Linggui Zhugantang Treats Chronic Bronchitis in Rats via PLA2-TRPV1/TRPA1 Pathway / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo study the effect and mechanism of Linggui Zhugantang in treating chronic bronchitis （CB） induced by exposure to cigarette smoke combined with tracheal instillation of lipopolysaccharide （LPS）. MethodSixty SPF-grade SD rats were randomly divided into normal， model， dexamethasone （1 mg·kg-1）， and high-， medium-， and low-dose （30.06， 15.03， 7.515 g·kg-1， respectively） Linggui Zhugantang groups by the body weight stratification method， with 10 rats in each group. Each group was administrated with 200 μL LPS （1 g·L-1） by tracheal instillation on days 1 and 14， respectively， while the normal group was administrated with an equal volume of normal saline. Except the normal group， the other groups were exposed to cigarette smoke on days 2-13 and 15-30 （10 cigarettes/time/30 min， twice/day） for the modeling of CB. The rats were administrated with corresponding drugs by gavage for 30 consecutive days from day 2 of modeling， and the mental status， behavior， and body weights of the rats were observed and measured. The wet/dry mass ratio （W/D） of the left lung was measured 30 days after modeling. Hematoxylin-eosin staining was employed to observe the pathological changes in the lung and bronchial tissues. The bronchial mucus secretion and goblet cell proliferation were observed by Alcian blue-periodic acid Schiff （AB-PAS） staining. The levels of mucin 5AC （MUC5AC）， interleukin （IL）-13， IL-6， and tumor necrosis factor （TNF）-α in the serum were determined by enzyme-linked immunosorbent assay. The expression of phospholipase A2 （PLA2）， transient receptor potential vanilloid receptor 1 （TRPV1）， and transient receptor potential ankyrin 1 （TRPA1） in the lung tissue was quantitatively analyzed by immunohistochemistry and Western blot. ResultCompared with the normal group， the model group showcased abnormal mental status and behaviors， bloody secretion in the nose and mouth， the mortality rate of 40%， decreased body weight， severe lung bronchial structure damage， a large number of inflammatory mediators and inflammatory cell infiltration in the tube wall， hyperemia， edema， and fibroplasia， massive proliferation of goblet cells， excessive secretion and accumulation of mucus， stenosis and deformation of the lumen， and aggravation of pulmonary edema （P<0.01）. In addition， the model group had higher levels of MUC5AC， IL-13， IL-6， and TNF-α in the serum and higher expression of PLA2 in the lung tissue than the normal group （P<0.01）. Compared with the model group， the medication groups showed normal mental status and behaviors， reduced mortality rate， stable weight gain， reduced lung and bronchial injuries， decreased goblet cell proliferation and mucus secretion， and alleviated pulmonary edema （P<0.01）. Furthermore， Linggui Zhugantang lowered the levels of MUC5AC， IL-13， IL-6， and TNF-α in the serum and down-regulated the protein levels of PLA2， TRPV1， and TRPA1 in the lung tissue （P<0.01）. ConclusionLinggui Zhugantang can reduce the pulmonary inflammation and airway mucus hypersecretion in the rat model of chronic bronchitis. It may exert the effects of reducing inflammation and resolving phlegm by regulating the PLA2-TRPV1/TRPA1 pathway.