Experimental Study In Ultrasonographic Evaluation Of MPTP-induced Parkinson's Disease Mice Model

Objective:Parkinson's disease (PD) is a common neutral degeneration disease in senior people, which characterized as bradykinesia, rigidity and static tremor. It is difficult to make a confirm diagnosis in the early stage. This study was designed to set up a MPTP-induced Parkinson's disease C57BL mice model and toobserve the echo characteristics of the brain tissue in different stages of the disease by ultrasound imaging technology and to validate this new method by comparision with the histology results. Methods:Twenty C57BL mice were randomly chosen to establish two groups of subacute and chronic stage of PD mice models separately. by injecting 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP). The verification of this model was by multi-behaviouristics test. Transcranial ultrasonography was performed in all model mice. The echo characteristics of the basal neuclei were observed by two dimensional ultrasound before and after the injection. The brain tissue was then taken out by perfusion method and processed by pathological section. HE and iron stain results were studied and compared to the ultrasonographic results.Results:Transcranial high-frequency ultrasound was performed successfully in all mice. by Two-dimensional ultrasound clearly displayed the brain tissue before the injection of MPTP. The midbrain presented as a very low echogenic area. All the 10 mice grouped as subacute PD model survived and showed positive results by behaviour test. There was no visible hyper echogenic sign in the midbrain area. HE staining shows that the dopaminergic neurons of substantia nigra (Substantia Nigra, SN) in brain tissue decreased while microglia abnormally increased. In chronic PD model group, seven out of the 10 mice survived 4-5 weeks after injection of MPTP. The behavioral test revealed positive results in 7 chronic PD mice model. Symmetrical and slightly hyper echoic were seen in bilateral area of SN. HE staining of SN showed that the dopaminergic neurons of SN decreased in a large number while microglia showed diffuse proliferation. Neither sub-acute nor chronic PD mice model showed positive results according to the iron staining. Conclusion:Chronic PD mice model shows hyperechoic texture by high frequency ultrasonography. by, which is similar to that in humans. hyper-echo in SN of PD mice model might be related to the large quantity of microglia proliferation. Ultrasonography could be an ideal and new method to evaluate the PD mice model and may contribute to the PD research in clinic.