Abstract:

Objective To investigate the effect of abnormally increased α ⁃synuclein（α ⁃Syn）on the expression of Dopamine receptor D1（D1DR）in the brain and colon of mice. Methods Sixteen C57BL/6J mice were randomly divided into control and model groups：the model group was injected with α⁃Syn preformed fibrils （PFF）into the striatum to build a mouse Parkinson′s disease（PD）model，and the control group with equal volume of PBS. Balance beam，pole ⁃ climbing and open field tests were performed to detect their behaviors at 6 months after operation；Western blot（WB），immunohistochemistry（IHC）and immunofluorescence（IF）were used to detect the expressions of D1DR，α⁃Syn，and tyrosine hydroxylation（TH）in the substantia nigra and colon. Results Compared with the controls，the model mice exhibited prolonged time in balance beam and pole⁃climbing （P < 0.001），and slower average moving speed in open field test（P < 0.001）. By WB，IHC and IF，the D1DR and TH positive cells were significantly reduced in number（all P < 0.05）and the expressions of D1DR and TH in the substantia nigra and colon of the model mice were lower than those in the control group（all P < 0.05）. The relative expression in the substantia nigra and colon was positively correlated（r = 0.8943，0.9026，P < 0.05）. Conclusion The expressions of D1DR and TH are decreased in the substantia nigra and colon of PD model mice built by injection of α⁃Syn PFF into the striatum，which provides a basis for application of colon biopsy to the path⁃ological assessment of central nerves of early PD patients. 

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