Effects Of Estrogen On Astrocytes Subjected To Oxygen-glucose Deprived Injury And The Mechanisms Mediated The Effects

Objective To investigate the effects of 17-βestradiol on cerebral cortical astrocytes subjected to oxygen-glucose deprived injury and explore the mechanisms mediated the effects.Methods Primary cultured cerebral cortical astrocytes were prepared from Sprague-Dawley rats,and a cell damage model was induced by oxygen-glucose deprivation(OGD).The change of cell morphology was observed by Giemsas staining and transmission electron microscope.The cell damage and viability were evaluated by 3-[4,5-dimehyl-2-thiazolyl]-2,5-diphenyl-2H-tetrazolium bromide(MTT) reduction assay and lactate dehydrogenase(LDH)released rate,and the detection of apoptotic cells was determined by the flow cytometry.We studied the effects of 17-βestradiol on astrocytes by the model.Then we detected the concentration of intracellular Ca²⁺by fluorescence duel wavelength spectrophotometer and the SOD activity and content of MDA by the kits.The level of Caspase-3 and Caspase-12 mRNA were evaluated by semi-quantitative reverse transcription polymerase chain reaction(RT-PCR).Immunocytochemistry was used to observe the expression of Caspase-3 and Caspase-12 protein.Resultsâ‘ The increase of cell viability by 17-βestradiol was observed at 10nmol/L,and the maximum effect was at 20nmol/L;The decrease of LDH release rate and the anti-apoptotic effect by 17-βestradiol were observed at 1nmol/L,and the maximum effect was at 20nmol/L.â‘¡The administration of 17-βestradiol at the same time of OGD,at 6h before OGD,12h before OGD,24h befor OGD and 36h before OGD all increased the cell viability,decreased the LDH release rate and the apoptotic rate.And the most potent effect of 17-βestradiol mediated cell survival was observed at 24h.â‘¢The concentration of intracellular Ca²⁺was increased by OGD,and the application of 17-βestradiol can decrease it.â‘£The activity of SOD of AS was decreased by OGD,and the content of MDA was increased by OGD;Application of 17-βestradiol can increase the the activity of SOD and decrease the content of MDA.⑤RT-PCR and immunocytochemistry analysis demonstrated that the level of Caspase3,Caspase-12 mRNA and protein increased by OGD,and the application of 17-βestradiol can inhibit these expression.Conclusionâ‘ 17-βestradiol has a direct protection on cultured cortical astrocytes subjected to OGD in a dose- and time- dependent manner.â‘¡The protection of 17-βestradiol on cortical AS subjected to OGD may be related to the concentration of Ca²⁺,the expression of Caspase-3 and Caspase-12.â‘¢The protection of 17-βestradiol on cortical AS subjected to OGD may be related to increasing the SOD activity(which can depress DNA and biomembrane injury induced by oxygen free radical)and depressing the lipid peroxidation reaction.