Mechanism of Combined Therapy of Lung and Intestine in Alleviating Pulmonary Edema in Treatment of Acute Lung Injury Based on VIP/cAMP/PKA/AQPs Signaling Pathway / 中国实验方剂学杂志

ABSTRACT

ObjectiveTo explore the mechanism of the combined therapy of lung and intestine （Mahuangtang + Da Chengqitang） in alleviating pulmonary edema in rats with acute lung injury （ALI） induced by lipopolysaccharide （LPS）. MethodWistar rats were randomly divided into blank group， model group， low-， medium-， and high-dose groups with combined therapy of lung and intestine， and positive control group. LPS （10 mg·kg-1） was given （ip） to induce ALI in rats. After modeling， the blank group was given normal saline （25 mL·kg-1）， the combined therapy of lung and intestine treatment groups were given （ig） low- （5 g·kg-1）， medium- （7.5 g·kg-1）， and high-dose （10 g·kg-1） Mahuangtang and Da Chengqitang， and the positive control group was given dexamethasone （5 mg·kg-1）. Medications were administered 0， 8， and 16 h after LPS injection for 3 times. Then lung tissue and serum were collected after administration. The lung tissues were stained with haematoxylin-eosin （HE）， and the pulmonary edema score was evaluated. The dry/wet （D/W） weight ratio of lung tissues in each group was measured， and the content of serum vasoactive intestinal peptide （VIP） in rats was detected by enzyme-linked immunosorbent assay （ELISA）. Western blot was used to detect the protein levels of aquaporin-1 （AQP1）， AQP5， VIP， cyclic adenosine monophosphate （cAMP）， phosphorylated protein kinase A （p-PKA）， and PKA in lung tissues of rats in each group. The level of VIP mRNA in lung tissues of rats was detected by real-time quantitative polymerase chain reaction （Real-time PCR）. ResultCompared with the blank group， the model group exhibited obvious lung injury， increased edema score， decreased D/W ratio （P<0.01）， declined AQP1， AQP5， cAMP， and p-PKA/PKA in lung tissues （P<0.05， P<0.01）， elevated VIP content （P<0.01）， and up-regulated levels of VIP protein and mRNA in lung tissues （P<0.05， P<0.01）. Compared with the model group， combined therapy of lung and intestine treatment groups showed alleviated lung injury， increased D/W ratio （P<0.01）， elevated AQP1， AQP5， VIP， cAMP， and p-PKA/PKA in lung tissues （P<0.05， P<0.01）， and up-regulated VIP levels in lung tissues （P<0.05， P<0.01）. ConclusionThe combined therapy of lung and intestine can alleviate ALI-induced lung tissue edema， and the mechanism may be related to the activation of the VIP/cAMP/PKA signaling pathway， which further promotes the expression of AQP1 and AQP5 and enhances the water metabolism of lung tissue.