Abstract
Purpose::
To assess the benefits of AREDS nutritional supplements in the Royal College of Surgeons (RCS) rat model of retinal degeneration by investigating the electrophysiological, morphological and biochemical parameters.
Methods::
Twenty albino RCS rats, 3 weeks of age, were randomly divided into 2 groups, group 1 received diet supplemented with AREDS nutritional supplements containing vitamin C, 50mg; vitamin E, 0.5g; beta carotene, 1.5mg; Zinc 8mg and Copper 0.2/kg of Purina powder diet 5001 (AREDS group) for 6 weeks, and group 2 received Purina 5001 without any supplementation (control). Full-field electroretinography (ERG) was performed at 5 and 9 weeks of age. The animals were sacrificed the day after the last ERG measurements. One eye was used to evaluate histology, and the retina from the other eye was used to determine the parameters of oxidative stress. Data were analyzed statistically using paired t-test.
Results::
Significant preservation of the ERG responses was observed in the AREDS group as compared to the control group of rats. In the AREDS group, ERG b-wave amplitudes reduced by 42.1±5.8% by the end of the study, whereas in the control group, 68.2±9.2% b-wave amplitudes reduction was observed (p=0.012). Quantitative histological analysis showed that in AREDS group the outer nuclear layer (ONL) cell counts were 32.75±7.25% greater than in the untreated controls (p<0.001). The total antioxidant capacity of the retina was 20% higher in the AREDS group compared to the control group (p=0.048). In the same retina, the activity of superoxide scavenging enzyme, superoxide dismutase, was about 20% higher (p=0.028) compared to the values obtained from the control group. Although the levels of intracellular antioxidant, GSH, were marginally higher (about 12%) in AREDS group compared to the control group, the values did not achieve statistical significance (p=0.057).
Conclusions::
AREDS-based nutritional supplements in RCS rat model of retinal degeneration preserved both the ONL cell counts and the ERG b-wave amplitudes. In the same rats, this supplementation had beneficial effects on the antioxidant defense mechanism of the retina. These findings suggest that AREDS nutritional supplements may have a therapeutic role in preventing retinal degenerations although additional studies are necessary both in other retinal degeneration models and to determine optimal doses of AREDS components.
Keywords: retinal degenerations: hereditary • antioxidants • retina