Effect of Progesterone on Neuronal Apoptosis and Nitric Oxide Level in Cortex and Hippocampus of Newborn Rats with Hypoxic-Ischemic Encephalopathy

Objective To explore the effect of progesterone on the rate of neuronal apoptosis and nitric oxide(NO) level in the cortex and hippocampus tissue of newborn rats with hypoxic-ischemic encephalopathy(HIE).Methods Thirty 7-day-old neonatal rats were randomly divided into 3 groups:sham-operated group,hypoxic-ischemic(HI) group and pretreatment group.Rats in HI group and pretreatment group were subjected to left common carotid artery ligation,then were exposed to 80 mL/L oxygen and 920 mL/L nitrogen gas in 37 ℃ closed container for up to 2.5 h to establish HIE model.Progesterone was injected intraperitoneally into rats in the pretreatment group respectively for 30 minutes before hypoxia,and solution was injected into the sham-operated group and HI group.All rats were killed at 24 h after operation.The neuron apoptosis was identified and analyzed by flow cytometry.Nitrate/nitrite was assayed to represent nitric oxide content of brain tissues.Results The ratio of neuronal apoptosis and NO contents in cortex and hippocampus tissue in HI group [(10.09±0.36)%,(12.32±0.28)%,(51.36±9.71) μmol/L,(52.34±4.26) μmol/L] were significantly higher than those in sham-operated group [(2.49±0.23)%,(2.58±0.26)%,(18.16±6.24) μmol/L,(19.28±3.58) μmol/L)](P_a0.01),and lower than those in pretreatment group [(3.47±0.32)%,(4.56±0.30)%,(33.47±8.02) μmol/L,(32.57±4.27) μmol/L](P_a0.05).Conclusions Progesterone can decrease the rate of neuronal apoptosis and NO level in brain tissue with HIE in newborn rats,so it plays an important role in preventing brain against hypoxic-ischemic brain damage by neuronal apoptosis.