Abstract: Objective To investigate the immune regulatory effects of tetramethylpyrazine( TMP) on allergic rhinitis (AR) rats by regulating the MCP-1 / CCR2 signaling pathway. Methods Rats were randomly separated into 6 groups: Control group, Model group, TMP low-dose (TMP-L) group, TMP high-dose (TMP-H) group, TMP-H + rMCP-1 (recombinant MCP-1 protein) group, and loratadine group. AR rats were rated for their symptoms. The blood cell count method was applied to detect the number of various types of cells in the nasal lavage fluid of each group. Flow cytometry was applied to detect the levels of CD4 + , CD8 + , and CD4 + / CD8 + ratio in serum. ELISA was applied to detect serum levels of IL-10, IL-17, IL-6, interferon-γ ( IFN-γ), immunoglobulin (IgE), and allergenic mediator histamine (HIS). HE staining was applied to observe the pathological morphology of rat nasal mucosa. Western blotting was applied to detect the expression levels of aquaporins AQP1, AQP2, MCP-1, and CCR2 in nasal mucosa tissues. Results Compared with those in the Model group, the TMP-L, TMP-H and loratadine groups showed an obvious reduction in nasal mucosal tissue damage in rats, the symptom score of allergic rhinitis, numbers of eosinophils, neutrophils, lymphocytes, and macrophages in nasal lavage fluid, serum CD8 + level, IL-17, IL-6, IgE, HIS levels, and the expression levels of AQP1, AQP2, MCP-1, and CCR2 proteins in nasal mucosa tissues were decreased, and the serum CD4 + , CD4 + / CD8 + ratio, IL-10, and IFN-γ levels were increased (P< 0. 05). The values of above indexes in the TMPH and loratadine groups were at the same level (P > 0. 05). RMCP-1 could alleviate the improvement effect of TMP on AR rats (P < 0. 05). Conclusion TMP can reduce inflammation, alleviatenasal mucosal damage, and improve immune function in AR rats, which may be related to the inhibition of the MCP-1 / CCR2 signaling pathway.

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