| Acute intracerebral haemorrhage (ICH) is the disease that of high mortality rate. Edema is the cause of high mortality rate in ICH and thrombin is the main point of cerebral edema formation in ICH. Recent studies demonstrated that AQP-4 played an important role in keeping balance in between extracellular and intracellular fluid. For understanding mechanism of edema damage to brain, it is necessary to investigate effect of thrombin on AQP4 expression after acute intracerebral hemorrhage. Traditional Chinese medicine have some advantages on protecting brain damage from ICH and Rhubarb is a common drug in treating ICH. Exploring its mechanism is accordingly an important and significant work in clinical research.Objective To investigate molecule mechanism of AQP4 expression alteration After acute intracerebral hemorrhage. Then to explore relationship between regulation mechanism and thrombin in experimental rat after acute intracerebral hemorrhage and the mechanism of rhubarb therapeutic efficacy in acute intracerebral hemorrhage.Methods —.Twenty weeks old SD adult rats were subjected to stereotaxic intrastriatal injections of 50μl autologous whole blood. AQP4 expression and brain water content were investigated at different time points in all groups. 二. Twenty weeks old SD adult rats were subjected to stereotaxic intrastriatal injections of 10 U thrombin. AQP4 expression and brain water content were investigated in all groups. Based on primary cultured neonate rat astrocytes, AQP4 mRNA and AQP4 protein expressiom were observed by RT-PCR and Western blot. Signal transduction pathway of thrombin effect on AQP4 expression were investigated using H7, TPA , SFLLRN. 三. Twenty weeks old SD adult rats were subjected to stereotaxic intrastriatal injections of 50μl autologous whole blood. Under the treatment of rhubarb, AQP4 expression, BBB permeability were investigated at different time points in all groups.Results 一. AQP4 expression appeared positive correlation with edema. 二.Intracerebralinfusion of 50ul saline containing 10U rat thrombin produced significant increase in brain water content in the ipsilateral basal ganglia compared to that measured in rats that received control saline (P < 0.05). Brain water content was 82.96±0.79%, 4.99% greater compared to animals receiving control saline. Western blot and RT-PCR revealed AQP4 expression decreased(P < 0.05). Thrombin inhibited AQP4 protein expression in a concentration and time-dependent manne. Cathepsin G (40 mU/mL) pretreated with 30 min before thrombin treatment, astrocytes were processed with RT-PCR and Western blot analysis revealed AQP4 expression increased. Pretreatment of astrocytes with 100μM H-7 for an hour abolished the thrombin-induced decreases in AQP4. After a 24h pretreatment of astrocytes with 1 μM TPA, the expression of AQP4 was not affected by subsequent thrombin stimulation and showed almost the same levels as the control. 三. As compared with the sham group, there appeared a significant increase in AQP-4 mRNA and protein expression following ICH (P<0.05) . Rhubarb reduced brain water content, inhibited AQP-4 gene transcription and translation. They also reduced EB pass blood-brain barrier tight-junction and reduced astrocyte foot process swelling.Conclusions 一 .AQP4 protein participate edema formation After acute intracerebral hrmorrhage. 二.Thrombin inhibits Aquaporins 4 expression in rats and rat astrocytes and this effects is mediate by protein kinase C pathway. 三.Rhubarb reduce brain edema by protect blood-brain barrier tight junction and decrease astrocyte foot process swelling and inhibited AQP-4 gene transcription and translation.
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