Effects of magnesium sulfate on oxidative stress injury and hypoxia-inducible factor 1α expression level in placental tissues of preeclampsia rats

Abstract

Objective To investigate the effects of magnesium sulfate on oxidative stress injury and hypoxia-inducible factor 1α (HIF-1α) expression level in placental tissues of preeclampsia rats. Methods Thirty SD rats were randomly divided into the blank control group, preeclampsia (PE) group, and magnesium sulfate group (n=10 each) . Except for the blank control group, endotoxin was used in the other groups to establish PE rat model. The magnesium sulfate group was given intraperitoneal injection of 80 mg/kg magnesium sulfate. The blank control group and PE group were injected with the same dose of normal saline. The cesarean section was performed at 21 d after pregnancy, and the placenta tissues were isolated. The level of HIF-1α in the placenta tissues was measured by real-time fluorescence quantitative polymerase chain reaction (RT-PCR) method. The levels of glutathione peroxidase (GPX) , malondialdehyde (MDA) and superoxide dismutase (SOD) in the placenta tissues were determined by ultraviolet colorimetry. The tissue homogenate method was used to determine the reactive oxygen species (ROS) level in the placenta tissues. Results (1) At 10 d after the pregnancy, there were no statistically significant differences in the blood pressure and 24 h urinary protein quantification between the groups (all P>0.05) . At 15 d and 21 d after the pregnancy, there were no significant change in the blood pressure and 24 h urinary protein quantification in the blank control group, whereas the above indexes increased in the PE group and magnesium sulfate group (all P<0.05) , and there were statistically significant differences compared with those at 10 d after pregnancy in the same group (all P<0.05) . The blood pressure and 24 h urine protein quantification in the PE group and magnesium sulfate group were higher than those in the blank control group during the same time period (all P<0.05) . The blood pressure and 24 h urine protein quantification in the magnesium sulfate group were lower than those in the PE group (all P<0.05) . (2) The placenta weight, and weight and length of newborn rats in the PE group were lower than those in the blank control group (all P<0.05) , whereas the indexes in the magnesium sulfate group were higher than those in the PE group (all P<0.05) . (3) The levels of GPX and SOD in placental tissues in the PE group and magnesium sulfate group were lower than those in the blank control group (all P<0.05) , whereas the levels of MDA, ROS and HIF-1α mRNA were higher than those in the blank control group (all P<0.05) . The levels of GPX and SOD in the magnesium sulfate group were higher than those in the PE group, whereas the levels of MDA, ROS and HIF-1α mRNA were lower than those in the PE group (all P<0.05) . Conclusion PE rats show significant oxidative stress injury, and the mRNA level of HIF-1α is significantly high in placenta tissues. The intervention with magnesium sulfate may reduce oxidative stress injury and down-regulate the mRNA expression level of HIF-1α. Key words: Pre-eclampsia; Magnesium sulfate; Oxidative stress; Placenta; Hypoxia-inducible factor 1α