The Expression Of AQP4,AQP9 And MCTs In Astrocytes Exposure To Chronic Hypoxiaand Its Possible Regulating Mechanism

ObjectiveTo establish astrocyte chronic hypoxia injury model in vitro,so as to investigate the expression of?aquaporin 4,AQP4?and?aquaporin 9,AQP9?and?monocarboxlate transporter,MCTs?,and to explore possible their roles on lactic acid transportion and whether AQP9 expression is regulated by p38-MAPK signal pathway.MethodsThe primary cultured rat astrocytes were divided into the control group and the chronic hypoxia group randomly.According to the duration of chronic hypoxia,the models of chronic hypoxia were examined at interval times of 12 h,24 h,48 h and 72 h respectively.The content of lactic acid?LD?and lactate dehydrogenase?LDH?activity in culture medium was detected by LD and LDH kits.The expression of HIF-1??AQP4?AQP9?MCTs and p38-MAPK in control group and chronic hypoxia group were detected by Immunofluorescence and western blotting.The effect of p38-MAPK on the expression of AQP9 was detected by western blotting with or without p38 inhibitor.Results?1?Compared with the control group,the content of LDH activity in hypoxia groups were higher than those in the control group,and increased gradually with time,peaked at 72 h?P<0.05?.The expression of HIF-1?increased in chronic groups compared with the control group detected by western blotting?P<0.05?.?2?Compared with the control group,the content of LD in hypoxia groups were higher than those in the control group,and increased gradually with time,peaked at 72 h?P<0.05?.?3?The results of immunofluorescence showed that AQP4 and AQP9was weakly expressed in astrocytes membrane and cytoplasm in the control group.In the chronichypoxia group,the expression of AQP4 and AQP9gradually increased with time duration of hypoxia.?4?The expression of AQP4 and AQP9 and the ratio of p-p38/p38increased in chronic groups compared with the control group detected by western blotting?P<0.05?.Mean while MCT₁ and MCT₄ protein were decreased compared with the control group?P<0.05?.And p38 chemical inhibitor?SB203580?could block the expression of AQP9 induced by chronic hypoxia partially.Conclusions?1?The expression of AQP4 and LDH increased at corresponding time points after chronic hypoxia in astrocytes,which may be related to the formation of astrocyte edema.?2?The expression of AQP9 increased and MCT1,4 decreased at corresponding time points after chronic hypoxia exposure,AQP9 may be one of the important pathways for lactic acid transportion after chronic hypoxia.?3?The expression of AQP9 is regulated by p38-MAPK signaling pathway partially in astrocyte after exposure to chronic hypoxia.