Effect And Mechanism Of NLRP3 Inflammasome In The Treatment Of Multiple Sclerosis Model Mice By Extremely Low Frequency Electromagnetic Fields

Background:Multiple sclerosis is a chronic disease involving the central nervous system.Neuropathological features include inflammatory demyelination,axonal injury,glial hyperplasia,and neurodegeneration.The pathogenesis of MS has not yet been determined,which may be related to oxidative stress and immune inflammation.Cuprizone(CPZ),a copper ion chelator,induces sustained demyelination in the brain of C57BL/6 mice by specifically injuring oligodendrocytes.CPZ-induced demyelinating mouse models have been widely used in the pathogenesis and treatment of MS.Extremely low frequency electromagnetic fields(ELF-EMFs)is one of the commonly used physical therapy methods,can be used in a variety of clinical conditions of adjunctive therapy.A large number of studies have confirmed that it has good anti-inflammatory and immunosuppressive effects,can enhance cell activity,promote nerve regeneration,improve nerve function.Current studies have found that ELF-EMFs can effectively improve the symptoms of MS patients,but the underlying mechanism remains unclear.In this study,the possible mechanism of ELF-EMFs in MS treatment was preliminarily explored through ELF-EMFs intervention in demyelinating mouse models,and theoretical basis was provided for its clinical application.Objective:To investigate the effects of extremely low frequency electromagnetic fields on anxiety,motor balance,inflammatory response and NLRP3 inflammasome signaling pathway in CPZ-induced demyelinating mice.Methods:Male C57BL/6J mice aged 6-8 weeks were randomly divided into control group,CPZ group and magnetic therapy group(CPZ+EMF group).Control group was fed with conventional feed for 6 weeks,CPZ group and magnetic therapy group were fed mixed diets containing 0.3%CPZ for 6 weeks.At the beginning of CPZ was fed,the magnetic therapy group was treated by magnetic therapy for 6 weeks.The magnetic field intensity was 7～10 mT,frequency was 50 Hz.The body mass of mice was observed every 7 days.At the end of the 6th week,the elevated cross maze experiment and the rotating rod experiment was conducted.The myelin sheath in the corpus callosum and hippocampus were observed by Luxol fast blue(LFB)staining and myelin basic protein(MBP)immunohistochemistry,and the contents of tumor necrosis factor-α(TNF-α)and interleukin-1β(IL-1β)in the corpus callosum were detected by enzyme-linked immunosorbent assays.The protein expression levels of NLRP3,Caspase-1 and IL-1β were detected by Western blot.Results:Compared with the CPZ group,the body mass of the mice in the magnetic therapy group improved significantly.Compared with the control group,the times of entering open arm,the percentage of open arm time and the percentage of open arm entries of the CPZ group were significantly reduced,while compared with the CPZ group,the times of entering open arm,the percentage of open arm time and the percentage of open arm entries of the CPZ group were significantly increased.Compared with the control group,the latency of falling on the rotating rod was significantly reduced in the CPZ group,while compared with the CPZ group,the incubation period of mice in the magnetic therapy group was significantly increased.LFB staining and MBP immunohistochemistry showed significant myelin loss in the corpus callosum and hippocampus of the CPZ group,and compared with the CPZ group,the loss of myelin sheath was significantly improved in the magnetic therapy group.Compared with the control group,TNF-α and IL-1β in the corpus callosum of the CPZ group were significantly increased.Compared with the CPZ group,the protein levels of TNF-α and IL-1β in the magnetic therapy group were significantly decreased.Compared with the control group,the expressions of NLRP3,Caspase-1 and IL-1β in the hippocampus of the CPZ group were significantly increased.Compared with the CPZ group,the magnetic therapy group significantly inhibited the expressions of NLRP3,Caspase-1 and IL-1β.Conclusion:ELF-EMFs can improve body weight,anxiety symptoms and motor balance in CPZ-induced MS model mice,which is probably related to the inhibition of inflammatory response caused by the NLRP3 inflammasome signaling pathway in the white matter region.