The Role Of Research Brain-Derived Neurotrophic Factor And TrkB In Prion Disease

Objective : Prion diseases(also called Transmissible spongiform encephalopathies,TSEs)is a kind of neurodegenerative diseases,which can infect human and many other animal.Its main neuropathological feature is including spongiform vacuolar degeneration,amyloid plaques,neuronal loss and astrogliosis appeared in brain tissue.BDNF is a kind of protein which can prevent neuronal disfunction.BDNF and its receptor TrkB is widely distributed in the central nervous system.It plays an important role in promoting central nervous system growth,development,differentiation and maintenance.In order to investigate the changes of BDNF and TrkB which may be happened in prion diseases,we preserved the prion strains,scrapie strain 263 K of brain tissue and intracranial infection hamster prion stability infected cell line as the research object,in order to observe BDNF and TrkB expression in prion infected diseases,and explore the role of its function in these kind of disease.Methods:(1)intracranial inoculation of scrapie infected hamster 263 K end-stage(80days)brain tissue,infected with period of 0 days,20 days,40 days,60 days and 80 days of hamster brain tissue and prion infection in SMB-S15 cell line,detecting the expression of BDNF and TrkB protein changes level by Western Blot and immunohistochemical method.(2)for further study the relationship between BDNF,TrkB,Neurons and PrPSc,whether there is relationship between prion infection in brain tissue and its cells,we use immunofluorescence double staining method to detect BDNF,TrkB expression and distribution hamster brain tissue.(3)using Western blotting and immunohistochemistry to detect the protein’s level in intracranial inoculation of scrapie infected hamster 263 K end-stage(80 days)brain tissue,we tested this condition by infected with the virus in period of 0 days,20 days,40 days,60 days and 80 days of hamster brain tissue,and in themean time we detected prion infection in SMB-S15 cell line BDNF downstream of molecular interactions p-TrkB,GRB2 and p75 NTR expression changes.We explored the related mechanism of BDNF in prion disease and the role of BDNF-TrkB signaling pathway changes in prion diseases.Results:The Western Blot results showed the significantly decreased expression in the transmissible spongiform encephalopathy of end-stage BDNF and TrkB,and the same condition happened in the downstream molecular interactions,suggested that BDNF might be involved in the pathogenesis of TSEs.Immunofluorescence showed that BDNF mainly neurons co-localized expression,no expression of astrocytes.The level of BDNF was decreased with different infection time points in brain tissue,and the interaction of the receptor of TrkB,especially the phosphorylation of TrkB(p-TrkB)is decreasing with the decline of the time dependent phenomenon.The trend is very similar with neurons’ losses.Contrary to the in vivo test results,the effect of BDNF,TrkB and its downstream molecules level in SMB-S15 cells infected with prions and cure type normal expression levels were no significant difference.Conclusion : In summary,by using Western blot,immunohistochemistry,immuno fluorescence and a series of experimental methods,we verified that the expression levels of BDNF in the brain tissue of hamster prion infection and its related receptors TrkB were significantly reduced.The experimental data showed that the function of BDNF and its related signal pathway changing played a crucial role in prion disease,which might be closely linked with a large number of neuronal losses.It is worth further discussion and research.