beta-carotene and Retinal-Degeneration

Topics: Animals; Ascorbic Acid; Awards and Prizes; beta Carotene; Carotenoids; Disease Models, Animal; Humans; Light; Ophthalmology; Photoreceptor Cells; Retina; Retinal Degeneration; Societies, Medical

BACKGROUND Fundus albipunctatus is a retinal dystrophy caused by a mutation in the gene encoding 11-cis-retinol dehydrogenase which delays the recovery of rod photoreceptor cells from light stimulation leading to night blindness. A recent study of a mouse model of fundus albipunctatus treated with 9-cis-retinal showed an improvement in visual function and structure. METHODS Seven patients with fundus albipunctatus were given a daily food supplement of four capsules containing high-dose 9-cis-beta-carotene for 90 days. The subjects were tested before and after treatment by visual field and electroretinogram in both eyes. This non-randomised prospective phase I study was registered at http://www.clinicaltrials.gov (NCT00478530). RESULTS All patients showed significant improvements in peripheral visual field (mean deviation improved from -4.77+/-2.0 to -3.28+/-2.28, p=0.009, t test) and a highly significant improvement in rod recovery rates measured electroretinographically (maximal scotopic b-wave amplitude responses, improved from 197+/-49 muV to 292+/-48 muV, p<0.001, t test). No complications or side effects were observed. CONCLUSION Oral treatment with 9-cis-beta-carotene led to reversal of a human retinal dystrophy. This potential therapy is readily available and should be evaluated in retinal dystrophies of similar mechanisms such as various types of retinitis pigmentosa.

Topics: Administration, Oral; Adolescent; Adult; beta Carotene; Dietary Supplements; Electroretinography; Eye Diseases, Hereditary; Female; Humans; Male; Middle Aged; Pilot Projects; Prospective Studies; Retinal Degeneration; Treatment Outcome; Visual Acuity; Visual Fields; Vitamins; Young Adult

The retinoid cycle enzymes regenerate the visual chromophore 11-cis retinal to enable vision. Mutations in the genes encoding the proteins of the retinoid cycle are the leading cause for recessively inherited retinal dystrophies such as retinitis pigmentosa, Leber congenital amaurosis, congenital cone-rod dystrophy and fundus albipunctatus. Currently there is no treatment for these blinding diseases. In previous studies we demonstrated that oral treatment with the 9-cis-β-carotene rich Dunaliella Bardawil algae powder significantly improved visual and retinal functions in patients with retinitis pigmentosa and fundus albipunctatus. Here we developed a convenient and economical synthetic route for biologically active 9-cis-β-carotene from inexpensive building materials and demonstrated that the molecule is stable for at least one month. Synthetic 9-cis-β-carotene rescued cone photoreceptors from degeneration in eye cup cultures of mice with a retinoid cycle genetic defect. This study suggests that synthetic 9-cis-β-carotene may serve as an effective treatment for retinal dystrophies involving the retinoid cycle.

Topics: Animals; beta Carotene; Cells, Cultured; Chemistry Techniques, Synthetic; Disease Models, Animal; Mice; Photoreceptor Cells, Vertebrate; Provitamins; Retinal Degeneration; Retinal Diseases; Retinitis Pigmentosa

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-β-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-β-carotene-rich alga, protects against the degradation of M-opsin using Rpe65(-/-) mouse retinal explant cultures.. 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.. 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.. 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.

Topics: Animals; beta Carotene; Blotting, Western; Chlorophyta; cis-trans-Isomerases; Cone Opsins; Fluorescent Antibody Technique, Indirect; Mice; Mice, Inbred C57BL; Mice, Knockout; Organ Culture Techniques; Plant Extracts; Retina; Retinal Cone Photoreceptor Cells; Retinal Degeneration; Rhodopsin; Rod Opsins

To test whether the saffron extract (Crocus sativus L.) given as a dietary supplement counteracts the effects of continuous light exposure in the albino rat retina.. Three experimental groups of Sprague-Dawley rats were used. Experimental animals were prefed either saffron or beta-carotene (1 mg extract/kg/d) before they were exposed to bright continuous light (BCL) for 24 hours. Flash electroretinograms (fERGs) were recorded in control and treated rats the day before and 1 week after light exposure. At the end of the second recording session, the animals were killed and the retinas were quickly removed, fixed, cryosectioned, and labeled so that the thickness of the outer nuclear layer (ONL) could be analyzed. Changes in protein level and cellular localization of fibroblast growth factor (FGF)2 were determined by Western blot analysis and retinal immunohistochemistry, respectively. In a second series of experiments, rats were killed at the end of light exposure, and the amount of apoptotic figures in the ONL was assessed by terminal transferase-mediated deoxyuridine triphosphate (d-UTP)-biotin nick-end labeling (TUNEL). BCL induced DNA fragmentation, characteristic of dying cells, almost exclusively in the photoreceptor layer. The rate of photoreceptor death induced by BCL is expressed as the frequency of TUNEL-positive profiles per millimeter.. The photoreceptor layer was largely preserved in saffron-treated animals because it was the fERG response. In addition, the rate of photoreceptor death induced by BCL appeared drastically reduced in treated animals. In beta-carotene prefeeding experiments, morphologic analysis showed preservation of the ONL similar to that obtained with saffron prefeeding, whereas the fERG response was unrecordable. Western blot analysis showed that exposure to light induced a strong upregulation of FGF2 in control and beta-carotene-treated rats, but s no change was noted in saffron-treated rats.. These results show that saffron may protect photoreceptors from retinal stress, maintaining both morphology and function and probably acting as a regulator of programmed cell death.

Topics: Animals; Apoptosis; beta Carotene; Blotting, Western; Crocus; Dark Adaptation; Electroretinography; Fibroblast Growth Factor 2; Flowers; Fluorescent Antibody Technique, Indirect; In Situ Nick-End Labeling; Light; Oxidative Stress; Photic Stimulation; Plant Extracts; Radiation Injuries, Experimental; Rats; Rats, Sprague-Dawley; Retina; Retinal Degeneration

To determine macular pigment (MP) optical density (OD) in patients with ABCA4-associated retinal degenerations (ABCA4-RD) and the response of MP and vision to supplementation with lutein.. Patients with Stargardt disease or cone-rod dystrophy and known or suspected disease-causing mutations in the ABCA4 gene were included. All patients had foveal fixation. MPOD profiles were measured with heterochromatic flicker photometry. Serum carotenoids, visual acuity, foveal sensitivity, and retinal thickness were quantified. Changes in MPOD and central vision were determined in a subset of patients receiving oral supplementation with lutein for 6 months.. MPOD in patients ranged from normal to markedly abnormal. As a group, patients with ABCA4-RD had reduced foveal MPOD, and there was a strong correlation with retinal thickness. Average foveal tissue concentration of MP, estimated by dividing MPOD by retinal thickness, was normal in patients, whereas serum concentration of lutein and zeaxanthin was significantly lower than normal. After oral lutein supplementation for 6 months, 91% of the patients showed significant increases in serum lutein, and 63% of the patients' eyes showed a significant augmentation in MPOD. The retinal responders tended to be female and to have lower serum lutein and zeaxanthin, lower MPOD, and greater retinal thickness at baseline. Responding eyes had significantly lower baseline MP concentration than did nonresponding eyes. Central vision was unchanged after the period of supplementation.. MP is strongly affected by the stage of ABCA4 disease leading to abnormal foveal architecture. MP could be augmented by supplemental lutein in some patients. There was no change in central vision after 6 months of lutein supplementation. Long-term influences of this supplement on the natural history of these macular degenerations require further study.

Topics: Administration, Oral; Adolescent; Adult; ATP-Binding Cassette Transporters; beta Carotene; Female; Humans; Lutein; Male; Middle Aged; Photometry; Pilot Projects; Retina; Retinal Degeneration; Retinal Pigments; Tomography, Optical Coherence; Visual Acuity; Xanthophylls; Zeaxanthins

Inferential evidence indicates that macular pigments (lutein and zeaxanthin) protect photoreceptors and/or retard age-related macular degeneration. These experiments tested the hypothesis that retinal zeaxanthin prevents light-induced photoreceptor cell death.. Retinal damage was assessed in quail fed a carotenoid-deficient (C-) diet for 6 months. Groups of 16 birds (8 male, 8 female) were fed a C- diet supplemented with 35 mg 3R,3'R-zeaxanthin for 1, 3, or 7 days; one group was continued on C- diets. Half of each group was exposed to intermittent 3200-lux white light (10 1-hour intervals separated by 2 hours in dark). After 14 additional hours in the dark, one retina of each quail was collected for HPLC analysis, and the contralateral retina was embedded in paraffin for counts of apoptotic nuclei.. After 7 days' supplementation, concentrations of zeaxanthin in serum, liver, and fat had increased by factors of 50.8, 43.2, and 6.5, respectively (all P < 0.001). In contrast, retinal zeaxanthin fluctuated significantly upward on day 3, but there was no net change on day 7. The number of apoptotic rods and cones in light-damaged eyes correlated significantly and inversely with zeaxanthin concentration in the contralateral retina (r = -0.61; P < 0.0001 and r = -0.54; P < 0.002), but not with serum zeaxanthin. Similar correlations were observed with retinal lutein, which correlated strongly with retinal zeaxanthin (r = 0.95; P < 0.0001).. Retinal zeaxanthin dose dependently reduced light-induced photoreceptor apoptosis; elevated serum levels did not. These data provide the first experimental evidence that xanthophyll carotenoids protect photoreceptors in vivo.

Topics: Adipose Tissue; Animals; Apoptosis; beta Carotene; Cell Count; Chromatography, High Pressure Liquid; Coturnix; Cytoprotection; Diet; Female; Light; Liver; Lutein; Male; Photoreceptor Cells, Vertebrate; Radiation Injuries, Experimental; Retina; Retinal Degeneration; Xanthophylls; Zeaxanthins