Research On The Relationships Between Ischemic Tolerance In Brain And Proliferation Of Endogenous Neural Stem Cells, And The Role Ofd-opioid Receptor (DOR) In Ischemic Tolerance

Part 1: Research on the relationships between ischemic tolerance in brain and proliferation of endogenous neural stem cellsObjective: to explore the relationship between ischemic preconditioning(IPC) and proliferation of endogenous neural stem cells in hippocampus at 7d post MCAO,and to observe influence of IPC on the status of rats' neurologic deficit at 3d,7d post MCAO.Materials and Methods: focal-focal ischemic tolerance(IP/IT) models were established with twice suture method. 40 SD rats were included and randomly divided into 4 groups:A:Sham group;B:MCAO group; C:Sham+MCAO group;D:IP+MCAO group.There is 10 rats in each group.To lebal proliferating cells,animals were given one set of BrdU injections(on day 6,three times,4h apart, 50mg / kg).We evaluate their neurological status,and make Brdu fluorescent immunolabeling.Results: According to Zea-longa neurologic deficit scores,MCAO group and Sham+MCAO group performed significantly difference with IP+MCAO group at 3d and 7d post MCAO(P＜0.01) .There is no difference between MCAO group and Sham+MCAO group (P＞0.05) . According to Brdu~+ cells in hippocampus at 7d post MCAO,Sham group performed significantly difference with MCAO group, Sham+MCAO group and IP+MCAO group(P＜0.01) . IP+MCAO group performed significantly difference with MCAO group and Sham+MCAO group(P＜0.01) . There is no difference between MCAO group and Sham+MCAO group (P＞0.05) .Conclusions: Acut ischemic cerebral infarct could induce the proliferation of endogenous neural stem cells in hippocampus in SD rats.IPC could facilitate the proliferation of endogenous neural stem cells in hippocampus post ischemic cerebral infarct in SD rats, and improve the status of rats' neurologic deficit.Part 2:Resaerch on the role of d-opioid receptor(DOR) in ischemic toleranceObjective: To investigate the expression of DOR, Bax, Bcl-2 mRNA in rat IP/IT model,and to explore the role of DOR in ischemic tolerance. Materials and Methods: focal-focal ischemic tolerance(IP/IT) models were established with twice suture method. 24 SD rats were included and randomly divided into 4 groups:A:Sham group;B:MCAO group; C:Sham+MCAO group;D:IP+MCAO group.Rats were sacrificed at 7d post MCAO.We detected the expression level of DOR,Bax,Bcl-2 mRNA by using RT-PCR technology.Results: DOR and Bcl-2 mRNA expression level is distinctly higher in IP+MCAO group than other groups,But Bax mRNA expression level is distinctly lower in IP+MCAO group than other groups. IP+MCAO group performed significantly difference with MCAO group and Sham+MCAO group (P＜0.01). There is no difference between MCAO group and Sham+MCAO group (P＞0.05) .Conclusions: IPC could increase the expression of DOR mRNA and Bcl-2 mRNA, but reduce the expression of BaxmRNA.Part 3:Research on the role of PTS in ischemic tolerance in brain and proliferation of endogenous neural stem cellsObjective: to observe influence of PTS on the proliferation of endogenous neural stem cells in hippocampus post ischemic cerebral infarct in SD rats,and on the expression level of DOR, Bax, Bcl-2 mRNA in rat IP/IT model.Materials and Methods:Based on part one and part two above,we added group E:PTS+MCAO group.Animals were injected with PTS(100mg/kg/d, i.p., once a day) for 14 days starting at 7d before MCAO.Results: According to Zea-longa neurologic deficit scores,MCAO group and Sham+MCAO group performed significantly difference with PTS+MCAO group at 3d and 7d post MCAO(P＜0.01) .There is no difference between IP+MCAO group and PTS+MCAO group(P＞0.05). According to Brdu~+ cells in hippocampus at 7d post MCAO,PTS+MCAO group performed significantly difference with Sham group,MCAO group and Sham+MCAO group(P＜0.01). There is no difference between Ip+MCAO group and PTS+MCAO group (P＞0.05) .PTS exerted no influence on DOR ,Bax,Bcl-2 mRNA expression level,and There is no difference among MCAO group ,Sham+MCAO group and PTS+MCAO (P＞0.05) .Conclusions: PTS could facilitate the proliferation of endogenous neural stem cells in hippocampus post ischemic cerebral infarct in SD rats, and improve the status of rats' neurologic deficit. But it had no influence on the expression of DORmRNA, Bcl-2mRNA and BaxmRNA.