Orally administered epigallocatechin gallate attenuates light-induced photoreceptor damage.
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.
Costa
Belmira Lara da Silveira Andrade da
BL
Departamento de Fisiologia e Farmacologia, CCB, Centro de Ciências Biológicas, CCB-UFPE, Avenue Prof. Moraes Rego, s/n, Cidade Universitária, 50670901 Recife, PE, Brazil.
Fawcett
Rebecca
R
Li
Guang-Yu
GY
Safa
Rukhsana
R
Osborne
Neville N
NN
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
D000975:Antioxidants; D051017:Apoptosis Regulatory Proteins; D005904:Glial Fibrillary Acidic Protein; D012333:RNA, Messenger; D002392:Catechin; D012243:Rhodopsin; C045651:epigallocatechin gallate