Résumé
Objective:To evaluate the effect of dexmedetomidine on the expression of DNA methyltransferases in septic mice with acute lung injury.Methods:Forty-eight clean-grade healthy male C57BL/6 mice, aged 6-8 weeks, weighing 20-25 g, were divided into 4 groups ( n=12 each) using a random number table method: sham operation group (group Sham), sham operation + dexmedetomidine group(group Sham+ DEX), sepsis group (group Sepsis) and sepsis + dexmedetomidine group(group Sepsis+ DEX). Sepsis model was established by cecal ligation and puncture(CLP)in anesthetized mice. At 30 min before model preparation, dexmedetomidine 0.05 μg/g (in 0.5 ml of normal saline) was administered in Sham + DEX and Sepsis + DEX groups, and normal saline 0.5 ml was given instead in Sham and Sepsis groups. The mice were sacrificed at 24 h after CLP, and the lung tissue was taken to determine the wet to dry lung weight ratio, contents of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and high mobility group box-1 (HMGB-1), activities of superoxide dismutase (SOD) and myeloperoxidase (MPO), and content of malondialdehyde (MDA) (by enzyme-linked immunosorbent assay), global DNA methylation (by colorimetric assay), and expression of DNA methyltransferases (DNMTl, DNMT3a, DNMT3b) (by Western blot) and to examine the histopathological changes of lung tissues (by HE staining) which were scored. Results:Compared with group Sham, the lung injury score, wet/dry lung weight ratio, contents of IL-6, TNF-α and HMGB1 and MDA, MPO activity and global DNA methylation were significantly increased, SOD activity was decreased, and the expression of DNMT1 and DNMT3a was up-regulated in group Sepsis and group Sepsis+ DEX ( P<0.05), and no significant change was found in the aforementioned indexes in group Sham+ DEX ( P>0.05). Compared with group Sepsis, the lung injury score, wet/dry lung weight ratio, contents of IL-6, TNF-α and HMGB1 and MDA, MPO activity and global DNA methylation were significantly decreased, SOD activity was increased, and the expression of DNMT1 and DNMT3a was down-regulated in group Sepsis+ DEX ( P<0.05). Conclusions:The mechanism by which dexmedetomidine reduces acute lung injury is related to inhibition of up-regulation of DNMT1 and DNMT3a expression in septic mice.
Résumé
Objective:To evaluate the role of DNA methyltransferase in acute lung injury in septic mice.Methods:Forty-eight healthy male C57BL/6 mice, aged 6-8 weeks, weighing 20-25 g, were divided into 4 groups ( n=12 each) using a random number table method: sham operation group (group Sham), sham operation+ DNA methyltransferase inhibitor group (group Sham+ 5-Aza), sepsis group (group Sepsis) and sepsis+ DNA methyltransferase inhibitor group (group Sepsis+ 5-Aza). Sepsis model was developed by cecal ligation and puncture (CLP) in anesthetized mice.Mice were sacrificed at 24 h after CLP, and lung tissues were obtained, DNA was extracted to determine the global DNA methylation by colorimetry, and RNA was extracted to detect the expression of DNA methyltransferase (DNMTl, DNMT3a, DNMT3b) mRNA by real-time fluorescent quantitative polymerase chain reaction, the wet/dry lung weight ratio (W/D ratio) was measured, the histopathological changes of lung tissues were determined by HE staining, the contents of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), high-mobility group box 1 protein (HMGB1) and malondialdehyde (MDA) and activities of superoxide dismutase (SOD) and catalase were measured by enzyme-linked immunosorbent assay. Results:Compared with group Sham, the global DNA methylation was significantly increased, the expression of DNMT1 and DNMT3a mRNA was up-regulated, the lung injury score, W/D ratio, and contents of IL-6, TNF-α, HMGB1 and MDA were increased, and activities of SOD and CAT were decreased at 24 h after CLP in group Sepsis and group Sepsis+ 5-Aza ( P<0.05), and no significant change was found in the indexes mentioned above in group Sham+ 5-Aza ( P>0.05). Compared with group Sepsis, the global DNA methylation was significantly decreased, the expression of DNMT1 and DNMT3a mRNA was down-regulated, the lung injury score, W/D ratio, contents of IL-6, TNF-α, HMGB1 and MDA were decreased, and the activities of SOD and CAT were increased in group Sepsis+ 5-Aza ( P<0.05). Conclusions:DNA hypermethylation mediated by DNMT1 and DNMT3a is involved in the process of acute lung injury in septic mice.
Résumé
Degenerative changes in autonomic nervous system happen in elderly. The cardiac function reduces, the ability of regulating the target organ decreases, and the stability of hemodynamics is not easy to maintain in old people. How to maintain the hemodynamic stability of elderly patients during anesthesia has become the focus of clinical research. Dexmedetomidine, as a new type of 2- alpha adrenergic agonist, has the function of anti-anxiety, sedation, analgesia and anti-sympathy, and which is wildly used in clinic. This article describes the research progress of dexmedetomidine used in elderly patients during anesthesia.