A network-based analysis and experimental validation of traditional Chinese medicine Yuanhu Zhitong Formula in treating neuropathic pain

The Yuanhu Zhitong Formula (YZF) consists of traditional Chinese herbs Corydalis Rhizoma (Corydalis yanhusuo (Y.H.Chou & Chun C.Hsu) W.T.Wang ex Z.Y.Su & C.Y.Wu; Chinese name, Yanhusuo) and Angelicae Dahuricae Radix (Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav.; Chinese name, Baizhi), which is usually administrated for painful conditions. It is well acknowledged that YZF has pharmacological effects on pain relief; nevertheless, limited data are available on its mechanism. This study aimed to explore the potential mechanism underlying YZF on nociception of rats. Also, the comprehensive mechanism of YZF was preliminarily determined based on network pharmacology on neuropathic pain. A spared nerve injury (SNI) model was established to reveal the effects of YZF administration on nociceptive behavior in rats. Von-Frey tests were used to evaluate the paw withdrawal mechanical thresholds in rats administrated with YZF or vehicle. The "drug-ingredients" and "disease-drug-target" networks were established with a network pharmacology approach. The analyses of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) profiles were performed based on the common targets between the herbs and neuropathic pain. Hub genes, identified with CytoHubba, were validated by Western blotting analysis. SNI rats developed significant nociceptive behavior as soon as 3 days after nerve injury, which was reversed by consecutive treatment with 300 mg/kg YZF for 7 days. Besides, 50 potential bioactive components in YZF with 1074 targets were identified. Then, 217 putative common genes related to YZF and neuropathic pain were identified for further study. After established a protein-protein interaction network, 12 subnetworks with CytoHubba and 10 predictive hub genes were obtained based on the maximal clique centrality model. Western blotting analysis indicated that SNI rats exhibited increased APP (Amyloid-beta precursor protein), SRC (Proto-oncogene tyrosine-protein kinase Src), and phosphorylation of JNK1 (Mitogen-activated protein kinase 8, JNK) and ERK1/2 (Mitogen-activated protein kinase 3/1). Obviously, continuous administration of YZF robustly reversed such changes. This study revealed that YZF modulates the nociceptive behavior in SNI rats. Moreover, the drug may be useful in the treatment of neuropathic pain through multi-components, multi-targets, and multi-pathways. Nevertheless, more attention should be paid to discriminating the potential ingredients in YZF contributing to its analgesic effects in the treatment of neuropathic pain.