Effect of dexmedetomidine pretreatment on lung injury following intestinal ischemia-reperfusion

Attenuation of intestinal ischemia-reperfusion-injury by anesthetics: a potentially protective effect of anesthetic management in experimental studies

Intestinal ischemia-reperfusion injury (IRI) is a potentially severe clinical syndrome after major surgical procedures. In addition to causing intestinal mucosa injury, intestinal IRI further damages distant organs, causing the severity of the condition in patients. So far, effective therapy for intestinal IRI is still absent, and the survival rate of the patients is low. Previous experimental studies have shown that some anesthetics can alleviate intestinal IRI and protect organs while exerting their pharmacological effects, indicating that reasonable perioperative anesthesia management may provide potential benefits for patients to avoid intestinal IRI. These meaningful findings drive scholars to investigate the mechanism of anesthetics in treating intestinal IRI in-depth to discuss the possible new clinical uses. In the present mini-review, we will introduce the protective effects of different anesthetics in intestinal IRI to help us enrich our knowledge in this area.

Umbilical cord blood exosomes from very preterm infants with bronchopulmonary dysplasia aggravate lung injury in mice

Bronchopulmonary dysplasia (BPD) is characterized by abnormal development of the blood vessels and alveoli in lungs, which largely occurs in premature infants. Exosomes (EXO) from very preterm infants (VPI) with BPD (BPD-EXO) impair angiogenic activities of human umbilical vein endothelial cells (HUVECs) via EXO-miRNAs cargo. This study aimed to determine whether and how BPD-EXO affect the development of BPD in a mouse model. We showed that treating BPD mice with BPD-EXO chronically and irreversibly aggravated lung injury. BPD-EXO up-regulated 139 and down-regulated 735 genes in the mouse lung tissue. These differentially expressed genes were enriched to the MAPK pathway (e.g., Fgf9 and Cacna2d3), which is critical to angiogenesis and vascular remodeling. BPD-EXO suppressed expression of Fgf9 and Cacna2d3 in HUVECs and inhibited migration, tube formation, and increased cell apoptosis in HUVECs. These data demonstrate that BPD-EXO aggravate lung injury in BPD mice and impair lung angiogenesis, plausibly leading to adverse outcomes of VPI with BPD. These data also suggest that BPD-EXO could serve as promising targets for predicting and treating BPD.

Dexmedetomidine improves acute lung injury by activating autophagy in a rat hemorrhagic shock and resuscitation model

Dexmedetomidine (DEX) can reduce lung injury in a hemorrhagic shock (HS) resuscitation (HSR) model in rats by inhibiting inflammation. Here, we aimed to investigate if these effects of DEX are due to autophagy activation. Therefore, we established HSR rat models and divided them into four groups. HS was induced using a blood draw. The rats were then resuscitated by reinjecting the drawn blood and saline. The rats were sacrificed 24 h after resuscitation. Lung tissues were harvested for histopathological examination, determination of wet/dry lung weight ratio, and detection of the levels of autophagy-related marker proteins LC3, P62, Beclin-1, and the ATG12-ATG5 conjugate. The morphological findings of hematoxylin and eosin staining in lung tissues and the pulmonary wet/dry weight ratio showed that lung injury improved in HSR + DEX rats. However, chloroquine (CQ), an autophagy inhibitor, abolished this effect. Detecting the concentration of autophagy-related proteins showed that DEX administration increased LC3, ATG12-ATG5, and Beclin-1 expression and decreased P62 expression. The expression levels of these proteins were similar to those in the HSR group after CQ + DEX administration. In summary, DEX induced autophagic activation in an HSR model. These findings suggest that DEX administration partially ameliorates HSR-induced lung injury via autophagic activation.

Use of dexmedetomidine to alleviate intestinal ischemia-reperfusion injury via intestinal microbiota modulation in mice

Background

Intestinal ischemia-reperfusion (I/R) injury is a serious condition with unacceptable mortality rates. Our previous study revealed a protective effect of dexmedetomidine (DEX) on intestinal I/R injury, but its underlying mechanism remains unclear. Gut microbiota imbalance is associated with the progression of I/R injury. We hypothesized that DEX would attenuate intestinal I/R injury via modulating gut microbiota.

Methods

An I/R injury model was established in C57BL/6 mice in the presence or absence of DEX preconditioning. Some mice were treated with antibiotics to deplete intestinal bacteria. Fecal microbiota transplantation (FMT) was performed by transplanting the feces of DEX-pretreated mice into a new batch of I/R mice. We analyzed the expression of Bacteroidetes and Firmicutes in feces, survival rate, and inflammatory cytokines.

Results

DEX reversed I/R-induced bacterial abnormalities by increasing the ratio of Firmicutes to Bacteroidetes [DEX + I/R 3.02±0.36 vs. normal saline (NS) + I/R 0.82±0.15; 95% CI: 0.80-3.60; P<0.05] and was accompanied by increased 72-hour survival (0.40±0.16 vs. 0.10±0.09; P<0.05). The protective effect of DEX did not significantly differ from that of DEX + antibiotics. Furthermore, the bacteria of the DEX-pretreated mice decreased the release of inflammatory factors.

Conclusions

This study revealed that DEX can alleviate intestinal I/R injury through a microbiota-related mechanism, providing a potential avenue for the management of intestinal I/R injury.

The Mechanism of Chaiyin Particles in the Treatment of COVID-19 Based on Network Pharmacology and Experimental Verification

Objective: To explore the potential active components of Chaiyin particles (CYPs) in the treatment of coronavirus disease 2019 (COVID-19) and their mechanism of action using network pharmacology and molecular docking technology. Methods: Based on the components of CYPs, we obtained potential targets of the interaction between CYPs and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The potential targets were analyzed by protein–protein interaction, gene ontology, and Kyoto Encyclopedia of Genes and Genomes pathway analyses. The key active components of CYPs were subjected to molecular docking with 3-chymotrypsin-like protease, angiotensin-converting enzyme II (ACE2), RNA-dependent RNA polymerase, and papain-like protease. The components that may bind to the key target proteins of SARS-CoV-2 were screened to obtain the potential active components, targets and pathways for CYP treatment of COVID-19. The above-described network analysis results were then verified experimentally. Results: CYPs may prevent and treat COVID-19 by inhibiting the release of inflammatory factors such as IL-6 and TNF-α; participating in the AGE-Rage signaling pathway, the HIF-1 signaling pathway, and other anti-inflammatory, antiviral, and immune regulatory signaling pathways; and blocking ACE2 via fortunellin and baicalin. Conclusion: This work illustrated that CYPs mainly play an anti-inflammatory and immunomodulatory role in COVID-19 prevention and treatment. The potential active components and molecular mechanism of CYPs can provide theoretical support and a pharmacological basis for further development and utilization of CYPs in the prevention and treatment of COVID-19. These results provide important insights into future studies of Traditional Chinese medicines (TCMs) modernization and prevention.

ONE-LUNG VENTILATION PATIENTS: CLINICAL CONTEXT OF ADMINISTRATION OF DIFFERENT DOSES OF DEXMEDETOMIDINE

Background

Open and endoscopic thoracic surgeries improve surgical exposure by One-lung ventilation (OLV). The aim of this study was to investigate the effects of different doses of dexmedetomidine on inflammatory response, oxidative stress, cerebral tissue oxygen saturation (SctO2) and intrapulmonary shunt in patients undergoing one-lung ventilation (OLV).

Methods

Seventy-five patients undergoing open pulmonary lobectomy in our hospital from January 2016 to December 2017 were enrolled and randomly divided into high-dose dexmedetomidine group (group D1, 1 mg/kg, n=25), low-dose dexmedetomidine group (group D2, 0.5 mg/kg, n=25) and control group (group C, n=25). Then, arterial blood and internal jugular venous blood were taken before anesthesia induction (T0) and at 15 min after twolung ventilation (T1) and 5 min (T2) and 30 min (T3) after OLV for later use. Next, the changes in hemodynamic parameters [mean arterial pressure (MAP), heart rate (HR) and pulse oxygen saturation (SpO2)] of patients were observed in each group. Enzyme-linked immunosorbent assay (ELISA) was carried out to detect serum inflammatory factors such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) and oxidative stress indicators [superoxide dismutase (SOD) and malondialdehyde (MDA)]. The changes in SctO2, arterial partial pressure of oxygen (PaO2) and intrapulmonary shunt Qs/Qt (a measurement of pulmonary shunt: right-to-left shunt fraction) were observed. Additionally, the changes in lung function indicators like lung dynamic compliance (Cdyn) and airway peak pressure (P_peak) were determined.

Results

There were no statistically significant differences in the MAP, HR and SpO2 among three groups at each observation time point (P>0.05). At T2 and T3, the levels of serum IL-6, TNF-α and IL-8 were obviously decreased in group D1 and D2 compared with those in group C (P<0.05), and the decreases in group D1 were overtly larger than those in group D2, and the decreases at T3 were markedly greater than those at T2 (P<0.05). In comparison with group C, group D1 and D2 had notably reduced levels of serum reactive oxygen species (ROS) and MDA (P<0.05) and remarkably increased SOD content (P<0.05) at T2 and T3, and the effects were markedly better in group D1 than those in group D2. Besides, they were significantly superior at T3 to those at T2 (P<0.05). The SctO2 in group D1 and D2 was evidently lowered at T2 and T3 compared with that at T0, and the decrease in group D1 was distinctly smaller than that in group D2 (P<0.05). The Qs/Qt was significantly lower in group D1 and D2 than that in group C at T2 and T3 (P<0.05), while the PaO2 content was notably raised (P<0.05), and the decrease and increase were significantly larger in group D1 than those in group D2, and they were obviously greater at T3 to those at T2 (P<0.05). At T0 and T1, no significant differences were detected in the Cdyn, Pplat and Ppeak among three groups. At T2 and T3, the Cdyn was significantly elevated, while the Pplat and Ppeak overtly declined (P<0.05), and group D1 had greater changes in comparison with group D2, and the changes were obviously more evident at T3 to those at T2 (P<0.05).

Conclusions

Dexmedetomidine effectively ameliorates inflammatory response and oxidative stress, lowers oxygenation, Qs/Qt and the decrease in SctO2 and improves lung function during OLV, with good efficacy.

Therapeutic potential of indole alkaloids in respiratory diseases: A comprehensive review

BACKGROUND

Indole alkaloids are very promising for potential therapeutic purposes and appear to be particularly effective against respiratory diseases. Several experimental studies have been performed, both in vivo and in vitro, to evaluate the effectiveness of indole alkaloids for the management of respiratory disorders, including asthma, emphysema, tuberculosis, cancer, and pulmonary fibrosis.

PURPOSE

The fundamental objective of this review was to summarize the in-depth therapeutic potential of indole alkaloids against various respiratory disorders.

STUDY DESIGN

In addition to describing the therapeutic potential, this review also evaluates the toxicity of these alkaloids, which have been utilized for therapeutic benefits but have demonstrated toxic consequences. Some indole alkaloids, including scholaricine, 19-epischolaricine, vallesamine, and picrinine, which are derived from the plant Alstonia scholaris, have shown toxic effects in non-rodent models.

METHODS

This review also discusses clinical studies exploring the therapeutic efficacy of indole alkaloids, which have confirmed the promising benefits observed in vivo and in vitro.

RESULTS

The indole alkaloidal compounds have shown efficacy in subjects with respiratory diseases.

CONCLUSION

The available data established both preclinical and clinical studies confirm the potential of indole alkaloids to treat the respiratory disorders.

Mesna ameliorates acute lung injury induced by intestinal ischemia-reperfusion in rats

The lung is severely affected by intestinal ischemia-reperfusion (I-R) injury. Mesna, a thiol compound, possess anti-inflammatory and antioxidant properties. We aimed in the present work to explore the potential beneficial effects of Mesna on the acute lung damage mediated by intestinal I-R in a rat model. Forty male adult albino rats were randomly separated into; control, intestinal I-R, Mesna I and Mesna II groups. Mesna was administered by intraperitoneal injection at a dose of 100 mg/kg, 60 min before ischemia (Mesna I) and after reperfusion (Mesna II). Arterial blood gases and total proteins in bronchoalveolar lavage (BAL) were measured. Lung tissue homogenates were utilized for biochemical assays of proinflammatory cytokines and oxidative stress markers. Lung specimens were managed for examination by light and electron microscopy. Our results revealed that Mesna attenuated the histopathological changes and apoptosis of the lung following intestinal I-R. Mesna also recovered systemic oxygenation. Mesna suppressed neutrophil infiltration (as endorsed by the reduction in MPO level), reduced ICAM-1 mRNA expression, inhibited NF-κB pathway and reduced the proinflammatory cytokines (TNF-α, IL-1β and IL-6) in the lung tissues. Mesna maintained the antioxidant profile as evidenced by the elevation of the tissue GPx and SOD and down-regulation of HSP70 immune-expressions. Accordingly, Mesna treatment can be a promising way to counteract remote injury of the lung resulted from intestinal I-R.

Pulmonary effects of dexmedetomidine infusion in thoracic aortic surgery under hypothermic circulatory arrest: a randomized placebo-controlled trial

Dexmedetomidine has emerged as a promising organ protective agent. We performed prospective randomized placebo-controlled trial investigating effects of perioperative dexmedetomidine infusion on pulmonary function following thoracic aortic surgery with cardiopulmonary bypass and moderate hypothermic circulatory arrest. Fifty-two patients were randomized to two groups: the dexmedetomidine group received 1 µg/kg of dexmedetomidine over 20 min after induction of anesthesia, followed by 0.5 µg/kg/h infusion until 12 h after aortic cross clamp (ACC)-off, while the control group received the same volume of normal saline. The primary endpoints were oxygenation indices including arterial O2 partial pressure (PaO2) to alveolar O2 partial pressure ratio (a/A ratio), (A-a) O2 gradient, PaO2/FiO2 and lung mechanics including peak inspiratory and plateau pressures and compliances, which were assessed after anesthesia induction, 1 h, 6 h, 12 h, and 24 h after ACC-off. The secondary endpoints were serum biomarkers including interleukin-6, tumor necrosis factor-α, superoxide dismutase, and malondialdehyde (MDA). As a result, dexmedetomidine did not confer protective effects on the lungs, but inhibited elevation of serum MDA level, indicative of anti-oxidative stress property, and improved urine output and lower requirements of vasopressors.

Dexmedetomidine Resists Intestinal Ischemia-Reperfusion Injury by Inhibiting TLR4/MyD88/NF-κB Signaling

BACKGROUND

Intestinal ischemia/reperfusion (I/R) is a common clinical problem that occurs during various clinical pathological processes. Dexmedetomidine (DEX), a widely used anesthetic adjuvant agent, can induce protection against intestinal I/R in vivo; however, the underlying mechanism is not fully understood. In the present study, we aimed to investigate the protective effects of DEX and examine whether its mechanism was associated with the TLR4/MyD88/NF-κB signaling pathway.

METHODS

Sprague-Dawley rats were pretreated with DEX and then subjected to I/R-induced intestinal injury. In vivo, intestinal histopathological examination and scoring were performed, the levels of serum intestinal fatty acid-binding protein (I-FABP), intestinal tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and expression levels of TLR4, MyD88, and NF-κB in the intestine were determined. In in vitro experiments, the human colon carcinoma cell line (Caco-2) was incubated with DEX before deprivation/reoxygenation (OGD/R) treatment. The cell viability of Caco-2 cells, the levels of lactate dehydrogenase (LDH), TNF-α, and IL-1β in the supernatant, as well as protein expression of TLR4, MyD88, and NF-κB in Caco-2 cells, were measured. Statistical analysis was performed using SPSS version 21.0.

RESULTS

DEX preconditioning significantly reduced the intestinal pathological Chiu's score, serum I-FABP, intestinal TNF-α, IL-1β levels, and the protein expression of TLR4, MyD88, and NF-κB in the rats with intestinal I/R injury. Similarly, in vitro, DEX pretreatment protected against OGD/R-induced Caco-2 cell damage and inhibited TLR4/MyD88/NF-κB signaling, as evidenced by increased cell viability, decreased LDH activity, reduced TNF-α and IL-1β levels, as well as downregulated TLR4, MyD88, and NF-κB protein levels.

CONCLUSIONS

Our findings suggested that DEX could reduce intestinal I/R injury in rats and OGD/R damage in Caco-2 cells, and this protection might be attributed to antiinflammatory effects and inhibition of the TLR4/MyD88/NF-κB signaling pathway.

Antioxidant effects of dexmedetomidine against hydrogen peroxide-induced DNA damage in vitro by alkaline Comet assay

Background/aim

Dexmedetomidine (DEX) is an alpha-2 adrenergic agonist that is commonly used as a sedative and anesthetic. The protective effects of DEX against oxidative damage under both in vitro and in vivo conditions have been demonstrated. It was aimed to evaluate and compare the protective effects of DEX and vitamin C (Vit C) on DNA against H₂O₂-induced DNA damage in human lymphocyte cell cultures in vitro by alkaline Comet assay.

Materials and methods

Lymphocyte cell cultures were divided into 5 groups, as the negative control, solvent control, positive control, hydrogen peroxide (H₂O₂; 150 μM) + DEX (1 μM; 2.5 μM; 5 μM), and H₂O₂ (150 μM) + Vit C (1 μM; 2.5 μM; 5 μM), and incubated at 37 °C for 1 h. Cell viability was measured using the Trypan blue test. DNA damage was measured using the Alkali Comet Technique and the % percent tail intensity was evaluated. Statistical analysis was performed using 1-way ANOVA and the Tukey multiple comparison test.

Results

It was observed that H₂O₂ significantly induced DNA damage in the lymphocytes and this damage was decreased significantly with Vit C and DEX. It was observed that Vit C at doses of 1 μM and 2.5 μM had a significantly stronger antioxidant effect, but there was no significant difference between the antioxidant effects of Vit C and DEX with a dose of 5 μM. The dose of 5 μM DEX was found to be the most effective in reducing oxidative DNA damage.

Conclusion

There is limited data on the protective effects of DEX against oxidative DNA damage. The primary effect might be cytoprotection. The results herein showed that DEX was protective against H₂O₂-induced in vitro oxidative DNA damage in lymphocyte cell cultures in a dose-dependent manner. DEX might have a potential therapeutic value in the prevention of oxidative DNA damage in patients.

Electroacupuncture Pretreatment Attenuates Intestinal Injury after Autogenous Orthotopic Liver Transplantation in Rats via the JAK/STAT Pathway

Background

Liver transplantation induces self-injury and affects remote organs, such as the lung, kidney, and intestine. Postoperative intestinal dysfunction has been associated with prolonged hospitalization and affects a patient's health and quality of life. Electroacupuncture (EA) has been proven effective in multiple organ protection. However, the potential mechanism underlying the protective effects of EA on intestinal injury after liver transplantation remains unclear.

Methods

After establishing an autogenous orthotopic liver transplantation (AOLT) model, we studied the effects of EA pretreatment on intestinal injury after AOLT. We used the JAK2-specific inhibitor AG490 to explore the underlying mechanism. Histological analysis and apoptosis assays were used to evaluate intestinal injury. Oxidative stress index and inflammatory response were also measured after AOLT. Furthermore, we detected the phosphorylation levels of JAK2, STAT1, and STAT3 by Western blot.

Results

We found that pretreatment with EA alleviated intestinal injury after AOLT, as shown by HE staining and TUNEL methods. EA pretreatment inhibited the expressions of p-JAK2, p-STAT1, and p-STAT3 in the intestines after AOLT. Upon treatment with JAK2-specific inhibitor AG490, intestinal injury was balanced.

Conclusion

The data indicated EA pretreatment alleviated intestinal injury after AOLT by inhibiting the JAK/STAT signaling pathway. These results provide basic evidence to support the potential therapeutic efficacy of EA.

The Effects of Dexmedetomidine and Ketamine on Oxidative Injuries and Histological Changes Following Blunt Chest Trauma

BACKGROUND

The objective of this research was to evaluate the oxidative and histopathological effects of dexmedetomidine and ketamine on the pulmonary contusion model resulting from blunt chest trauma.

METHODS

Rats were randomly assigned to 5 equal groups (n=6): control group (Group C), pulmonary contusion group (Group PC), PC-dexmedetomidine group (Group PC-D), PC-ketamine group (Group PC-K), and PC-dexmedetomidine + ketamine (Group PC-D+K). The PC was performed by dropping a weight of 500 g (2.45 Joules) from a height of 50 cm. In Group PC-D, after chest trauma, dexmedetomidine (100 µg/kg) was administered intraperitoneally. In Group PC-K, after chest trauma, ketamine (100 mg/kg) was administered intraperitoneally. In Group PC-D+K, dexmedetomidine and ketamine were administered together. At the end of the 6th hour, rats were sacrificed. Malondialdehyde (MDA) level, superoxide dismutase (SOD) enzyme activities, neutrophil infiltration/aggregation, and thickness of the alveolar wall were evaluated.

RESULTS

MDA levels were significantly higher in Group PC than Groups C, PC-D, and PC-D+K. SOD enzyme activity was significantly higher in Group PC than Groups C, PC-D, and PC-D+K. In addition, neutrophil infiltration/aggregation and total pulmonary injury scores were significantly higher in Group PC than in other groups, and the thickness of the alveolar wall was significantly higher in Group PC compared to Groups C, PC-D, and PC-D+K. MDA level, SOD enzyme activities, neutrophil infiltration/aggregation, and thickness of alveolar wall were similar in PC-D and PC-D+K groups.

CONCLUSION

Dexmedetomidine and dexmedetomidine+ketamine have protective effects on blunt chest trauma but no protective effect was observed when ketamine was administered alone. We concluded that the administration of dexmedetomidine and ketamine after contusion is beneficial against pulmonary injury in rats.

Dexmedetomidine Ameliorates Lung Injury Induced by Intestinal Ischemia/Reperfusion by Upregulating Cannabinoid Receptor 2, Followed by the Activation of the Phosphatidylinositol 3-Kinase/Akt Pathway

Intestinal ischemia/reperfusion (I/R) is a clinical emergency, which often causes lung injury with high morbidity and mortality. Although dexmedetomidine has been identified to have a protective effect on lung injury caused by intestinal I/R, its specific mechanism is still elucidated. In recent years, the cannabinoid (CB₂) receptor pathway has been found to be involved in I/R injury of some organs. In the current study, we investigated whether the CB₂ receptor pathway contributes to the protective effect of dexmedetomidine on the intestinal I/R-induced lung injury in rats. Dexmedetomidine treatment upregulated the expression of CB₂ receptor and suppressed the I/R-induced increases in lung injury scores, inflammatory cell infiltration, lung wet/dry ratio, MPO activity, MDA level, inflammatory cytokines, and caspase-3 expression while augmenting SOD activity and Bcl-2 expression, indicating attenuation of lung injury. Dexmedetomidine treatment also increased the expression of Akt. The protective effects of dexmedetomidine treatment were reversed by the CB₂ receptor antagonist AM630 or the PI3K inhibitor wortmannin. And the CB₂ receptor antagonist AM630 also downregulated the expression of Akt. Thus, our findings suggest that treatment with dexmedetomidine provides a protective role against lung injury caused by intestinal I/R in rats, possibly due to the upregulation of the CB₂ receptor, followed by the activation of the PI3K/Akt pathway.

The effect of dexmedetomidine and clonidine on the inflammatory response in critical illness: a systematic review of animal and human studies

Background

The α2 agonists, dexmedetomidine and clonidine, are used as sedative drugs during critical illness. These drugs may have anti-inflammatory effects, which might be relevant to critical illness, but a systematic review of published literature has not been published. We reviewed animal and human studies relevant to critical illness to summarise the evidence for an anti-inflammatory effect from α2 agonists.

Methods

We searched PubMed, the Cochrane library, and Medline. Animal and human studies published in English were included. Broad search terms were used: dexmedetomidine or clonidine, sepsis, and inflammation. Reference lists were screened for additional publications. Titles and abstracts were screened independently by two reviewers and full-text articles obtained for potentially eligible studies. Data extraction used a bespoke template given study diversity, and quality assessment was qualitative.

Results

Study diversity meant meta-analysis was not feasible so descriptive synthesis was undertaken. We identified 30 animal studies (caecal ligation/puncture (9), lipopolysaccharide (14), acute lung injury (5), and ischaemia-reperfusion syndrome (5)), and 9 human studies. Most animal (26 dexmedetomidine, 4 clonidine) and all human studies used dexmedetomidine. In animal studies, α2 agonists reduced serum and/or tissue TNFα (20 studies), IL-6 (17 studies), IL-1β (7 studies), NFκB (6 studies), TLR4 (6 studies), and a range of other mediators. Timing and doses varied widely, but in many cases were not directly relevant to human sedation use. In human studies, dexmedetomidine reduced CRP (4 studies), TNFα (5 studies), IL-6 (6 studies), IL-1β (3 studies), and altered several other mediators. Most studies were small and low quality. No studies related effects to clinical outcomes.

Conclusion

Evidence supports potential anti-inflammatory effects from α2 agonists, but the relevance to clinically important outcomes is uncertain. Further work should explore whether dose relationships with inflammation and clinical outcomes are present which might be separate from sedation-mediated effects.

Effects of dexmedetomidine on cerebral oxygen saturation and postoperative cognitive function in elderly patients undergoing minimally invasive coronary artery bypass surgery

OBJECTIVE

This study aimed to investigate the effects of dexmedetomidine on cerebral oxygen saturation [Sct(O2)] and postoperative cognitive function in elderly patients undergoing minimally invasive coronary artery bypass graft surgery.

METHODS

Sixty elderly patients who received minimally invasive coronary artery bypass graft surgery were randomly equally divided into dexmedetomidine group (group D) and control group (group N). The patients in group D were pumped with 1 μg/kg dexmedetomidine for 15 min before incision, followed by continuous pumping at 0.3-0.5 μg/(kg·h) till the end of the operation. The patients in group N received same dose of normal saline during the operation. Sct(O2) was monitored at pre-induction (T0), post-induction (T1), 30 min (T2) after single-lung ventilation, and after surgery (T3). Mini-mental state examination (MMSE) was used to assess the cognitive function at 1 day before, 72 hour and 7 days after surgery.

RESULTS

Sct(O2) level in group D was significantly higher than that in group N at T2 (P < 0.05). Sct(O2) level was statistically lower at T2 than that at T0, T1 and T3 in the same group N (P < 0.05). At 72 h and 7d after operation, the incidence of cognitive dysfunction in group D was markedly lower than that in group N (P < 0.05), the MMSE score in group D was markedly higher than those in group N, but was significantly lower than that before surgery (P < 0.05).

CONCLUSION

Dexmedetomidine can alleviate the decrease of Sct(O2) during single-lung ventilation, improve postoperative cognitive function, and reduce the incidence of POCD in elderly patients with minimally invasive coronary artery bypass surgery.

Protective effect of dexmedetomidine against organ dysfunction in a two-hit model of hemorrhage/resuscitation and endotoxemia in rats

Dexmedetomidine (DEX), a selective agonist of α₂-adrenergic receptors, has anti-inflammation properties and potential beneficial effects against trauma, shock, or infection. Therefore, this study aimed to investigate whether DEX might protect against multiple-organ dysfunction in a two-hit model of hemorrhage/resuscitation (HS) and subsequent endotoxemia. Eighty Wistar rats were randomized into four groups: NS (normal saline), HS/L (HS plus lipopolysaccharide), HS/L+D (HS/L plus dexmedetomidine), and HS/L+D+Y (HS/L+D plus yohimbine). Six hours after resuscitation, blood gas (PaO₂) and serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urine nitrogen (BUN), creatinine (Cr), TNF-α, IL-β, IL-6, IL-8, IL-10, and nitric oxide (NO) were measured. The histopathology was assayed by staining. Malondialdehyde (MDA) and superoxide dismutase (SOD) levels and heme oxygenase-1 (HO-1) were assayed. The PaO₂ levels in HS/L rats were lower whereas the ALT, AST, BUN, Cr, TNF-α, IL-β, IL-6, IL-8, IL-10, and NO levels were higher compared to the control group. The HS/L+D increased PaO₂ and further increased IL-10 and decreased ALT, AST, BUN, Cr, TNF-α, IL-β, IL-6, IL-8, and NO levels of the HS/L groups. In addition, the MDA in the HS/L groups increased whereas SOD activity decreased compared to the control group. Moreover, the HO-1 expression levels were increased by DEX administration in lung, liver, and kidney tissues. Lungs, livers, and kidneys of the HS/L group displayed significant damage, but such damage was attenuated in the HS/L+D group. All of the above-mentioned effects of DEX were partly reversed by yohimbine. DEX reduced multiple organ injury caused by HS/L in rats, which may be mediated, at least in part, by α₂-adrenergic receptors.

miR‑223‑3p/TIAL1 interaction is involved in the mechanisms associated with the neuroprotective effects of dexmedetomidine on hippocampal neuronal cells in vitro

Dexmedetomidine (DEX), an α2 adrenoceptor agonist, is a commonly used anesthetic drug in surgical procedures. Previous studies have indicated that DEX exerts neuroprotective effects. However, the molecular mechanism underlying this process remains to be elucidated. The present study investigated a potential implication of microRNA (miR)-223-3p in the DEX-induced anti-oxidative effect on neuronal cells. The results indicated that following hydrogen peroxide (H₂O₂)-mediated induction of oxidative stress, the viability of human hippocampal neuronal cells was markedly decreased, as determined by an MTT assay. In addition, treatment with H₂O₂ induced cell apoptosis, the release of lactate dehydrogenase, accumulation of intracellular calcium, phosphorylation of calmodulin-2, and production of malondialdehyde and reactive oxygen species. Furthermore, treatment with H₂O₂ inhibited the expression of mir-223-3p and enhanced the expression of its target cytotoxic granule associated RNA binding protein like 1 (TIAL1), and these effects were reversed by treatment with DEX. Mechanistic studies demonstrated that the 3′-untranslated region of TIAL1 is a direct target of mir-223-3p. The results of the present study demonstrated that DEX may induce its neuroprotective effects by regulating the interaction between miR-223-3p and TIAL1. Therefore, the manipulation of miR-223-3p/TIAL1 interaction may be involved in the neuroprotective effects of DEX.

Protective effects of dexmedetomidine on lung in rats with one-lung ventilation

Protective effect of dexmedetomidine (DEX) on the lungs of one-lung ventilation (OLV) rat model and its effect on inflammatory factors were investigated. Ninety-two rats were selected and divided into groups A, B, C and D (n=23) according to the principle of similar body weight. OLV rat model was established. Before modeling (15 min), rats in group C were injected with sodium chloride. Rats in group D were injected with DEX at a speed of 5 µg/kg/h. Group A rats were ventilated in both lungs for 2 h. Rats in groups B and C (0.9% sodium chloride injection + OLV) and in group D (DEX + OLV) were subjected to OLV for 2 h and bilateral ventilation for 10 min. Concentrations of interleukin (IL)-6, IL-10 and tumor necrosis factor-α (TNF-α) in lung tissue of rats were detected by ELISA. The malondialdehyde (MDA) concentration and superoxide dismutase (SOD) activity in rat lung tissue were detected by radioimmunoassay. Wet weight (W)/dry weight (D) of lung tissue was calculated and indexes of the four groups of rats were compared. Compared with group A, IL-6, TNF-α and MDA concentrations and W/D of lung tissue of rats in groups B, C and D were significantly increased (p<0.05); SOD activity and IL-10 concentration were significantly decreased (p<0.01). Compared with groups B and C, the concentrations of IL-6, TNF-α and W/D in rats of group D were significantly decreased (p<0.01), but IL-10 significantly increased (p<0.01). Compared with groups B and C, the MDA concentration in lung tissue of rats in group D was significantly decreased (p<0.01), but SOD activity significantly increased (p<0.01). DEX can inhibit the production of inflammatory factors in the development and progression of pulmonary inflammation. It can inhibit lipid peroxidation, relieve pulmonary edema, and reduce lung injury after OLV, sin order to protect the lung.

Protective Role of Dexmedetomidine on Ileum and Kidney Damage Caused by Mesenchymal Ischaemia in Rats

Objective

The aim of this study was to demonstrate ischaemia reperfusion (IR) injury on the ileum and kidney tissue in rats and to evaluate the effect of dexmedetomidine administered at different doses and dosing schedules on recovery.

Methods

A total of 30 rats were randomly divided into five groups. Group I: sham; Group II: control; Group III: dexmedetomidine before ischaemia; Group IV: dexmedetomidine after ischaemia; and Group V: dexmedetomidine before and after ischaemia. The malondialdehyde (MDA) and signal peptide-CUB-EGF (epidermal growth factor) domain-containing protein 1 (SCUBE-1) levels of all subjects were studied from the serum, ileum, and kidney tissues. Moreover, the histopathology of ileum and kidney tissues was examined.

Results

The SCUBE-1 levels were found to be highly similar to the MDA levels in ischaemic groups. The serum SCUBE-1 levels obtained were significantly lower in Group V compared to Groups II, III and IV (p<0.001, p=0.003, p=0.013, respectively). The apoptosis indexes were found to be lower in groups receiving dexmedetomidine compared to Group II. The groups receiving dexmedetomidine were detected to have normal morphological appearance when compared to Group II.

Conclusion

In this study, the use of dexmedetomidine in the preoperative and peroperative periods may be beneficial in reducing the negative effects of IR injury.

Protective Effect of Dexmedetomidine on Endotoxin-Induced Acute Lung Injury in Rats

BACKGROUND The purpose of this study was to investigate whether DEX exerts protective mechanisms in rats with acute lung injury (ALI) induced by the endotoxin lipopolysaccharide (LPS). The mortality rate of ALI is extremely high. DEX, an a2 adrenergic receptor agonist, has potent anti-inflammatory and organ-protective effects in addition to its sedative and analgesic properties. We sought to elucidate whether DEX can attenuate acute lung injury. MATERIAL AND METHODS Forty-eight Wister rats were randomly divided into 4 groups (n=12, per group): the normal saline control (NS) group, receiving tail-vein injection of 0.9% normal saline (5 mL/kg); the LPS (L) group, receiving tail-vein injection of LPS (8 mg/kg); the LPS+DEX (L+D) group, receiving tail-vein injection of LPS (8 mg/kg), 0.5h before treated with DEX (50 ug/kg); and the DEX+LPS (D+L) group, receiving tail-vein injection of LPS (8 mg/kg) 0.5 h after being treated with DEX (50 ug/kg). Then, we measured the wet‑to‑dry weight ratio of lung tissue, the ALI pathology score, and HE staining of lung tissue, and assessed the Oxygen Tension index. RESULTS The present study revealed that LPS‑induced rats exhibited significant lung injury, characterized by the deterioration of histopathology, ALI Pathology Score, wet‑to‑dry weight ratio, and Oxygen Tension index (MBP, PaO2, PaCO2, PH, HCO3-, and Lac), which were attenuated by DEX treatment. CONCLUSIONS Collectively, the present results demonstrate elucidate the molecular mechanisms by which DEX ameliorates LPS‑induced ALI.

Clonidine preconditioning improved cerebral ischemia-induced learning and memory deficits in rats via ERK1/2-CREB/ NF-κB-NR2B pathway

Clonidine, a classical α-2 adrenergic agonists, has been shown to antagonize brain damage caused by hypoxia, cerebral ischemia and excitotoxicity and reduce cerebral infarction volume in recent studies. We herein investigate the regulatory effect and possible underlying mechanism of clonidine on learning and memory in rats with cerebral ischemia. The cerebral ischemia rat model was established by right middle cerebral artery occlusion for 2h and reperfusion for 28 days. Drugs were administrated to the rats for consecutive 7 days intraperitoneally and once again on the day of surgery. The learning and memory in rats was assayed by Morris water maze. Moreover, protein expression levels of NMDAR2B (NR2B)/ phosphor - NR2B, ERK1/2/phosphor- ERK1/2, CREB/phosphor-CREB and NF-κB/phosphor-NF-κB in the cortex and hippocampus of the rats were assayed by western blotting. Our results demonstrated that clonidine treatment significantly abrogated the negative effect induced by cerebral ischemia on the learning and memory in the rats. In the Western blotting assay, clonidine treatment led to significant up-regulation of the expression level of NR2B and Phospho-NR2B in the hippocampus of the rats when compared with the cerebral ischemia group. Furthermore, clonidine also significantly decreased the protein expression levels of ERK1/2, Phospho-ERK1/2, CREB, Phospho-CREB and Phospho-NF-κB in the hippocampus of the rats when compared with the cerebral ischemia group. In conclusion, clonidine could improve the learning and memory ability of rats with cerebral ischemia, and NR2B, ERK1/2, CREB, NF-κB were involved in this effect.

Interleukin‑6 RNA knockdown ameliorates acute lung injury induced by intestinal ischemia reperfusion in rats by upregulating interleukin‑10 expression

Acute lung injury (ALI) is a common complication following intestinal ischemia/reperfusion (II/R) injury and contributes to the associated high mortality rate. However, the underlying mechanism is poorly understood and treatments are limited. RNA interference (RNAi) has been demonstrated to provide a promising disease treatment strategy both in vitro and in vivo. Therefore, the present study aimed to test whether blocking the proinflammatory cytokine IL‑6 by RNAi may protect the lungs from remote organ injury following II/R, and to investigate the potential underlying mechanisms. A total of 176 adult healthy male Sprague‑Dawley rats were randomly divided into sham, II/R, negative‑control and IL‑6‑short hairpin (sh)RNA groups. The rats underwent II/R injury with occlusion of the superior mesenteric artery and coeliac artery to induce ischemia for 40 min, and were subsequently reperfused for 0‑48 h. The negative‑control group received a control lentiviral vector containing scrambled or non‑specific sequences, and the IL‑6‑shRNA groups were administered with a vector containing an IL‑6 shRNA sequence to affect RNAi‑mediated knockdown of IL‑6. ALI severity was determined by lung edema (lung wet/dry ratio) and histological analysis (lung injury scores). IL‑6 localization, and mRNA and protein expression levels, were detected by immunofluorescence, reverse transcription‑quantitative polymerase chain reaction and western blot analysis, respectively. IL‑10 expression induced by IL‑6 knockdown in lung tissues was additionally detected. IL‑6 RNAi was revealed to significantly reduce the expression of IL‑6, which was associated with upregulated IL‑10 expression in lung tissues. Consequently, the severities of ALI and edema induced by II/R were substantially improved. In conclusion, the present study demonstrated that IL‑6 RNAi may protect the lung from ALI induced by II/R, and that this protective role may be associated with upregulation of IL‑10. These findings may contribute to the development of an IL‑6‑RNAi‑based therapeutic strategy for the treatment of II/R‑induced ALI.

Dexmedetomidine: Current Role in Burn ICU

Dexmedetomidine (DEX) is a relativelyrecent a₂-adrenergic agonist which provides sedation, anxiolysis and analgesia with much less respiratory depression than other sedatives. These characteristics have implemented the use of the drug in the ICUs in order to achieve the target of a "arousable sedation", thanks to its significant manageability. Its sedative-analgesic properties are also particularly suitable for use in burn ICUs, both adult and pediatric, which is why the current Guidelines have recognized a central role in the management of these categories of patients. Finally, DEX has showed significant anti-inflammatory effect both in animal models and in preliminary clinical trials, reducing vasopressor requirements and main mediators levels of the systemic inflammatory response involved in sepsis and similar processes, suggesting its use for improved outcome in ICU septic patients.

Dexmedetomidine preconditioning protects against lung injury induced by ischemia-reperfusion through inhibition of autophagy

The present study aimed to evaluate the role of autophagy in the protective effect of dexmedetomidine in lung injury caused by ischemia-reperfusion (IR) in rats. In total 48 adult male Sprague-Dawley rats were randomly divided into 6 groups (n=8) as follows: i) Sham group; ii) the IR group; iii) IR + 1 µg/kg dexmedetomidine preconditioning group (pre-LD); iv) IR + 10 µg/kg dexmedetomidine preconditioning group (pre-HD); v) IR + 1 µg/kg dexmedetomidine postconditioning group (post-LD); and vi) IR + 10 µg/kg dexmedetomidine postconditioning group (post-HD). After the rats were anesthetized, the hilum of the left lung was occluded with a non-invasive microvascular clip for 30 min to induce ischemia. The clip was then removed and the left lung was allowed to regain ventilation and blood for 2 h. The rats were then sacrificed, the left lung removed and the wet/dry (W/D) lung weight ratio was determined. Pathological changes to the lungs were evaluated by light and transmission electron microscopy. Furthermore, the rate of lung cell apoptosis was determined by the TUNEL assay. The expression of hypoxia-inducible factor 1α (HIF-1α), Bcl-2/adenovirus E1B 19-kDa interacting protein 3 (BNIP3), BNIP3 like (BNIP3 L) and microtubule-associated protein 1A/1B light chain 3B (LC3II) was determined by western blotting. Compared with the sham group, a significant increase in the W/D lung weight ratio, and malondialdehyde (MDA), BNIP3, BNIP3 L and LC3II levels were observed in the IR group, and HIF-1α levels and superoxide dismutase (SOD) activity were decreased. Furthermore, the W/D ratio was lower in the pre-LD and pre-HD groups than in the IR group. Additionally, SOD activity was significantly higher and MDA expression was significantly lower in the pre-LD and pre-HD groups compared with the IR group. BNIP3, BNIP3 L and LC3II protein levels were significantly lower in the pre-LD and pre-HD groups compared with the IR group, while HIF-1α was notably upregulated in the pre-LD and pre-HD groups compared with the IR group. In conclusion, the results of the present study indicate that dexmedetomidine preconditioning protects against lung injury induced by IR through inhibition of autophagy and apoptosis.

Two Phase Modulation of [Formula: see text] Entry and Cl-/[Formula: see text] Exchanger in Submandibular Glands Cells by Dexmedetomidine

Dexmedetomidine (Dex), a highly selective α2-adrenoceptor agonist, attenuates inflammatory responses induced by lipopolysaccharide (LPS) and induces sedative and analgesic effects. Administration of Dex also reduces salivary secretion in human subjects and inhibits osmotic water permeability in rat cortical collecting ducts. However, little is known about the mechanisms underlying the effects of Dex on salivary glands fluid secretion. We demonstrated the α2-adrenoceptor expression in the basolateral membrane of mouse submandibular glands (SMG). To investigate fluid secretion upon treatment with Dex, we studied the effects of Dex on the activity of Na+-K+-2Cl- cotransporter1 (NKCC1) and Cl-/[Formula: see text] exchange (CBE), and on downstream pro-inflammatory cytokine expression in isolated primary mouse SMG cells. Dex acutely increased CBE activity and NKCC1-mediated and independent [Formula: see text] entry in SMG duct cells, and enhanced ductal fluid secretion in a sealed duct system. Dex showed differential effects on cholinergic/adrenergic stimulations and inflammatory mediators, histamine, and LPS, stimulations-induced Ca2+ in mouse SMG cells. Both, histamine- and LPS-induced intracellular Ca2+ increases were inhibited by Dex, whereas carbachol-stimulated Ca2+ signals were not. Long-lasting (2 h) treatment with Dex reduced CBE activity in SMG and in human submandibular glands (HSG) cells. Moreover, when isolated SMG cells were stimulated with Dex for 2 h, phosphodiesterase 4D (PDE4D) expression was enhanced. These results confirm the anti-inflammatory properties of Dex on LPS-mediated signaling. Further, Dex also inhibited mRNA expression of interleukin-6 and NADPH oxidase 4. The present study also showed that α2-adrenoceptor activation by Dex reduces salivary glands fluid secretion by increasing PDE4D expression, and subsequently reducing the concentration of cAMP. These findings reveal an interaction between the α2-adrenoceptor and PDE4D, which should be considered when using α2-adrenoceptor agonists as sedative or analgesics.

Effect Of α2-Adrenergic Agonists And Antagonists On Cytokine Release From Human Lung Macrophages Cultured In Vitro

The most trusted hypothesis to explain how α2-adrenergic agonists may preserve pulmonary functions in critically ill patients is that they directly act on macrophages by interfering with an autocrine/paracrine adrenergic system that controls cytokine release through locally synthetized noradrenaline and α1- and α2-adrenoreceptors. We tested this hypothesis in primary cultures of resident macrophages from human lung (HLMs). HLMs were isolated by centrifugation on percoll gradients from macroscopically healthy human lung tissue obtained from four different patients at the time of lung resection for cancer. HLMs from these patients showed a significant expression of α2A, α2B and α2C adrenoreceptors both at the mRNA and at the protein level. To evaluate whether α2 adrenoreceptors controlled cytokine release from HMLs, we measured IL-6, IL-8 and TNF-α concentrations in the culture medium in basal conditions and after preincubation with several α2-adrenergic agonists or antagonists. Neither the pretreatment with the α2-adrenergic agonists clonidine, medetomidine or dexdemetomidine or with the α2-adrenergic antagonist yohimbine caused significant changes in the response of any of these cytokines to LPS. These results show that, different from what reported in rodents, clonidine and dexdemetomidine do not directly suppress cytokine release from human pulmonary macrophages. This suggests that alternative mechanisms such as effects on immune cells activation or the modulation of autonomic neurotransmission could be responsible for the beneficial effects of these drugs on lung function in critical patients.

Dexmedetomidine protects against lung ischemia-reperfusion injury by the PI3K/Akt/HIF-1α signaling pathway

PURPOSE

To evaluate the role of the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt)/hypoxia-inducible factor 1α (HIF-1α) signaling pathway in the protection by dexmedetomidine against lung ischemia-reperfusion injury (IRI) in rats.

METHODS

Forty-eight male Sprague-Dawley rats weighing 250-350 g were randomly divided into six groups (n = 8 each group): sham group, IRI group, low-dose dexmedetomidine group (LD group), high-dose dexmedetomidine group (HD group), combined low-dose dexmedetomidine and LY294002 group (LDL group), and combined high-dose dexmedetomidine and LY294002 group (HDL group). A 30-min ischemia was induced by occluding the hilum of the left lung, followed by a 120-min reperfusion by removing occlusion of the hilum. After the left lung was removed, the wet/dry weight ratio (W/D) of the lung tissues was determined. Pathological changes of lung tissues were evaluated by light and electron microscopes and the expression of p-Akt and HIF-1α in the lung tissues was determined by western blotting.

RESULTS

Compared with the sham group, both the W/D ratio and lung injury were significantly increased, the p-Akt expression was down-regulated and HIF-1α expression was up-regulated in the five experimental groups. Compared with the LD and LDL groups, both the W/D ratio and lung injury were decreased, but the expression of p-Akt and HIF-1α was increased in the HD and HDL groups.

CONCLUSIONS

Administration of dexmedetomidine before ischemia can provide a protection against lung IRI by re-installing the PI3K/Akt/HIF-1α signaling pathway.

Effect of dexmedetomidine on acute lung injury in experimental ischemia-reperfusion model

PURPOSE

Ischemia-reperfusion injury is one of the consequences of tourniquet application for extremity surgery. The aim of the study was to establish the effect of dexmedetomidine on the acute lung injury following lower extremity experimental ischemia-reperfusion model in rats.

METHODS

Twenty-eight Wistar-Albino breed Rats were recruited after Ethics Committee approval and allocated into 4 groups, each with 7 subjects. Group 1 (SHAM) received only anesthesia. Group 2 (IR) had experienced 3h of ischemia and 3h of reperfusion using left lower extremity tourniquet after anesthesia application. Groups 3 (D-50) and 4 (D-100) had undergone the same procedures as in the Group 2, except for receiving 50 and 100mg·kg^-1, respectively, dexmedetomidine intraperitoneally 1h before the tourniquet release. Blood samples were obtained for the analysis of tumor necrosing factor-α and interleukin-6. Pulmonary tissue samples were obtained for histological analysis.

RESULTS

No significant difference regarding blood tumor necrosing factor-α and interleukin-6 values was found among the groups, whereas pulmonary tissue injury scores revealed significant difference. Histological scores obtained from the Group 2 were significantly higher from those in the Groups 1, 3 and 4 with p-values 0.001 for each comparison. Moreover, Group 1 scores were found to be significantly lower than those in the Groups 3 and 4 with p-values 0.001 and 0.011, respectively. No significant difference was observed between the Groups 3 and 4.

CONCLUSION

Dexmedetomidine is effective in reduction of the experimental ischemia-reperfusion induced pulmonary tissue injury in rats, formed by extremity tourniquet application.

Dexmedetomidine Attenuates Bilirubin-Induced Lung Alveolar Epithelial Cell Death In Vitro and In Vivo

Objective:

To investigate bilirubin-induced lung alveolar epithelial cell injury together with the protection afforded by dexmedetomidine.

Design:

Prospective, randomized, controlled study.

Setting:

Research laboratory.

Subjects:

Sprague Dawley rats.

Interventions:

Alveolar epithelial A549 cell lines were cultured and received bilirubin (from 0 to 160 μM) to explore the protective pathway of dexmedetomidine on bilirubin-induced alveolar epithelial cell injury assessed by immunochemistry and flow cytometry. Sprague-Dawley rats were subjected to common bile duct ligation surgery to explore the protective effect of dexmedetomidine on hyperbilirubinemia-induced alveolar epithelial cell injury and respiratory failure in comparison with the Sham (subjected to the surgery procedure but without bile duct ligation) or dexmedetomidine control (only received intraperitoneal injection of dexmedetomidine).

Measurements and Main Results:

In vitro, dexmedetomidine reversed the collapse of mitochondrial membrane potential (Δψm), upregulation of cytochrome C, B cell leukemia 2 associated X protein, and cleaved-caspase 3 and 9 in A549 epithelial cells with bilirubin challenge. Furthermore, dexmedetomidine reversed the arrest of cell cycle and the downregulation of the transforming growth factorβ, phosphorylated mammalian target of rapamycin, and p42/44 mitogen-activated protein kinase induced by bilirubin. In vivo, pulmonary edema and inflammation were found after common bile duct ligation. Bilirubin and Paco₂ were significantly increased, and oxygen (Pao₂) was significantly decreased in the blood of common bile duct ligation rats from the postsurgery day 7 to day 21 when compared with those in the sham controls, respectively (p < 0.01). Daily intraperitoneal injection of dexmedetomidine significantly alleviated the lung edema and injury and prevented respiratory failure.

Conclusion:

Our data both in vitro and in vivo demonstrated that dexmedetomidine protected alveolar epithelial cell from bilirubin-induced injury. Dexmedetomidine may be a good choice of anesthetic/sedative for patients with chronic liver disease during the perioperative period.

Dexmedetomidine protects from post-myocardial ischaemia reperfusion lung damage in diabetic rats

OBJECTIVE

Diabetic complications and lipid peroxidation are known to have a close association. Lipid peroxidation commonly occurs at sites exposed to ischaemia, but distant organs and tissues also get damaged during ischaemia/reperfusion (I/R). Some of these targets are vital organs, such as the lung, liver, and kidney; the lung is the most frequently affected. The aim of our study was to investigate the effects of dexmedetomidine on I/R damage in lung tissue and on the oxidant/anti-oxidant system in diabetic rats.

MATERIAL AND METHODS

Diabetes was induced with streptozotocin (55 mg/kg) in 18 Wistar Albino rats, which were then randomly divided into three groups (diabetes control (DC), diabetes plus ischaemia-reperfusion (DIR), and diabetes plus dexmedetomidine-ischaemia/reperfusion (DIRD)) after the effects of diabetes were clearly evident. The rats underwent a left thoracotomy and then ischaemia was produced in the myocardium muscle by a left anterior descending artery ligation for 30 min in the DIR and DIRD groups. I/R was performed for 120 min. The DIRD group received a single intraperitoneal dose of dexmedetomidine (100 µg/kg); the DIR group received no dexmedetomidine. Group DC was evaluated as the diabetic control group and also included six rats (C group) in which diabetes was not induced. These mice underwent only left thoracotomy and were closed without undergoing myocardial ischaemia. Histopathological changes, activities of catalase (CAT) and glutathione-S-transferase anti-oxidant enzymes, and malondialdehyde (MDA) levels were evaluated in the lung tissues of all rats.

RESULTS

Neutrophil infiltration/aggregation was higher in the DIR group than in the C, DC, and DIRD groups (p=0.001, p=0.013, and p=0.042, respectively). The lung injury score was significantly higher in the DIR group than in the C and DC groups (p<0.0001 and p=0.024, respectively). The levels of MDA were significantly higher in the DIR group than in the C and DIRD groups. CAT activity was significantly higher in the DIR group than in the DIRD and C groups.

CONCLUSION

Our results confirm that dexmedetomidine has protective effects against the lung damage resulting from I/R in diabetic rats. Future studies conducted to evaluate the effects of the use of dexmedetomidine on damage to various organs following different I/R durations may help understanding possible protective effects of dexmedetomidine and underlying mechanisms in tissue damage related to I/R injury.

Dexmedetomidine Ameliorate CLP-Induced Rat Intestinal Injury via Inhibition of Inflammation

The aim was to verify that dexmedetomidine (DEX) can attenuate CLP-induced intestinal injury via inhibition of inflammation. Male Sprague-Dawley (SD) rats were randomly allocated into Sham group and the other three CLP model groups, in terms of different treatments: placebo, DEX, and yohimbine plus DEX (DEX + YOH) groups. Pathology examination was conducted with HE stain. To identify differences among groups, the levels of DAO, and D-lactate in serum were measured by spectrophotometry, and the levels of TNF-α, IL-1β, and IL-6 in serum and organ were measured by ELISA. The expressions of occludin and TLR4 in tissue were detected by Western blot. The survival rate of an additional group of animals within 7 d was recorded. In DEX group, mortality was lower, histology change was minor, DAO, and D-lactate levels were reduced, and occludin expression was increased; the expressions of TNF-α, IL-1β, IL-6, and TLR4 were also decreased in DEX group. These results indicated that acute intestinal injury induced by CLP was mitigated by DEX treatment. However, these effects of DEX were significantly attenuated by yohimbine in DEX + YOH group. Our study indicated the protective effects of DEX on CLP-induced injury, which may be associated with the inhibition of inflammation via modulating TLR4 pathway and can be blocked by yohimbine.

Ginsenoside Rb1 Treatment Attenuates Pulmonary Inflammatory Cytokine Release and Tissue Injury following Intestinal Ischemia Reperfusion Injury in Mice

Objective. Intestinal ischemia reperfusion (II/R) injury plays a critical role in remote organ dysfunction, such as lung injury, which is associated with nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway. In the present study, we tested whether ginsenoside Rb1 attenuated II/R induced lung injury by Nrf2/HO-1 pathway. Methods. II/R injury was induced in male C57BL/6J mice by 45 min of superior mesenteric artery (SMA) occlusion followed by 2 hours of reperfusion. Ginsenoside Rb1 was administrated prior to reperfusion with or without ATRA (all-transretinoic acid, the inhibitor of Nrf2/ARE signaling pathway) administration before II/R. Results. II/R induced lung histological injury, which is accompanied with increased levels of malondialdehyde (MDA), interleukin- (IL-) 6, and tumor necrosis factor- (TNF-) α but decreased levels of superoxide dismutase (SOD) and IL-10 in the lung tissues. Ginsenoside Rb1 reduced lung histological injury and the levels of TNF-α and MDA, as well as wet/dry weight ratio. Interestingly, the increased Nrf2 and HO-1 expression induced by II/R in the lung tissues was promoted by ginsenoside Rb1 treatment. All these changes could be inhibited or prevented by ATRA. Conclusion. Ginsenoside Rb1 is capable of ameliorating II/R induced lung injuries by activating Nrf2/HO-1 pathway.

Dexmedetomidine ameliorates acute lung injury following orthotopic autologous liver transplantation in rats probably by inhibiting Toll-like receptor 4-nuclear factor kappa B signaling

BACKGROUND

To investigate whether pretreatment with dexmedetomidine (Dex) has a protective effect against acute lung injury (ALI) in an orthotopic autologous liver transplantation (OALT) rat model and to explore the mechanisms responsible for the protective effect of Dex against lung injury.

METHODS

Forty-eight rats underwent OALT and were randomly divided into six groups (n = 8 in each group) that received 10 µg/kg Dex, 50 µg/kg Dex, 50 µg/kg Dex + nonspecific α2-adrenergic receptor (AR) antagonist atipamezole, 50 µg/kg Dex + specific α2B/C-AR antagonist ARC-239, 50 µg/kg Dex + specific α2A-AR antagonist BRL-44408, or the same amount of normal saline. The sham rats (n = 8) underwent anesthesia induction, laparotomy, and separation of the portal vein without liver ischemia and reperfusion. Lung tissue sections were stained with hematoxylin and eosin (HE) to visualize the damage. The expression of Toll-like receptor 4 (TLR4) and the phospho-nuclear factor (NF)-κB p65 subunit as well as inflammatory cytokines was measured.

RESULTS

Rats exhibited increased histological lung injury scores and pulmonary edema following OALT. Pretreatment with 50 μg/kg Dex attenuated OALT-induced lung injury in rats, probably by inhibiting the activation of the TLR4-NF-κB signaling pathway. The protective effect of Dex could be blocked by atipamezole or BRL-44408, but not by ARC-239, suggesting these effects of Dex were mediated, at least in part, by the α2A-AR.

CONCLUSIONS

Dex exerts protective effects against ALI following OALT, and this protection is associated with the suppression of TLR4-NF-κB signaling. Thus, pretreatment with Dex may be a useful method for reducing lung damage caused by liver transplantation.

Protective effects of dexmedetomidine on intestinal ischemia-reperfusion injury

Dexmedetomidine (DEX) has been hypothesized to possess anti-oxidative properties that may mitigate the damage caused by ischemia-reperfusion (IR) injury. The aim of the present study was to examine the effects of DEX on intestinal contractile activity, inflammation and apoptosis following intestinal IR injury. Intestinal IR injury was induced in rats by complete occlusion of the superior mesenteric artery for 60 min, followed by a 60-min reperfusion period. Rats received an intraperitoneal injection of 25 µg/kg DEX at 30 min prior to the mesenteric IR injury. Following reperfusion, segments of the terminal ileum were rapidly extracted and transferred into an isolated organ bath. The contractile responses to receptor-mediated acetylcholine (Ach) and non-receptor-mediated potassium chloride (KCl) were subsequently examined. Nitric oxide (NO) levels were determined and the expression levels of tumor necrosis factor (TNF)-α, interleukin (IL)-6, Bax and Bcl-2 were measured using an enzyme-linked immunosorbent assay. The levels of telomerase and caspase-3 were determined using reverse transcription-quantitative polymerase chain reaction. The results indicated that DEX treatment produced a significant reduction in the IR-induced contractile response to Ach and KCl in the intestinal tissue. Furthermore, DEX appeared to significantly ameliorate intestinal IR injury, in addition to reducing the production of NO. Similar reductions were observed in the intestinal expression levels of TNF-α and IL-6. In addition, DEX treatment resulted in a reduction in the expression levels of Bax in the intestinal tissues, while increasing those of Bcl-2, in addition to significantly increasing the mRNA levels of telomerase and caspase-3. Therefore, the present study indicated that NO, TNF-α and IL-6 may partially contribute to the pathogenesis of intestinal IR injury in addition to the increased expression levels of Bax, Bcl-2, telomerase and caspase-3. These findings suggest that DEX possesses beneficial anti-apoptotic and anti-inflammatory effects in intestinal tissue following bowel injury.

The Use of Intraoperative Dexmedetomidine Is Not Associated With a Reduction in Acute Kidney Injury After Lung Cancer Surgery

OBJECTIVE

To evaluate whether the use of intraoperative dexmedetomidine (DEX) during lung cancer surgery may reduce the incidence of acute kidney injury (AKI).

DESIGN

A retrospective study.

SETTING

An academic hospital.

PARTICIPANTS

Data were collected from 1,207 adult patients who underwent resection for non-small-cell lung cancer between January 2004 and December 2012.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

All patients had a general balanced anesthetic technique, and dexmedetomidine use was at the discretion of the anesthesiologist. Data analysis was done utilizing the Wilcoxon rank sum tests and Chi-square tests to compare continuous variables and categoric variables between the 2 groups, respectively. Multivariate logistic analysis with backward selection was fitted to find out factors for AKI incidence. Overall, 8.1% of the patients developed AKI during their hospital stay. There were no statistically significant differences in demographic, perioperative variables, and the incidence of AKI between patients who did and did not receive DEX. A logistic regression model was fitted to determine factors independently associated with AKI. Factors that were independently associated with AKI included body mass index, American Society of Anesthesiologists 3-4, hypertension, smoking status, and thoracotomy procedure.

DISCUSSION

The authors hypothesized that DEX use would be associated with a decreased incidence of AKI in thoracic surgery; however, they were unable to prove this hypothesis. Their results did demonstrate that there are 5 factors independently associated with AKI.