title: Orally administered epigallocatechin gallate attenuates light-induced photoreceptor damage.
abstract: EGCG, a major component of green tea, has a number of properties which includes it being a powerful antioxidant. The purpose of this investigation was to deduce whether inclusion of EGCG in the drinking water of albino rats attenuates the effect of a light insult (2200lx, for 24h) to the retina. TUNEL-positive cells were detected in the outer nuclear layer of the retina, indicating the efficacy of the light insult in inducing photoreceptor degeneration. Moreover, Ret-P1 and the mRNA for rhodopsin located at photoreceptors were also significantly reduced as well as the amplitude of both the a- and b-waves of the electroretinogram was also reduced showing that photoreceptors in particular are affected by light. An increase in protein/mRNA of GFAP located primarily to Müller cells caused by light shows that other retinal components are also influenced by the light insult. However, antigens associated with bipolar (alpha-PKC), ganglion (Thy-1) and amacrine (GABA) cells, in contrast, appeared unaffected. The light insult also caused a change in the content of various proteins (caspase-3, caspase-8, PARP, Bad, and Bcl-2) involved in apoptosis. A number of the changes to the retina caused by a light insult were significantly attenuated when EGCG was in the drinking water. The reduction of the a- and b-waves and photoreceptor specific mRNAs/protein caused by light were significantly less. In addition, EGCG attenuated the changes caused by light to certain apoptotic proteins (especially at after 2 days) but did not appear to significantly influence the light-induced up-regulation of GFAP protein/mRNA. It is concluded that orally administered EGCG blunts the detrimental effect of light to the retina of albino rats where the photoreceptors are primarily affected.
authors.affiliation: Departamento de Fisiologia e Farmacologia, CCB, Centro de Ciências Biológicas, CCB-UFPE, Avenue Prof. Moraes Rego, s/n, Cidade Universitária, 50670901 Recife, PE, Brazil.
authors.forename: Belmira Lara da Silveira Andrade da
authors.initials: BL
authors.lastname: Costa
authors.forename: Rebecca
authors.initials: R
authors.lastname: Fawcett
authors.forename: Guang-Yu
authors.initials: GY
authors.lastname: Li
authors.forename: Rukhsana
authors.initials: R
authors.lastname: Safa
authors.forename: Neville N
authors.initials: NN
authors.lastname: Osborne
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology* / Q000627:therapeutic use; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D051017:Apoptosis Regulatory Proteins / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D005904:Glial Fibrillary Acidic Protein / Q000235:genetics / Q000378:metabolism; D008027:Light / Q000009:adverse effects; D008564:Membrane Potentials / Q000187:drug effects / Q000528:radiation effects; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D010786:Photoreceptor Cells / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000187:drug effects* / Q000503:physiopathology / Q000528:radiation effects; D012162:Retinal Degeneration / Q000188:drug therapy* / Q000209:etiology / Q000503:physiopathology; D012243:Rhodopsin / Q000235:genetics
chemical_list: D000975:Antioxidants; D051017:Apoptosis Regulatory Proteins; D005904:Glial Fibrillary Acidic Protein; D012333:RNA, Messenger; D002392:Catechin; D012243:Rhodopsin; C045651:epigallocatechin gallate