Mechanism of Banxia Houpo Decoction in Treating Gastroesophageal Reflux Disease: An Integrated Approach of Compound Analysis, Network Pharmacology and Empirical Verification.

Objective: To elucidate the mechanism of Banxia Houpo Decoction (BHD) in treating gastroesophageal reflux disease (GERD) by integrating and utilizing the compound analysis, network pharmacology, and empirical verification.

Methods: Ultra-high performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS) was utilized to identify the primary compounds in BHD. Network pharmacology was employed to retrieve target genes. A GERD rat model was developed and 32 SD rats were randomly divided into model, BHD-L (3 g/kg), BHD-H (6 g/kg), and mosapride (0.75 mg/kg) groups using a random number table, 8 rats in each group. Eight rats without the construction of a GERD model were selected as the blank group. Esophageal damage was evaluated through visualization and histopathology evaluation. 5-hydroxytryptamine (5-HT) levels in serum and lower esophageal sphincter (LES) were determined by ELISA. LES contractility was measured with a force transducer, and serotonin transporter (SERT) and 5-HT4R expressions in LES were assessed by RT-PCR, Western blot, and immunofluorescence staining, respectively.

Results: UPLC-HRMS analysis identified 37 absorption peaks and 157 compounds in BHD. Functional enrichment identified SERT as a significant target for LES contractility. Histopathological findings indicated less severe esophageal mucosal damage in the BHD-H group compared with the model group. Although serum 5-HT levels showed no significant difference, 5-HT concentration in LES tissue was notably higher in the BHD-H group (P<0.05). Within the range from 10^-10 to 10^-7 mmol/L, LES contractility in the BHD-H and mosapride groups was significantly increased (P<0.05). Within the range from 3 × 10^-7 to 3 × 10^-6 mmol/L 5-HT, LES contractility in the BHD-H group was increased (P<0.05). No significant difference was detected within the range from 10^-5 to 10^-4 mmol/L 5-HT. Notably, SERT expression in the BHD-H group assessed by RT-PCR, Western blot, and immunofluorescence staining were significantly lower than that in the model group (all P<0.01); while 5-HT4R expression remained unchanged.

Conclusion: BHD may increase LES contractility by inhibiting SERT expression in LES tissue.