| Parkinson’s disease(PD)is a common degenerative disease of the central nervous system,affecting up to 2%of people over the age of 65.The clinical manifestations of PD patients mainly include motor symptoms such as tardiness of action and quiescent tremor,as well as non-motor symptoms such as constipation and dysphagia.The disease progression of PD gradually worsens over time,and patients find it difficult to take care of themselves,bringing huge burden to themselves,their families and society.At present,drug therapy and surgical treatment are commonly used in the clinical treatment of PD.However,in the later stage of treatment,drug therapy may have problems such as reduced efficacy and aggravated side effects,while surgical treatment is expensive and indications must be strictly controlled.Therefore,it is extremely urgent to explore an effective way to treat PD.In recent years,more and more studies have shown that gut microflora plays an important role in the occurrence and development of PD.The previous study of our group found that the gut microflora of normal mice was transplanted into PD model mice by fecal bacteria transplantation technique,which could significantly improve the behavioral disorders and neuropathology of PD model mice.Oral vancomycin can also play a neuroprotective role in PD model mice by changing gut microflora and inhibiting intestinal and brain inflammation.These results suggest that gut microflora is an important participant in the development of PD pathology.Meanwhile,PD is one of the most common diseases affected by the aging process,which is often accompanied by changes in gut microflora.Therefore,we raised the scientific question:Does the gut microflora of elderly mice play a protective role in PD or exacerbate the progression of PD.To answer this scientific question,we randomly divided the mice into four groups:(I)The control group receiving gut microflora transplantation from young mice(denoted as YM group),(II)the control group receiving gut microflora transplantation from old mice(denoted as AM group),(III)The PD model group receiving gut microflora transplantation from young mice(named YM+MPTP group)and(IV)the PD model group receiving gut microflora transplantation from old mice(named AM+MPTP group).The operation process is as follows:(1)antibiotic treatment;(2)Fecal bacteria transplantation treatment;(3)Modeling of acute PD.In this study,behavioral,molecular biology,histopathology,high-throughput sequencing and other experimental techniques were used to carry out the research.Intestinal transport capacity was detected by intestinal propulsion rate experiment.High performance liquid chromatography(HPLC)was used to detect the neurotransmitters(including Dopamine(DA)and 5-hydroxytryptamine(5-HT))in the striatum.Western blot was used to detect the expression of Tyrosine hydroxylase(TH)in striatum and claudin-1 and Occludin in colon.Immunofluorescence(IF)was used to detect Substantia nigra pars compacta(SNpc)TH~+dopaminergic neurons,glial cells(including Iba1~+microglia and GFAP~+astrocytes)and hippocampal DCX~+neurons;The composition and distribution of gut microflora were analyzed by 16S r RNA gene sequencing.The contents of short chain fatty acids(SCFAs)in feces were detected by Gas chromatography-mass spectrometry(GC-MS),including acetic acid,butyric acid,isobutyric acid,valeric acid,isovaleric acid and propionic acid.The contents of inflammatory cytokines(TNF-α,IL-1β,IL-6,IL-10)in striatum were determined by Enzyme Linked immunosorbent assay(ELISA).Real-time quantitative PCR(RT-q PCR)was used to detect the expression of inflammatory cytokines in colon.Immunohistochemistry(IHC)determined the number of Ki67~+cells in the hippocampus.The experimental results showed that compared with YM group and AM group,YM+MPTP group and AM+MPTP group showed motor dysfunction(significantly prolonged pole climbing time),significantly decreased levels of DA,5-HT and TH in striatum,and abnormally increased levels of butyric acid,isobutyric acid,valeric acid,isovaleric acid and propionic acid in feces.Furthermore,compared with YM+MPTP group,AM+MPTP group transplanted intestinal flora of elderly mice improved motor function,increased the contents of DA and 5-HT in striatum,and increased TH level in striatum.Abnormal elevations of butyric,isobutyric,valeric,isovaleric and propionic acids in the feces of mice were also recovered.16S r RNA results showed that compared with YM group,the levels of Candidatus＿Saccharimonas and Akkermansia in feces of YM+MPTP group were significantly decreased.Compared with YM+MPTP group,Candidatus＿Saccharimonas,Akkermansia,Rikenellaceae＿RC9＿gut＿group,Desulfovibrio and Desulfovibrio＿fairfieldensis have been significantly increased,indicating that the gut microflora of aged mice can improve the composition of gut microflora in PD model mice.GC-MS results showed that gut microflora of aged mice could significantly improve SCFAs disorder in PD mice.Neuroinflammation,intestinal inflammation and intestinal permeability were not affected by intestinal microflora transplantation in young or old mice.It is noteworthy that compared with YM+MPTP group,the number of Ki67~+cells and DCX~+neurons in the hippocampal region of AM+MPTP group was increased,suggesting that the gut microflora of elderly mice can promote the increase of neurogenesis in PD mice.Conclusion:gut microflora transplantation in aged mice has a protective effect on PD model mice,which may be achieved by improving dopaminergic nervous system and inducing neurogenesis... |
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