OBJECTIVE: To investigate the therapeutic effect of Epothilone D on traumatic optic neuropathy (TON) in rats. METHODS: Forty-two SD rats were randomized to receive intraperitoneal injection of 1.0 mg/kg Epothilone D or DMSO (control) every 3 days until day 28, and rat models of TON were established on the second day after the first administration. On days 3, 7, and 28, examination of flash visual evoked potentials (FVEP), immunofluorescence staining and Western blotting were performed to examine the visual pathway features, number of retinal ganglion cells (RGCs), GAP43 expression level in damaged axons, and changes of Tau and pTau-396/404 in the retina and optic nerve. RESULTS: In Epothilone D treatment group, RGC loss rate was significantly decreased by 19.12% (P=0.032) on day 3 and by 22.67% (P=0.042) on day 28 as compared with the rats in the control group, but FVEP examination failed to show physiological improvement in the visual pathway on day 28 in terms of the relative latency of N2 wave (P=0.236) and relative amplitude attenuation of P2-N2 wave (P=0.441). The total Tau content in the retina of the treatment group was significantly increased compared with that in the control group on day 3 (P < 0.001), showing a consistent change with ptau-396/404 level. In the optic nerve axons, the total Tau level in the treatment group was significantly lower than that in the control group on day 7 (P=0.002), but the changes of the total Tau and pTau-396/404 level did not show an obvious correlation. Epothilone D induced persistent expression of GAP43 in the damaged axons, detectable even on day 28 of the experiment. CONCLUSION Epothilone D treatment can protect against TON in rats by promoting the survival of injured RGCs, enhancing Tau content in the surviving RGCs, reducing Tau accumulation in injured axons, and stimulating sustained regeneration of axons.
Animals ; Disease Models, Animal ; Epothilones ; Evoked Potentials, Visual ; Nerve Regeneration/physiology* ; Optic Nerve Injuries/metabolism* ; Rats ; Rats, Sprague-Dawley ; Retinal Ganglion Cells/physiology*

Objective To assess the in vivo dynamic blood flow features of posterior optic nerve head (ONH) in rat model of nonarteritic anterior ischemic optic neuropathy (rNAION). Methods rNAION was established with Rose Bengal and argon green laser in Sprague-Dawley rats. Fundus photography and fundus fluorescein angiography (FFA) were performed to assess the dynamic changes of optic disc in morphology in 90 days and in blood perfusion in 3 hours after the induction of disease. Histological examinations were performed to evaluate the success of modeling. The dynamic blood flow kinetics of posterior ONH in rNAION were measured by Laser Doppler Flowmetry (LDF) on the day 3, 7, 14, 21, and 40 after the disease induction. One-way ANOVA, Student's t-test and Bonferroni adjustment were used for multiple comparisons of kinetic measurements of blood flow. Results Optic disc edema and subsequent resolution associated with the development of optic disc pallor were observed in rNAION. FFA showed that the optic disc was hypofluorescence in the early phase and hyperfluorescence in the late phase. Histological studies suggested edema and loosened tissues of ONH, loss of retinal ganglion cells (RGCs), optic nerve substance and gliosis. Compared to the naive rats, the blood flow kinetics of posterior ONH in rNAION significant reduced at each time point after modeling (F=175.06, P<0.0001). The reductions were specifically remarkable in 14 days after the disease induction (All P<0.01). Conclusions Continuous blood perfusion reduction was found in rNAION, with significant alteration in 14 days after disease induction. Our results provided important information for understanding the hemodynamic changes in rNAION.
Animals ; Disease Models, Animal ; Fluorescein Angiography ; Hemodynamics ; physiology ; Humans ; Male ; Optic Disk ; pathology ; physiopathology ; Optic Neuropathy, Ischemic ; pathology ; physiopathology ; Rats ; Rats, Sprague-Dawley ; Retinal Ganglion Cells ; physiology

BACKGROUNDGlaucoma is a progressive optic neuropathy characterized by degeneration of neurons due to loss of retinal ganglion cells (RGCs). High intraocular pressure (HIOP), the main risk factor, causes the optic nerve damage. However, the precise mechanism of HIOP-induced RGC death is not yet completely understood. This study was conducted to determine apoptosis of RGC-5 cells induced by elevated hydrostatic pressures, explore whether laminin is associated with apoptosis under pressure, whether laminin can protect RGCs from apoptosis and affirm the mechanism that regulates the process of RGCs survival.

METHODSRGC-5 cells were exposed to 0, 20, 40, and 60 mmHg in a pressurized incubator for 6, 12, and 24 h, respectively. The effect of elevated hydrostatic pressure on RGC-5 cells was measured by Annexin V-fluorescein isothiocyanate/propidium iodide staining, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and Western blotting of cleaved caspase-3 protein. Location and expression of laminin were detected by immunofluorescence. The expression of β1-integrin, phosphorylation of focal adhesion kinase (FAK) and protein kinase B (PKB, or AKT) were investigated with real-time polymerase chain reaction and Western blotting analysis.

RESULTSElevated hydrostatic pressure induced apoptosis in cultured RGC-5 cells. Pressure with 40 mmHg for 24 h induced a maximum apoptosis. Laminin was declined in RGC-5 cells after exposing to 40 mmHg for 24 h. After pretreating with laminin, RGC-5 cells survived from elevated pressure. Furthermore, β1-integrin and phosphorylation of FAK and AKT were increased compared to 40 mmHg group.

CONCLUSIONSThe data show apoptosis tendency of RGC-5 cells with elevated hydrostatic pressure. Laminin can protect RGC-5 cells against high pressure via β1-integrin/FAK/AKT signaling pathway. These results suggest that the decreased laminin of RGC-5 cells might be responsible for apoptosis induced by elevated hydrostatic pressure, and laminin or activating β1-integrin/FAK/AKT pathway might be potential treatments to prevent RGC loss in glaucomatous optic neuropathy.

Apoptosis ; Cells, Cultured ; Focal Adhesion Protein-Tyrosine Kinases ; physiology ; Humans ; Hydrostatic Pressure ; Integrin beta1 ; physiology ; Intraocular Pressure ; Laminin ; physiology ; Proto-Oncogene Proteins c-akt ; physiology ; Retinal Ganglion Cells ; physiology ; Up-Regulation

PURPOSE: Though there are many reports regarding the structure-function relationship in glaucoma, they are too complicated to apply to the routine clinical setting. The aim of this study was to investigate the direct relationship between peripapillary retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) and visual field (VF) severity indices computed by standard automated perimetry. METHODS: This cross-sectional comparative study included 104 glaucomatous patients and 59 healthy subjects. Peripapillary RNFL thickness was measured by spectral domain (SD) and time domain (TD) OCTs. Four glaucoma VF severity indices, including mean deviation (MD), pattern standard deviation (PSD), Collaborative Initial Glaucoma Treatment Study (CIGTS) VF score, and Advanced Glaucoma Intervention Study (AGIS) VF score, were calculated using standard automated perimetry. The Pearson's correlation coefficients (r) between the average and quadrants of peripapillary RNFL thicknesses and the four VF severity indices were calculated. RESULTS: In glaucomatous eyes, the r value between the average RNFL thickness measured by SD OCT and each VF severity index were 0.562, -0.514, -0.577, and -0.567 for the MD, PSD, CIGTS VF score, and AGIS VF score, respectively (all p < 0.001). Among each quadrant, the inferior RNFL thickness showed the largest r value; 0.587, -0.552, -0.613, and -0.598 for the MD, PSD, CIGTS VF score, and AGIS VF score, respectively (all p < 0.001). Measurements by TD OCT showed similar strengths of association with SD OCT. CONCLUSIONS: Moderate correlation was identified between peripapillary RNFL thicknesses measured by SD/TD OCT and glaucoma VF severity indices. Among each quadrant, the inferior RNFL thickness showed the greatest association with glaucoma VF severity indices. There was no significant difference according to the type of VF severity index or the type of OCTs.
Adult ; Aged ; Cross-Sectional Studies ; Female ; Humans ; Male ; Middle Aged ; Nerve Fibers/*pathology ; Optic Nerve/*pathology ; Optic Nerve Diseases/*diagnostic imaging/physiopathology ; Retinal Ganglion Cells/*pathology ; Severity of Illness Index ; Tomography, Optical Coherence/*methods ; Visual Field Tests/methods ; Visual Fields/*physiology ; Young Adult

The knowledge about electrophysiological properties of retinal ganglion cells (RGCs), as well as modulation of these properties, is important not only for understanding the unique physiological functions of RGCs under normal conditions, but also for exploring the cellular mechanisms of retinal neurodegeneration diseases, such as glaucoma. In this paper, we reviewed the progress in electrophysiological studies of RGCs by using patch-clamp techniques, concerning the voltage-gated ion channels, the ligand-gated ion channels and the effects of neuromodulators on these channels.
Animals ; Electrophysiological Phenomena ; Humans ; Ion Channels ; physiology ; Patch-Clamp Techniques ; Retinal Ganglion Cells ; physiology

PURPOSE: To evaluate the effect of pattern scan laser (PASCAL) photocoagulation on peripapillary retinal nerve fiber layer (RNFL) thickness, central macular thickness (CMT), and optic nerve morphology in patients with diabetic retinopathy. METHODS: Subjects included 35 eyes for the PASCAL group and 49 eyes for a control group. Peripapillary RNFL thickness, cup-disc area ratio and CMT were measured before PASCAL photocoagulation and at 2 and 6 months after PASCAL photocoagulation in the PASCAL or control groups. RESULTS: The average RNFL thickness had increased by 0.84 microm two months after and decreased by 0.4 microm six months after PASCAL photocoagulation compared to baseline, but these changes were not significant (p = 0.83, 0.39). The cup-disc area ratio was unchanged after PASCAL photocoagulation. CMT increased by 18.11 microm (p = 0.048) at two months compared to baseline thickness, and partially recovered to 11.82 microm (p = 0.11) at six months in the PASCAL group. CONCLUSIONS: PASCAL photocoagulation may not cause significant change in the peripapillary RNFL thickness, CMT, and optic nerve morphology in patients with diabetic retinopathy.
Adult ; Aged ; Aged, 80 and over ; Diabetic Retinopathy/physiopathology/*surgery ; Female ; Fluorescein Angiography ; Follow-Up Studies ; Humans ; Laser Coagulation/*methods ; Lasers, Solid-State/*therapeutic use ; Macula Lutea/*pathology ; Male ; Middle Aged ; Nerve Fibers/*pathology ; Optic Nerve/*pathology ; Prospective Studies ; Retinal Ganglion Cells/*pathology ; Tomography, Optical Coherence ; Visual Acuity/physiology

PURPOSE: To investigate patterns of subsequent progression of localized retinal nerve fiber layer (RNFL) defects and to quantify the extent of progression in normal-tension glaucoma (NTG) patients. METHODS: Thirty-three eyes of 33 consecutive NTG patients who had shown continuous progression of localized RNFL defect on serial red-free fundus photographs were selected for the study. Patterns of subsequent progression of localized RNFL defects were categorized, and extents of progression were quantified. Serial evaluations of disc stereophotographs and visual fields were also performed to detect progression. RESULTS: The most common pattern was continuous widening of the defect towards the macula (n = 11, 33.3%) followed by sharpening of the defect border after widening of the defect towards the macula (n = 5, 15.2%), continuous widening of the defect away from the macula (n = 2, 6.1%), and deepening of the defect after appearance of a new defect (n = 2, 6.1%). Four eyes (12.1%) simultaneously showed two patterns of subsequent progression. In 13 eyes that showed continuous widening of the defect, subsequent angular widening towards the macula and away from the macula were 9.2 ± 6.0degrees (range, 1.1degrees to 24.4degrees; n = 11) and 5.2 ± 4.9degrees (range, 0.3degrees to 11.3degrees; n = 2), respectively. Thirty-two eyes showed no progression of optic disc cupping. Out of the 21 eyes in which Humphrey central 30-2 threshold visual field tests were performed after progression of RNFL defects, 15 eyes showed no deterioration in the visual field. CONCLUSIONS: There were nine patterns of subsequent progression of localized RNFL defects. Among them, continuous RNFL loss proceeding temporally was the most common one. Initial progression of the defect proceeded temporally, especially in the defect located at the inferior fundus, might be at a risk of further RNFL loss temporally.
Adult ; Aged ; Disease Progression ; Female ; Follow-Up Studies ; Humans ; Intraocular Pressure/physiology ; Low Tension Glaucoma/*diagnosis/physiopathology ; Male ; Middle Aged ; Nerve Fibers/*pathology ; Optic Disk/pathology ; Photography ; Retinal Ganglion Cells/*pathology ; Tonometry, Ocular ; Visual Fields/physiology

PURPOSE: To evaluate the relationship between the structural damage as assessed by time-domain optical coherence tomography (OCT) and functional changes in glaucoma. METHODS: In total, 190 patients with normal tension glaucoma or primary open angle glaucoma were included in this study. The thickness of retinal nerve fiber layer (RNFL) around the optic disc and the area of RNFL defect were determined using OCT scans. The relationships between the RNFL thickness or area of the defect and visual field (VF) indices were assessed using the Lowess function, regression analysis and partial Spearman correlation. The differences between these associations depending on the stage of VF damage were further analyzed. Age, optic disc size, refraction, central corneal thickness and the presence of systemic disease were corrected for in order to exclude confounding factors. RESULTS: A logarithmic scale of RNFL thickness showed a negative linear relationship with VF indices. The area of the RNFL defect showed a weak correlation with the pattern of standard deviation, whereas the remnant RNFL thickness was moderately correlated with the pattern of standard deviation (partial Spearman correlation coefficient, 0.39, -0.47, respectively; p < 0.0001). Many outliers were detected in the Lowess-plotted graphs. Multiplication of the area and the inverted RNFL thickness showed a moderately correlated logarithmic relationship with the VF indices (partial Spearman correlation coefficient, 0.46; 95% confidence interval, 0.34 to 0.57; p < 0.0001). In the severe stage of VF damage, correlation between the area of the RNFL defect and mean deviation was significantly greater than in other stages (partial Spearman correlation coefficient, -0.66; p = 0.02). CONCLUSIONS: The thickness of the RNFL had a negative logarithmic correlation with the VF indices and was more relevant to the VF indices than the area of the RNFL defect, as measured by OCT.
Aged ; Female ; Glaucoma, Open-Angle/*physiopathology ; Humans ; Low Tension Glaucoma/*physiopathology ; Male ; Middle Aged ; Nerve Fibers/*pathology ; Optic Nerve Diseases/*physiopathology ; Retinal Ganglion Cells/*pathology ; Tomography, Optical Coherence ; Visual Field Tests ; Visual Fields/*physiology

Activation of cannabinoid CB1 receptors (CB1Rs) regulates a variety of physiological functions in the vertebrate retina through modulating various types of ion channels. The aim of the present study was to investigate the effects of this receptor on cell excitability of rat retinal ganglion cells (RGCs) in retinal slices using whole-cell patch-clamp techniques. The results showed that under current-clamped condition perfusing WIN55212-2 (WIN, 5 μmol/L), a CB1R agonist, did not significantly change the spontaneous firing frequency and resting membrane potential of RGCs. In the presence of cocktail synaptic blockers, including excitatory postsynaptic receptor blockers CNQX and D-APV, and inhibitory receptor blockers bicuculline and strychnine, perfusion of WIN (5 μmol/L) hardly changed the frequencies of evoked action potentials by a series of positive current injection (from +10 to +100 pA). Phase-plane plot analysis showed that both average threshold voltage for triggering action potential and delay time to reach threshold voltage were not affected by WIN. However, WIN significantly decreased +dV/dtmax and -dV/dtmax of action potentials, suggestive of reduced rising and descending velocities of action potentials. The effects of WIN were reversed by co-application of SR141716, a CB1R selective antagonist. Moreover, WIN did not influence resting membrane potential of RGCs with synaptic inputs being blocked. These results suggest that activation of CB1Rs may regulate intrinsic excitability of rat RGCs through modulating evoked action potentials.
Action Potentials ; Animals ; Benzoxazines ; pharmacology ; Evoked Potentials ; In Vitro Techniques ; Membrane Potentials ; Morpholines ; pharmacology ; Naphthalenes ; pharmacology ; Patch-Clamp Techniques ; Piperidines ; pharmacology ; Pyrazoles ; pharmacology ; Rats ; Receptor, Cannabinoid, CB1 ; physiology ; Retinal Ganglion Cells ; physiology

OBJECTIVETo review the updated research on neuroprotection in glaucoma, and summarize the potential agents investigated so far.

DATA SOURCESThe data in this review were collected from PubMed and Google Scholar databases published in English up to September 2012, with keywords including glaucoma, neuroprotection, and retinal ganglion cells, both alone and in combination. Publications from the past ten years were selected, but important older articles were not excluded.

STUDY SELECTIONArticles about neuroprotection in glaucoma were selected and reviewed, and those that are cited in articles identified by this search strategy and judged relevant to this review were also included.

RESULTSAlthough lowering the intraocular pressure is the only therapy approved as being effective in the treatment of glaucoma, increasing numbers of studies have discovered various mechanisms of retinal ganglion cells death in the glaucoma and relevant neuroprotective strategies. These strategies target neurotrophic factor deprivation, excitotoxic damage, oxidative stress, mitochondrial dysfunction, inflammation, activation of intrinsic and extrinsic apoptotic signals, ischemia, and protein misfolding. Exploring the mechanism of axonal transport failure, synaptic dysfunction, the glial system in glaucoma, and stem cell used in glaucoma constitute promising research areas of the future.

CONCLUSIONSNeuroprotective strategies continue to be refined, and future deep investment in researching the pathogenesis of glaucoma may provide novel and practical neuroprotection tactics. Establishing a system to assess the effects of neuroprotection treatments may further facilitate this research.

Apoptosis ; Axonal Transport ; Brain-Derived Neurotrophic Factor ; physiology ; Ciliary Neurotrophic Factor ; physiology ; Glaucoma ; etiology ; therapy ; Humans ; Mitochondria ; physiology ; Neuroprotective Agents ; therapeutic use ; Oxidative Stress ; Protein Folding ; Receptors, N-Methyl-D-Aspartate ; physiology ; Retinal Ganglion Cells ; physiology