Study On The Role And Mechanism Of Salidroside And Curcumin In Regulating Gut Microbiome-Metabolome Axis During Parkinson’s Disease

Background:Parkinson’s disease(PD)is the most common movement disorder among elderly people,but its etiology and pathogenesis are still unclear.Clinical drugs fail to delay and reverse the disease process,accompanied by serious side effects.Therefore,it is urgent to clarify the pathogenesis of PD and open up a new direction for clinical diagnosis and treatment.Clinical symptoms of PD involve multiple systems,including motor symptoms and non-motor symptoms,of which gastrointestinal symptoms are the most common non-motor symptoms.It is worth noting that gastrointestinal symptoms of PD can appear decades earlier than motor symptoms,and there is evidence to support that the onset of PD may originate from the gastrointestinal system.Intestinal flora is the key medium to mediate the two-way communication between the gut and brain,and can play important physiological and pathological functions by regulating metabolites and other mechanisms.The active monomer extracts of traditional Chinese medicine have the advantages of multi-target coordinated regulation,fewer gastrointestinal side effects,and can participate in the regulation of intestinal flora,which is an ideal intervention treatment targeting the gut microbiota-metabolite axis of PD.However,its research in PD is still not in-depth,which needs to be further explored.Aim:This study focuses on Salidroside(SAL)and Curcumin(CUR),two active monomer extracts,and establishes animal models through chemically induction and antibiotic treatment(ABX).16s rRNA sequencing,high-throughput mass spectrometry sequencing,fecal microbiota transplantation(FMT),and other experimental methods were used to explore the regulatory role of active monomer components in the gut-brain axis of PD and its potential mechanism.Methods:①Chemical induction was used to establish the PD mouse model,and the results were confirmed by behavioral tests,stereotactic concussion section,western blot,immunofluorescence and immunohistochemistry.②The effects of SAL and CUR on the composition,structure and function of gut microbiota were determined by sequencing and analysis of fecal samples.③ABX and FMT experiments were conducted to determine whether gut microbiota mediated the protective role of SAL and CUR in PD.④The effects of SAL and CUR on serum metabolites were determined using metabolite spectrum detection technology and bio-confidence analysis technology.⑤qPCR and HE staining showed that SAL and CUR could regulate the inflammatory pathway in the gut-brain axis of PD.⑥Pearson correlation analysis confirmed the role of key intestinal flora and key metabolites in the gut-brain axis.⑦In vivo intervention experiment to clarify the mechanism of specific metabolites in the gut-brain axis.Results:①SAL and CUR intervention significantly alleviated the motor dysfunction of PD-induced model mice;SAL and CUR intervention significantly increase the number of dopaminergic(DA)neurons in the substantia nigra-striatum system,and prevented the aggregation of α-Synuclein(α-syn)and the activation of glial cells.②SAL and CUR intervention significantly altered the composition and structure of gut microbiota;SAL intervention group remarkably elevated the abundance of Lactobacillus,but decreased the abundance of Aerococcus,Desulfvibrio and Staphylococcus.CUR intervention group significantly decreased the abundance of Aerococcus and Staphylococcus,but increased the abundance of Lactobacillus,Lachnospiraceae,Muribaculaceae,and Eggerthellaceae.③ABX intervention inhibited the protective effects of SAL and CUR on motor dysfunction and DA neurons in PD mice.The FMT experiment verified that the intestinal flora extracted from mice of SAL and CUR intervention groups could improve motor dysfunction and protect DA neurons in PD mice,and simulated the neuroprotective effect of SAL and CUR on PD.④SAL and CUR intervention can significantly change the spectrum of serum metabolites;SAL intervention significantly up-regulated the Taurine(TAU)level and the metabolic pathway of TAU;CUR significantly up-regulated the Tyrosine(TYR)level and the metabolic pathway of TYR.⑤SAL and CUR intervention significantly improved PDinduced intestinal histopathological changes,increased intestinal length and improved intestinal defecation function;SAL intervention significantly down-regulated the expression of IL6,IL10 and TNFα in brain tissue and down-regulated the expression of intestinal inflammatory factors IL6,IL1b and TNFα.⑥Pearson correlation analysis showed that the abundances of Aerococcus,Staphylococcus and Desulfvibrio in SAL intervention group were significantly correlated with PD-related experimental results.At the same time,the levels of serum TAU,1H 2-oxindole,fructose-1-phosphate,creatine,tyrosine and N-aacetyl glutaminewere significantly related to the behavioral and pathological manifestations of PD.Among them,the correlation between the TAU level and PD-related results is the most significant.In addition,TAU is significantly related to the abundance of Aerococcus,Staphylococcus and Desulfvibrio.⑦Pearson correlation analysis showed that the abundance of Lactobacillaceae,Spirochloaceae,Muribaculaceae,Aerococcaceae and Staphylococcus in CUR intervention group was related to PD behavior and pathological estimations;The serum levels of TYR,methionine,sarcosine,and creatine were positively correlated with PD-related results and were significantly correlated with the abundance of Aerococcaceae and Lactobacillus.After CUR intervention,the levels of YTR and L-dopa in brain tissue significantly increased,which were related to PD behavior and pathological evaluations,Aerococcaceae and Lactobacillaceae.⑧TAU intervention in vivo significantly improved the motor dysfunction and the decrease of DA neurons in PD model mice,inhibited the activation of microglia,and down-regulated the expression of IL6 and TNFα in the brain tissue and intestine.⑨TAU transporter inhibitor eliminated the effect on improving motor dysfunction and decreasing DA neurons in PD model mice.TAU transporter inhibitor blocks the neuroprotective effect of SAL on PD.Conclusion:①After SAL and CUR intervention,PD-related motor dysfunction,DA neurons decrease,α-Syn pathology,and neuroinflammation were significantly improved;meanwhile,SAL and CUR intervention can improve intestinal pathological characteristics,intestinal function,the composition and structure of gut microbiota,and the spectrum of serum metabolites were significantly changed.Furthermore,intestinal flora mediates the neuroprotective effects of SAL and CUR on PD.②In SAL intervention group,the differential metabolite TAU down-regulated the expression of IL6 and TNFα in brain tissue and intestine,inhibited the activation of microglia,protected dopaminergic neurons,and improved PD motor dysfunction.③In CUR intervention group,the differential metabolite TYR significantly activated TYR-Ldopa-levodopa metabolic pathway,protected DA neurons,and improved PD motor dysfunction.