The Effect Of P75NTR On Oligodendrocyte Progenitor Cells Differentiation In The Hippocampus Of A Cuprizone-Induced Schizophrenia Mouse Model

Objective To explore the effect and mechanism of neurotrophic receptor P75(P75NTR)on oligodendrocyte progenitor cells(OPCs)differentiation in the hippocampus of a cuprizone-induced schizophrenia mouse model.Methods Mice were fed cuprizone(CPZ)diet for 6 weeks to establish acute demyelination model,and then Illumina sequencing platform was used to analyze the differentially expressed genes of demyelinating mice.Elevated Plus Maze(EPM)and Morris Water Maze(MWM)were used to assess the behavioral change of these mice.Fast-blue staining was used to study the change of myelin sheath in the corpus callosum.The expressions of myelin associated glycoprotein(MAG),P75 NTR,Neural/glial antigen 2(NG2)and 2’,3’-cyclic nucleotide 3’ phosphodiesterase(CNPase)were detected by Western blot in hippocampus.Immune fluorescent double labeling was used to detect the expression of NG2 and P75NTR in hippocampus.To confirm the relationship between hippocampal oligodendrocyte and P75 NTR.(2)Mice were fed the CPZ diet for 5 weeks.Then the γ-secretase inhibitor N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester(DAPT)was injected into the the hippocampus to inhibit P75 NTR cleavage,while normal saline(NS)group was set up.At the 6th week,EPM and MWM were used to evaluate the behavioral change.Immunohistochemistry and Western blot were used to detect the expression of NG2 and CNPase in hippocampus.We also use immunohistochemistry to investigate the change of myelin sheath in the hippocampus between two group.To confirm the mechanism of P75 NTR in inhibiting the differentiation of hippocampal OPCs in mice.Results(1)Compared with the control group,the EPM test showed that the number of entering the open arm and the time of staying in the open arm of CPZ group mice were reduced(P<0.05).MWM experiment showed that the escape latency of CPZ group mice were prolonged,while the number of platform crossing was reduced(P<0.05).The fast-blue staining result showed that the mouse treated with CPZ presented demyelination in the corpus callosum.Western blot results showed that the expression of P75 NTR and NG2 in the hippocampus of CPZ group was increased,while the expression of MAG and CNPase was decreased(P<0.05).Immunohistochemical showed that NG2 increased and CNPase decreased in the hippocampus of CPZ group(P<0.05).Immune fluorescent double labeling results showed that P75 NTR was expressed in hippocampal OPCs of CPZ group.Illumina sequencing platform results suggested that the neurotrophin receptor-associated death domain(Nradd)gene,which affects P75 NTR expression,was significantly up-regulated.(2)MWM experiment showed that the escape latency of mice was shortened after DAPT treatment,and the number of cross-platform was increased(P<0.05).In the EPM test,the number of mice entering the open arm and the activity time in the open arm decreased after the intervention of DAPT(P<0.05).Immunohistochemical and Western blot results showed that NG2 expression decreased and CNPase expression increased after DAPT treatment(P<0.05).The immunohistochemistry showed the expression of MBP was increased after DAPT treatment(P<0.05).Conclusion1.After demyelination,cognitive function is impaired,P75 NTR was expressed in mice hippocampal’s OPCs,and it can inhibit the differentiation of OPCs.2.Blocking the cleavage of P75 NTR in the hippocampus of demyelinated mice promotes the differentiation and myelin regeneration of OPCs,and reverses the cognitive dysfunction in mice.