Protective effects of Quercetin and chronic moderate exercise (training) against oxidative stress in the liver tissue of streptozotocin-induced diabetic rats

Abstract

Background: To investigate the protective effects of Quercetin administration associated with chronic moderate exercise (training) on oxidative stress in the liver in streptozotocin-induced diabetic rats. Methods: Diabetic rats that performed exercise training were subjected to a swimming training program (1 hour/day, 5 days/week, 4 weeks). The diabetic rats received natural antioxidant, Quercetin (20 mg/kg body weight/day) for 4 weeks. At the end of the study, all animals were sacrificed and liver samples were collected for estimation: some oxidative stress markers (malondialdehyde, MDA and protein carbonyls groups, PC), the activity of antioxidant enzymes (superoxide dismutase, SOD and catalase, CAT), reduced glutathione (GSH) level and reduced (GSH) and oxidized (GSSG) glutathione ratio. Results: Diabetic rats submitted to exercise training showed significantly increased the oxidative stress markers (MDA and PC) and a reduction of antioxidant enzyme (SOD and CAT) activity, GSH level and GSH/ GSSG ratio in hepatic tissues. A decrease in the levels of oxidative stress markers associated with elevated activity of antioxidant enzymes, the GSH level and GSH/GSSG ratio in the hepatic tissue were observed in Quercetin-treated diabetic trained rats. Conclusions: These findings suggest that Quercetin administration in association with chronic moderate exercise exerts a protective effect in diabetes by attenuating hyperglycemia-mediated oxidative stress in hepatic tissue.

Vascular impact of quercetin administration in association with moderate exercise training in experimental type 1 diabetes

“…The micro-and macrovascular complications of diabetes are a consequence of endothelial dysfunction and inflammation. The major causal factors involved in the pathogenesis of endothelial dysfunction in T1DM are hyperglycemia, dyslipidemia and oxidative stress (3)(4)(5)(6). Atherosclerosis represents the principal cause of disability and death in patients with T1DM.…”

“…Quercetin exerts multiple biological effects -antioxidant, hypoglycemic, neuroprotective and anti-inflammatory -in T1DM (3,(10)(11)(12)(13)(14)(15)(16)(17). Recent research has demonstrated the beneficial effects of exercise training on preventing diabetic vascular compli-cations by reducing oxidative/nitrosative stress and inflammation (3,14,(18)(19)(20)(21)(22). Therefore, in the current study we evaluated the effects of combining quercetin treatment with moderate exercise training in preventing carotid artery injuries in diabetic rats through a reduction of glycemia and oxidative stress.…”

Effect of crocin on antioxidant gene expression, fibrinolytic parameters, redox status and blood biochemistry in nicotinamide-streptozotocin-induced diabetic rats

“…Regarding the kidney, Palsamy and Subramanian [34] administered per os resveratrol to healthy rats with no effect on protein carbonyls concentration. Diabetes tends to increase the concentration of protein carbonyls in the rat liver [35,36] due to the formation of active carbonyl forms. Our findings do not confirm these reports, but this could be just due to the high standard deviation of our results.…”

Quercetin preserves redox status and stimulates mitochondrial function in metabolically-stressed HepG2 cells

“…High glucose-induced oxidative stress is linked to mitochondrial dysfunction, insulin resistance and metabolic syndrome [57]. Quercetin is thought to have a beneficial effect in various aspects of these metabolic diseases [20,25,31,32,58], either through restriction of ROS generation locally, or enhancement of cellular oxidative defences [34, [59][60][61][62]. Mechanisms of quercetin action have been reviewed [20] and it is apparent that information in the high glucose environment, and on longer term metabolic effects, remains limited.…”

“…At the same time quercetin and other flavonoids are also known to influence glucose in the intestine through modulation of carbohydrate digestion and absorption [26][27][28] and thus affect hepatic glucose, and expression of glycolytic genes in the liver [29]. In streptozotocin-induced diabetic rats, quercetin dose-dependently decreased blood glucose, cholesterol and triglycerides [30] alongside hepatic oxidative stress markers [31], while it increased hepatic glucokinase activity [30]. Such bioactivities have attracted research in the potential application of quercetin in the prevention and management of type 2 diabetes [32,33], but data on its mechanism of action in high glucose stress environments is lacking.…”