Phil-Ok Koh
Gyeongsang National University, South Korea
Title: Quercetin prevents the ischemic injury-induced decrease of thioredoxin expression in brain tissue
Biography
Biography: Phil-Ok Koh
Abstract
Quercetin is a bioactive flavonoid abundant in vegetables and fruits. Quercetin is an especially effective agent against
neuronal damage following global and focal cerebral ischemia. Thioredoxin has various physiological functions including
regulation of cellular redox homeostasis and apoptosis. The aim of this study was to investigate whether quercetin regulates
thioredoxin expression in focal cerebral ischemia. Male Sprague Dawley rats (210–230 g) were used for experiments and
injected with either quercetin (10 mg/kg) or vehicle via the intraperitoneal cavity one hour prior to middle cerebral artery
occlusion (MCAO). Cerebral cortex tissues were isolated 24 h after MCAO. Using a proteomics approach, thioredoxin
expression was found to be decreased in vehicle-treated MCAO animals, while treatment with quercetin attenuated this
decrease. The effect of quercetin on the MCAO-induced decrease in thioredoxin expression was confirmed by Western blot and
reverse-transcription-PCR analyses. Immunofluorescence staining showed that quercetin treatment alleviated the decrease in
thioredoxin positive cells in the cerebral cortex of animals with MCAO surgical injury. Furthermore, immunoprecipitation
analysis demonstrated that binding between apoptosis signal-regulating kinase 1 (ASK1) and thioredoxin were decreased in
vehicle-treated MCAO animals, while treatment with quercetin attenuated this effect. Our results indicate that thioredoxin
has neuroprotective functions against oxidative stress in brain ischemic injury. Maintenance of thioredoxin expression by
quercetin administration may help to prevent neuronal cell death following cerebral ischemia. Our findings suggest that
quercetin mediates its neuroprotective function by regulating thioredoxin.