| Parkinson's disease(PD)is a progressive neurodegenerative disorder primarily resulting from degeneration of dopaminergic neurons.The current therapies for PD are symptomatic and do not affect the course of the disease.Accumulating evidence indicates that alterations in autophagy-lysosomal pathways of ?-synuclein may be preferentially involved in neuronal death and contribute to the pathogenesis of PD.Therapies targeting these processes may provide preventive strategies and potential treatments,as they can delay,revert or compensate for the neurodegeneration that lead to motor impairments.Resveratrol(RV),a natural polyphenolic compound,has been shown to exert neuroprotective effects through its antioxidant or anti-inflammatory properties and its capacity to cross the blood-brain barrier.Related to PD,RV has been revealed to provide beneficial effects in MPTP-or 6-OHDA-induced PD models.Our previous study indicates that RV could alleviate rotenone induced SH-SY5 Y cell injury and increases ?-synuclein clearance in PC12 cells,and the mechanism of RV is probably mediated through SIRT1 activation.In order to observe the neuroprotective effects of RV on MPTP-induced mouse model of PD,and explore its potential neuroprotective mechanism,herein,subacute intoxication regimen,which involves one injection of 30 mg/kg/free base MPTP daily for five consecutive days,was applied in our study.RV(100 mg/kg/day)was administrated by intragastric gavage(i.g.).EX527(10 mg/kg/day),a specific SIRT1 inhibitor,was injected intraperitoneally.The motor functions were observed by behavioral tests,including open field test,stride length test and pole test.Meanwhile,the levels of dopamine(DA),dihydroxyphenylacetic acid(DOPAC)and homovanillic acid(HVA)were determined by high performance liquid chromatography analysis.Tyrosine hydroxylase(TH)positive cells,protein level of TH,SIRT1,AMPK,p-AMPK,LC3(microtubule-associated protein 1 light chain 3,LC3),p62/SQSTM1,?-synuclein,Caspase 3,Cleaved caspase 3 and acetylated LC3 were determined by immunofluorescence staining,western blot and immunoprecipitation experiment.Our work was mainly be carried out from the following two sections:Firstly,SIRT1/AMPK pathway is involved in neuroprotective effects of RV in MPTP mouse model of Parkinson's disease.We found that the activation of SIRT1 by RV,accompanied by up-regulation of p-AMPK,significantly attenuated MPTP-induced behavioral impairments in open field test,stride length test and pole test,the loss of TH positive neurons in SN and the decreased levels of DA and TH protein in striatum in vivo.Treatment with EX527,a specific SIRT1 inhibitor,caused down-regulation of p-AMPK and blocked the neuroprotective effects of RV in MPTP mice,indicating that RV-mediated neuroprotection is through regulation of SIRT1/AMPK pathway.Secondly,SIRT1-deacetylated LC3 and consequential autophagic degradation of ?-synuclein were involved in the neuroprotective effects of RV to ameliorate motor deficits and pathological changes in PD,which provided one molecular pathway for RV capacity to attenuate tissue injury in PD.In this part,we demonstrated that following the activation of SIRT1 by RV,the acetylation level of LC3 was decreased,led to LC3 redistributing from the nucleus into the cytoplasm,accompanied by the increase of LC3-II as well as autophagic degradation of ?-synuclein and p62 in dopaminergic neurons.Inhibition of SIRT1 with a specific SIRT1 inhibitor EX527,blocked the decrease of acetylation level of LC3,prevented nuclear to cytoplasmic redistribution of LC3,accompanied by the decrease of LC3-II as well as accumulation of ?-synuclein and p62 in the cytoplasm of dopaminergic neurons.In conclusion,our studies showed that RV ameliorated both motor deficits and pathological changes of PD mice through activation of AMPK/SIRT1 pathway and subsequent LC3 deacetylation mediated autophagic degradation of ?-synuclein.These results also proposed a mechanism to support RV as a prophylactic or therapeutic agent for PD. |
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