Raloxifene Protects Oxygen-glucose-deprived Astrocyte Cells Used To Mimic Hypoxic-ischemic Brain Injury

Abstract

. Background. Hypoxic-ischemic brain injury is one primary cause of long-term neurological disability, morbidity, and death worldwide. The decrease in blood flow and oxygen concentration leads to insufficient nutrient supply to the brain, energy depletion, increased free radical generation, and mitochondrial dysfunction. Perinatal asphyxia — the oxygen supply suspension near birth-time — causes hypoxic-ischemic brain injury and is a major risk factor for neurodevelopmental damage. In pathological scenarios, raloxifene, a selective estrogen receptor modulator, has shown neuroprotective effects. Purpose. To examine whether raloxifene showed neuroprotection in an oxygen-glucose deprivation/reoxygenation astrocyte cell model. Methods. T98G cells in culture were treated with a glucose-free DMEM medium and incubated at 37ºC in a hypoxia chamber with 1% O2 for 3, 6, 12, and 24 hours. Cultures were supplemented with raloxifene 1, 10, and 100 nM during both glucose and oxygen deprivation and reoxygenation periods. Results. Raloxifene 100 nM and 10 nM improved cell survival — 65.34% and 70.56% — respectively compared to the control cell groups. Mitochondrial membrane potential was preserved by 58.9% 10 nM raloxifene and 81.57% 100 nM raloxifene cotreatment. Raloxifene cotreatment reduced superoxide production by 72.72% and peroxide production by 57%. Mitochondrial mass was preserved by 47.4%, 75.5%, and 89% in T98G cells exposed to 6-hour oxygen-glucose deprivation followed by 3, 6, and 9 hours of reoxygenation, respectively. Conclusions. Raloxifene improved cell survival and mitochondrial membrane potential, and reduced lipid peroxidation and reactive oxygen species (ROS) production, suggesting a direct effect on mitochondria. Raloxifene protected the oxygen-glucose-deprived astrocyte cells used to mimic hypoxic-ischemic brain injury in this study.