Epigallocatechin Gallate Improves Visual Function And Reduces Nitrosative Stress in An Animal Model Of Retinitis Pigmentosa

Abstract

Purpose: Retinitis pigmentosa (RP) is a heterogeneous group of inherited conditions that lead to blindness. Apoptosis of photoreceptors and retinal disorganization are common features in animal models of the disease. Epigallocatechin-3-gallate (EGCG), the major polyphenol of green tea, is an antioxidant exhibiting multifunctional properties, and has been reported to exhibit anti-inflammatory, anti-apoptosis, and neuroprotective effects. Thus, the aim of this work was to evaluate the protective effect of EGCG in an animal model of RP, the P23H rat.

Methods: Twelve heterozygous pigmented P23H line 1 rats and Long Evans (LE) rats were used for this study. Animals were treated in accordance to the ARVO statement for the use of animals in ophthalmic and vision research. 25 mg/kg of EGCG were administered intraperitoneally weekly. The administration was started at 100 postnatal day (P100) ending at P160. Visual function was evaluated by electroretinography (ERG) and optomotor test; in addition, nitrite levels and total plasma antioxidant activity were measured. Anatomical assessment was performed by ICC.

Results: In the absence of EGCG treatment, P23H rats showed a greater visual loss and a higher nitrosative level than LE rats. EGCG slowed the loss of visual function registered by the ERG and optomotor in P23H rats. Also EGCG improved total antioxidant capacity and reduced P23H nitrosative damage in rats. Photoreceptors and synaptic connectivity was preserved in the EGCG treated group.

Conclusions: Intraperitoneal application of EGCG was able to delay vision loss and to reduce nitrosative stress in P23H rats. This suggests potential protective effect of EGCG against retinal diseases associated with nitrosative stress including RP.

Keywords: 695 retinal degenerations: cell biology • 696 retinal degenerations: hereditary • 634 oxidation/oxidative or free radical damage