Neuroprotective Effect Of Aspirin On The 1-Methyl-4-phenyl-1,2,3,6-Tetrahydropyridine Induced Mouse Model Of Parkinson’s Disease By Blocking NLRP3 Inflammasome Activation

Objective: Parkinson’s disease(PD)is closely related to the occurrence and development of nerve inflammation.Some clinical studies reported that long-term using of aspirin could reduce the incidence of PD.This article aimed to explore the role of NLRP3 inflammasome in the course of PD and the possible mechanism of aspirin therapy on PD.Methods: Pole test and rotarod test were usded to select normal mice,36 adult wild-type mice,12 adult NLRP3 knockout(NLRP3-/-)mice and 12 adult ASC knockout(ASC-/-)mice,without dyskinesia.WT mice were divided into three groups: normal saline(NS,n = 12),MPTP(n = 12),Aspirin + MPTP group(n =12).NLRP3-/-and ASC-/-mice were assigned to NLRP3-/-+ MPTP group(n = 12),and ASC-/-+ MPTP group(n = 12).We housed the animals by groups.For MPTP treatment we injected the mice with 25 mg/kg MPTP(Sigma,USA,dissolved in 0.9% saline)intraperitoneally(ip)four times at two hour interval.The mice in the NS group were similarly injected intraperitoneally with saline only(10ml/kg).Aspirin(Sigma,USA,dissolved in 0.9% saline)at 30 mg/kg body weight was co-injected together with MPTP at first and last MPTP injections.This dose(30 mg/kg)is based on our preliminary experiments and published paper.The behavior test began at 24 hours after the last administration,and then each group of mice were randomly selected six animals,euthanized and dissected whole brain.Midbrain dopaminergic neurons in PD model mice were measured by Western blot and immunofluorescence.7 days after the last administration,the same method was used in all groups of remaining animals to dissect whole brain.To understand whether NLRP3 inflammasome plays a role in acute MPTP-induced PD in mice,we examined IL-1β,caspase-1,pro-caspase-1,pro-IL-1β and NLRP3 levels by Western blot.Results: Compared with the control group,athletic ability and coordination capacity of PD model mice were significantly weakened.Aspirin could inhibit the process of PD,improving athletic ability and coordination in mice.NLRP3 knockout or ASC knockout could suppress the process of PD,improving athletic ability and coordination in mice.Western blot experiments showed that NLRP3,Pro-caspase-1,Pro-IL-1β with the control group,however,in the PD model group were significantly higher than the control group.Aspirin,NLRP3 knockout or ASC knockout could significantly reduce the amount of these five proteins.However,the level of tyrosine hydroxylase was just the opposite.Immunofluorescence assay showed that midbrain dopaminergic neurons in PD model mice were significantly impaired,while aspirin,NLRP3 knockout or ASC knockout could significantly reduce dopaminergic neuron damage.The study also found that ASC gene knockout had a stronger improvement than Nlrp3 gene knockout in exercise capacity,reducing of caspase-1 and releasing of IL-1d in PD mice.Conclusion:(1)MPTP can induce mouse model of PD;(2)NLRP3 inflammasome was involved in the pathogenesis of PD;(3)Neuroprotective effect of aspirin on the MPTP induced mouse model of PD may be by blocking NLRP3 inflammasome activation.