RÉSUMÉ
ObjectiveTo investigate the pharmacodynamic characteristics and explore the molecular mechanism of Honghua oral liquid （HOL） in relieving neuropathic pain （NP）. MethodHealthy male SD rats were randomly assigned into sham group， model group， low-， medium-， high-dose （0.5， 1.0， 2.0 mL·kg-1·d-1， respectively） HOL groups， and a positive drug （pregabalin， 25 mg·kg-1·d-1） group， with 6 rats in each group. Spinal nerve ligation （SNL） of L5 was conducted in other groups except the sham group. Drug administration was performed 3 days after the SNL surgery for 2 consecutive weeks， and samples were collected after the end of the administration. During the treatment period， the mechanical pain threshold and cold pain threshold were determined to measure the pain-relieving effect of HOL. Transcriptome sequencing was performed on hippocampal tissue samples from the sham， model， and high-dose HOL groups， and differentially expressed genes between the sham group and the model group as well as the model group and HOL high-dose group were obtained. After pathway enrichment analysis， we selected the targets which were closely related to neuroinflammation for validation， and predicted the specific binding sites of the major active components in HOL with the targets through molecular docking. In addition， the serum levels of tumor necrosis factor-α （TNF-α） and interleukin-10 （IL-10） were determined by enzyme-linked immunosorbent assay （ELISA） to evaluate the effect of HOL on neuroinflammation in NP rats. ResultCompared with the sham group， SNL decreased the mechanical pain threshold and cold pain threshold （P<0.05）. Compared with the model group， HOL recovered the mechanical pain threshold and cold pain threshold （P<0.05）. The transcriptome data showed that 376 differentially expressed genes （DEGs） were identified between the model group and the sham group， including 124 upregulated genes and 252 downregulated genes， and 194 DEGs between the model group and the high-dose HOL group， including 33 upregulated genes and 161 downregulated genes. Among them， insulin-like growth factor 1（IGF1）， matrix metallopeptidase-2 （MMP-2）， matrix metallopeptidase-14 （MMP-14）， erb-B2 receptor tyrosine kinase 2 （ERBB2）， and integrin subunit alpha 5 （ITGA5） associated with NP were selected for further validation. The Real-time fluorescence quantitative polymerase chain reaction（Real-time PCR） results showed that compared with the sham group， the modeling up-gurelated the mRNA levels of the above five molecules in the hippocampus （P<0.01）. Compared with model group， HOL down-regulated the mRNA levels of these molecules （P<0.01）. The molecular docking results showed that the main active components of safflower， hydroxysafflor yellow A， kaempferol， and quercetin， formed stable hydrogen bonds with the amino acid residues of IGF1， MMP-2， MMP-14， ERBB2， and ITGA5. The enzyme-linked immunosorbent assay（ELISA） results showed that compared with those in the sham group， the serum levels of TNF-α and IL-10 were out of balance in the model rats （P<0.01）. Compared with the model group， HOL lowered the level of the pro-inflammatory cytokine TNF-α （P<0.01） and elevated that of the anti-inflammatory cytokine IL-10 （P<0.05）. ConclusionHOL exerts analgesic effect on SNL rats by inhibiting neuroinflammation.