Intervention Effect and Dose-dependent Response of Tanreqing Injection on Airway Mucus Hypersecretion in Lipopolysaccharide-induced Rats

Background: Tanreqing injection, a Chinese herbal formulation comprising Radix Scutellariae, Fructus Forsythiae, Flos Lonicerae, Antelope horn, and Bear bile powder, has been used to treat bronchitis and pneumonia for many years in China. However, its anti-mucus-hypersecretion mechanism has yet not been fully interpreted. We aim to assess the effect and dose-response relationships of Tanreqing injection on lipopolysacchaide (LPS) induced airway mucus hypersecretion in rats. Material and methods: Forty-eight male rats were randomly divided into four groups (12 per group). A rat model of airway mucus hypersecretion was generated with LPS. Tanreqing injection was given by intratracheal instillation, and bronchoalveolar lavage fluid (BALF) from the right lung was collected. BALF total protein was determined by bicinchoninic acid disodium assay (BCA). Muc5ac was measured using enzyme linked immunosorbent assay (ELISA) and immunohistochemistry. The expression of muc5ac mRNA was detected by real-time polyermase chain reaction (RT-PCR). The middle lobe of the right lung was stained with alcian blue-periodic acid sthiff (AB-PAS) and positive staining relative shading area examined. Results: LPS caused airway mucus hypersecretion, The LPS-induced airway mucus hypersecretion increased beginning at 24 hr, and peaked at 96 hr. Tanreqing injection could inhibit airway mucus hypersecretion, and suppress the expression of muc5ac mRNA. Conclusion: Tanreqing injection inhibits airway mucus hypersecretion in a certain dose-dependent trend.