| α-synuclein-related diseases are mainly including Parkinson’s disease(PD),Parkinson’s dementia(PDD),Lewy body dementia(DLB),etc.PDD,DLB are manifested by the accumulation of Lewy bodies in the cortex and brain stem.in addition,the a53 t point mutation also increased oxidative damage,leading to abnormal aggregation of α-synuclein.The characteristics of α-synuclein a53 t transgenic mouse models are α-synuclein aggregation and TH cells reduction,which are used as PD models.However,evidence show that the phenotypes of α-synuclein a53 t mouse models regulated by different exogenous promoters are different.Therefore,this study intends to systematically recognize the motor and anxiety,cognitive behavioral evaluation of α-synuclein a53 t mice in PDGF-β promoter;immunohistochemical observation of the pathological changes in the brain of mice,and whether it can be used as a synuclein-related cognitive impairment animal models such as(DLB /PDD).Clinically,dl-3-N-butylphthalide(nbp)can alleviate neurological damage in cerebrovascular diseases,and the literature indicates that it can alleviate cognitive impairment in neurological models such as AD.Besides,recent studies have shown that nbp has a protective effect in neurodegenerative diseases,and it can reduce cognitive impairments in models such as Alzheimer’s(AD),however,there are currently no experimental reports of nbp in the treatment of α-synuclein-related cognitive impairment,and the application of nbp in the treatment of α-synuclein a53 t mouse models.Therefore,this experiment is intended to evaluate the behavior of α-synuclein a53 t mouse models,and to explore the mechanism of nbp treatment in the a53 t mice.Part One α-synuclein a53 t mutation impairs cognitive function in miceObjectives: To explore the motor coordination,cognitive function and anxiety-like behavioral changes and pathological characteristics of α-synuclein a53 Tt transgenic mice.Methods: The α-synuclein a53 t transgenic mice with PDGF-β promoter(a53t mice)were used as the experimental group,and the negative were used as the control group.The open field test and the cylinder test were used to measure anxiety in mice.Rotarod test and Grip test are used to assess dyskinesias.The morris water maze test and Fear condition test was used to assess cognitive ability in mice.The pathological characteristics were detected by immunohistochemical staining.Observation of mitochondrial morphology in mice by electron microscope.Results:1.Compared with the control group,moving distance of a53 t mice was increased;time freezing was decreased;There is no difference in Cylinder test,Rotarod test,Grip test and Morris water maze test.2.Phosphorylate α-synuclein level of the substantia nigra and striatum,piriform cortex and hippocampus were increased;lewy body was found in the prefrontal cortex,deposition of α-synuclein in the substantia nigra,striatum were increased;and the number of TH cells in the substantia nigra decreased significantly;mitochondrial fission increased,and the contents were not clear.Conclusions:1.Cognitive function was impaired in the a53 t mice,which was prior to movement disorder.2.Pathological features were α-synuclein/LBs deposited in the prefrontal and piriform cortex,dopaminergic neuron decreased in the substantia nigra,as well as mitochondrial morphology changed in the amygdala,which can be used as an animal model of synucleinopathy related cognitive disease such as DLB and PDD.Part Two Effect and mechanism of butylphthalide on cognitive impair-ment of α-synuclein a53 t transgenic miceObjectives: To investigate the effect of intraperitoneal injection of nbp on cognitive function in a53 t mice,and whether nbp can maintain mitochondrial stability and improve cognitive impairment by regulating mitochondrial morphology.Methods: The a53 t mice were used as the a53 t group,and the negative were used as the Control group,the a53 t mice with nbp treatment via intrap-eritoneal injection for 2 weeks were used as the nbp group.The behavior of mice was assessed using the rotarod test,open field test,olfactory discrimination test,and fear conditioning test.Tyrosine hydroxylase(TH),α-synuclein and phosphorylated α-synuclein immunostaining in the substantia nigra(SN)and striatum were performed to evaluate the pathological changes;the prefrontal glutamatergic action potentials of mice was recorded;the mitochondria and synaptic structure in the prefrontal cortex,the striatum,hippocampus(HIP),SN and amygdala region were observed using transmission electron microscopy;the expression levels of the mitochondria fusion(MFN1 and MFN2),fission(DRP1),and mitophagy(Parkin),synaptophysin and α-synuclein related proteins were determined using western blotting.Results: 1.Compared with the a53 t group,nbp treatment significantly reduced the motor coordination ability,olfactory recognition ability and cognitive deficits of a53 t mice.2.Compared with a53 t group,Immunohistochemical staining of TH and α-synuclein showed that TH cells of nigra and striatum in the nbp group were recovered,and synuclein accumulation was reduced.3.Compared with the a53 t group,prefrontal glutamate action potential of a53 t mice decreased in the nbp group.4.After nbp treatment,mitochondrial structure was clear,fission was reduced,and the number of synapses was increased.5.Western blot showed that the expression of mitochondrial fission proteins MFN1 and MFN2 was increased after nbp treatment,and the levels of mitophagy proteins Parkin and DRP1 were reduced,Besides,the synaptophysin was incresed and the α-synuclein reduced after nbp treatment.Conclusions: 1.nbp can improve the cognitive impairment of mice.2.The specific mechanism may reduce mitochondrial autophagy by regulating mitochondrial fusion fission,maintain mitochondrial stability,increase synaptic density,and improve cognition. |
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