| Objective: To investigate the relationship between the formation of ischemic cerebral edema and the changes of AQP9 expression during pathological course of ischemic cerebral edema in rats, and to preliminary discuss the role of AQP9 and its expression regulation mechanism during ischemic cerebral edema. Methods: A total of 240 healthy adult Wistar rats were divided into two groups randomly, the ischemic group and the sham operation control group. MCAO (middle cerebral artery occluding) models were established by occluding unilateral middle cerebral artery (MCA) of the rats with the suture method. The operation procedure of the control group was as same as the ischemic group but without occluding unilateral MCA. The brains of the animals were taken out at interval times of 3h,6h,24h,48h and 72h, respectively. Subsequently, the morphological changes were observed with HE staining and transmission electron microscope (TEM). Brain water content (BWC) was measured by using wet-dry weighing method. The mRNA and protein expression of AQP9 in the edema brain tissue were detected with in situ hybridization (ISH) and immunohistochemistry (IHC), respectively. The content changes of AQP9 and its mRNA in the edema brain tissue was detected with Western Blot analysis and reverse transcription polymerase chain reaction (RT-PCR). The content changes of cAMP in the edema brain tissue were measured by radioimmunoassay (RIA). Results: After operation, the morphological phenotype, BWC, content changes of AQP9 and its mRNA expression, content of cAMP were not significantly changed in the control group. While in the ischemic group, HE staining and transmission electron microscope (TEM) showed that the brain tissue had ischemic changes. The space around the neurons and capillaries became larger, some of the neurons showed necrosis phenotype, the nuclei were deeply stained or disappeared and the number of the neurogliocyte increased. The brain water content of ischemic brain tissue significant increased from MCAO 3h, and gradually increased along with the ischemic time extendence, and reached its peak at MCAO 48~72h. The results of IHC and ISH showed that the positive expression of AQP9 and its mRNA were observed in the hippocampus,choroid plexes,supraoptic nuclei,brain cortex and other regions. The content of AQP9 and its mRNA was up-regulated along with the content changes of cAMP and reached its peak at MCAO 72h. At the same time, the content of cAMP increased with the ischemic time extendence, too. The expression of AQP9 protein was positively correlated with AQP9 mRNA(r =0.9068, p <0.05). The expression of AQP9 was correlated with BWC after MCAO (r=0.9139, p<0.05). The expression of AQP9 was positively correlated with the content changes of cAMP (r=0.7392, p<0.05) during the brain edema formation. Conclusions: Both the expression enhancement of AQP9 and its mRNA were correlated with the content changes of cAMP after MCAO, which increased with brain edema aggravation. The results imply that the expression changes of AQP9 would have a close relationship with the formation of brain edema after MCAO. The content enhancement of AQP9 and its mRNA, which lead by the second transmitter cAMP, play an important role in the formation and development of brain edema. Objective: To investigate the expressions rules of aquaporin-9 (AQP9) and the molecular mechanism of its regulation in cultured rat astrocytes after exposury to different osmotic stress. Methods: Rat cerebral cortical astrocytes from 2 days newborn Wistar rats were undergone the primary culture. The cells were divided into control group,hypotonic groups and hypertonic groups randomly. The cells of the control group were cultured in normal culture medium, the model of cell edema in the hypotonic group was established by exposed to hypotonic medium, and cell dehydration in the hypertonic group was established by exposed to hypertonic medium. Each group was examined at interval times of 3h, 6h, 12h and 24 h, respectively. HE staining and transmission electron microscope were...
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