The neuroprotective effect of curcumin by inhibiting the aggregation of α-synuclein on lipopolysaccharide-induced Parkinson's disease model
Objective To explore the neuroprotective effect of curcumin(Cur)on Parkinson's disease model and its mechanism.Methods Sprague-Dawley rats were randomly divided into the control(CON)group,the model(PD)group,and the low-,medium-,and highdose curcumin(Cur)groups,with ten rats in each group.Lipopolysaccharide was injected into the substantia nigra to establish a Parkinson's disease model.Rats in the Cur groups were administered Cur intraperitoneally at doses of 20 mg/kg,40 mg/kg,and 60 mg/kg daily for 21 days.α-synuclein(α-syn),nuclear transcription factor κB proteins(NF-κB,IKBα,p-NF-κB,p-IKBα)and the activation levels of astrocytes were detected in rat brain tissues by immunohistochemistry(IHC).mRNA levels of pro-inflammatory cytokines(TNF-α,IL-β,IFN-γ,IL-6),inducible nitric oxide synthase(iNOS),cyclooxygenase-2(COX-2),NADPH oxidase complex(gp47phox,gp91phox,gp67phox),and apoptosis-related factors(Bax,Bcl-2,Caspase-3,and Caspase-9)were measured by quantitative reverse transcription polymerase chain reaction(qRT-PCR).The rotarod and pole climbing tests were used to evaluate the motor coordination of the rats.Results Compared to the CON group,PD rats showed significantly increased levels of α-syn,p-NF-κB,p-IKBα proteins,activation of astrocytes,TNF-α,IL-β,IFN-γ,IL-6,iNOS,COX-2,Bax,Caspase-3,Caspase-9,gp47phox,gp91phox and gp67phox mRNA levels(P<0.05);while the Bcl-2 level was significantly decreased(P<0.05).Compared with the PD group,the medium-and high-dose Cur treatment groups inhibited the aggregation of α-syn protein,reduced the activation of the NF-κB pathway,and the expression of inflammatory and apoptosis-related factors(P<0.05).Moreover,medium and high doses of Cur significantly improved the motor coordination in rats,and compared with the PD group,the performance of rotarod and pole climbing tests was significantly improved(P<0.05).Conclusion cur may inhibit the aggregation of α-syn by suppressing neuroinflammation and oxidative stress responses,thereby improving motor coordination in Parkinson's disease rats and exerting neuroprotective effects.
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