Exploration of Intervention in Xiongma Herb Pair on Cholinergic Synaptic Signal Pathway in Vascular Cognitive Impairment Rats Based on Serum Exosomes

OBJECTIVE To investigate the effect of Xiongma herb pair on exosomes expression in the brain and serum of rats with vascular cognitive impairment(VCI) and its intervention mechanism.

METHODS A total of 50 SPF male Wistar rats aged 8–10 weeks were used in this study. The rats were randomly assigned to a sham-operated group(sham group) and 2-vessel occlusion(2-VO) group. The VCI model was established using the 2-VO method, while rats in the sham group only underwent isolation of the bilateral common carotid arteries without ligation. Postoperatively, cerebral blood flow was assessed to evaluate the success of model establishment. Rats that met the predefined criteria for successful modeling were further randomly divided into a VCI model group, a donepezil hydrochloride positive control group, the high-, low-dose of the Xiongma herb pair group, with 10 rats in each group. Starting three days after the successful establishment of the model, gastric gavage was carried out twice daily. The intervention effect of the Xiongma herb pair on the cerebral blood flow in rats was carefully observed. Meanwhile, the learning and memory capabilities of the rats were evaluated through the Morris water maze experiment, and their social abilities were explored via social interaction tests. Additionally, the content of acetylcholine(Ach) and the activity of acetylcholinesterase(AChE) were determined. Furthermore, the expression levels as well as the contents of AKT1, AChE, and PKCβ1 in the brain, serum, and serum exosomes were examined.

RESULTS The outcomes of the Morris water maze experiment and the social interaction experiment manifested that the rats in the model group constantly exhibited learning and memory impairments along with social behavior disorders commencing from the 28th day and persisting until the 56th day. The groups that received drug administration effectively enhanced the learning and memory abilities and alleviated the social behavior disorders of the rats with VCI. According to the test results regarding the ACh content and the AChE activity within the brains of rats in each group, it was demonstrated that, in comparison to the model group, the ACh content in the high-dose Xiongma herb pair group and the positive drug group was notably elevated, while the AChE activity values in all the administration groups were significantly reduced. The results concerning the expression of relevant proteins in the brains of rats in each group indicated that, when contrasted with the model group, the expressions of AKT1 and AChE in all the administration groups were significantly enhanced, and the expression of PKCβ1 in the high-dose Xiongma herb pair group and the positive drug group was significantly increased. The results of the expression of key proteins in the cholinergic synapse signaling pathway within the serum exosomes of rats in each group disclosed that, compared to the model group, the expression levels of PKCβ1 and AChE in the serum exosomes of rats in all the administration groups were significantly boosted. All these differences were statistically significant(P<0.05).

CONCLUSION The Xiongma herb pair accomplishes the treatment of VCI through inhibiting the activity of AChE within the brains of VCI rats and enhancing the content of ACh. The variations of the key proteins AChE and PKCβ1 in the cholinergic synapse pathway in the brain are largely in line with those in the serum exosomes, suggesting that serum exosomes might carry AChE and PKCβ1 and convey disease information between the peripheral blood and brain tissue.