Effects of ginkgo biloba extracts on oxidative stress of islet β-cells in chronic intermittent hypoxic rats

LI Wushuang; ZHOU Yan; ZHOU Xuan

doi:10.3969/j.issn.1002-266X.2017.30.002

Abstract：Objective To investigate the effects of ginkgo biloba extracts (EGB) on oxidative stress of islet β-cells in rats with chronic intermittent hypoxia (CIH) and its mechanism.Methods Ten SD rats were placed in hypoxia chamber to simulate intermittent hypoxia to prepare CIH models, and the other 10 rats were fed under normoxic conditions.At the end of 12 weeks, the primary islet β-cells from CIH model rats and normoxic rats were extracted.The primary islet cells of the normoxic rats were used as the normoxic control group;the primary islet cells of CIH model rats were divided into the CIH model group, anti-Nrf2 antibody group, Nrf2 activator group, low-dose EGB group, medium-dose EGB group, and high-dose EGB group.Rats in the oxygen control group and CIH model group were cultured in DMEM medium;Nrf2 antibody was added to the Nrf2 antibody group;Nrf2 activator sulforaphane with final concentration of 20 μg/mL was added to the Nrf2 activator group;5, 10, and 20 mg/mL EGB were added to the low-dose EGB group, medium-dose EGB group, and high-dose EGB group, respectively.The cells were taken from rats in each group after 24-hour intervention.The content of reactive oxygen species (ROS), the content of malondialdehyde (MDA) and glutathione peroxidase (GSH-Px) in the supernatant was measured.The expression levels of Nrf2-ARE signal pathway related protein Nrf2 and downstream antioxidant enzyme-target protein HO-1, NQO1 and γ-GCS were detected by Western blotting.Results Compared with the normoxic control group, MDA and ROS increased and GSH-Px decreased in the CIH model group (all P<0.01).Compared with the CIH model group, MDA and ROS increased and GSH-Px decreased in anti-Nrf2 antibody group (P<0.01 or P<0.05).In the Nrf2 activator group, medium-dose EGB group, and high-dose EGB group, MDA and ROS were reduced, and GSH-Px increased (P<0.01 or P<0.05).MDA and ROS were lower and GSH-Px was higher in the high-dose EGB group than in the low-dose EGB group (P<0.01 or P<0.05).Compared with the normoxic control group, the level of Nrf2 increased, and HO-1, NQO1 and γ-GCS decreased in the CIH model group (all P<0.01).Compared with the CIH model group, HO-1 and NQO1 decreased in the anti-Nrf2 antibody group (both P<0.01).In the Nrf2 activator group, medium-dose EGB group, and high-dose EGB group, Nrf2, HO-1, NQO1, and γ-GCS increased (P<0.01 or P<0.05).The levels of Nrf2, HO-1, NQO1, and γ-GCS in the high-dose EGB group were higher than those of the medium-dose EGB group (P<0.01 or P<0.05).Conclusion EGB can reduce the level of oxidative stress in islet cells caused by CIH, and its mechanism may be related to the activation of Nrf2-ARE signaling pathway.