Objective To investigate the protective effects of astragalus preconditioning on the tolerance of ischemia time of mouse small intestine . Methods C57BL/6 mice were randomly divided into 5 groups (n = 7): sham operation group (Sham group),intestinal ischemia reperfusion group (IR group) and astragalus preconditioning group (ASIR group). IR group and ASIR group include 2 sub-groups respectively, specifically, 2 h reperfusion was performed 45 min (ASIR1) and 60 min (ASIR1) after blocking superior mesenteric artery. Intestinal terminal morphology was observed by light microscope after HE coloration . Serum levels of LPS , DAO and intestinal mucosa TNF-α were measured by ELISA. Intestinal Cyto C expression were detected by immunofluorescence. Results Astragalus preconditioning reduces Chiu′s score significantly. Expression of Cyto C was significantly down-regulated in astragalus preconditioning groups, and levels of LPS, DAO and TNF-αsignificantly decreased. The damages in IR2 group is obviously severe than in IR1, but there were no significant differences between this two groups after pretreatment with astragalus. Conclusion Astragalus preconditioning has obvious protective effects to intestinal ischemia reperfusion, and enhances the tolerance to longer time of ischemia.

Objective To evaluate the role of α2A adrenergic receptor (α2AAR) in dexmedetomidine-induced inhibition of TLR4/NF-κB signaling pathway activation during hypoxia-reoxygenation (H/R)caused injury to alveolar type Ⅱ epithelial cells.Methods Type Ⅱ] alveolar epithelial cells of rats RLE6TN cells cultured in vitro were divided into 4 groups (n =6 each) using a random number table method:control group (group C),H/R injury group (group H/R),dexmedetomidine group (group D) and α2A AR small interfering RNA (siRNA) plus dexmedetomidine group (group α2AAR-siRNA+D).H/R was produced by exposing cells to 1％ O2-5％ CO2-94％ N2 for 24 h followed by 4-h reoxygenation.Cells were incubated for 1 h with dexmedetomidine at the final concentration of 1 nmol/L,and then H/R model was established in group D.In group α2AAR-siRNA+D,cells were transfected with 50 nmol/L α2AAR-siRNA,48 h later dexmedetomidine at the final concentration of 1 nmol/L was added,cells were incubated for 1 h,and then H/R model was established.The cell viability was measured using CCK-8 method,cell apoptosis rate was determined by flow cytometry,and the expression of TLR4 and NF-κB was detected by immunofluorescence.Results Compared with group C,the cell viability was significantly decreased,the apoptosis rate was increased,and the expression of TLR4 and NF-κB was up-regulated in group H/R (P＜0.05),and no significant change was found in the parameters mentioned above in group D (P＞0.05).Compared with group H/R,the cell viability was significantly increased,the apoptosis rate was decreased,and the expression of TLR4 and NF-κB was down-regulated in group D (P＜0.05),and no significant change was found in the parameters mentioned above in group α2AAR-siRNA+D (P＞0.05).Compared with group D,the cell viability was significantly decreased,the apoptosis rate was increased,and the expression of TLR4 and NF-κB was up-regulated in group α2AAR-siRNA+D (P＜0.05).Conclusion The mechanism by which dexmedetomidine inhibits TLR4/NF-κB signaling pathway activation may be related to activating α2AAR during H/R-caused injury to alveolar type Ⅱ epithelial cells.