The Neuroprotective Effect Of Ultrasound Neuromodulation In Mouse Model Of Parkinson's Disease

Parkinson's disease(PD)is a serious neurodegenerative disease around the world.The typical clinical symptoms of PD include akinesia,bradykinesia,resting tremor and muscle rigidity.The pathological changes are mainly related to the dysfunction of corticobasal gangliacortical circuit.The use of physical methods to regulate the neural circuit is the basic way to understand the pathogenesis of PD.Neuromodulation techniques based on physical methods,such as electro-,magnetic-and optogenetictechnology,promote the rapid development of neuroscience in recent years,and provide a new method for the treatment of brain diseases.The noninvasive neurostimulation technology based on ultrasound radiation force is considered to be one of the next generation tool with the most clinical prospect,which has the advantages of noninvasive,large penetration depth and multi-points stimulation.The neurostimulaiton effect has been verified on neurons,rodents,non-human primates.However,whether ultrasound radiation force has therapeutic effect on the mouse model of Parkinson's disease has not been explored.This paper explores the neuroprotection effect of ultrasound radiation force on the mouse model of Parkinson's disease in three aspects:(1)Ultrasound stimulation of the motor cortex improves motor function in a mouse model of PD.PD is linked with motor cortex abnormality and stimulating the motor cortex is able to improve the symptoms of PD.However,whether ultrasound stimulation of the motor cortex could improve the motor symptoms of PD mice is not demonstrated currently.(2)The neuroprotective effect of noninvasive ultrasound deep brain stimulation in a subacute model mouse of PD.The subthalamic nucleus(STN)and the internal segment of the globus pallidus(GPi)are the two targets for the treatment of PD and there was no significant difference in the effectiveness of the two targets.However,whether ultrasound stimulation of the two targets is effective remain unclear.(3)The anti-inflammation effect of ultrasound stimulation in a chronic mouse model of PD.The accumulation of misfolded protein and activation of glial cells are important factors leading to the loss of dopamine neurons.Anti-inflammatory treatment is an important strategy for PD.However,whether ultrasound stimulation has antiinflammatory effect on PD remains unclear.(1)Objective: The aim of this study was to examine whether ultrasound stimulation of motor cortex could improve parkinsonian motor deficit in a mouse model induced by 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP).Methods: Acute PD mouse model was built by injection of MPTP(20mg/kg)every 4 h in a total of four doses in one day.Mice were randomized into control,MPTP,sham-US+MPTP and US+MPTP group.For US+MPTP group,7 days of US(800 kHz,10% duty cycle,100 Hz pulse repetition frequency,40 min/day)was delivered to motor cortex after MPTP injection.Open field test(OFT)was conducted on day 4 and pole test on day 5,respectively.Striatal total superoxide dismutase(T-SOD)and glutathione peroxidase(GSH-PX)were measured on day 8.The safety of US was verified using Hematoxylin and esosin(HE)staining and Nissl staining.Results: US treatment improved rearing number in OFT on day 4(n = 8,p = 0.037)and locomotor activity in pole test on day 5(n = 8,p = 0.007)compared with sham-US+MPTP group.Moreover,US increased TSOD(n = 7,p = 0.006)and GSH-PX(n = 7,p = 0.030)compared with sham-US+MPTP group.In addition,HE and Nissl staining showed no brain tissue injury induced by US.Conclusion: These findings demonstrate that US may have neuromodulation effects in PD mice.(2)Objective: The aim of this study was to examine whether ultrasound stimulation of deep brain improves motor symptoms in the mouse model of PD.Mothod: Subacute mouse model was built by MPTP injection for five days.Mice were randomized into sham-control,sham-MPTP,STN-US+MPTP and GP-US+MPTP group.For STN-US+MPTP and GP-US+MPTP groups,7 days of US(3.8 MHz,50% duty cycle,1 kHz pulse repetition frequency,30 min/day)was delivered to deep brain targets.Behavioral test were conducted to evaluate the motor function of PD mouse.The number of DA neurons was observed by immunoflouorescence staining and the protein levels of Bcl-2,Bax,Cyt C and cleaved-caspase 3 were dected by western blotting analysis.The safety of US was verified using Hematoxylin and esosin(HE)staining and Nissl staining.Results: STN-US+MPTP or GP-US+MPTP signifcantly increases the latency to fall in the rotarod test on day 9(p < 0.05)and decreases the time spent climbing down a vertical rod in the pole test on day 12(p < 0.05).Moreover,our results reveal that STN-US or GP-US protects the dopamine(DA)neurons from MPTP neurotoxicity by downregulating Bax(p < 0.001),upregulating Bcl-2(p < 0.01),blocking cytochrome c(Cyt C)release from mitochondria(p < 0.05),and reducing cleaved-caspase 3 activity(p < 0.01)in the ipsilateral substantia nigra(SN).Additionally,the safety of ultrasound stimulation is characterized by hematoxylin and eosin(HE)and Nissl staining;no hemorrhage or tissue damage is detected.Conclusion:US enables modulation of STN or GP neural activity and leads to neuroprotection in PD mice,potentially serving as a noninvasive strategy for the clinical treatment of PD.(3)Objective: The aim of this study was to examine whether ultrasound stimulation has anti-inflammatory effect for the treatment of PD.Method: Chronic mouse model was built by MPTP injection and probenecid injection twice a week for five weeks.Mice were randomized into control-sham,MPTP-sham,MPTP-STN-US group.For MPTP-STN-US groups,US(3.8 MHz,50% duty cycle,1 kHz pulse repetition frequency,30 min/day)was delivered to the STN.Behavioral test were conducted to evaluate the motor function of PD mouse.The number of DA neurons was observed by immunoflouorescence staining and the protein levels of TNF-?,IL-1? and ?-synuclein were detected by western blotting analysis.The safety of US was verified using Hematoxylin and esosin(HE)staining and Nissl staining.Results:MPTP-STN-US mice spent less time climbing the pole(p = 0.002)and increased the latency to fall in the rotarod test(p = 0.033)compared with the sham-MPTP group mice.Moreover,our results reveal that US protected the dopamine(DA)neurons(p =0.038)from MPTP neurotoxicity and inhibited the expression of Iba-1(p < 0.001)and GFAP(p < 0.001)compared with MPTP-sham group.The protein levels of ?-synuclein(p = 0.002),TNF-?(p = 0.024)and IL-1?(p = 0.001)in the SN was decreased in MPTPSTN-US group compared with MPTP-sham group.Conclusion: US provided antiinflammatory effct for the PD mouse and inhibited ?-synuclein in the SN.In summary,this thesis demonstrated that ultrasound stimulation improves themotor symptoms in the mouse model of PD and has neuroprotective effect on dopamine neurons through improving antioxidant stress and inhibiting neuroinflammation.These results provide basic data for the clinical application of PD.