Objectives: 

Objetives: Body exposure to ionizing radiation is associated with increased oxidative stress producing imbalance with antioxidant defenses, altering vital biological functions. Quercetin is a known flavonoid with high antioxidant and anti-inflammatory activity. Epidemiological evidences have shown that a quercetin-rich diet decreases the incidence of cardiovascular and neoplasic diseases. This study was aimed to verify the radioprotective effects of quercetin, analyzing both short and long-term benefits in rats exposed to oxidative stress induced by X-radiation.

Materials: 

Material and Methods: We used male Wistar rats assigned 4 groups (CV, CQ, RV, RQ) receiving quercetin [Q] or vehicle (propylene glycol) [V], and whole-body X-irradiated [R] or non-irradiated animals [C]. Irradiation dose was 6 Gy (0,4 Gy/min). Quercetin (50 mg/kg) was intragastrically administered 5 days before and 6 days after irradiation. Oxidative stress was confirmed by TBARS test and protein expression of major antioxidant enzymes catalase, Cu/ZnSOD, and NQO1, as well as Nrf2 transcription factor, and its inhibitor Keap-1, were measured by Western-Blot in liver extracts. Statistical signification was assessed by ANOVA and Newman-Keuls tests.

Results: 

X-irradiation induced hepatic oxidative stress revealed as an increase in TBARS concentration. Quercetin treatment was able to revert oxidative stress, both at short and long term. X-ray exposure induced a significant increase in protein expression of Cu/ZnSOD and NQO1, nuclear Nrf2, and cytosolic Keap-1, effects that were maintained for both short and long term. Quercetin had the opposite effects. Contrarily, catalase only showed significant increase in short-term maintained rats, also reversed with quercetin.

Conclusions: 

Our results confirm that X-radiation induces oxidative stress and free radical formation. Interestingly, quercetin administration is able to counteract cellular damages caused by X-rays, both at short and long term, pointing to its useful radioprotective features.