Abstract:

This study aims to investigate the effects of kaempferol (KPF) on oxidative stress,ferroptosis and inflammation in diabetic kidney disease (DKD) rat model by activating the AMP-activated protein kinase/nuclear factor erythroid 2-related factor 2 (AMPK/Nrf2) signaling pathway.SD rats were randomly divided into experimental group and control group (six rats in each group).After construction of the DKD model by intraperitoneal injection of streptozotocin (STZ),rats in the experimental group were randomly divided into four groups: DKD group,KPF in low dose group (KPF-L,50 mg/kg),KPF in high dose group (KPF-H,100 mg/kg),and high dose KPF intervened by AMPK inhibitor (compound C,CC;0.2 mg/kg) group (KPF-H+CC).The levels of fasting blood glucose (FBG),blood urea nitrogen (BUN),serum creatinine (SCr),and urine albumin-to-creatinine ratio (UACR) were measured.Hematoxylin eosin and masson staining were conducted to observe pathological changes and fibrosis of renal tissue.TUNEL method was applied to evaluate cell apoptosis in renal tissue.Biochemical kits were applied to detect levels of malondialdehyde (MDA) and glutathione (GSH).Enzyme-linked immunosorbent assay was applied to detect levels of phosphorylated nuclear transcription factor κB-p65 (p-NF-κB-p65),tumor necrosis factor-α (TNF-α),interleukin-1β (IL-1β),and interleukin-6 (IL-6) in renal tissue.Colorimetric assay was used to detect ferrous ion level.The level of reactive oxygen species (ROS) was measured by dihydroethidium fluorescent probe method.Western blot analysis was applied to detect the levels of AMPK/Nrf2 pathway-related proteins in kidney tissues.Results showed that,compared with the DKD group,the KPF-L and KPF-H groups showed significant reductions in FBG,BUN,SCr,and UACR levels,as well as decreased renal damage (all P<0.05).KPF treatment also decreased the levels of ROS,MDA,ferrous ion,p-NF-κB-p65,inflammation-related factors (TNF-α,IL-1β,and IL-6),and increased the content of GSH in renal tissue (all P<005).KPF treatment increased the phosphorylated levels of AMPK and Nrf2,therefore promoting the activation of the AMPK/Nrf2 pathway (all P<0.05).However,the co-treatment of CC partially reversed the therapeutic effects of KPF on oxidative stress,ferroptosis and inflammation.The above results indicated that KPF effectively mitigate oxidative stress,ferroptosis and inflammation in DKD rats by activating the AMPK/Nrf2 signaling pathway,thus improving the renal function of DKD rats.

Key words: kaempferol, diabetic kidney disease, AMPK/Nrf2 signaling pathway, oxidative stress, ferroptosis, inflammation