The Neuroprotective Effect And Mechnasims Of Fecal Microbiota Transplantation On MPTP-induced Parkinson's Disease Model Of Mice

Parkinson's disease(PD)is one of most common neurodegenerative disorder clinically characterized by motor and non-motor symptoms.The classical motor symptoms include bradykinesia,resting tremor,rigidity and late postural instability,due to progressive death of dopaminergic neurons in the substantia nigra pars compacta(SNpc).However,there is also a wide spectrum of non-motor manifestations involving gastrointestinal(GI)dysfunction,such as dysphagia,constipation and weight loss,which occur frequently in PD and may precede motor symptoms.At present,the exact pathogenesis of PD is not fully understood.Studies have shown that the neuroinflammation,oxidative stress,and cellular autophagy may be involved in PD.The emerging role of gut microbiota in GI pathogenesis and bidirectional communication between the gut and brain in PD has received much attention.PD patients display gut microbial dysbiosis.However,mechanisms between gut microbial dysbiosis and pathogenesis of PD remains unexplored,and there are no recognized therapies available to halt or slow progression of PD.Given that gut microbiota plays an important role in PD and the dysbiosis of gut microbiota in PD,we intend to use the method of fecal microbiota transplantation(FMT)to explore the neuroprotective effects of gut microbial dysbiosis on PD mice by correcting gut microbial dysbiosis,as well as to analyze the potentatial mechanisms of FMT.8 weeks aged male C57BL/6J mice were obtained for making PD mouse model by intraperitoneal injection for 5 days with 30mg/Kg 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride(MPTP)administration.Mice were randomly divided into normal control group,MPTP+PBS group and MPTP+FMT group to verify the neuroprotective effect of FMT on MPTP-induced PD mice.The PD mice recived FMT treatment by gavage for 7 days,that the feces from normal mice were collect to get supernatant of fecal microbiota for FMT.After the administration,then the feces of mice were collected for the gut microbial compositions analysis by 16 S rRNA sequencing and the analysis of short-chain fatty acids(SCFAs)of by gas-mass spectrometry(GC-MS).The pole test and traction test were performed to assess the behavior functions of mice.The immunofluorescence staining was performed for assessing the number of dopaminergic neurons in SN.And the high performance liquid chromatography(HPLC)was performed for dection of striatal DA,5-hydroxytryptamine(5-HT)and their metabolites.The western blot was used for detection of striatal tyrosine hydroxylase(TH)in the striatum,and expression changes of TLR4,TBK1,and NF-?B in the striatum and colon.The Enzyme-linked immunosorbent assay(ELISA)assays were used for detection of TNF-? in striatum and colon.Moreover,the immunofluorescence staining was used to detect the distribution and activation of microglia and astrocytes in the SN.In addition,in order to verify the role of gut microbial dysbiosis in the pathogenesis of PD,we also transplanted the gut microbiota of PD mice into normal mice to observe changes in motor functions and striatum neurotransmitters.Here,we identified that gut microbiota from PD mice induced motor dysfunctions and striatal neurotransmitters decrease on normal mice.Sequencing of 16 S rRNA revealed that phylum Firmicutes and order Clostridiales decreased,while phylum Proteobacteria,order Turicibacterales and Enterobacteriales increased in fecal samples of PD mice,along with increased fecal short-chain fatty acids(SCFAs)detected by GC-MS.Remarkably,FMT reduced gut microbial dysbiosis,decreased fecal SCFAs,alleviated physical impairment,and increased striatal DA and 5-HT and their metabolites content in PD mice.Further,FMT alleviated the activation of microglia and astrocytes in the SN,and reduced high expression of TLR4/TNF-a signaling pathway components in colon and striatum.Our study demonstrates that gut microbial dysbiosis is involved in PD pathogenesis,and FMT can protect PD mice by suppressing gut inflammation and neuroinflammation by suprssing TLR4/TNF-a signaling pathway and glia activation.