Green tea catechins are potent anti-oxidants that ameliorate sodium iodate-induced retinal degeneration in rats

Sci Rep. 2016 Jul 7;6:29546. doi: 10.1038/srep29546.

Abstract

Green tea extracts exhibit anti-oxidative and anti-inflammatory actions in different disease conditions. We hypothesized that green tea extract and its catechin constituents ameliorate sodium iodate-induced retinal degeneration in rats by counteracting oxidative stress. In this study, adult Sprague-Dawley rats were intravenously injected with a single dose of sodium iodate. Green tea extract (GTE; Theaphenon-E) or combinations of its catechin constituents, including (-)-epigallocatechin gallate (EGCG), were administered intra-gastrically before injection. Live imaging analysis using confocal scanning laser ophthalmoscopy and spectral-domain optical coherence tomography showed a progressive increase of degenerating profile across the retinal surface and decrease in thickness of outer nuclear layer (ONL) at Day-14 of post-injection. These lesions were significantly ameliorated by Theaphenon-E and catechin combinations with EGCG. Catechins with exclusion of EGCG did not show obvious protective effect. Histological analyses confirmed that Theaphenon-E and catechins containing EGCG protect the retina by reducing ONL disruption. Retinal protective effects were associated with reduced expression of superoxide dismutase, glutathione peroxidase and caspase-3, and suppression of 8-iso-Prostaglandin F2α generation in the retina. In summary, GTE and its catechin constituents are potent anti-oxidants that offer neuroprotection to the outer retinal degeneration after sodium iodate insult, among which EGCG is the most active constituent.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Oral
  • Animals
  • Antioxidants / pharmacology
  • Catechin / administration & dosage
  • Catechin / analogs & derivatives
  • Catechin / pharmacology*
  • Dinoprost / analogs & derivatives
  • Dinoprost / metabolism
  • Gene Expression Regulation / drug effects
  • Iodates / toxicity
  • Ophthalmoscopy / methods
  • Oxidative Stress / drug effects
  • Rats, Sprague-Dawley
  • Retinal Degeneration / chemically induced
  • Retinal Degeneration / drug therapy*
  • Retinal Degeneration / pathology
  • Retinal Pigment Epithelium / drug effects
  • Retinal Pigment Epithelium / pathology
  • Tea / chemistry*

Substances

  • Antioxidants
  • Iodates
  • Tea
  • 8-epi-prostaglandin F2alpha
  • Catechin
  • Dinoprost
  • epigallocatechin gallate
  • sodium iodate