The Neuroprotective Effects Of Urolithin A In Experimental Model Of Parkinson’s Disease By Promoting Mitophagy

Research BackgroundParkinson’s disease(PD)is the second most common neurodegenerative disease in the world.Microglia-mediated neuroinflammation and mitochondrial dysfunction play a critical role in the pathogenic process of PD.Mitophagy refers to the delivery of damaged or redundant mitochondria to lysosomes for subsequent degradation and recycling,which is essential for regulating mitochondrial mass and maintaining normal mitochondrial function.Mitophagy has been found to be related to various neurodegenerative diseases,such as PD,Huntington’s disease,and Alzheimer’s disease.Urolithin A(UA)is a natural compound produced by intestinal bacteria from foods containing ellagitannin and ellagic acid(such as pomegranates,berries,and nuts),which has a variety of effects such as anti-inflammatory,anti-apoptosis,anti-oxidation,and anti-tumor proliferation,and most importantly,UA can promote mitophagy.However,the potential functions and mechanisms of UA in PD are still unclear,especially whether UA can promote mitophagy in microglia.Based on the above research background,this study will focus on the specific role of UA in PD,and explore whether it can protect mitochondrial function and inhibit neuroinflammation by promoting mitophagy in microglia,and ultimately protect dopaminergic neurons.Methods1.After 7 days of intraperitoneal injection of UA,the acute PD model was induced by intraperitoneal injection of MPTP.Rotating rod experiment,climbing rod experiment,and suspension experiment were carried out to evaluate the changes of mouse motor behavior;immunohistochemistry,Nissl staining,and western blot were used to evaluate the degeneration of dopaminergic neurons;western blot and immunofluorescence were used to detect the changes of autophagy and neuroinflammation.2.BV2 microglial cells were treated with UA and LPS,real time RT-PCR,immunofluorescence,and western blot were used to observe the inflammatory response and the activation of NLRP3 inflammasome;western blot and immunofluorescence were used to observe the changes of autophagy and mitophagy;mitochondrial function was assessed by flow cytometry,immunofluorescence,Seahorse extracellular flux analyzer,and transmission electron microscopy.3.3-Methyladenine(3-MA)was used to block the mitophagy of BV2 microglial cells,real time RT-PCR,western blot,and flow cytometry were used to detect the changes of cellular inflammation and mitochondrial function.4.Microglia conditional Atg5 knockout mice(Atg5 flox/flox;CX3CR1-Cre)were used to block microglial-mitophagy,dopaminergic neurodegeneration was assessed by immunohistochemistry,Nissl staining,and western blot.Results1.In the MPTP-induced acute PD mice model,UA alleviates motor dysfunction and dopaminergic neurodegeneration in mice,promotes autophagy and inhibits neuroinflammation.2.UA can inhibit LPS-induced inflammatory response and NLRP3 inflammasome activation in BV2 microglial cells,UA treatment can improve autophagy and mitophagy disorders,and protect mitochondrial function,including mitochondrial membrane potential,ROS,mitochondrial morphology,and mitochondrial metabolism in BV2 microglial cells.3.Blocking mitophagy reverses the protective effect of UA on LPS-induced inflammatory response and mitochondrial function in BV2 microglial cells.4.In Atg5 flox/flox;CX3CR1-Cre mitophagy-deficient mice,the protective effect of UA on dopaminergic neurons was partially abolished.ConclusionsUA reduces the loss of dopaminergic neurons,improves movement disorder and neuroinflammation in vivo.UA promotes mitophagy,protects dysfunctional mitochondria,and inhibits inflammatory responses in vitro,and the protective effects of UA were dependent on mitophagy.