OBJECTIVEThe objective was to evaluate the protective effects of dexmedetomidine (DEX), a selective agonist of α2-adrenergic receptor, on sepsis-induced diaphragm injury and the underlying molecular mechanisms.

DATA SOURCESThe data used in this review were mainly from PubMed articles published in English from 1990 to 2015.

STUDY SELECTIONClinical or basic research articles were selected mainly according to their level of relevance to this topic.

RESULTSSepsis could induce severe diaphragm dysfunction and exacerbate respiratory weakness. The mechanism of sepsis-induced diaphragm injury includes the increased inflammatory cytokines and excessive oxidative stress and superfluous production of nitric oxide (NO). DEX can reduce inflammatory cytokines, inhibit nuclear factor-kappaB signaling pathways, suppress the activation of caspase-3, furthermore decrease oxidative stress and inhibit NO synthase. On the basis of these mechanisms, DEX may result in a shorter period of mechanical ventilation in septic patients in clinical practice.

CONCLUSIONSBased on this current available evidence, DEX may produce extra protective effects on sepsis-induced diaphragm injury. Further direct evidence and more specific studies are still required to confirm these beneficial effects.

Dexmedetomidine ; pharmacology ; Diaphragm ; drug effects ; injuries ; Humans ; Sepsis ; complications

OBJECTIVETo evaluate the influence of small-dose dexmedetomidine infusion on recovery of patients undergoing vertebral operation.

METHODSSixty ASA I-II patients undergoing vertebral operation were randomly divided into two groups (n=30). In group I, dexmedetomidine infusion was pumped at the rate of 0.5 µg·kg(-1)·h(-1) from tracheal intubation to incision suture, and in group II, 0.9%saline was pumped instead. The mean arterial pressure, heart rate, Riker Sedation-Agitation Scale and Ramesay sedation score were recorded at the time points of autonomous respiration (T1), eye opening (T2), extubation (T3), 1 min after extubation (T4), 10 min after extubation (T5), and 30 min after extubation (T6).

RESULTSThe recovery time of autonomous respiration and eye opening time in group I were significantly longer than those in group II, and the extubation time was significantly shorter in group I (P<0.05). Riker Sedation-Agitation Scale scores in group II were significantly higher than those in group I at T2 and T4, and Ramesay sedation scores in group I were significantly higher than those in group II at T1, T2 and T5 (P<0.05). The mean arterial pressure and heart rate at each time point was significantly lower in group I than in group II (P<0.05), especially at T3 and T4 (P<0.01). In both groups, the mean arterial pressure and heart rate at T3 and T4 were significantly higher than those at rest (P<0.05).

CONCLUSIONSSmall-dose dexmedetomidine infusion can reduce dysphoria and lower the risks during recovery from general anesthesia following vertebral operation.

Adult ; Aged ; Anesthesia Recovery Period ; Dexmedetomidine ; administration & dosage ; pharmacology ; Humans ; Middle Aged ; Spine ; surgery

OBJECTIVES: To investigate the effects of dexmedetomidine (Dex) on injury of A549 cells induced by hypoxia/reoxygenation(H/R)and the influence of C/EBP homologous protein (CHOP) expression. METHODS: Logarithmic growth phase A549 cells(it originated from alveolar type Ⅱ epithelial cell line) were randomly divided into 4 groups (=10):normoxic control group (N), Dex group (D), hypoxia/reoxygenation group (H), hypoxia/reoxygenation + Dex group(HD). At the beginning of modeling, 1 nmol/L Dex was puted into D and HD groups. N and D groups were cultured in the normoxic incubator for 30 h. H and HD group were incubated in the anoxic cultivation for 6 h, fo llowed by normoxic culture for 24 h. Then A549 cells were observed under the inverted microscope to observe the morphological changes. Cell activity was detected by cell counting Kit-8(CCK-8) and the apoptosis index(AI) was detected by in situ end labeling (TUNEL) method. The expression of CHOP、glucose-regulated protein of molecular weight 78 kDa (Grp78)、cysteinyl aspirate-specificprotease-3 (caspase-3) protein and CHOP、Grp78 mRNA were detected by Western blot and RT-PCR. RESULTS: Compared with N group, the number of adherent cells in H group decreased significantly, and cell morphology changed. The absorbance value in H group decreased obviously (<0. 01). The AI value and expression of CHOP, Grp78, caspase-3 proteins and CHOP, Grp78 mRNA were significantly increased (<0.01). Compared with H group, the cell damage in HD group was decreased, the absorbance value increased (<0.01), the number of apoptosis cells decreased relatively (<0.01), the expression of CHOP, caspase-3 protein and CHOP mRNA decreased (<0. 01). CONCLUSIONS Dex has notable effects against H/R injury, which may be related to effective inhibition of apoptosis mediated by the CHOP's signal path.
A549 Cells ; Apoptosis ; Cell Hypoxia ; Dexmedetomidine ; pharmacology ; Humans ; Transcription Factor CHOP ; physiology

The aim of this study was to investigate the effects of dexmedetomidine (Dex) on hepatic ischemia/reperfusion injury (HIRI) and the underlying mechanism. The in vitro HIRI was induced by culturing HL-7702 cells, a human hepatocyte cell line, under 24 h of hypoxia and 12 h of reoxygenation. Quantitative real time PCR (qRT-PCR) and Western blot were performed to detect the expression levels of long non-coding RNA MALAT1, microRNA-126-5p (miR-126-5p) and high mobility group box-1 (HMGB1). Bioinformatics prediction and double luciferase assay were used to verify the targeting relationship between miR-126-5p and MALAT1, HMGB1. Reactive oxygen species (ROS), malondialdehyde (MDA) and ATP levels in culture medium were detected by corresponding kits. The results showed that Dex significantly reduced the levels of ROS and MDA, but increased the level of ATP in HL-7702 cells with HIRI. HIRI up-regulated the expression levels of MALAT1 and HMGB1, and down-regulated the level of miR-126-5p. Dex reversed these effects of HIRI. Furthermore, Dex inhibited HIRI-induced cellular apoptosis, whereas MALAT1 reversed the effect of Dex. This inhibitory effect of Dex could be restored by up-regulation of miR-126-5p. The results suggest that Dex protects hepatocytes from HIRI via regulating MALAT1/miR-126-5p/HMGB1 axis.
Dexmedetomidine/pharmacology* ; HMGB1 Protein/genetics* ; Humans ; MicroRNAs/genetics* ; RNA, Long Noncoding/genetics* ; Reperfusion Injury/genetics*

Objective Dexmedetomidine is a highly selective alpha-2 adrenergic receptor agonist with sedative and analgesic properties but without respiratory depression effect and has been widely used in perioperative anesthesia. Here we performed a systematic review and meta-analysis to evaluate the effect of dexmedetomidine on maintaining perioperative hemodynamic stability in elderly patients.Methods PubMed, Web of Science, the Cochrane Library, China National Knowledge Infrastructure (CNKI), and Wanfang Data were searched for randomized-controlled trials (RCTs) on the application of dexmedetomidine in maintaining perioperative hemodynamic stability in elderly patients from their inception to September, 2021. The standardized mean differences (SMD) with 95% confidence interval (CI) were employed to analyze the data. The random-effect model was used for the potential clinical inconsistency.Results A total of 12 RCTs with 833 elderly patients (dexmedetomidine group, 546 patients; control group, 287 patients) were included. There was no significant increase in perioperative heart rate (HR), mean arterial pressure (MAP), and diastolic blood pressure (DBP) in the dexmedetomidine group before and during the operation. In addition, the variations of hemodynamic indexes including HR, MAP, SBP (systolic blood pressure), and DBP were significantly lower in the dexmedetomidine group compared with the control group (HR: SMD = -0.87, 95% CI: -1.13 to -0.62; MAP: SMD = -1.12, 95% CI: -1.60 to -0.63; SBP: SMD = -1.27, 95% CI: -2.26 to -0.27; DBP: SMD = -0.96, 95% CI: -1.33 to -0.59). Subgroup analysis found that with the prolongation of 1.0 μg/kg dexmedetomidine infusion, the patient's heart rate declined in a time-dependent way.Conclusion Dexmedetomidine provides more stable hemodynamics during perioperative period in elderly patients. However, further well-conducted trials are required to assess the effective and safer doses of dexmedetomidine in elderly patients.
Humans ; Aged ; Dexmedetomidine/adverse effects* ; Hemodynamics ; Hypnotics and Sedatives/pharmacology* ; Blood Pressure ; Heart Rate

OBJECTIVETo investigate the effect of dexmedetomidine on 5-HT-induced constrictions of isolated human intrapulmonary arteries and explore the mechanisms.

METHODSLung tissue was obtained from patients undergoing surgery for lung carcinoma. Intrapulmonary arteries were dissected and cut into rings, which were mounted in a Multi Myograph system to determine the effect of dexmedetomidine (0.3-3 nmol/L) on 5-HT-induced vasoconstrictions. The influences of the endothelium removal and various drugs including L-NAME, yohimbine and indomethacin were tested on the effects of dexmedetomidine.

RESULTSDexmedetomidine (0.1-100 nmol/L) did not obviously affect the resting tension of endothelium-intact human intrapulmonary arteries. 5-HT induced concentration-dependent contraction in endothelium-intact intrapulmonary arteries [pD2: 6.11∓0.05, Emax: (102.10∓1.96)%]. In the rings with intact endothelium, dexmedetomidine (0.3-3 nmol/L) significantly attenuated the Emax and pD2 of 5-HT-induced vasoconstriction [pD2: 5.94∓0.03, Emax: (79.96∓1.31)%]. 5-HT also induced concentration-dependent contraction in endothelium-denuded intrapulmonary arteries [pD2: 6.10∓0.07, Emax: (107.40∓3.20)%]. Dexmedetomidine produced no significant effects on the rings with denuded endothelium. The effects of dexmedetomidine on 5-HT-induced vasoconstriction was suppressed by L-NAME and yohimbine, but not by indomethacin.

CONCLUSIONDexmedetomidine can inhibit 5-HT-induced vasoconstriction of isolated human intrapulmonary arteries probably through α2-adrenergic acceptor and NO released from the endothelium.

Adult ; Aged ; Dexmedetomidine ; pharmacology ; Female ; Humans ; In Vitro Techniques ; Male ; Middle Aged ; Pulmonary Artery ; drug effects ; Serotonin ; pharmacology ; Vasoconstriction ; drug effects

BACKGROUND: Postoperative cognitive dysfunction (POCD) is a serious complication after surgery, especially in elderly patients. The anesthesia technique is a potentially modifiable risk factor for POCD. This study assessed the effects of dexmedetomidine, propofol or midazolam sedation on POCD in elderly patients who underwent hip or knee replacement under spinal anesthesia. METHODS: The present study was a prospective randomized controlled preliminary trial. From July 2013 and December 2014, a total of 164 patients aged 65 years or older who underwent hip or knee arthroplasty at China-Japan Friendship Hospital and 41 non-surgical controls were included in this study. Patients were randomized in a 1:1:1 ratio to 3 sedative groups. All the patients received combined spinal-epidural anesthesia (CSEA) with midazolam, dexmedetomidine or propofol sedation. The sedative dose was adjusted to achieve light sedation (bispectral index[BIS] score between 70 and 85). All study participants and controls completed a battery of 5 neuropsychological tests before and 7 days after surgery. One year postoperatively, the patients and controls were interviewed over the telephone using the Montreal cognitive assessment 5-minute protocol. RESULTS: In all, 60 of 164 patients (36.6%) were diagnosed with POCD 7 days postoperatively, POCD incidence in propofol group was significantly lower than that in dexmedetomidine and midazolam groups (18.2% vs. 40.0%, 51.9%, χ = 6.342 and 13.603, P = 0.012 and < 0.001). When the patients were re-tested 1 year postoperatively, the incidence of POCD was not significantly different among the 3 groups (14.0%, 10.6% vs. 14.9%, χ = 0.016 and 0.382, P = 0.899 and 0.536). CONCLUSION Among dexmedetomidine, propofol and midazolam sedation in elderly patients, propofol sedation shows a significant advantage in term of short-term POCD incidence.
Aged ; Cognitive Dysfunction ; epidemiology ; Dexmedetomidine ; pharmacology ; Female ; Humans ; Hypnotics and Sedatives ; pharmacology ; Male ; Midazolam ; pharmacology ; Middle Aged ; Neuropsychological Tests ; Postoperative Complications ; epidemiology ; Propofol ; pharmacology ; Prospective Studies

OBJECTIVETo investigate the effect of dexmedetomidine on oxygenation function in adult patients with balanced anesthesia by propofol-fentanyl under one-lung ventilation (OLV).

METHODSTwenty-two patients undergoing thoracic operation were randomly divided into the study group and control group, both receiving propofol and fentanyl balanced anesthesia. In the study group, additional infusion of dexmedetomidine (0.3 µg/kg loading dose, 0.3 µg·kg(-1)·h(-1) maintenance dose) was administered, and the patients in the control group received only normal saline. Arterial blood samples were obtained at 4 time points from each patient during anesthesia for blood gas analysis.

RESULTSIn the study group, the pH values remained stable, the oxygenation index tended to decline progressively, but the incidence of hypoxemia was low; in the control group, the pH value and oxygenation index both declined progressively with a higher incidence of hypoxemia.

CONCLUSIONDexmedetomidine can better maintain the oxygenation function of OLV patients in balanced anesthesia by propofol and fentanyl, and its mechanism may be related to the decreased dose of propofol used.

Adult ; Balanced Anesthesia ; Blood Gas Analysis ; Dexmedetomidine ; pharmacology ; Female ; Fentanyl ; Humans ; Male ; Middle Aged ; One-Lung Ventilation ; Propofol

OBJECTIVE: To investigate the effects of dexmedetomidine (DEX) on hippocampal neuron development process and the expressions of molecules in brain-derived neurotropic factor (BDNF)-tyrosine receptor kinase B (TrkB) signaling pathway in neonatal rats. METHODS: The hippocampal neurons were isolated from neonatal rats and cultured in vitro. The cells were seeded in 96-well plates,which were divided into 4 groups (control group, 1 μmol/L DEX treatment group, 5 μmol/L DEX treatment group, 50 μmol/L DEX treatment group), six wells were set in each group, and different concentrations of dexmedetomidine 1, 5 and 50 μmol/L were administered respectively. Cell viability was detected at 2, 4, 6, 8, and 10 d after treatment, and apoptosis was detected 10 days after treatment. The mRNA expression levels of synaptophysin (SYN) and postsynaptic density protein 95 (PSD95) were detected by q-PCR, and the expressions of BDNF, TrkB and N-methyl-D-aspartate receptor (NMDAR) protein were analyzed. RESULTS: Compared with the control group, there was no significant difference in neuronal cell viability between the different doses of DEX treatment group. There was no significant difference in the expression of SYN and PSD95 mRNA and TrkB protein between the 1 μmol/L and 5 μmol/L DEX treatment groups (P＞0.05). The expression levels of SYN and PSD95 mRNA in the 50 μmol/L DEX group were increased significantly (P＜0.01), and the expression level of BDNF protein was up-regulated significantly (P＜0.01), the expression of the p-N-methyl-D-aspartate receptor was increased (P＜0.01). CONCLUSION 50 μmol/L DEX has a certain effect on rat hippocampal neurons, which may be achieved by up-regulating the expression of BDNF and the phosphorylation level of N-methyl-D-aspartate receptor.
Animals ; Brain-Derived Neurotrophic Factor ; Dexmedetomidine ; pharmacology ; Growth and Development ; Hippocampus ; drug effects ; growth & development ; Hypnotics and Sedatives ; pharmacology ; Neurons ; drug effects ; Rats

OBJECTIVETo investigate the protective effects of dexmedetomidine (Dex) against glutamate-induced cytotoxicity in PC12 cells and its mechanism.

METHODSPC12 cells were treated with varying concentrations of dexmedetomidine 1 h before exposure to a high concentration of glutamate. The cell viability was measured by MTT assay, and LDH release, MDA content and SOD activity were measured. The level of ROS was tested by DCFH-DA staining and flow cytometry. The level of intracellular Cawas detected by Fluo-8 staining and flow cytometry, and the mitochondrial membrane potential (MMP) was determined with JC-1 staining and flow cytometry.

RESULTSWithin the concentration range of 0.01 to 100 µmol/L, Dex dose-dependently protected PC12 cells against glutamate-induced cytotoxicity. Treatment with 100 µmol/L Dex significantly increased the cell viability to (86.6∓2.2)% of that of the control cells (P<0.01) and decreased LDH release to 1.4∓0.1 folds of the control level (P<0.01). In PC12 cells exposed to glutamate, Dex pretreatment significantly reduced MDA content (P<0.01), enhanced SOD activity (P<0.01), inhibited ROS overproduction (P<0.01), reduced intracellular Calevel (P<0.01) and maintained a stable MMP (P<0.01).

CONCLUSIONDexmedetomidine can protect PC12 cells against glutamate-induced injury possibly in relation with its anti-oxidative activity, inhibitory effect on intracellular calcium overload and protective effect of the mitochondria.

Animals ; Apoptosis ; Calcium ; metabolism ; Cell Survival ; drug effects ; Dexmedetomidine ; pharmacology ; Glutamic Acid ; adverse effects ; Membrane Potential, Mitochondrial ; Mitochondria ; drug effects ; metabolism ; PC12 Cells ; Rats ; Reactive Oxygen Species ; metabolism