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Objective To explore the effect of blood-brain barrier disruption on expression of AQP-4,through comparing the cell morphology and the expression of aquaporin-4(AQP-4)of cultured astrocytes in medium with and without fetal bovine serum(FBS). Methods Cerebral cortical astrocytes from female Wistar rats were cultured in serum free medium,DMEM supplement-ed with 10% FBS,and serum free medium supplemented with 10% FBS.Phase contrast microscope was used to detect the cell morphology and cell size. Immunofluorescence staining and reverse real-time quantitative poly-merase chain reaction(RT-qPCR)were used to examine the expression of glial fibrillary acidic protein(GFAP), AQP-4 and metabotropic glutamate receptor 5(mGluR5). Results Astrocytes in serum free medium showed extensive process bearing morphology,small body and nucleus,and high refractivity.In contrast,in two kinds of 10% FBS-containing medium,astrocytes were flat with large body and nucleus,weak refractivity,as well as short process.Analysis of immunofluorescence staining and RT-qPCR revealed a down-regulation of GFAP and AQP-4 protein and mRNA expression in two kinds of 10% FBS-con-taining medium, compared with that in serum free medium (P<0.001), however, there was no difference in mGluR5 protein and mRNA expression(P>0.05). Conclusion FBS changed astrocyte morphology and down-regulated the expression of GFAP and AQP-4.
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<p><b>OBJECTIVE</b>To investigate the role of extracellular signal-regulated kinase1/2 (ERK1/2) pathway in the regulation of aquaporin 4 (AQP4) expression in cultured astrocytes after scratch-injury.</p><p><b>METHODS</b>The scratch-injury model was produced in cultured astrocytes of rat by a 10-μL plastic pipette tip. The morphological changes of astrocytes and lactate dehydrogenase (LDH) leakages were observed to assess the degree of scratch-injury. AQP4 expression was detected by immunofluorescence staining and Western blot, and phosphorylated-ERK1/2 (p-ERK1/2) expression was determined by Western blot. To explore the effect of ERK1/2 pathway on AQP4 expression in scratch-injured astrocytes, 10 µmol/L U0126 (ERK1/2 inhibitor) was incubated in the medium at 30 min before the scratch-injury in some groups.</p><p><b>RESULTS</b>Increases in LDH leakage were observed at 1, 12, and 24 h after scratch-injury, and AQP4 expression was reduced simultaneously. Decrease in AQP4 expression was associated with a significant increase in ERK1/2 activation. Furthermore, pretreatment with U0126 blocked both ERK1/2 activation and decrease in AQP4 expression induced by scratch-injury.</p><p><b>CONCLUSION</b>These results indicate that ERK1/2 pathway down-regulates AQP4 expression in scratch-injured astrocytes, and ERK1/2 pathway might be a novel therapeutic target in reversing the effects of astrocytes that contribute to traumatic brain edema.</p>