Protective effects of dexmedetomidine on blunt chest trauma–induced pulmonary contusion in rats

Dexmedetomidine versus ketamine in improving tolerance to noninvasive ventilation after blunt chest trauma: A randomized, double-blinded, placebo-controlled trial

Background and Aims

Even though patient tolerance is critical to the success of noninvasive ventilation (NIV), research on using sedation to improve tolerance to NIV after traumatic chest injuries is limited. We hypothesized that dexmedetomidine would be superior to ketamine in terms of patient tolerance and lengthening the NIV sessions after blunt chest trauma.

Material and Methods

This randomized, double-blinded, placebo-controlled trial included 45 patients of both genders aged 18-60 who needed NIV after blunt chest trauma. The patients were randomly assigned to one of three groups (n = 15) for receiving dexmedetomidine, ketamine, or placebo (0.9% sodium chloride solution) infusion to maintain a Richmond Agitation Sedation Scale (RASS) score between 0 and - 3 during two successive NIV sessions. Patients were evaluated for the duration of the NIV sessions, RASS, Visual Analog Scale (VAS), and the total amount of rescue analgesia consumed.

Results

The mean duration of the NIV sessions was significantly longer in patients who received dexmedetomidine (P < 0.001) or ketamine (P < 0.001) compared to placebo. However, the NIV durations did not differ significantly between the dexmedetomidine and ketamine groups (P > 0.05). The dexmedetomidine group had a significantly lower RASS score compared to the ketamine (P < 0.001) and placebo (P < 0.001) groups, whereas the ketamine group had a significantly lower VAS compared to the dexmedetomidine (P = 0.005) and placebo (P = 0.022) groups and required significantly less total morphine (P = 0.001) compared to the other groups.

Conclusion

The duration of the NIV sessions for patients with blunt chest trauma did not differ significantly between the dexmedetomidine and ketamine groups.

Dexmedetomidine Improves Lung Function by Promoting Inflammation Resolution in Patients Undergoing Totally Thoracoscopic Cardiac Surgery

Objective

Totally thoracoscopic cardiac surgery under cardiopulmonary bypass combined with one-lung ventilation has been identified as the trend in cardiac surgery. The aim of this study was to examine the effects of the selective α ₂ adrenergic receptor agonist dexmedetomidine on the pulmonary function of patients who underwent mitral valve surgery using the totally thoracoscopic technique.

Methods

Fifty-seven patients who underwent thoracoscopic mitral valve surgery between July 2019 and December 2019 were selected. The patients were randomly divided into the control (Con) group (n = 28) and the dexmedetomidine (DEX) group (n = 29) using the random number table method. Arterial blood gas analyses were performed, and the oxygenation (PaO₂/FiO₂) and respiratory indexes (P(A-a)O/PaO₂) were calculated 5 min after tracheal intubation (T1), 2 h after operation (T2), 6 h after operation (T3), and 24 h after operation (T4). Moreover, the serum cytokines interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and intercellular adhesion molecule-1 (ICAM-1) were detected using the enzyme-linked immunosorbent method at all time points. Chest radiography was performed 24 h after surgery. Peripheral blood samples were collected before and after the operation for a complete hemogram. Additionally, the procalcitonin concentration was measured and recorded when the patients were transported to the intensive care unit (ICU). The postoperative extubation time, length of ICU stay, and pulmonary infection rate were also recorded.

Results

Inflammatory reaction after surgery was evident. However, the inflammatory cytokines IL-6, TNF-α, and ICAM-1 in the DEX group were lower than those in the Con group after surgery (T2 to T4; P < 0.05). Neutrophil counts and procalcitonin concentration were higher in the Con group than in the DEX group (P < 0.05). In addition, in the DEX group, pulmonary exudation on chest radiography was lower, and pulmonary function, as shown by an increase in oxidation index and decrease in the respiratory index, improved after surgery (P < 0.05). Moreover, the duration of mechanical ventilation in the Con group was 3.4 h longer than that in the DEX group.

Conclusion

Dexmedetomidine has a protective effect on pulmonary function in patients undergoing mitral valve surgery using a totally video-assisted thoracoscopic technique, which may be related to a reduction in the concentration of inflammatory cytokines in the early perioperative period.

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 alleviates blunt chest trauma and hemorrhagic shock‑resuscitation‑induced acute lung injury through inhibiting the NLRP3 inflammasome

Blunt chest trauma with hemorrhagic shock frequently induces pulmonary inflammation that leads to acute lung injury (ALI). The present study aimed to explore the protective effects of dexmedetomidine (Dex) in blunt chest trauma and hemorrhagic shock-resuscitation (THSR)-induced ALI by mediating nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome formation in rats. An ALI model in rats induced by THSR was constructed and Dex was administered intraperitoneally (5 µg/kg/h) immediately after blunt chest trauma. Blood samples were collected for the determination of proinflammatory factor levels, and lung tissue specimens were harvested for wet/dry (W/D) weight ratio, hematoxylin and eosin staining, and transmission electron microscopy analyses. Additionally, malondialdehyde (MDA), superoxide dismutase (SOD), lactate dehydrogenase (LDH) and myeloperoxidase (MPO) activity were evaluated, and the expression of protein in lung tissues was examined via western blot analysis. Compared with the sham group, pathological alterations in the ALI group and the W/D ratios were significantly increased. MDA, LDH and MPO activity, and the levels of interleukin (IL)-1β, IL-18, IL-6 and tumor necrosis factor-α were significantly elevated. NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain and caspase-1 expression was significantly increased. Conversely, Dex treatment significantly reversed these changes. The present study demonstrated that by reducing inflammatory responses, Dex exerted protective effects against THSR-ALI in rats, potentially via the inhibition of NLRP3 signaling pathways.

Organ-Protective Effects and the Underlying Mechanism of Dexmedetomidine

Dexmedetomidine (DEX) is a highly selective α2 adrenergic receptor (α2AR) agonist currently used in clinical settings. Because DEX has dose-dependent advantages of sedation, analgesia, antianxiety, inhibition of sympathetic nervous system activity, cardiovascular stabilization, and significant reduction of postoperative delirium and agitation, but does not produce respiratory depression and agitation, it is widely used in clinical anesthesia and ICU departments. In recent years, much clinical study and basic research has confirmed that DEX has a protective effect on a variety of organs, including the nervous system, heart, lungs, kidneys, liver, and small intestine. It acts by reducing the inflammatory response in these organs, activating antiapoptotic signaling pathways which protect cells from damage. Therefore, based on wide clinical application and safety, DEX may become a promising clinical multiorgan protection drug in the future. In this article, we review the physiological effects related to organ protection in α2AR agonists along with the organ-protective effects and mechanisms of DEX to understand their combined application value.

Effect of hesperetin on systemic inflammation and hepatic injury after blunt chest trauma in rats

We investigated the protective effect of hesperetin on hepatic damage after blunt chest trauma in rats using histological and biochemical methods. We used 18 adult male rats in three groups of six: control, chest trauma and chest trauma + hesperetin. Chest trauma was caused by dropping a metal cylinder onto the right hemithorax. Hesperetin, 100 mg/kg, was administered orally for 7 days. At the end of the seventh day, liver tissue samples were obtained. Serum tumor necrosis factor-alpha (TNF-α), interleukin 1-beta (IL-1β), alanine aminotransferase (AST), aspartate transferase (ALT) and lactate dehydrogenase (LDH) enzyme activities were measured in blood samples taken from the heart. The general structure of liver tissue was investigated using hematoxylin and eosin staining. Nuclear factor kappa beta (Nf-κβ) expression in liver tissue was determined by the indirect immunohistochemical method. Apoptosis was determined using the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) method. Decreased TNF-α, AST and ALT enzyme activity, fewer histopathological changes and lower Nf-kB expression were observed in the hesperetin treated group compared to the chest trauma group. We also found reduced hepatic apoptosis in the chest trauma + hesperetin group compared to the chest trauma group. Hesperetine inhibits liver damage by reducing proinflammatory cytokines and by suppressing Nf-κβ activity in a blunt chest trauma model in rats.

The effect of aerosolized indomethacin on lung inflammation and injury in a rat model of blunt chest trauma

Background

Acute lung contusion from blunt chest trauma (BCT) is characterized by an intense inflammatory response in the pulmonary parenchyma, which is associated with acute lung injury (ALI), acute respiratory distress syndrome and ventilator-associated pneumonia. We hypothesized that aerosolized indomethacin may reduce pulmonary inflammation and ALI in a rat model of BCT.

Methods

Sprague-Dawley rats were anesthetized and received a tracheotomy for administration of aerosolized medication through a catheter. The BCT procedure involved free-dropping a hollow metal weight (200 g) from a height of 25.5, 38.3 or 51.2 cm onto the right thorax. We administered 1 mg/kg of indomethacin or 1 mL/kg of saline intratracheally 15 minutes after BCT. The sham group had a similar procedure without the exposure to BCT and treatment. Three hours postimpact, we obtained arterial blood gas and analyzed bronchoalveolar lavage for protein concentration, polymorphonuclear leukocytes (PMN) and cytokine levels, and lung tissue samples were taken for histopathological analysis.

Results

The rats’ mean arterial pressure and heart rate dropped immediately postimpact but recovered close to that of the sham group after 30 minutes in both control and treatment groups. Compared to BCT alone, indomethacin significantly reduced the total protein level in the lungs (1.06 ± 0.39 mg/mL v. 3.75 ± 1.95 mg/mL, p = 0.006) and alveolar FD-70 leak (0.23 ± 0.19 μg/mL v. 0.53 ± 0.19 μg/mL, p = 0.02). Indomethacin also significantly attenuated the acute inflammatory response in percent PMN (13.33 ±7.5% v. 28.0 ± 12.96%, p = 0.04). Tumour necrosis factor-α and interleukin-6 decreased in the indomethacin group, but the decreases were not significant compared with other groups.

Conclusion

Aerosolized indomethacin has a protective effect against alveloar tissue permeability and inflammatory response induced by BCT.

Cardioprotective effect of caffeic acid phenethyl ester on cardiac contusion following blunt chest trauma in rats

We investigated the effects of caffeic acid phenethyl ester (CAPE) on cardiac damage after blunt chest injury. Forty male adult Wistar albino rats were divided into four groups; control, cardiac contusion, cardiac contusion + CAPE, and CAPE. CAPE, 10 mmol/kg, was administered intraperitoneally for 7 days following cardiac contusion. Heart tissue and blood were obtained at the end of the experimental period. Cardiac histopathology was determined using hematoxylin & eosin (H & E) staining. Expression of tumor necrosis factor-alpha (TNF-α) in cardiomyocytes was determined using immunohistochemistry. Cardiac apoptosis was determined using the TUNEL method. Serum creatine kinase (CK), creatine kinase-muscle/brain (CK-MB) and lactate dehydrogenase (LDH) levels were determined using spectrophotometric methods. The serum cardiac troponin I (C-TI) level was measured using the ELISA method. Myofibril loss was detected in the cardiomyocytes of the cardiac contusion group. Increased apoptosis and TNF-α expression were observed in the cardiac contusion group compared to the control group. Increased CK, CK-MB, LDH and C-TI levels were found in the cardiac contusion group. We found that CAPE administration improved myocardial function. Compared to the cardiac contusion group, CK, CK-MB, LDH and C-TI levels decreased significantly in the cardiac contusion + CAPE group. Administration of CAPE significantly inhibited apoptosis and cardiac TNF-α expression. Our findings demonstrate the therapeutic effects of CAPE for cardiac contusion damage after blunt chest trauma.

Penehyclidine hydrochloride exerts protective effects in rats with acute lung injury via the Fas/FasL signaling pathway

Acute lung injury (ALI) is a critical syndrome that is associated with high morbidity and mortality rates. The activation of the Fas/Fas ligand (FasL) signaling pathway may be an important pathophysiological mechanism during ALI development. Penehyclidine hydrochloride (PHC) has been revealed to exhibit anti-apoptotic properties and may attenuate the observed systemic inflammatory response. The present study was performed to elucidate the molecular mechanism of PHC in the regulation of the Fas/FasL signaling pathway in rats with ALI. An ALI rat model was constructed by inducing blunt chest trauma and hemorrhagic shock (T/HS), with PHC administration prior to or following T/HS. At 6 h following T/HS, blood samples and lung tissues were collected. Western blotting, arterial blood gas analysis, ELISA, hematoxylin and eosin staining, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling staining and biochemical indicator analysis were performed to determine the degree of lung injury and the key signaling pathways associated with lung damage. The results indicated that the administration of PHC following T/HS effectively attenuates lung injury by improving pulmonary oxygenation, decreasing histopathological damage, decreasing polymorphonuclear neutrophil count and decreasing Fas, FasL, caspase-8, caspase-3, tumor necrosis factor-α, interleukin (IL)-6 and IL-1β expression. The results indicated that PHC exhibits anti-apoptotic functions and exerts protective effects in ALI rats induced by T/HS, which may be attributed to the inhibition of the Fas/FasL signaling pathway.

A Study of the Therapeutic Effects of Resveratrol on Blunt Chest Trauma-Induced Acute Lung Injury in Rats and the Potential Role of Endocan as a Biomarker of Inflammation

The present study focused on the therapeutic effects of resveratrol in a rat model of blunt chest trauma-induced acute lung injury and the potential role of endocan as a biomarker of inflammation. They were randomly divided into the following four groups (n = 7 in each group): control group (no treatment or trauma); trauma group (trauma-induced group); resveratrol group (resveratrol [0.3 mg/kg] administered via the i.p. route group); and resveratrol + trauma group (resveratrol [0.3 mg/kg] administered via the i.p. route 1 h prior to the induction of trauma At the end of the 24 h, all the experimental rats were sacrificed. Lung lobe and blood samples were collected for biochemical, histopathological, and immunohistochemical investigations. Serum endocan levels were found to be significantly higher in the travma, resveratrol, and resveratrol + trauma groups than in the control group (p < 0.001, p < 0.001, p < 0.001). Moreover, in resveratrol + trauma group, endocan showed a significant increase compared to trauma and resveratrol group (p < 0.001, p < 0.001). Serum MDA level was significantly higher in the trauma group than in the control group (p = 0.017). SOD showed a significant increase in resveratrol and resveratrol + trauma groups compared to control group (p < 0.001, p < 0.001). The present study suggested that resveratrol exerted antioxidant properties in a rat model of lung injury after blunt chest trauma. Thus, it may have therapeutic potential in cases of blunt chest trauma-induced lung injury. Serum levels of endocan were not correlated with the inflammation response. The clinical use of endocan as a biomarker of inflammation in lung injury caused by blunt chest trauma is not recommended.

Use of Dexmedetomidine in Cardiothoracic and Vascular Anesthesia

Dexmedetomidine is a highly selective α₂-adrenergic agonist with analgesic and sedative properties. In the United States, the Food and Drug Administration approved the use of the drug for short-lasting sedation (24 h) in intensive care units (ICUs) in patients undergoing mechanical ventilation and endotracheal intubation. In October 2008, the Food and Drug Administration extended use of the drug for the sedation of nonintubated patients before and during surgical and nonsurgical procedures. In the European Union, the European Medicine Agency approved the use of dexmedetomidine in September 2011 with a single recognized indication: ICU adult patients requiring mild sedation and awakening in response to verbal stimulus. At present, the use of dexmedetomidine for sedation outside the ICU remains an off-label indication. The benefits of dexmedetomidine in critically ill patients and in cardiac, electrophysiology-related, vascular, and thoracic procedures are discussed.

Effects of dexmedetomidine on TNF-α and interleukin-2 in serum of rats with severe craniocerebral injury

Background

Dexmedetomidine is a highly selective adrenergic receptor agonist, which has a dose-dependent sedative hypnotic effect. Furthermore, it also has pharmacological properties, and the ability to inhibit sympathetic activity and improve cardiovascular stability during an operation. However, its protective effect on patients with severe craniocerebral injury in the perioperative period remains unclear.

Method

Eighty adult male SD rats were used and divided into two groups (n = 40, each group): dexmedetomidine injury group (experimental group), and sodium chloride injury group (control group). Models of severe craniocerebral injury were established in these two groups using the modified Feeney’s free-fall method. As soon as the establishment of models was succeed, rat in the experimental group received 1 μg of dexmedetomidine (0.1 ml), while each rat in the control group was given 0.1 ml of 0.9% sodium chloride. Blood was sampled from an incision at the femoral vein to detect TNF-α and IL-2 levels at 1, 12, 24,36,48 and 72 h after establishing the model in the two groups.

Results

After severe craniocerebral injury, TNF-α levels of rats were lower in every stage and at different degrees in the experimental group than in the control group (P < 0.05), while IL-2 levels were lower in the experimental group to different extents (P < 0.05).

Conclusion

Dexmedetomidine protects the brain of rats with severe craniocerebral injury by reducing the release of inflammatory mediators.

Perioperative "remote" acute lung injury: recent update

Perioperative acute lung injury (ALI) is a syndrome characterised by hypoxia and chest radiograph changes. It is a serious post-operative complication, associated with considerable mortality and morbidity. In addition to mechanical ventilation, remote organ insult could also trigger systemic responses which induce ALI. Currently, there are limited treatment options available beyond conservative respiratory support. However, increasing understanding of the pathophysiology of ALI and the biochemical pathways involved will aid the development of novel treatments and help to improve patient outcome as well as to reduce cost to the health service. In this review we will discuss the epidemiology of peri-operative ALI; the cellular and molecular mechanisms involved on the pathological process; the clinical considerations in preventing and managing perioperative ALI and the potential future treatment options.

Dexmedetomidine decreases the inflammatory response to myocardial surgery under mini-cardiopulmonary bypass

Cardiopulmonary bypass (CPB) with extracorporeal circulation produces changes in the immune system accompanied by an increase in proinflammatory cytokines and a decrease in anti-inflammatory cytokines. We hypothesize that dexmedetomidine (DEX) as an anesthetic adjuvant modulates the inflammatory response after coronary artery bypass graft surgery with mini-CPB. In a prospective, randomized, blind study, 12 patients (4 females and 8 males, age range 42-72) were assigned to DEX group and compared with a conventional total intravenous anesthesia (TIVA) group of 11 patients (4 females and 7 males). The endpoints used to assess inflammatory and biochemical responses to mini-CPB were plasma interleukin (IL)-1, IL-6, IL-10, interferon (INF)-γ, tumor necrosis factor (TNF)-α, C-reactive protein, creatine phosphokinase, creatine phosphokinase-MB, cardiac troponin I, cortisol, and glucose levels. These variables were determined before anesthesia, 90 min after beginning CPB, 5 h after beginning CPB, and 24 h after the end of surgery. Endpoints of oxidative stress, including thiobarbituric acid reactive species and delta-aminolevulinate dehydratase activity in erythrocytes were also determined. DEX+TIVA use was associated with a significant reduction in IL-1, IL-6, TNF-α, and INF-γ (P<0.0001) levels compared with TIVA (two-way ANOVA). In contrast, the surgery-induced increase in thiobarbituric acid reactive species was higher in the DEX+TIVA group than in the TIVA group (P<0.01; two-way ANOVA). Delta-aminolevulinate dehydratase activity was decreased after CPB (P<0.001), but there was no difference between the two groups. DEX as an adjuvant in anesthesia reduced circulating IL-1, IL-6, TNF-α, and INF-γ levels after mini-CPB. These findings indicate an interesting anti-inflammatory effect of DEX, which should be studied in different types of surgical interventions.

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.

Inflammatory Response in Patients under Coronary Artery Bypass Grafting Surgery and Clinical Implications: A Review of the Relevance of Dexmedetomidine Use

Despite the fact that coronary artery bypass grafting surgery (CABG) with cardiopulmonary bypass (CPB) prolongs life and reduces symptoms in patients with severe coronary artery diseases, these benefits are accompanied by increased risks. Morbidity associated with cardiopulmonary bypass can be attributed to the generalized inflammatory response induced by blood-xenosurfaces interactions during extracorporeal circulation and the ischemia/reperfusion implications, including exacerbated inflammatory response resembling the systemic inflammatory response syndrome (SIRS). The use of specific anesthetic agents with anti-inflammatory activity can modulate the deleterious inflammatory response. Consequently, anti-inflammatory anesthetics may accelerate postoperative recovery and better outcomes than classical anesthetics. It is known that the stress response to surgery can be attenuated by sympatholytic effects caused by activation of central (α-)2-adrenergic receptor, leading to reductions in blood pressure and heart rate, and more recently, that they can have anti-inflammatory properties. This paper discusses the clinical significance of the dexmedetomidine use, a selective (α-)2-adrenergic agonist, as a coadjuvant in general anesthesia. Actually, dexmedetomidine use is not in anesthetic routine, but this drug can be considered a particularly promising agent in perioperative multiple organ protection.

N-Acetylcysteine counteracts oxidative stress and protects alveolar epithelial cells from lung contusion-induced apoptosis in rats with blunt chest trauma

The aim of this study was to investigate the protective effects of N-acetylcysteine (NAC) on peroxidative and apoptotic changes in the contused lungs of rats following blunt chest trauma. The rats were randomly divided into three groups: control, contusion, and contusion + NAC. All the rats, apart from those in the control group, performed moderate lung contusion. A daily intramuscular NAC injection (150 mg/kg) was given immediately following the blunt chest trauma and was continued for two additional days following cessation of the trauma. Samples of lung tissue were taken in order to evaluate the tissue malondialdehyde (MDA) level, histopathology, and epithelial cell apoptosis using terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay and active caspase-3 immunostaining. In addition, we immunohistochemically evaluated the expression of surfactant protein D (SP-D) in the lung tissue. The blunt chest trauma-induced lung contusion resulted in severe histopathological injury, as well as an increase in the MDA level and in the number of cells identified on TUNEL assay together with active caspase-3 positive epithelial cells, but a decrease in the number of SP-D positive alveolar type 2 (AT-2) cells. NAC treatment effectively attenuated histopathologic, peroxidative, and apoptotic changes, as well as reducing alterations in SP-D expression in the lung tissue. These findings indicate that the beneficial effects of NAC administrated following blunt chest trauma is related to the regulation of oxidative stress and apoptosis.

The antinociceptive effect of dexmedetomidine modulates spleen cell immunity in mice

BACKGROUND

Pain plays roles in both the nervous system and immune system. Changes in the neuroendocrine pathway under pain conditions give rise to sympathetic outflow with increased plasma catecholamines and activate immune reactions. Dexmedetomidine exerts sedative, analgesic, and anesthetic-sparing effects and is known to diminish pro-inflammatory processes by central sympatholytic effects. To investigate the influence of the analgesic effect of dexmedetomidine on immunomodulation under pain conditions, splenic natural killer (NK) tumoricidal cytotoxic activity, proliferative ability of T lymphocytes, and cytokine changes were assessed.

METHODS

After evaluation of the analgesic efficacy of dexmedetomidine in C57BL mice that were subjected to formalin-induced pain, dexmedetomidine (30 µg/kg) or saline was injected intraperitoneally (ip) 30 min before formalin (20 µL of 2% formalin in 0.9% saline) injection. NK cell activity against NK-sensitive YAC-1 lymphoma cells was evaluated by the percentage of specific lactate dehydrogenase (LDH) release. Various numbers of effector cells (NK cells) were added to the wells of a microtiter plate containing 2 × 10(4) target YAC-1 cells in 100 μL, to achieve final effector-to-target cell ratios of 80:1, 40:1, and 20:1. The level of lymphocyte proliferation in response to phytohemagglutinin (PHA) was detected by bromodeoxyuridine (BrdU) incorporation assay. TNF-α, IL-1β, and IL-10 levels were determined in blood samples and supernatants of splenocyte preparations.

RESULTS

IP administration of dexmedetomidine significantly decreased the time of licking and biting during the first and second phases of the formalin test (p <0.001). Formalin-induced pain led to higher activity of NK cells than in sham-treated mice (p <0.05), but NK activity was not increased significantly by ip dexmedetomidine treatment. Formalin-induced pain significantly increased splenic lymphocyte proliferation (p <0.05), but dexmedetomidine did not alter this response. There was a significant increase in plasma TNF-α (p = 0.048) and IL-6 (p = 0.014) levels after formalin-induced pain. However, the differences between the responses after ip dexmedetomidine did not change significantly.

CONCLUSIONS

Dexmedetomidine showed antinociceptive effect on both of acute pain phase 1 and hyperalgesic phase 2 of formalin pain model. Formalin-induced pain alters cellular immunity of spleen in mice. Dexmedetomidine attenuates the activation of NK cells under pain condition, but neither the proliferative response of the splenic lymphocytes nor the cytokine production was affected by dexmedetomidine.

Dexmedetomidine regulates inflammatory molecules contributing to ventilator-induced lung injury in dogs

BACKGROUND

Dexmedetomidine reduced mortality and inhibited the inflammatory response during endotoxemia in rats. The aim of this study was to clarify the effect of dexmedetomidine-regulating inflammation on a noninfectious, ventilator-induced lung injury (VILI) in dogs.

METHODS

Thirty healthy Beagles weighing between 8 and 12 kg were randomly divided into five groups: control group (group C, n = 6), mechanical ventilation (group MV, n = 6), and three different doses of dexmedetomidine group (group DEX1-3, n = 6). VILI was induced by high-tidal volume ventilation (tidal volume 20 mL/kg; respiratory rate 15 breaths/min; FiO2 0.5). Group DEX received intravenous Dex 20 min before endotracheal intubation (0.5, 1.0, and 2.0 μg/kg Dex was infused within 20 min and then a maintenance dose of 0.5, 1.0, and 2.0 μg/kg/h Dex was infused intravenously). Arterial blood samples were obtained from femoral artery at base state, MV1h, MV2h, and MV4h for blood gas analysis. After being mechanically ventilated for 4 h, dogs were killed and the levels of pulmonary inflammatory response and polymorphonuclear neutrophils (PMNs) count in bronchoalveolar lavage fluid were evaluated.

RESULTS

Histologic findings of the MV, DEX1, DEX2, and DEX3 groups revealed severe, moderate, mild, and normal to minimal inflammation, respectively. Myeloperoxidase level, PMNs/alveoli ratio, nuclear factor-κB messenger RNA (mRNA), tumor necrosis factor-alpha mRNA, and inducible nitric oxide synthase mRNA expression in lung tissues of the DEX2 and DEX3 were significantly lower than those of the MV group. Partial pressures of oxygen was decreased significantly at MV4h as compared with the baseline. There was no statistical significance in partial pressures of oxygen between MV and DEX2 group as well as between group MV and group DEX3.

CONCLUSIONS

Dexmedetomidine could mitigate pulmonary inflammatory response induced by VILI in dogs.