Abstract
Purpose :
Apoptosis of photoreceptors and retinal disorganization are common features in Retinitis Pigmentosa. Melatonin and epigallocatechin gallate (EGCG) have been reported to exhibit anti-apoptosis, antioxidant and neuroprotective effects. Thus, we evaluated the synergistic effects of melatonin and EGCG in an animal model of Retinitis Pigmentosa, the P23H rat.
Methods :
20 heterozygotes P23H line 1 rats, offspring of P23H Sprague-Dawley(SD)-background crossed with Long Evans (LE) rats, were used and compared to 20 SD crossed with LE rats, the reference group. Animals were treated in accordance to the ARVO statement for the use of animals in ophthalmic and vision research. Vehicle, or 10 mg/kg/day of Melatonin and/or EGCG were administered in the drinking water from 30 to 180 postnatal days. Visual function was evaluated by a monthly optomotor test that measures visual acuity and contrast sensitivity.
Results :
P23HxLE 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 (90 days old), 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.
Conclusions :
Oral treatment of melatonin or EGCG improved vision in wild type animals and delayed vision loss in P23H rats. Furthermore, combination of melatonin and EGCG had a better effect than any of those treatments alone. This suggests both compounds have different mechanisms of action and their effects improving visual function in wild type and in an animal model of Retinitis Pigmentosa are synergistic.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.