Ethnic medicine Bauhinia brachycarpa Benth regulates microglia-neuron interaction in neuropathic pain via P2X4R-BDNF-TrkB pathway

Background: Neuropathic pain (NP) is a debilitating condition with limited treatment options. The ethanolic extract of Bauhinia brachycarpa Benth (EEBb) has demonstrated antinociceptive effects in NP, but its active components and underlying mechanisms of action remain largely unexplored. Objectives: Bauhinia brachycarpa Benth (BBB), an ethnic medicine in China, has antinociceptive effect on neuropathic pain (NP). In this study, an effective portion from BBB was screened and its antinociceptive mechanism was investigated. Methods: After the preparation of ethanolic extract from BBB (EEBb) and different soluble portion from EEBb (peEEBb, eaEEBb, nbEEBb), the total content of flavonoids and phenolic acids were measured. A partial sciatic nerve ligation (PSNL) model in vivo was applied to evaluate the antinociceptive effect and the influence on microglia function of these samples. The possible acting target of BBB was predicted by network pharmacology. And the mechanism of nbEEBb, the most effective antinociceptive portion, were studied by PSNL model in vivo and ATP-induced activation of BV2 model in vitro. Results: nbEEBb had the strongest ability of alleviating NP as well as the obvious effect on microglia polarization. The action of nbEEBb was positively correlated to the total content of flavonoids or phenolic acids. nbEEBb inhibited the protein and gene expressions of most key components in P2X4-BDNF-TrkB signaling pathway. Conclusion: nbEEBb is the most effective portion from BBB on NP, and its mechanism refers to the inhibition of P2X4-BDNF-TrkB signaling pathway, which involved in neuron-microglia interaction.