RESUMO
Objective To investigate the changes of microglia cell phenotypes in the injured brains of rats following repetitive mild traumatic brain injury (rmTBI).Methods Sixty male SD rats were randomly divided into sham-operated group,injury of one-week group,injury of two-week group,injury of four-week group,and injury of six-week group (n=12).Rats in the injury groups were induced rmTBI models by controlled cortical impact (CCI),and rats in the sham-operated group were only performed bone window opening without hitting.Six rats from each group were sacrificed;immunofluorescent staining was used to detect the Iba-1 positive microglial cells in the injured cortex and changes ofmicroglia subsets in the injured brain after rmTBI were analyzed by flow cytometry.Results As compared with the sham-operated group,the injury of one-week group and injury of six-week group had significantly increased percentages of Iba-1 positive microglial cells in the injured cortex (19％ and 12％,P＜0.05).flow cytometry indicated that CD451ow/CD11b+ cells were the microglial cells,accountting for 90％ ofCD11b+ cells;as compared with the sham-operated group,the injury of one-week group,injury of two-week group,injury of four-week group,and injury of six-week group had significantly increased M1 type microglial cells (P＜0.06),with injury of six-week group enjoying the highest level;as compared with the sham-operated group,the injury of one-week group,injury of two-week group and injury of four-week group had significantly increased M2 type microglial cells (P＜0.06),with injury of two-week group enjoying the highest level.Conclusion Dynamic changes ofmicroglia subsets after rmTBI are noted,which reveals that different subsets of microglia phenotypes might play their unique roles in the acute or chronic phases after rmTBI.
RESUMO
Objective To study the cognitive impairment in SD rats after intermittent hypoxia (IH),and explore the relation of miR-26b up-regulated expression and neuron apoptosis in the hippocampus of SD rats after IH.Methods Eight-week-old male SD rats (n=20,each weighing approximately 300±10 g) were randomly divided into normal oxygen control group,IH 1-week group,IH 2-weeks group and IH 4-weeks group (n=5).Rats in the later three groups were given IH for different times,and rats in the normal oxygen control group were given normal oxygen.The spatial learning and memory abilities were detected by Morris Water Maze (MWM) in the normal oxygen control group and IH 4-weeks group.The levels of apoptosis proteins Caspase3 and Bax and anti-apoptosis protein Bcl-2 in the hippocampus of 4 groups were detected by Western blotting.The miR-26b expression level in the 4 groups was detected by real time-PCR.Results (1) The results of MWM revealed that the mean escape latency in the IH 4-weeks group was significantly prolonged as compared with that in the normal oxygen control group (P＜0.05);the time entering into the target quadrant in the IH 4-weeks group ([22.0±6.7] s) was significantly shorter than that in the normal oxygen control group ([39.8±8.8] s,P＜0.05).(2) Western blotting indicated that up-regulated expressions of apoptosis proteins Bax and Casepase3 and down-regulated expression of anti-apoptosis protein Bcl-2 in the IH 1-week group,IH 2-weeks group and IH 4-weeks group were noted as compared with those in the control group,with significant differences (P＜0.05);significantly higher apoptosis protein Bax and Casepase3 expressions in the IH 1-week group were noted as compared with those in the IH 2-weeks group and IH 4-weeks group (P＜0.05),while significantly decreased Bcl-2 expression in the IH 1-week group was noted as compared with that in the IH 2-weeks group and IH 4-weeks group (P＜0.05).(3) The results of real time-PCR revealed that the miR-26b expression level in the hippocampus was up-regulated in the IH 1-week group,IH 2-weeks group and IH 4-weeks group as compared with that in the control group,with significant differences (P＜0.05);miR-26b expression level in the IH 1-week group was significantly higher as compared with that in the IH 2-weeks group and IH 4-weeks group (P＜0.05).Conclusion The miR-26b up-regulated expression in the hippocampus might refer to Bax /Bcl-2-related mitochondrial apoptotic signaling pathway after IH brain injury;miR-26b could be a potential mean ofgene therapy after IH brain injury.