The Activity Of Na~+, K~+-ATPase During The Oncosis Of Astrocyte Caused By OGD And Drug Intervention

Background and objectives:Astrocyte is one of the most important elements in central nerves system(CNS), the astrocyte death manner has been studied by more and more investigators. In the previous study, using middle cerebral artery occlusion (MCAO) animal model, oncosis was found to be the main death manner in the astrocytes whereas in the central area or in the peripheral area of the ischemic lesions. Majno (1995) and his colleagues reviewed the cell death manner systemetically, they suggested that the cell death manners included apoptosis, oncosis, autophagy and so on. The mechanisms of oncosis maybe included damage of cytomembrane and mitochondia, disfunction of energy metabolism and ion pump, mis-expression of proteinases, and so on. However, all the mechanisms metioned above could not explain the oncosis clearly, some other mechanisms are still unclear. In the present sduty, oxygen glucose deprivation (OGD) mode was first built in the in vitro primary astrocyte culture, then the relation of the Na+,K+ -ATPase function and oncosis in the astrocyes under OGD model was investigated. It has been proved that magnesium sulfate increases the actvity of Na+,K+ -ATPase, while, ouabain decreases the activity. Therefore, the actvity of Na+,K+-ATPase and the ratio of the oncotic asrocytes to the the total astrocytes after OGD were measured to discuss whether these two drugs protected the astrocytes against oncosis process via changing the activity of Na+,K+ -ATPase.The present study aimed to find some new methods of neuroprotecition to against cerebral ischemia.Methods:Astocytes of the newborn SD rats within 24 h were cultured in vitro. After 18-21d, GFAP staining was used to detect the purity of the astrocyes, the morphological changes and the pathological process of oncosis were observed by electron microscope. The cells were divided into OGD control group, precondition magnesium sulfate group and ouabain group. The activity of Na+,K+ -ATPase at different time point of OGD(0,1,2,3,4,6h) was measured, and the ratio of oncotic and apoptotic astrocyes to the total astrocytes at different time points of OGD were detected on Flow cytometry by Annexin V-FITC/PI Apoptosis Detection Kit.Results:The activity of Na+,K+ -ATPase decreased along with the increased OGD period (P<0.05). There was no difference of the activity of Na+,K+ -ATPase among the blank group, magnesium sulfate and ouabain group (P>0.05). In the meanwhile, the ratio of the oncotic asrocytes to the total asrocytes increased along with the increased OGD period (P<0.05).However, there was no significant difference among the blank group, magnesium sulfate and ouabain group (P>0.05). Both oncosis and apoptosis occurred after OGD, apoptosis ratio decreased 1-2h after OGD, while oncosis ratio increased, thereafter the oncosis ratio (9.54±1.47%) exceeded the apoptosis ratio (7.69±0.80%) 3 h after OGD (P<0.05).