关键词: 人参属, 二醇类, 皂苷类, 地塞米松, 抗原, CD14, IκBα, NF-κB

Abstract: Objective To explore the molecular mechanism of protective effects of Panaxadiol Saponins (PDS) on lung tissues of endotoxic shock rats. Methods Wistar rats were randomly divided into control group (CTRG), lipopolysaccharide (LPS) shock group (LPSG), LPS shock+dexamethasone group (DEXG) and LPS shock+PDS group (PDSG), respectively. Endotoxin shock models were duplicated by injection of LPS (4 mg•kg^-1). The histological changes of the lung tissues stained with hematoxylin and eosin (HE) among four groups were compared through microscopic examination. Meanwhile, the expressions of CD14 and IκBα mRNA were measured by semi-quantitative reverse transcriptase polymerase chain reaction (RT-PCR) and the expressions of CD14 and NF-κB proteins were determined by Western blotting assay. Results ①The histological and pathological changes: in LPSG, there was the effusion of a large amount of lymphocytes, mono-macrophages and neutrophils around the alveolar and vascular walls; incrassated alveolar septums and bronchiole walls were caused by hyperemia ,edema and infiltration of pulmonary interstitial;focal atrophia and formation of pneumatocele could be observed; only small amount of alveolus containing air could be found; however, the lung pathologic changes in DEXG and PDSG were significantly slighter than those in LPSG, and they merely showed slight effusion of inflammatory cells, and the content of air in alveolus was near to that in CTRG. ②The expressions of CD14 mRNA and protein in LPSG were significantly higher than those in CTRG（P<0.05）, while those in DEXG and PDSG were close to those in CTRG（P>0.05）, significantly lower than those in LPSG（P<0.05）. The expression of lung IκBα mRNA in LPSG was significantly lower than those in CTRG（P<0.01）, while those in DEXG and PDSG were close to that in CTRG（P>0.05） and higher than that in LPSG（P<0.05 and P<0.01）. The expression of NF-κB P65 protein in LPSG was significantly strengthened than that in CTRG（P<0.05）, while those in PDSG and DEXG were lower than that in LPSG（P<0.05）, close to that in CTRG（P>0.05）. Conclusion LPS activates the signaling pathway mediated by LPS receptors, the decreasing of IκBα mRNA expression and the increasing of CD14 and NF-kB expressions are the molecular mechanism for the lung tissue injuries, while the opposite changes in PDSG reveal the molecular mechanism of their protective effects on cells and tissues; PDS has the same effects with DEX to protect against the lung tissue injuries of endotoxic shock in rats.

Key words: panax, glycols, saponins, dexamethasone, antigens, CD14, IκBα, NF-κB