Alterations in Oxidative Stress Markers and Na,K-ATPase Enzyme Properties in Kidney after Fructose Intake and Quercetin Intervention in Rats

Abstract

The study aimed to characterize the consequences of a 15-week intake of 10% fructose on the kidney, with the focus on oxidative stress markers and properties of the Na,K-ATPase enzyme. Various antioxidants naturally occurring in common food were demonstrated to be protective against fructose-induced deterioration of kidneys. Therefore, we also aimed to observe the effect of 6-week quercetin administration (20 mg/kg/day) that was initiated following the 9-week period of higher fructose intake, by determining the concentration of sodium, potassium, creatinine, urea, and glucose in blood plasma and oxidative status directly in the renal tissue. Kinetic studies of renal Na,K-ATPase were utilized for a deeper insight into the molecular principles of expected changes in this enzyme activity under conditions of presumed fructose-induced renal injury. Fructose intake led to increase in body weight gain, plasma glucose and sodium levels, and deterioration of kidney properties, although some compensatory mechanisms were observable. Quercetin administration improved glycemic control in rats exposed to fructose overload. However, an increase in plasma creatinine, a decrease in GSH/GSSG ratio in renal tissue homogenate, and a controversial effect on renal Na,K-ATPase enzyme suggest that quercetin treatment may not be beneficial in the condition of pre-existing renal pathology.

Oxidative Stress Induced by Lipotoxicity and Renal Hypoxia in Diabetic Kidney Disease and Possible Therapeutic Interventions: Targeting the Lipid Metabolism and Hypoxia

“…Contrary to expectations, the administration of the anti-oxidant quercetin unexpectedly exacerbated some situations including the elevation of serum creatinine levels. Furthermore, quercetin failed to normalize the activity of renal Na + /K + ATPase, which is upregulated by the administration of a 10% fructose solution [211].…”

“…Therefore, despite oxidative stress playing a crucial role in the pathogenesis of DKD and the apparent importance of anti-oxidants as potential therapeutic agents, the possibility of adverse effects must be considered [210]. For instance, in a study involving male Wistar rats administered 10% fructose-enriched drinking water, notable increases in body weight, plasma glucose, and sodium levels, and a decline in renal properties were observed [211]. Contrary to expectations, the administration of the anti-oxidant quercetin unexpectedly exacerbated some situations including the elevation of serum creatinine levels.…”