The effect of high dietary fructose on the kidney of adult albino rats and the role of curcumin supplementation: A biochemical and histological study

Consumption of fructose, in the form of added sugars such as high fructose corn syrup (HFCS) or sucrose, has increased markedly in the last few years, which is strongly correlated with the prevalence of metabolic syndrome. It is widely used as a food ingredient and has potential to increase oxidative stress. Curcumin is a phenolic compound, and it exhibits protective effects against oxidative damage. Objective: The aim of the study was to investigate the effects of curcumin on renal injury in fructose-fed rats and the possible underlying mechanism. Methods: Eighty male rats were randomly divided into control group, fructose group, 200 mg/kg curcumin group and curcumin-fructose group. The histopathological changes in the kidney of rats were observed using hematoxylin and eosin and Masson's trichrome stains. The expressions of renal reduced glutathione (GSH) concentration, glutathione reductase (GR), super oxide dismutase (SOD), catalase activities, lipid peroxidation (LPO), DNA fragmentation %, inducible nitrous oxide (INOS) and homooxygenase 1 (HO-1) mRNA in renal tissue homogenates were assessed. Immunohistochemical detection of alpha-smooth muscle actin (α-SMA) and tumor necrosis factor alpha (TMF-α) were also investigated. Results: Compared to the control group, GSH, GR, SOD and catalase activities were significantly decreased in the fructose group, while there was a significant increase in LPO, DNA fragmentation %, INOS and HO-1. These changes were accompanied by renal tubular injury, increased collagen deposition and lipid accumulation. Immunohistochemical results revealed increased expression of both α-SMA and TNF-α. Curcumin at 200 mg/kg evidently improved renal tubular injury, suppressed the expressions of renal LPO, DNA fragmentation %, INOS and HO-1, and decreased the expression of both α-SMA and TNF-α in kidney tissue. Conclusion: Curcumin administration protected the kidney cells from fructose induced oxidative stress by increasing the antioxidant defence mechanism of the kidney cells and its ability to act as a free radical scavenger