Melatonin and epigallocatechin gallate reduce the loss of visual function in an animal model of retinal degeneration, P23H rat

Abstract

PurposeRetinitis Pigmentosa (RP) is a heterogeneous group of retinal degenerative disorders which represent a major cause of blindness in adult people with no effective therapy found.Most RP cases are due to rhodopsin mutations, which cause retinal disorganization due to rod degeneration and oxidative stress. Melatonin and epigallocatechin gallate (EGCG) have been reported to exhibit anti‐apoptosis, antioxidant and neuroprotective effects. The aim of this study was to evaluate the synergistic effects of these two natural antioxidants in the P23H rat.Methods20 P23H rats crossed with Long Evans (LE) rats, were used and compared to 20 SD (P23H background) crossed with LE rats. Vehicle, or 10 mg/kg/day of Melatonin and/or 10 mg/kg/day of EGCG were orally administered for 6 months. Visual acuity and contrast sensitivity was evaluated by a monthly optomotor test.ResultsP23HxLE rats showed lower values than SDxLE rats in all optomotor parameters studied. SDxLE rats treated with melatonin or EGCG increased, after 60 days of treatment, visual function parameters even higher than young animals. P23HxLE rats treated with melatonin or EGCG showed better visual acuity and contrast sensitivity than those treated with vehicle in all measurements done after 30 days of treatment, slowing the disease progression. In all animal groups, treatment with melatonin and EGCG simultaneously obtained better visual acuity and contrast sensitivity values than treatment with any of those compounds alone.ConclusionsIn conclusion, oral treatment of melatonin or EGCG improved vision in wild type animals and delayed vision loss in P23H rats. Furthermore, combination of both compounds had a better effect than any of those treatments alone, suggesting different mechanisms of action.