells as well as N-methyl-d-aspartate (NMDA) receptor with regard to glutamate toxicity in glaucoma. We also investigated whether α2-adrenoceptor activation could modulate glutamate transporters and NMDA receptors in a chronic ocular hypertension model. Brimonidine 0.15% was administered topically to the eyes of experimental glaucoma and control animals twice daily. After 8 weeks of intraocular pressure (IOP) elevation, staining with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) revealed an increase in the ganglion cell layer, and the number of TUNEL-positive cells was reduced by brimonidine treatment (P<0.05). Animals with experimentally induced glaucoma exhibited an increase in retinal stress marker glial fibrillary acidic protein (GFAP) immunoreactivity; brimonidine treatment reduced GFAP. Excitatory amino acid transporter 1(EAAT1) expression remained stable throughout the period of chronic ocular hypertension. α2-Adrenergic treatment upregulated EAAT1 protein levels (P<0.05). NMDA receptor (GluN1) expression was stimulated by chronic elevation of IOP, and GluN1-positive cells in ganglion cell layer were co-localized with TUNEL staining. Brimonidine administration suppressed GluN1 levels (P<0.05). These results indicate that brimonidine decreased RGC apoptosis, upregulating EAAT1 and downregulating NMDA receptors. We suggest that topical brimonidine treatment may decrease the glutamate excitotoxicity through modulation of glutamate transporter and NMDA receptor in glaucoma.

β-III-Tubulin: a reliable marker for retinal ganglion cell labeling in experimental models of glaucoma.

To evaluate the reliability of β-III-Tubulin protein as a retinal ganglion cell (RGC) marker in the experimental glaucoma model. Glaucoma mouse models were established by injecting polystyrene microbeads into the anterior chamber of C57BL/6J mice, then their retinas were obtained 14d and 28d after the intraocular pressure (IOP) was elevated. Retinal flat mounts and sections were double-labeled by fluorogold (FG) and β-III-Tubulin antibody or single-labeled by β-III-Tubulin antibody, then RGCs were counted and compared respectively. IOP of the injected eyes were elevated significantly and reached the peak at 22.8±0.7 mm Hg by day 14 after injection, then dropped to 11.3±0.7 mm Hg by day 28. RGC numbers counted by FG labeling and β-III-Tubulin antibody labeling were 64 807±4930 and 64614±5054 respectively in the control group, with no significant difference. By day 14, RGCs in the experimental group decreased significantly compared to the control group, but there was no significant difference between the FG labeling counting and the β-III-Tubulin antibody labeling counting either in the experimental group or in the control group. The result was similar by day 28, with further RGC loss. Our result suggested that the β-III-Tubulin protein was not affected by IOP elevation and can be used as a reliable marker for RGC in experimental models of glaucoma.

Effects of bevacizumab loaded PEG-PCL-PEG hydrogel intracameral application on intraocular pressure after glaucoma filtration surgery

PEG-PCL-PEG (PECE) hydrogel for intracameral injection as a sustained delivery system can get a stable release of the medication and achieve an effective local concentration. The injectable PECE hydrogel is thermosensitive nano-material which is flowing sol at low temperature and can shift tononflowing gel at body temperature. This study evaluated the intracameral injection of bevacizumab combined with a PECE hydrogel drug release system on postoperative scarring and bleb survival after experimental glaucoma filtration surgery. The best result was achieved in the bevacizumab loaded PECE hydrogels group, which presented the lowest IOP values after surgery. And the blebs were significantly more persistent in this group. Histology, Massion trichrome staining and immunohistochemistry further demonstrated that glaucoma filtration surgery in combination with bevacizumab loaded PECE hydrogel resulted in good bleb survival due to scar formation inhibition. In conclusions, this study demonstrated that bevacizumab-loaded PECE hydrogel for intracameral injection as a sustained delivery system provide a great opportunity to increase the therapeutic efficacy of glaucoma filtration surgery.

In Vivo Changes in Lamina Cribrosa Microarchitecture and Optic Nerve Head Structure in Early Experimental Glaucoma

The lamina cribrosa likely plays an important role in retinal ganglion cell axon injury in glaucoma. We sought to (1) better understand optic nerve head (ONH) structure and anterior lamina cribrosa surface (ALCS) microarchitecture between fellow eyes of living, normal non-human primates and (2) characterize the time-course of in vivo structural changes in the ONH, ALCS microarchitecture, and retinal nerve fiber layer thickness (RNFLT) in non-human primate eyes with early experimental glaucoma (EG). Spectral domain optical coherence tomography (SDOCT) images of the ONH were acquired cross-sectionally in six bilaterally normal rhesus monkeys, and before and approximately every two weeks after inducing unilateral EG in seven rhesus monkeys. ONH parameters and RNFLT were quantified from segmented SDOCT images. Mean ALCS pore area, elongation and nearest neighbor distance (NND) were quantified globally, in sectors and regionally from adaptive optics scanning laser ophthalmoscope images. In bilaterally normal monkeys, ONH parameters were similar between fellow eyes with few inter-eye differences in ALCS pore parameters. In EG monkeys, an increase in mean ALCS Depth (ALCSD) was the first structural change measured in 6 of 7 EG eyes. A decrease in mean minimum rim width (MRW) simultaneously accompanied this early change in 4 of 6 EG eyes and was the first structural change in the 7th EG eye. Mean ALCS pore parameters were among the first or second changes measured in 4 EG eyes. Mean ALCS pore area and NND increased in superotemporal and temporal sectors and in central and peripheral regions at the first time-point of change in ALCS pore geometry. RNFLT and/or mean ALCS radius of curvature were typically the last parameters to initially change. Survival analyses found mean ALCSD was the only parameter to significantly show an initial change prior to the first measured loss in RNFLT across EG eyes.

Ocular Inserts for Sustained Release of the Angiotensin-Converting Enzyme 2 Activator, Diminazene Aceturate, to Treat Glaucoma in Rats.

The aim of this study was to develop and evaluate the effects of chitosan inserts for sustained release of the angiotensin-converting enzyme 2 (ACE2) activator, diminazene aceturate (DIZE), in experimental glaucoma. Monolayer DIZE loaded inserts (D+I) were prepared and characterized through swelling, attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR), differential scanning calorimetry (DSC) and in vitro drug release. Functionally, the effects of D+I were tested in glaucomatous rats. Glaucoma was induced by weekly injections of hyaluronic acid (HA) into the anterior chamber and intraocular pressure (IOP) measurements were performed. Retinal ganglion cells (RGC) and optic nerve head cupping were evaluated in histological sections. Biodistribution of the drug was accessed by scintigraphic images and ex vivo radiation counting. We found that DIZE increased the swelling index of the inserts. Also, it was molecularly dispersed and interspersed in the polymeric matrix as a freebase. DIZE did not lose its chemical integrity and activity when loaded in the inserts. The functional evaluation demonstrated that D+I decreased the IOP and maintained the IOP lowered for up to one month (last week: 11.0±0.7 mmHg). This effect of D+I prevented the loss of RGC and degeneration of the optic nerve. No toxic effects in the eyes related to application of the inserts were observed. Moreover, biodistribution studies showed that D+I prolonged the retention of DIZE in the corneal site. We concluded that D+I provided sustained DIZE delivery in vivo, thereby evidencing the potential application of polymeric-based DIZE inserts for glaucoma management.

A framework to explore the visual brain in glaucoma with lessons from models and man

Vision loss in glaucoma is associated with death of retinal ganglion cells. High intraocular pressure is a major risk factor for vision loss from glaucoma, and lowering eye pressure is the goal of all available medical and surgical treatments. Taking a bold step forward, the restoration of vision after severe glaucoma damage is a new Audacious Goal established by National Eye Institute (Sieving, 2012). This means that retinal ganglion cell repair, and replacement, must be considered in the context of visual function restoration. To restore visual function, retinal ganglion cells, after long-distance axonal growth and guidance, should connect to specific target neurons in subcortical visual structures. At the time of the establishment of these connections, the fate of target cells is critical along with the health of retinal ganglion cells. In fact, several lines of evidence demonstrate glaucomatous neural degeneration occurs throughout the central visual system where most information processing takes place. Evidence from multiple studies in experimental glaucoma models, human autopsy cases and neuroimaging studies point to the degeneration of neurons in the lateral geniculate nucleus, a subcortical hub of functional connectivity between the eye and the visual cortex. Maintaining and re-establishing connections of retinal ganglion cells to target neurons in major visual structures is a key endpoint for regenerative medicine strategies. This paper critically reviews studies of visual brain changes in man and experimental animal models, and discusses key factors in the experimental design that are relevant to restoring vision loss in human disease.

Microbead models in glaucoma

The sustained and moderate elevation of intraocular pressure, which can be initiated at precise time points, remains the cornerstone of research into the mechanisms of glaucomatous retinal damage. We focus on the use of microbeads to block the outflow of aqueous following anterior chamber injection in a range of animals (mouse, rat and primate). We describe some of the most commonly used parameters and present guidance on injection technique and bead manipulation to facilitate the successful generation of experimental glaucoma.

Relating Retinal Ganglion Cell Function and Retinal Nerve Fiber Layer (RNFL) Retardance to Progressive Loss of RNFL Thickness and Optic Nerve Axons in Experimental Glaucoma.

To relate changes in retinal function and retinal nerve fiber layer (RNFL) retardance to loss of RNFL thickness and optic nerve axon counts in a nonhuman primate (NHP) model of experimental glaucoma (EG). Bilateral longitudinal measurements of peripapillary RNFL thickness (spectral-domain optical coherence tomography, SDOCT; Spectralis), retardance (GDxVCC), and multifocal electroretinography (mfERG; VERIS) were performed in 39 NHP at baseline (BL; median, 5 recordings; range, 3-10) and weekly after induction of unilateral EG by laser photocoagulation of the trabecular meshwork. Multifocal ERG responses were high-pass filtered (>75 Hz) to measure high- and low-frequency component (HFC and LFC) amplitudes, including LFC features N1, P1, and N2. High-frequency component amplitudes are known to specifically reflect retinal ganglion cell (RGC) function. Complete (100%) axon counts of orbital optic nerves were obtained in 31/39 NHP. Postlaser follow-up was 10.4 ± 7.9 months; mean and peak IOP were 18 ± 5 and 41 ± 11 mm Hg in EG eyes, 11 ± 2 and 18 ± 6 mm Hg in control (CTL) eyes. At the final available time point, RNFL thickness had decreased from BL by 14 ± 14%, retardance by 20 ± 11%, and the mfERG HFC by 30 ± 17% (P < 0.0001 each). Longitudinal changes in retardance and HFC were linearly related to RNFL thickness change (R2 = 0.51, P < 0.0001 and R2 = 0.22, P = 0.002, respectively); LFC N2 was weakly related but N1 or P2 (N1: R2 = 0.07, P = 0.11; P1: R2 = 0.04, P = 0.24; N2: R2 = 0.13, P = 0.02). At zero change from BL for RNFL thickness (Y-intercept), retardance was reduced by 11% (95% confidence interval [CI]: -15.3% to -6.8%) and HFC by 21.5% (95% CI: -28.7% to -14.3%). Relative loss of RNFL thickness, retardance, and HFC (EG:CTL) were each related to axon loss (R2 = 0.66, P < 0.0001; R2 = 0.42, P < 0.0001; R2 = 0.42, P < 0.0001, respectively), but only retardance and HFC were significantly reduced at zero relative axon loss (Y-intercept; retardance: -9.4%, 95% CI: -15.5% to -3.4%; HFC: -10.9%, 95% CI: -18.6% to -3.2%; RNFL thickness: +1.8%, 95% CI: -4.9% to +5.4%). Retinal nerve fiber layer retardance and RGC function exhibit progressive loss from baseline before any loss of RNFL thickness or orbital optic nerve axons occurs in NHP EG. These in vivo measures might serve as potential biomarkers of early-stage glaucomatous damage preceding axon loss and RGC death.

The non-human primate experimental glaucoma model

The purpose of this report is to summarize the current strengths and weaknesses of the non-human primate (NHP) experimental glaucoma (EG) model through sections devoted to its history, methods, important findings, alternative optic neuropathy models and future directions. NHP EG has become well established for studying human glaucoma in part because the NHP optic nerve head (ONH) shares a close anatomic association with the human ONH and because it provides the only means of systematically studying the very earliest visual system responses to chronic intraocular pressure (IOP) elevation, i.e. the conversion from ocular hypertension to glaucomatous damage. However, NHPs are impractical for studies that require large animal numbers, demonstrate spontaneous glaucoma only rarely, do not currently provide a model of the neuropathy at normal levels of IOP, and cannot easily be genetically manipulated, except through tissue-specific, viral vectors. The goal of this summary is to direct NHP EG and non-NHP EG investigators to the previous, current and future accomplishment of clinically relevant knowledge in this model.

In vivo imaging methods to assess glaucomatous optic neuropathy

The goal of this review is to summarize the most common imaging methods currently applied for in vivo assessment of ocular structure in animal models of experimental glaucoma with an emphasis on translational relevance to clinical studies of the human disease. The most common techniques in current use include optical coherence tomography and scanning laser ophthalmoscopy. In reviewing the application of these and other imaging modalities to study glaucomatous optic neuropathy, this article is organized into three major sections: 1) imaging the optic nerve head, 2) imaging the retinal nerve fiber layer and 3) imaging retinal ganglion cell soma and dendrites. The article concludes with a brief section on possible future directions.

Neuroprotective and antioxidant effects of ghrelin in an experimental glaucoma model.

Damage to retinal ganglion cells due to elevation of intraocular pressure (IOP) is responsible for vision loss in glaucoma. Given that loss of these cells is irreversible, neuroprotection is crucial in the treatment of glaucoma. In this study, we investigated the possible antioxidant and neuroprotective effects of ghrelin on the retina in an experimental glaucoma model. Twenty-one Sprague–Dawley rats were randomly assigned to three groups comprising seven rats each. The rats in the control group were not operated on and did not receive any treatment. In all rats in the other groups, IOP was increased by cauterization of the limbal veins. After creation of the IOP increase, saline 1 mL/kg or ghrelin 40 μg/kg was administered intraperitoneally every day for 14 days in the vehicle control group and ghrelin groups, respectively. On day 14 of the study, the eyes were enucleated. Levels of malondialdehyde (MDA), nitric oxide (NO), and nitric oxide synthase-2 (NOS2) in anterior chamber fluid were measured. The retinas were subjected to immunohistochemistry staining for glial fibrillary acidic protein (GFAP), S-100, and vimentin expression. Mean levels of MDA, NO, and NOS2 in the aqueous humor were higher in the vehicle control group than in the control group (P<0.05). Mean levels of MDA, NO, and NOS2 in the ghrelin group did not show a significant increase compared with levels in the control group (P>0.05). Retinal TUNEL and immunohistochemistry staining in the vehicle control group showed an increase in apoptosis and expression of GFAP, S-100, and vimentin compared with the control group (P<0.05). In the ghrelin group, apoptosis and expression of GFAP, S-100, and vimentin was significantly lower than in the vehicle control group (P<0.05). This study suggests that ghrelin has antioxidant and neuroprotective effects on the retina in an experimental glaucoma model.

Time-dependent retinal ganglion cell loss, microglial activation and blood-retina-barrier tightness in an acute model of ocular hypertension

Glaucoma is a group of neurodegenerative diseases characterized by the progressive loss of retinal ganglion cells (RGCs) and their axons, and is the second leading cause of blindness worldwide. Elevated intraocular pressure is a well known risk factor for the development of glaucomatous optic neuropathy and pharmacological or surgical lowering of intraocular pressure represents a standard procedure in glaucoma treatment. However, the treatment options are limited and although lowering of intraocular pressure impedes disease progression, glaucoma cannot be cured by the currently available therapy concepts. In an acute short-term ocular hypertension model in rat, we characterize RGC loss, but also microglial cell activation and vascular alterations of the retina at certain time points. The combination of these three parameters might facilitate a better evaluation of the disease progression, and could further serve as a new model to test novel treatment strategies at certain time points. Acute ocular hypertension (OHT) was induced by the injection of magnetic microbeads into the rat anterior chamber angle (n = 22) with magnetic position control, leading to constant elevation of IOP. At certain time points post injection (4d, 7d, 10d, 14d and 21d), RGC loss, microglial activation, and microvascular pericyte (PC) coverage was analyzed using immunohistochemistry with corresponding specific markers (Brn3a, Iba1, NG2). Additionally, the tightness of the retinal vasculature was determined via injections of Texas Red labeled dextran (10 kDa) and subsequently analyzed for vascular leakage. For documentation, confocal laser-scanning microscopy was used, followed by cell counts, capillary length measurements and morphological and statistical analysis. The injection of magnetic microbeads led to a progressive loss of RGCs at the five time points investigated (20.07%, 29.52%, 41.80%, 61.40% and 76.57%). Microglial cells increased in number and displayed an activated morphology, as revealed by Iba1-positive cell number (150.23%, 175%, 429.25%,486.72% and 544.78%) and particle size analysis (205.49%, 203.37%, 412.84%, 333.37% and 299.77%) compared to contralateral control eyes. Pericyte coverage (NG2-positive PC/mm) displayed a significant reduction after 7d of OHT in central, and after 7d and 10d in peripheral retina. Despite these alterations, the tightness of the retinal vasculature remained unaltered at 14 and 21 days after OHT induction. While vascular tightness was unchanged in the course of OHT, a progressive loss of RGCs and activation of microglial cells was detected. Since a significant loss in RGCs was observed already at day 4 of experimental glaucoma, and since activated microglia peaked at day 10, we determined a time frame of 7–14 days after MB injection as potential optimum to study glaucoma mechanisms in this model.

The Suppression of Wound Healing Response with Sirolimus and Sunitinib Following Experimental Trabeculectomy in a Rabbit Model

Purpose: To investigate the effects of sirolimus and sunitinib on wound healing in experimental glaucoma filtering surgery (GFS).Material and Methods: Thirty-five male New Zealand pigmented rabbits were randomly assigned to five groups, each including seven rabbits: The rabbits in the control group were not operated on and did not receive any treatment. The rabbits in the sham group underwent trabeculectomy and had one drop of saline instilled four times a day for 14 days. The rabbits in the mitomycin-C (MMC) group underwent trabeculectomy, and a sponge soaked in 0.4 mg/mL MMC was applied intraoperatively to the scleral surgical site for three minutes. The rabbits in the sirolimus group underwent trabeculectomy and 30 ng/mL sirolimus-soaked sponge was applied intraoperatively to the scleral surgical site for three minutes. Sunitinib 0.5 mg/mL four drops in a day were applied in the sunitinib group for 14 days after surgery. On day 14 of the experiment, eyes were enucleated and histologically and immunohistochemically analyzed. Statistical analyses of the study were performed with Kruskal–Wallis variance analysis and Mann–Whitney U test.Results: The mean fibroblast and MNC numbers and the mean immunostaining intensities of transforming growth factor-β (TGF-β), fibroblast growth factor-β (FGF-β) and platelet derived growth factor (PDGF) in the MMC, sirolimus and sunitinib groups were statistically significantly lower than those of the sham group (p < 0.01). The mean fibroblast and MNC numbers and the mean immunostaining intensities of TGF-β, FGF-β and PDGF in the MMC, sirolimus and sunitinib groups were similar (p > 0.05).Conclusions: Our study suggests that the applications of sirolimus and sunitinib effectively suppress the subconjunctival scarring after experimental GFS.

Neuroprotective effect of edaravone in experimental glaucoma model in rats: a immunofluorescence and biochemical analysis.

To evaluate the neuroprotective activity of systemically administered edaravone in early and late stage of experimental glaucoma in rats. In this study, 60 Wistar albino rats were used. Experimental glaucoma model was created by injecting hyaluronic acid to the anterior chamber once a week for 6wk in 46 of 60 subjects. Fourteen subjects without any medication were included as control group. Edaravone administered intraperitoneally 3 mg/kg/d to the 15 of 30 subjects starting at the onset of glaucoma induction and also administered intraperitoneally 3 mg/kg/d to the other 15 subjects starting at three weeks after the onset of glaucoma induction. The other 16 subjects who underwent glaucoma induction was administered any therapy. Retinal ganglion cells (RGCs) have been marked with dextran tetramethylrhodamine (DTMR) retrograde at the end of the sixth week and after 48h, subjects were sacrificed by the method of cardiac perfusion. Alive RGC density was assessed in the whole-mount retina. Whole-mount retinal tissues homogenized and nitric oxide (NO), malondialdehyde (MDA) and total antioxidant capacity (TAC) values were measured biochemically. RGCs counted with Image-Pro Plus program, in the treatment group were found to be statistically significantly protected, compared to the glaucoma group (Bonferroni, P<0.05). The neuroprotective activity of edaravone was found to be more influential by administration at the start of the glaucoma process. Statistically significant lower NO levels were determined in the glaucoma group comparing treatment groups (Bonferroni, P<0.05). MDA levels were found to be highest in untreated glaucoma group, TAC levels were found to be lower in the glaucoma induction groups than the control group (Bonferroni, P<0.05). Systemic administration of Edaravone in experimental glaucoma showed potent neuroprotective activity. The role of oxidative stress causing RGC damage in glaucoma was supported by this study results.

Возможность медикаментозной коррекции нейротропными препаратами нарушений в метаболическом цикле нейротоксического трансмиттера — глутамата в сетчатке при экспериментальной глаукоме

Возможность медикаментозной коррекции нейротропными препаратами нарушений в метаболическом цикле нейротоксического трансмиттера — глутамата в сетчатке при экспериментальной глаукоме

Glutathione attenuates nitric oxide-induced retinal lipid and protein changes.

Elevated levels of nitric oxide (NO(•) ), a pro-oxidant that has been associated with numerous retinal diseases, have been implicated in experimental glaucoma models. This study investigated the oxidative effects of sodium nitroprusside (SNP), a nitric oxide donor, on the retinal lipids and proteins and evaluated the potential protective effects of glutathione (GSH). Porcine retinal homogenates were incubated with 0, 1, 2, 3, 4 and 5μm SNP. Malondialdehyde (MDA) levels were assayed spectrophotometrically to quantify lipid peroxidation. Differential protein expressions of 3μm SNP-treated retinal homogenates were compared with controls after the conduction of two-dimensional gel electrophoresis. Mass spectrometric data was used to identify proteins in NCBInr database. Furthermore, GSH was co-incubated with 3μm SNP-treated retinal homogenates. MDA levels and protein expressions were compared with SNP-treated controls. SNP significantly increased retinal-MDA levels (p=0.0002). 2-D gel electrophoresis images displayed a significant change in 13 protein spot expressions (p<0.05). GSH suppressed SNP-induced MDA elevation (p<0.0001) and selected protein changes (p<0.05). SNP down-regulated paraoxonase/arylesterase 2 precursor (PON2), β-actin and β-tubulin; however, these effects were prevented by a co-incubation with GSH, as confirmed by Western blots. Nitric oxide induced lipid and protein changes in retinal tissues. The effects were partially reversed by co-incubation with GSH. Data from this study suggests that nitric oxide-induced retinal oxidative stress induces specific molecular changes. This may enable us to better understand the pathogenesis of glaucoma. Further studies are indicated to explore potential pharmacological applications of GSH in nitric oxide-related retinal diseases.