Dexmedetomidine alleviates H2O2-induced oxidative stress and cell necroptosis through activating of α2-adrenoceptor in H9C2 cells.

Oxidative stress induced necroptosis is important in myocardial ischemia/reperfusion injury. Dexmedetomidine (Dex), an α2-adrenoceptor (α2-AR) agonist, has protective effect on oxidative stress induced cell apoptosis, but effects of Dex and Dex-mediated α2-AR activation on oxidant induced necroptosis was unclear. H9C2 cardiomyocytes were pre-treated with or without Dex and α2-AR antagonist yohimbine hydrochloride (YOH) before being exposed to H2O2 to induce oxidative cellular damage. Cell viability and lactate dehydrogenase (LDH) were detected by ELISA kits, protein expressions of Heme Oxygenase 1(HO-1), receptor interacting protein kinase 1 (RIPK1) and receptor interacting protein kinase 3 (RIPK3) were observed by WB, and TUNEL was used to detected cell apoptosis. H2O2 significantly decreased cell viability and increased LDH release and necroptotic and apoptotic cell deaths (all p < 0.05, H2O2 vs. Control). Dex preconditioning alleviated these injuries induced by H2O2. Dex preconditioning significantly increased expression of protein HO-1 and decreased expressions of proteins RIPK1 and RIPK3 induced by H2O2, while all these protective effects of Dex were reversed by YOH (all p < 0.05, Dex + H2O2 vs. H2O2; and YOH + Dex + H2O2 vs. Dex + H2O2). However, YOH did not prevent this protective effect of Dex against H2O2 induced apoptosis (YOH + Dex + H2O2 vs. Dex + H2O2, p > 0.05). These findings indicated that Dex attenuates H2O2 induced cardiomyocyte necroptotic and apoptotic cell death respectively dependently and independently of α2-AR activation.

[Effects of L. lactis recombinant heme oxygenase-1 gene on the intestinal barrier in rats with hemorrhagic shock].

OBJECTIVE: To evaluate the effect of gavage of L. lactis recombinant heme oxygenase-1 (HO-1) gene on protection of the intestinal mucosa and the inflammation of lower intestine during hemorrhagic shock. METHODS: A model of hemorrhagic shock was reproduced in 30 SD healthy male rats. They were randomly divided into the L. lactis recombinant HO-1 gene group (HO group, n=10), L. lactis group (LL group, n=10), and glutamine group (Glu group, n=10). Glu was gavaged 6 hours and other agents were gavaged 24 hours before the experiment. Samples were collected 1 hour after hemorrhagic shock and fluid resuscitation. The mortality, mean arterial pressure (MAP) during hemorrhagic shock and fluid resuscitation, myeloperoxidase (MPO) activity, the pathological changes, and the contents of HO-1, tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10) of the lower intestine were determined immunohistochemically and compared. RESULTS: When the results of HO group were compared with Glu and LL groups, the mortality was significantly decreased in the former (both P<0.05). In HO group, MAP values at 5, 10, 20 and 30 minutes after fluid resuscitation were significantly elevated (all P<0.05). Compared with LL group, the gray levels of IL-10 and HO-1 in HO group and Glu group were significantly increased (all P<0.05). Compared with Glu group, the gray level of HO-1 was significantly increased in HO group (P<0.05). There were no significant differences in the gray levels of TNF-alpha among three groups. The Chiu's grade of HO group [(1.41+/-0.28) scores] was significantly lower than those of LL group and Glu group [(1.93+/-0.49) scores and (1.75+/-0.58) scores, respectively, both P<0.05]. CONCLUSION: The L. lactis recombinant HO-1 has the virtue to deliver HO-1 activity in rats with hemorrhagic shock, which is beneficial for the maintenance of intestinal barrier and anti-inflammation response of the lower intestine.

Effects of two fluid resuscitations on the bacterial translocation and inflammatory response of small intestine in rats with hemorrhagic shock.

OBJECTIVE: To investigate the effects of two fluid resuscitations on the bacterial translocation and the inflammatory factors of small intestine in rats with hemorrhagic shock. METHODS: Fifty SD healthy male rats were randomly divided into 5 groups (n equal to 10 per group): Group A (Sham group), Group B (Ringer's solution for 1 h), Group C (Ringer's solution for 24 h), Group D (hydroxyethyl starch for 1 h) and Group E ((hydroxyethyl starch for 24 h). A model of rats with hemorrhagic shock was established. The bacterial translocation in liver, content of tumor necrosis factor-alpha (TNF-alpha) and changes of myeloperoxidase enzyme (MPO) activities in small intestine were pathologically investigated after these two fluid resuscitations, respectively. RESULTS: The bacterial translocation and the expression of TNF-alpha in the small intestine were detected at 1 h and 24 h after fluid resuscitation. There were significant increase in the number of translocated bacteria, TNF-alpha and MPO activities in Group C compared with Group B, significant decrease in Group E compared with Group D and in Group B compared with Group D. The number of translocated bacteria and TNF-alpha expression significantly decreased in Group E as compared with Group C. CONCLUSIONS: The bacterial translocation and the expression of TNF-alpha in the small intestine exist 24 h after fluid resuscitation. 6% hydroxyethyl starch can improve the intestinal mucosa barrier function better than the Ringer's solution.