Objective To investigate the mechanism of Buyang Huanwu Decoction (补阳还五汤) in ameliorating diabetes cognitive impairment (DCI) based on nuclear factor erythroid 2-related factor 2 (Nrf2)/glutathione peroxidase 4 (GPX4) signaling pathway. Methods A rat model of DCI was established by feeding a high-fat and high-sugar diet combined with low-dose streptozotocin (STZ) injection. The successfully modeled rats were randomly divided into model group, Buyang Huanwu Decoction low-, high-dose (7.125, 28.500 g/kg) groups and metformin (0.2 g/kg) group, control group was set up separately. After four weeks of administration, the cognitive and memory abilities of rats were evaluated by Morris water maze. Hematoxylin-eosin (HE) staining was used to observe the pathological changes of hippocampal tissue in rats. The activities of superoxide dismutase (SOD), catalase (CAT) and levels of glutathione (GSH), malondialdehyde (MDA) in serum and ferrous ions (Fe2+) in brain tissue of rats were detected by biochemical methods. Immunohistochemistry was used to observe the expressions of Nrf2 and GPX4 proteins in CA1 region of hippocampus in rats. Western blotting was used to detect the expressions of Kelch-like ECH-associated protein 1 (Keap1), Nrf2, heme oxygenase-1 (HO-1), solute carrier family 7 member 11 (SLC7A11), GPX4, transferrin receptor (TFR), ferroportin 1 (FPN1) and ferritin heavy chain (FTH) proteins in hippocampal tissue of rats. Human neuroblastoma cells SHSY-5Y were cultured in vitro and a damage model was established by inducing with 160 mmol/L glucose. Control group, model group, Buyang Huanwu Decoction low-, high-dose drug containing serum groups and Buyang Huanwu Decoction high-dose drug containing serum + Nrf2 inhibitor ML385 (10 μmol/L) group were set up. Biochemical methods were used to detect the activities of SOD, CAT and levels of GSH, MDA in cells. JC-1 fluorescent probe was used to detect changes in mitochondrial membrane potential in cells. Western blotting was used to detect the expressions of Keap1, Nrf2, HO-1, SLC7A11 and GPX4 proteins in cells. Results The results of in vivo experiments showed that Buyang Huanwu Decoction could delay weight loss of DCI rats (P < 0.05), reduce fasting blood glucose (P < 0.05, 0.01), shorten the escape latency (P < 0.05, 0.01), increase the distance moved, dwell time and number of crossings in target quadrant (P < 0.05, 0.01), alleviate the damage of hippocampal neurons, reduce the levels of MDA in serum and Fe2+ in brain tissue (P < 0.05, 0.01), increase the activities of SOD, CAT and levels of GSH in serum (P < 0.05, 0.01), downregulate the expressions of TFR and Keap1 proteins in hippocampus (P < 0.05, 0.01), upregulate the expressions of Nrf2, HO-1, SLC7A11, GPX4, FTH and FPN1 proteins (P < 0.05, 0.01). The results of in vitro experiments showed that Buyang Huanwu Decoction drug-containing serum could significantly increase the survival rate of SHSY-5Y cells induced by high glucose (P < 0.01), reduce MDA level (P < 0.05), increase the activities of SOD, CAT and level of GSH (P < 0.05, 0.01), increase the mitochondrial membrane potential, downregulate the expression of Keap1 protein (P < 0.01), and upregulate the expressions of Nrf2, HO-1, SLC7A11 and GPX4 proteins (P < 0.05, 0.01). Compared with Buyang Huanwu Decoction high-dose drug containing serum group, the administration of ML385 significantly reversed the changes in the above indicators (P < 0.05, 0.01). Conclusion Buyang Huanwu Decoction could improve cognitive dysfunction, alleviate oxidative stress damage, and improve iron metabolism disorders in DCI rats. Its effects may be related to the activation of Nrf2/GPX4 signaling pathway and the regulation of ferroptosis processes.

diabetes  /  cognitive impairment  /  Buyang Huanwu Decoction  /  ferroptosis  /  oxidative stress  /  Nrf2/GPX4 signaling pathway  /  hydroxysafflor yellow A  /  paeoniflorin  /  ferulic acid  /  calycosin-7-glucoside  /  ononin  /  calycosin