Objective

2

To investigate the potential mechanisms underlying the therapeutic effects of

Bushen Huoxue Formulation

（补肾活血方， BSHXF） in Parkinson's disease （PD） from the perspectives of synaptic vesicle cycling and intestinal barrier function.

Methods

2

Forty-eight male SD rats were randomly divided into four groups， control group， model group， Madopar group， and BSHXF group， with 12 rats in each group. Except for the control group， rats were administered rotenone by gavage once daily for 4 consecutive weeks to establish a PD rat model. After successful modeling， rats in the BSHXF group received concentrated BSHXF solution by gavage at a dose of 13.5 g/（kg·d）， while rats in the Madopar group received Madopar tablet suspension at 2 g/（kg·d）. Rats in the control group and the model group were administered distilled water by gavage at 10 ml/（kg·d）. All groups received continuous gavage treatment for 2 weeks. Motor function was evaluated using the open field test （total distance traveled， average speed， and total d

istance traveled in the central zone）， rotarod test （latency to fall）， and balance beam test （traversal time）. Histopathological changes in colon tissues were observed by HE staining. Western Blotting was used to detect the protein levels of α-synuclein （α-syn）， phosphorylated serine 129 α-synuclein （pSer129-α-syn）， vesicle-associated membrane protein 2 （VAMP2）， and synaptophysin （SYP） in the substantia nigra and colon tissues. The mRNA expression levels of

α

-

syn

，

VAMP2

， and

SYP

were detected by RT-PCR， and α-syn expression was examined by immunohistochemistry. Immunofluorescence staining was performed to assess the levels of tight junction protein 1 （ZO-1） and occludin in colon tissues， as well as tyrosine hydroxylase （TH） levels in substantia nigra tissues.

Results

2

Compared with the control group， rats in the model group showed reduced total distance traveled， average speed， and central-zone distance in the open field test， decreased latency to fall in the rotarod test， and prolonged traversal time in the balance beam test. The protein levels of pSer129-α-syn and α-syn， as well as

α

-

syn

mRNA expression were increased in the substantia nigra and colon tissues， whereas the protein and mRNA expression levels of

VAMP2

and

SYP

were decreased. The relative integrated optical density of α-syn in the substantia nigra and colon tissues was increased， while the relative fluorescence intensities of ZO-1 and occludin in colon tissues and TH in the substantia nigra were decreased （

P

＜0.05）. HE staining showed focal necrosis in the mucosal layer of colon tissues， disappearance of some intestinal glands， extensive inflammatory cell infiltration， and proliferation of fibrous connective tissue in the submucosa. Compared with the model group， both the Madopar group and BSHXF group showed varying degrees of improvement in the above indicators （

P

＜0.05）. Pathological damage in colon tissues was also alleviated， with only mild fibrous tissue proliferation and limited diffuse inflammatory cell infiltration observed in the mucosal layer. Compared with the Madopar group， rats in the BSHXF group exhibited increased average speed， central-zone distance， and latency to fall in the rotarod test. The levels of pSer129-α-syn and α-syn proteins in the substantia nigra were decreased， while VAMP2 protein expression was increased. In colon tissues， SYP protein levels and mRNA expression were elevated. The relative fluorescence intensity of ZO-1 in colon tissues and TH in substantia nigra tissues was also increased （

P

＜0.05）.

Conclusion

2

BSHXF may improve motor dysfunction in PD by regulating synaptic vesicle cycling， restoring intestinal barrier integrity， and improving neuronal synaptic function through modulation of synaptic vesicle-associated protein expression in the substantia nigra and colon tissues.