Effect Of Osthole On Cognitive Function Of Vascular Dementia Rats

Objective:To investgate the ameliorative effect of osthole?OST?on cognitive dysfunction in vascular dementia?VD?rats and explore its possible mechanism.Methods:In this experiment,SD rats were divided into 5 groups:model group rats with bilateral common carotid artery occlusion,model+treatment with low,medium and high doses of OST groups,and sham group rats that were only isolated common carotid artery but not occlusion.Twelve rats were in each group after operation,totally 60 rats were in the study.Treated rats were given OST 5,10 and 20 mg/kg by gavage.Sham and model rats were given the same volume of double distilled water once a day for 61 days.Morris water maze test was performed on the 53th day after modeling,followed by Y-maze test.After the behavioral test,all of the rats were anesthetized and sacrificed.Four rats from each group were used for Hematoxylin-Eosin?HE?staining,Nissl staining,immunofluorescence staining after fixation,dehydration,embedding and other procedures,to observe the morphological and quantitative changes of neurons in the hippocampus and the number of activated microglia.Western blot?WB?was used to detect the protein level of beta-amyloid precursor protein?APP?,?-site APP cleavage enzyme?BACE1?,beta-amyloid 1-40(A?_1-40),A?_1-42 and NLR family pyrin domain containing 3?NLRP3?of the other hippocampus tissues.Results:The result of Morris water maze showed that compared with the sham group,the escape latency of the model group was significantly longer from day 4 to day 7,and the escape latency of the treated groups was obviously shorter after oral administration of different doses of OST.According to the statistical results of Y-maze,compared with the sham group,the spontaneous response alternation rate of the model group was distinctly reduced,and after the administration of OST,the spontaneous response alternation rate of the treated groups was evidently increased.According to the results of HE and Nissl staining,compared with the sham group,the neurons in CA3 area of hippocampus in the model group showed obvious pathological damage,which was manifested in loose arrangement,incomplete structure,uneven staining,unclear nucleus,deep staining of nucleolus and serious pyknosis,and the decreased number of Nissl body and cells;after the administration of OST,the pathological damage of neurons in CA3 area of hippocampus was overtly improved.According to the results of immunofluorescence staining of ionized calcium binding adaptor 1?IBA1?antibody and WB statistics of NLRP3 antibody,compared with the sham group,the number of activated microglia was increased in the hippocampus of the model group,and with the protein level of NLRP3 increased.After the administration of OST,the number of activated microglia was decreased in hippocampus,the protein level of NLRP3 was decreased as well.According to the results of WB protein statistics,compared with the sham group,the protein level of APP,BACE1,A?_1-40 and A?_1-42 in the hippocampus of model group was obviously increased,after the administration of OST,the abovementioned proteins levels were significantly reduced in the hippocampus.Conclusion:OST improves cognitive dysfunction of VD rats,and its possible mechanism may be related to the inhibition of NLRP3 inflammasome and the reduction of A?level in hippocampus.