We examined the cytoprotective effect of
quercetin via activator
protein (AP-1) and the
heat shock protein 70 (Hsp70) pathway against light-induced
retinal degeneration in rats.
Quercetin was administered intraperitoneally to Sprague-Dawley rats for seven days before light exposure to intense white fluorescent light (3000 lux) for 24 h. Light-induced
retinal damage was determined by the number of rows of photoreceptor cell nuclei, the microstructures of the rod outer segments and retinal pigment epithelium, and
terminal deoxynucleotidyl transferase (TdT)-mediated 2'-Deoxyuridine-5'-triphosphate (dUTP) nick end labeling. To elucidate the cytoprotective mechanism of
quercetin, expression levels were measured in the rat retinas of 8-hydroxy-deoxyguanosine (8-OHdG), a marker of oxidative stress; Hsp70; and
transcription factor AP-1 transcription activity. Pretreatment with
quercetin inhibited light-induced photoreceptor cellular apoptosis and subsequent
retinal degeneration in rats. 8-OHdG and Hsp70
protein expressions were up-regulated markedly by light exposure and suppressed by
quercetin pretreatment. The results of an electrophoretic mobility shift assay showed that AP-1-binding activity was activated by light exposure, and binding of c-Fos and c-Jun, but not JunB, mediated the binding activity. Intraperitoneal administration of
quercetin decreases photooxidative damage in the retina and mediates cytoprotection against light-induced photoreceptor cell degeneration in rats. Suppression of the heterodimeric combination of c-Jun and
c-Fos proteins at the
AP-1 binding site is highly involved in
quercetin-mediated cytoprotection.