Expression Of RβD-2and Effect Of Dexamethasone To RβD-2in Acute Lung Injury Induced By Lipopolysaccharide In Rats

Objective:To investigate the expression of r β D-2and the Influence of low-dose dexamethasone in acute lung injury induced by lipopolysaccharide in rats.Methods:Forty-eight adult healthy SD rats were randomly divided into three groups:normal controls group(group C:C6h, C24h), acute lung injury induced by LPS group (group A:A6h, A24h)and dexamethasone group(group D:D6h, D24h). To form ALI model in rats,5mg/kg of LPS were injected into rats intraperitoneal Immediately lmg/kg of dexamethasone were injected into rats by intraperitoneal to form group D, equal doses of normal saline were injected into rats in group C by intraperitoneal.At6h,24h two time points,8rats from each group were killed.Both left BALF and right lung tissue were obtained to measure wet to dry weight ratio (W/D), the levels of r β D-2and TNF-α in BALF by ELISA, and the histopathologyResults:1r β D-2BALF:There were no significant difference among group C6h, C24h, A6h and D6h,but it increased sharply in group A24h, D24h,and no difference between the two groups (P>0.05);the content of rβD-2had significant difference between A6h and A24h (P <0.05), D6h and D24h(P<0.05).2TNF-α BALF contents:compared with group C,the content of TNF-α was significantly increased in group ALI, and increased with time, the difference was statistically significant (P<0.05);it decreased compared with group ALI,but still higher than the group C,compared with the other two groups were statistically significant (P<0.05).3lung W/D:group C,the difference was not statistically significant at two time points;group ALI was significantly higher compared with group C at each time point,and the difference was significantly (P <0.05);in group D,it decreased significantly compared with group ALI.but still higher than the group C.4Histopathology changes in lung tissue:group ALI with varying degrees of swelling of the lungs appear congestion, scattered severe bleeding; optical microscopy shows diffuse alveolar septal thickening, some alveolar collapse, interstitial diffuse pulmonary hemorrhage, alveolar shows a large number of inflammatory cell infiltration and exudate. Group D,lung congestion and swelling, inflammatory cell infiltration and alveolar exudate, alveolar septal thickening and the degree of alveolar collapse was significantly reduced compared with ALI.Conclusion:r β D-2. is involved in Rat ALI process induced by LPS,and it expresses significantly at24h.Early application of small dose dexamethasone had no effect on the BALF expression of r β D-2in rat model of ALI.