OBJECTIVETo explore the anti-inflammatory effect and possible mechanism of Xiaochaihu Decoction (XCHD) and the different herbal formulations of its components.

METHODSRat model of pleuritis was established by thoracic injecting 0.2 ml of 1% carrageenan. Rats in the treated groups were medicated with XCHD (11 g/kg) and the different herbal formulations of its components respectively as follows: thorowax root-scutellaria root (A, 3.5 g/kg), fresh ginger-pinellia tuber (B, 3 g/kg), ginseng-licorice root-jujube (C, 4.5 g/kg), A + B (6.5 g/kg), A + C (8 g/kg) and B + C (7.5 g/kg), and those in the normal group and the model group were given equal volume of instilled water, by way of gastrogavage for successive 5 days. Modeling was performed 2 hrs after the last medication. The amount of pleurorrhea, and leucocyte (WBC), marrow peroxidase (MPO), tumor necrosis factor alpha (TNF-alpha) and interleukin-1beta (IL-1beta) in pleurorrhea, and serum level of interleukin-8 (IL-8) were measured 12 hrs after modeling.

RESULTSAs compared with the model group, all the parameters measured were lower in all the treated group (P < 0.05) , and IL-1beta content in pleurorrhea in the XCHD group and Group A, B and C were significantly lower (P < 0.01).

CONCLUSIONXCHD and the different herbal formulations have obvious anti-inflammatory effect, showing certain preventive and therapeutic effect on pleuritis. Among the different formulations, the XCHD, A, B and C had better effects. The effects might be related to inhibiting the increase of cytokines as TNF-alpha, IL-1beta, and IL-8 to suppress the activation, infiltration and wandering of leucocytes.