| BACKGROUND:Following intracerebral hemorrhage(ICH)induction,intensively oxidative stress(OS)responses,inflammatory processes and a large number of neutrophil infiltration in the brain tissue surrounding the hematoma are induced,and as a result,triggering severe blood-brain barrier(BBB)disruption,brain edema and massive neuronal cell death and these impairments are tightly related to the prognosis and neurological deterioration of patients suffered to ICH ictus.However,currently there are no effective methods to treatment the brain injury post ICH.Isoliquiritigenin(ILG)possesses multiple biological functions and can activate nuclear factor erythroid-2 related factor 2(Nrf2)-mediated antioxidant system,negatively regulate nuclear factor-KB(NF-κB)and nod-like receptor family,pyrin domain-containing 3(NLRP3)inflammasome pathways,but its role and relevant molecular mechanisms on the early brain injury following ICH remain unclear.After ICH ictus,Nrf2-induced antioxidant system exerts neuroprotective effects and the activation of NLRP3 inflammasome pathway aggravates the brain injury.However,the relationship of them in the early brain injury after ICH is also remaining to be elucidated.OBJECT:To explore the effects and potentially relevant molecular mechanisms of ILG on the early brain injury after ICH induction.To probe,in the early brain injury following ICH,the relationship of Nrf2-mediated antioxidant system and NLRP3 inflammasome pathway activation.METHODS:Experimental rat ICH model was induced by sterile collagenase type IV and sham-operated rats were prepared.Rats were intracerebroventricularly(right)administrated with Nrf2 small interfering RNA(siRNA)24 hours(h)before modeling.ILG(10,20 or 40 mg/kg)was administrated intraperitoneally at 30 minutes(min),12 h,24 h,48 h after modeling.At 24 h or 72 h following modeling,brain tissues were obtained and performed the relative scoring,measurements and analyses:neurological deficits(modified Neurological Severity Score,mNSS),histological damages(Hematoxylin&eosin staining,H&E staining),brain edema[Brain water content(BWC)wet/dry weight method],BBB disruption(Evans blue,EB)dye extravasation,neuronal degeneration(Fluoro-Jade(?)C staining,FJC staining),Quantitative real-time RT-PCR(qRT-PCR),Western blot(WB),Immunohistochemistry(IHC)/Immunofluorescence(IF),Enzyme-linked immunosorbent assay(ELISA).Related kits were used for the measurements of Catalase(CAT),Superoxide dismutase(SOD)activities and Reactive oxygen species(ROS),Glutathione/oxidized glutathione(GSH/GSSG)contents.RESULTS:1.ILG(20 and 40 mg/kg)markedly alleviated the early brain injury post ICH by intraperitoneal administration(Neurological deficits,Histological damages,BBB disruption,Brain edema and Neuronal degeneration),but there were no significant difference between the two dosages.ILG at the dosage of 20 mg/kg was selected for the following experiments.2.ILG(20 mg/kg)significantly suppressed the activation of NF-κB and NLRP3 inflammasome pathways,production of ROS and promoted the triggering of the Nrf2-mediated antioxidant system.3.Gene silencing of Nrf2 by Nrf2 siRNA aggravated the early brain injury after ICH(Neurological deficits,Brain edema,Neuronal degeneration)and increased the protein levels of NF-κB p65,NLRP3 inflammasome components(NLRP3,ASC,Caspase-1)and IL-1β.ILG delivery significantly attenuated the effects of Nrf2 siRNA interference mentioned above.CONCLUSION:1.ILG can notably reduce early brain impairments following ICH and holds the brain protective effects.2.Triggering of Nrf2 activity and Nrf2-induced antioxidant system can inhibit the activation of NLRP3 inflammasome pathway and related mechanisms are involved in the blockades of ROS and/or NF-κB pathway.3.ILG exerts its brain protective effects by the regulation of Nrf2—ROS/NF-κB—NLRP3 inflammasome pathway.4.ILG may be a new option of medical therapy for the brain injury post ICH and Nrf2—ROS/NF-κB-NLRP3 inflammasome pathway may be a new treatment target. |
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