RESUMO
Objective To examine the effects and mechanisms of siRNA targeting aquaporin 4 (AQP 4) in combination with hyperbaric oxygen therapy(HBO) on cerebral edema and apoptosis in the brain tissue of rats after hemorrhage.Methods Rats were randomly divided into four groups,the control group,the hyperbaric oxygen group,the AQP-4 siRNA group and the combination therapy group (24 rats).Thrombin Ⅶ was injected into the caudate nucleus to establish the hemorrhage model.Construction of siRNA targeting aquaporin 4 was conducted.The mRNA expression of AQP-4 was detected by RT-PCR at day 3.Changes in brain moisture and blood-brain barrier perme ability were measured by a wet/dry weight method and Evans blue fluorometry.The nerve cell apoptosis rate was analyzed by Annexin V andTdT-mediated dUTP-biotin nick end labeling (TUNEL).The expression of proteins including AQP-4,MMP-2,MMP-9,Bcl-2 and caspase-3 was detected by Western Blotting.All the animals were given a score for their nerve function at day 3.Results AQP-4 siRNA treatment obtained better effects than HBO in decreasing the brain edema leveland silencing AQP-4 mRNA(P＜0.05)while,the combination therapy group achieved the best results(P＜ 0.05).Compared with the control group,the percentage of apoptotic cells decreased in all the three treatment groups,with the most marked decrease observed in the combination treatment group(4.24± 0.04)％(F=13.76,P=0.001).The expression of AQP-4,MMP-2,MMP-9 and caspase-3 was lower (P＜0.05) and the expression of Bcl-2 was higher(P＜0.01)in the combination treatment group than in the other three groups.Compared with the control group,all the other three groups received better scores on nerve function defect evaluation at day 3 after hemorrhage(P＜0.05),with the combination treatment group again achieving the most favorable score (4.7 ± 1.1) (F=7.21,P =0.013).Conclusions Targeted siRNA interference combined with hyperbaric oxygen can effectively reduce cerebral edema after cerebral hemorrhage,inhibit neuronal apoptosis and promote neuron function recovery.The underlying mechanisms may be related to down-regulation of AQP-4,MMP 2,MMP-9 and caspase-3 expression and up-regulation of Bcl-2 expression.