Mechanism of action of Shaoyao-Gancao decoction in relieving chronic inflammatory pain via Sema3G protein regulation in the dorsal root ganglion.

ABSTRACT

Objective: The purpose of this study was to analyze the impact of Shaoyao-Gancao decoction (SGD) on proteins with significant changes in the dorsal root ganglion (DRG) in rats and to explore the role of the Semaphorin 3G (Sema3G) protein in the DRG and its downstream factors, interleukin-6 (IL-6) and CC-motif chemokine ligand 2(CCL2), in the treatment of chronic inflammatory pain (CIP). Methods: We created a CIP rat model using 100 µL of complete Freund's adjuvant (CFA) that was injected into the left posterior plantar of rats. Then, we administered SGD intragastrically. We tested the animals for behavioral changes and protein expression levels in DRG pre- and post-drug intervention. Results: Rats in the SGD group showed significantly increased paw withdrawal threshold (PWT), paw withdrawal latency (PWL), and relative expression levels of the Sema3G protein in the DRG (all P < 0.05), while the relative mRNA expression levels of IL-6 and CCL2 in the DRG of the rats were significantly decreased (P < 0.05) when compared with the model group. Conclusion: In this study, we found that Shaoyao-Gancao decoction was effective in improving the PWT and PWL of rats with CIP. It reduced CIP by upregulating the expression of Sema3G in the DRG and inhibiting the relative mRNA expression levels of IL-6 and CCL2.