The protective effect of astaxanthin on the ganglion cell complex in glutamate/aspartate transporter deficient mice, a model of normal tension glaucoma, analyzed by spectral domain-optical coherence tomography.

Astaxanthin (AST), a natural marine carotenoid, possess a wide variety of biological functions. In particular, as a strong antioxidant, AST effectively scavenges oxygen free radicals and reduces oxidative stress. In addition, recent in vitro studies have suggested that AST attenuates glutamate-induced apoptosis and cytotoxicity. The glutamate/aspartate transporter (GLAST) deficient (GLAST-/-) mouse is a mouse model of normal tension glaucoma (NTG) caused by both the glutamate neurotoxicity and oxidative stress in the retina. In the present study, we investigated the effects of AST on the ganglion cell complex, indicator of glaucomatous structural damage, using spectral domain-optical coherence tomography. As a result, AST significantly attenuated the thinning of ganglion cell complex in GLAST-/- mice in comparison to an AST-free control group. Our results suggest the possibility that AST has protective effects against glutamate neurotoxicity and oxidative stress in the retina. At present, the only treatment for NTG that is available in the clinical setting is to reduce the IOP as much as possible. Thus, our results suggest that AST supplementation may be effective for some types of NTG in which glutamate neurotoxicity and oxidative stress are involved.

Protection of cone photoreceptor M-opsin degradation with 9-cis-ß-carotene-rich alga Dunaliella bardawil in Rpe65(-/-) mouse retinal explant culture.

PURPOSE: RPE65, a retinal pigment epithelium-specific 65-kDa protein, plays a critical role in the visual cycle of the eye. Rpe65(-/-) mice develop vision loss due to a lack of 11-cis-retinal, degradation of M-opsin and mislocalization of S-opsin. Several studies have suggested that 9-cis-ß-carotene, a precursor of 9-cis-retinal and all-trans-retinal, could have therapeutic applications in vision loss. We therefore examined whether Dunaliella bardawil, a 9-cis-ß-carotene-rich alga, protects against the degradation of M-opsin using Rpe65(-/-) mouse retinal explant cultures. METHODS: The eyes of three-week-old Rpe65(-/-) and C57BL/6 J mice were enucleated, and the corneas were removed. The eyecups were incubated with culture medium in the absence or presence of D. bardawil for 6 h to 4 days. Localizations of M-opsin proteins in the retina were observed immunohistochemically. Expression levels of M-opsin, S-opsin and rhodopsin proteins were evaluated by Western blot analysis. RESULTS: In C57BL/6 J mouse retina, no change was observed in localization and expression levels of M-opsin in the explant culture system. In Rpe65(-/-) mouse retina, the amount of M-opsin protein was decreased in the photoreceptor outer segment after 6 h to 4 days of culture. However, the presence of D. bardawil significantly ameliorated this decrease. In contrast, expression levels of S-opsin and rhodopsin were unchanged in the presence of the explant culture. CONCLUSIONS: These results demonstrate that D. bardawil treatment protects against M-opsin degradation in Rpe65(-/-) mouse retina and suggest that D. bardawil has therapeutic potential for retinal degeneration caused by Rpe65 gene mutation, such as Leber congenital amaurosis and retinitis pigmentosa.

Effect of nilvadipine on central visual field in retinitis pigmentosa: a 30-month clinical trial.

PURPOSE: To assess the effects of nilvadipine on the progression of central visual field defect in retinitis pigmentosa (RP). DESIGN: Prospective, randomized, nonmasked, single-center trial. METHODS: Patients with RP were randomly divided into a treated group receiving oral nilvadipine at 4 mg/day for ≥30 months and a control group receiving tocopherol nicotinate at 300 mg/day, helenien at 15 mg/day or no medication for the same periods. Progression of RP was evaluated using the 10-2 SITA Fast Program of the Humphrey Visual Field Analyzer, and regression coefficients calculated from the time courses of mean deviation (MD slope) were compared between groups. RESULTS: Nineteen patients in the treated group and 14 patients in the control group completed the follow-up for ≥30 months. The mean (±standard deviation) duration of observation was 48.8 ± 11.8 months (median 48 months, range 30-66 months) for the treated group and 49.2 ± 18.1 months (median 48 months, range 30-90 months) for the control group (p = 0.94). Mean (±standard error of the mean, SEM) regression coefficients of the averaged MD values for the initial 30 months were -0.35 ± 0.17 dB/year in the treated group and -0.75 ± 0.06 dB/year in the control group (p < 0.01). Mean (±SEM) MD slopes for total observational periods were -0.49 ± 0.17 dB/year in the treated group and -0.89 ± 0.16 dB/year in the control group (mean ± SEM, p = 0.042). CONCLUSION: Nilvadipine at 4 mg/day significantly retarded progression of central visual field defects in RP in this small patient series.

Systemic administration of nilvadipine delays photoreceptor degeneration of heterozygous retinal degeneration slow (rds) mouse.

To investigate the effect of nilvadipine, a calcium channel blocker, upon the retina of retinal degeneration slow (rds) mouse, nilvadipine was intraperitoneally injected into heterozygous rds mice for up to 200 days. The effect of nilvadipine was evaluated by electroretinography (ERG), light and electron microscopies, DNA microarray, quantitative reverse transcriptase polymerase chain reaction (RT-PCR), and western-blot analysis. After nilvadipine treatment, both a- and b-waves of ERG were significantly higher than in the control group (p<0.01). Although there was no difference in histological findings by light microscopy between the nilvadipine treated group and control group, apparent preservation of photoreceptor disc was demonstrated by electron microscopy in the treated group. Rhodopsin level was also increased in the treated group comparing to the control group. The DNA microarray analysis detected increased expression of genes encoding proteins which function in protein synthesis, growth factors and neurotrophic factor like ciliary neurotrophic factor (CNTF) and fibroblast growth factors (FGFs22 and 13). Decreased expression of genes coding for proteins related to proteolysis, apoptosis and growth factor (FGF18) was also demonstrated. Increased expression of CNTF, FGF22 and FGF13 and decreased expression of FGF18 were confirmed by both quantitative RT-PCR and western-blot analysis. In addition, FGF2 was constitutively expressed in both treated and control groups. Since CNTF has been known to retard retinal degeneration by rds mouse or other models of inherited retinal degeneration, it is possible that nilvadipine has a photoreceptor survival effect on rds retinal degeneration partly by enhancing expression of endogenous CNTF in the retina.

A case of normal tension glaucoma associated with Buerger's disease.

Open angle glaucoma, a slowly progressive optic atrophy, is clinically characterized by visual field defects corresponding to excavation of the optic disc, called glaucomatous cupping. Open angle glaucoma is further divided into primary open angle glaucoma caused by elevated intraocular pressure (higher than the normal limit of 21 mmHg), and normal tension glaucoma, in which intraocular pressure is in the normal range. Here we report a case of normal tension glaucoma associated with Buerger's disease, also known as thromboangiitis obliterans, which causes systemic blood flow disturbance. A 66-year-old man suffering from Buerger's disease for 10 years was diagnosed as having branch retinal artery occlusion in his left eye. He was referred to our clinic due to progressive visual field disturbance in that eye. Ophthalmologic examinations revealed occlusion in the infero-temporal retinal artery in the left eye, and glaucomatous cupping, normal intraocular pressure, retinal vessel tortuosity and retinal arteriosclerosis in both eyes. Visual field examination revealed decreased retinal sensitivities in the areas within the visual field arches above and below fixation from the blind spot to the median raphe, corresponding to the arcuate retinal nerve fibers comprising the Bjerrum areas and the area corresponding to the retinal artery occlusion. Buerger's disease is characterized by the development of segmental thrombotic occlusions and vasospasm of the medium and small arteries. Our case suggests that the blood flow disturbance due to arteriosclerosis, thrombotic occlusions and vasospasm associated with Buerger's disease might affect the ophthalmic circulation system, thereby contributing to the etiology of normal tension glaucoma.

Study of pharmacological effects of nilvadipine on RCS rat retinal degeneration by microarray analysis.

In our recent study, we found that the Ca(2+) antagonist, nilvadipine caused significant preservation of photoreceptor cells in The Royal College of Surgeons (RCS) rats [Invest. Ophthalmol. Vis. Sci. 43 (2002) 919]. Here, to elucidate the mechanisms of nilvadipine-induced effects we analyzed altered gene expression of 1101 genes commonly expressed in rodent by DNA microarray analysis in the retinas of nilvadipine-treated and untreated RCS rats and SD rat. In the total number of genes, the expression of 30 genes was altered upon administration of nilvadipine to RCS rats, including several genes related to the apoptotic pathway and other mechanisms. Remarkably, neurotrophic factors, FGF-2 and Arc, known to suppress the apoptosis in the central nervous system, were up-regulated. These changes were also confirmed by real-time quantitative (Taqman) RT-PCR and Western blot analysis. Therefore, our present data suggested that administration of nilvadipine to RCS rats increases the expression of endogenous FGF-2 and Arc in retina, and potentially has a protective effect against retinal degeneration.

Clinical significance of serum antibody against neuron-specific enolase in glaucoma patients.

PURPOSE: In a recent study, we found the presence of serum autoantibody against neuron-specific enolase (NSE) in glaucoma patients. The purpose of the present paper is to investigate further the clinical significance of the presence of the serum antibody against NSE in glaucoma patients. METHODS: Serum autoantibody against NSE was examined by Western blot analysis in 143 patients with glaucoma (normal tension glaucoma [NTG], 45 cases; primary open angle glaucoma [POAG] 98 cases). Clinical characteristics including visual acuity, visual field, intraocular pressure (IOP), and optic disc features were compared between the serum autoantibody-positive and the serum autoantibody-negative patients. RESULTS: Maximum IOP in the serum anti-NSE antibody-positive patients was significantly lower than that in the negative patients (P <.05). However, no statistical differences were observed in visual field loss, disc cupping, or other clinical factors. During the clinical course, rates of the presence of anti-NSE antibody were significantly higher in the early stages of POAG (P <.0001) with visual field deterioration than without it. Although it was not statistically significant, the positive rates of serum anti-NSE antibody were relatively higher in the later stages of POAG and NTG with visual field deterioration than without it. CONCLUSION: The present observations suggest that the presence of serum autoantibody against NSE may be clinically useful for predicting the progression of visual field loss in POAG patients.