Lidocaine inhibition of inducible nitric oxide synthase and cationic amino acid transporter-2 transcription in activated murine macrophages may involve voltage-sensitive Na+ channel

A Review of the Lidocaine in the Perioperative Period

This review analyzes the controversies surrounding lidocaine (LIDO), a widely recognized local anesthetic, by exploring its multifaceted effects on pain control in the perioperative setting. The article critically analyzes debates about lidocaine's efficacy, safety, and optimal administration methods. While acknowledging its well-documented analgesic attributes, the text highlights the ongoing controversies in its application. The goal is to provide clinicians with a comprehensive understanding of the current discourse, enabling informed decisions about incorporating lidocaine into perioperative protocols. On the other hand, emphasizes the common uses of lidocaine and its potential role in personalized medicine. It discusses the medication's versatility, including its application in anesthesia, chronic pain, and cardiovascular diseases. The text recognizes lidocaine's widespread use in medical practice and its ability to be combined with other drugs, showcasing its adaptability for individualized treatments. Additionally, it explores the incorporation of lidocaine into hyaluronic acid injections and its impact on pharmacokinetics, signaling innovative approaches. The discussion centers on how lidocaine, within the realm of personalized medicine, can offer safer and more comfortable experiences for patients through tailored treatments.

Pharmacology of the Equine Foot: Medical Pain Management for Laminitis

One of the biggest challenges in managing laminitis in horses remains the control of pain. The best analgesic approach is a multimodal approach, including nonsteroidal anti-inflammatory drugs, opioids, and/or constant rate infusions of α-2 agonists, ketamine, and lidocaine. Recent literature indicates that amitriptyline and soluble epoxide hydrolase inhibitor might be beneficial. Clinically oriented studies will be needed if they have a place in laminitis pain management. The systemic pain control can be combined with local techniques such as long-acting local anesthetics or epidural catheterization that allows for administration of potent analgesic therapy with a lower risk of negative side effects.

The Efficacy of Lidocaine in Disrupting Cocaine Cue-Induced Memory Reconsolidation

RATIONAL

Cue-induced craving memories, linked to drug-seeking behaviors, require key molecular processes for memory reconsolidation. Lidocaine, a sodium channel blocker, inhibits NMDA receptor activation and suppresses nitric oxide and ERK production. These processes are required for memory re-consolidation; inhibiting them may reduce cue-related craving memories in cocaine dependent subjects.

OBJECTIVES

To assess the efficacy of lidocaine in decreasing cue-induced cocaine craving and cocaine use.

METHODS

Treatment-seeking cocaine-dependent participants (n = 33, 25 men) were recruited. Personalized craving and relaxation scripts were developed. Participants were then randomly assigned in a double-blind design to either receive intravenous lidocaine immediately following a cocaine craving script (lidocaine/craving), saline following a craving script (saline/craving), or lidocaine following a relaxation script (lidocaine/relax). One week following the infusion, cue-induced craving was assessed in the same paradigm without an infusion. Cocaine use and craving were assessed for 4 weeks following infusion.

RESULTS

The administration of lidocaine during craving induction (lidocaine/craving) did not decrease cue-induced craving during craving reactivation one week later or craving and cocaine use over the 4-week follow-up period compared to the saline/craving group. There were no significant differences in craving and cocaine use between the lidocaine/relax and saline/craving groups.

CONCLUSION

Lidocaine administered following craving induction did not decrease subsequent cue-induced craving or cocaine use. Blocking the reconsolidation of craving-related memories with pharmacological agents remains an important area of investigation.

Neosaxitoxin Inhibits the Expression of Inflammation Markers of the M1 Phenotype in Macrophages

(1) Background: Neosaxitoxin (NeoSTX) has been used as a local anesthetic, but its anti-inflammatory effects have not been well defined. In the present study, we investigate the effects of NeoSTX on lipopolysaccharide (LPS)-activated macrophages. (2) Methods: Raw 264.7 and equine PBMC cells were incubated with or without 100 ng/mL LPS in the presence or absence of NeoSTX (1µM). The expression of inflammatory mediators was assessed: nitric oxide (NO) content using the Griess assay, TNF-α content using the ELISA assay, and mRNA of inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) using a real-time polymerase chain reaction. (3) Results: NeoSTX (1 μM) significantly inhibited the release of NO, TNF-α, and expression of iNOS, IL-1β, and TNF-α in LPS-activated macrophages of both species studied. Furthermore, our study shows that the LPS-induced release of inflammatory mediators was suppressed by NeoSTX. Additionally, NeoSTX deactivated polarized macrophages to M1 by LPS without compromising its polarization towards M2. (4) Conclusions: NeoSTX inhibits LPS-induced release of inflammatory mediators from macrophages, and these effects may be mediated by the blockade of voltage-gated sodium channels (VGSC).

The in vitro mechanisms and in vivo efficacy of intravenous lidocaine on the neuroinflammatory response in acute and chronic pain

INTRODUCTION

The neuroinflammatory response plays a key role in several pain syndromes. Intravenous (iv) lidocaine is beneficial in acute and chronic pain. This review delineates the current literature concerning in vitro mechanisms and in vivo efficacy of iv lidocaine on the neuroinflammatory response in acute and chronic pain.

DATABASES AND DATA TREATMENT

We searched PUBMED and the Cochrane Library for in vitro and in vivo studies from July 1975 to August 2014. In vitro articles providing an explanation for the mechanisms of action of lidocaine on the neuroinflammatory response in pain were included. Animal or clinical studies were included concerning iv lidocaine for acute or chronic pain or during inflammation.

RESULTS

Eighty-eight articles regarding iv lidocaine were included: 36 in vitro studies evaluating the effect on ion channels and receptors; 31 animal studies concerning acute and chronic pain and inflammatory models; 21 clinical studies concerning acute and chronic pain. Low-dose lidocaine inhibits in vitro voltage-gated sodium channels, the glycinergic system, some potassium channels and Gαq-coupled protein receptors. Higher lidocaine concentrations block potassium and calcium channels, and NMDA receptors. Animal studies demonstrate lidocaine to have analgesic effects in acute and neuropathic pain syndromes and anti-inflammatory effects early in the inflammatory response. Clinical studies demonstrate lidocaine to have advantage in abdominal surgery and in some neuropathic pain syndromes.

CONCLUSIONS

Intravenous lidocaine has analgesic, anti-inflammatory and antihyperalgesic properties mediated by an inhibitory effect on ion channels and receptors. It attenuates the neuroinflammatory response in perioperative pain and chronic neuropathic pain.

Sodium chloride promotes pro-inflammatory macrophage polarization thereby aggravating CNS autoimmunity

The increasing incidence in Multiple Sclerosis (MS) during the last decades in industrialized countries might be linked to a change in dietary habits. Nowadays, enhanced salt content is an important characteristic of Western diet and increased dietary salt (NaCl) intake promotes pathogenic T cell responses contributing to central nervous system (CNS) autoimmunity. Given the importance of macrophage responses for CNS disease propagation, we addressed the influence of salt consumption on macrophage responses in CNS autoimmunity. We observed that EAE-diseased mice receiving a NaCl-high diet showed strongly enhanced macrophage infiltration and activation within the CNS accompanied by disease aggravation during the effector phase of EAE. NaCl treatment of macrophages elicited a strong pro-inflammatory phenotype characterized by enhanced pro-inflammatory cytokine production, increased expression of immune-stimulatory molecules, and an antigen-independent boost of T cell proliferation. This NaCl-induced pro-inflammatory macrophage phenotype was accompanied by increased activation of NF-kB and MAPK signaling pathways. The pathogenic relevance of NaCl-conditioned macrophages is illustrated by the finding that transfer into EAE-diseased animals resulted in significant disease aggravation compared to untreated macrophages. Importantly, also in human monocytes, NaCl promoted a pro-inflammatory phenotype that enhanced human T cell proliferation. Taken together, high dietary salt intake promotes pro-inflammatory macrophages that aggravate CNS autoimmunity. Together with other studies, these results underline the need to further determine the relevance of increased dietary salt intake for MS disease severity.

Modulation of Dendritic Cell Activation and Subsequent Th1 Cell Polarization by Lidocaine

Dendritic cells play an essential role in bridging innate and adaptive immunity by recognizing cellular stress including pathogen- and damage-associated molecular patterns and by shaping the types of antigen-specific T cell immunity. Although lidocaine is widely used in clinical settings that trigger cellular stress, it remains unclear whether such treatment impacts the activation of innate immune cells and subsequent differentiation of T cells. Here we showed that lidocaine inhibited the production of IL–6, TNFα and IL–12 from dendritic cells in response to toll-like receptor ligands including lipopolysaccharide, poly(I:C) and R837 in a dose-dependent manner. Notably, the differentiation of Th1 cells was significantly suppressed by the addition of lidocaine while the same treatment had little effect on the differentiation of Th17, Th2 and regulatory T cells in vitro. Moreover, lidocaine suppressed the ovalbumin-specific Th1 cell responses in vivo induced by the adoptive transfer of ovalbumin-pulsed dendritic cells. These results demonstrate that lidocaine inhibits the activation of dendritic cells in response to toll-like receptor signals and subsequently suppresses the differentiation of Th1 cell responses.

Intravenous lidocaine decreases tumor necrosis factor alpha expression both locally and systemically in pigs undergoing lung resection surgery

BACKGROUND

Lung resection surgery is associated with an inflammatory reaction. The use of 1-lung ventilation (OLV) seems to increase the likelihood of this reaction. Different prophylactic and therapeutic measures have been investigated to prevent lung injury secondary to OLV. Lidocaine, a commonly used local anesthetic drug, has antiinflammatory activity. Our main goal in this study was to investigate the effect of IV lidocaine on tumor necrosis factor α (TNF-α) lung expression during lung resection surgery with OLV.

METHODS

Eighteen pigs underwent left caudal lobectomy. The animals were divided into 3 groups: control, lidocaine, and sham. All animals received general anesthesia. In addition, animals in the lidocaine group received a continuous IV infusion of lidocaine during surgery (1.5 mg/kg/h). Animals in the sham group only underwent thoracotomy. Samples of bronchoalveolar lavage (BAL) fluid and plasma were collected before initiation of OLV, at the end of OLV, at the end of surgery, and 24 hours after surgery. Lung biopsy specimens were collected from the left caudal lobe (baseline) before surgery and from the mediastinal lobe and the left cranial lobe 24 hours after surgery. Samples were flash-frozen and stored to measure levels of the following inflammatory markers: interleukin (IL) 1β, IL-2, IL-10, TNF-α, nuclear factor κB, monocyte chemoattractant protein-1, inducible nitric oxide synthase, and endothelial nitric oxide synthase. Markers of apoptosis (caspase 3, caspase 9, Bad, Bax, and Bcl-2) were also measured. In addition, levels of metalloproteinases and nitric oxide metabolites were determined in BAL fluid and in plasma samples. A nonparametric test was used to examine statistical significance.

RESULTS

OLV caused lung damage with increased TNF-α expression in BAL, plasma, and lung samples. Other inflammatory (IL-1β, nuclear factor κB, monocyte chemoattractant protein-1) and apoptosis (caspase 3, caspase 9, and BAX) markers were also increased. With the use of IV lidocaine there was a significant decrease in the levels of TNF-α in the same samples compared with the control group. Lidocaine administration also reduced the inflammatory and apoptotic changes observed in the control group. Hemodynamic values, blood gas values, and airway pressure were similar in all groups.

CONCLUSIONS

Our results suggest that lidocaine can prevent OLV-induced lung injury through reduced expression of proinflammatory cytokines and lung apoptosis. Administration of lidocaine may help to prevent lung injury during lung surgery with OLV.

P2X7 is involved in the anti-inflammation effects of levobupivacaine

BACKGROUND

We sough to elucidate whether purinergic P2X7 receptor is actively involved in the effects of levobupivacaine on inhibiting microglia activation.

MATERIALS AND METHODS

Microglia were treated with lipopolysaccharide (LPS, 50 ng/mL), LPS plus levobupivacaine (50 μM), or LPS plus levobupivacaine plus the P2X7 receptor agonist Bz-ATP (100 μM) and denoted as the LPS, LPS + Levo, and LPS + Levo + Bz-ATP group, respectively. Microglia activation was measured by assaying inflammatory molecules expression. Microglia activation was also measured by assaying neuronal cell viability using coculture of microglia and neurons, as activated microglia may cause neuron injury. We also measured the levels of P2X7 receptor activation in microglia using ethidium uptake assay.

RESULTS

Our data confirmed the effects of levobupivacaine on inhibiting inflammatory molecules upregulation in activated microglia, as the concentrations of interleukin (IL)-1β, tumor necrosis factor α, IL-6, and macrophage inflammatory protein 2, of the LPS + Levo group were significantly lower than those of the LPS group (all P < 0.05). Moreover, Bz-ATP significantly abrogated the inhibitory effects of levobupivacaine, as concentrations of IL-1β, tumor necrosis factor α, IL-6, and macrophage inflammatory protein 2 of the LPS + Levo + Bz-ATP group were significantly higher than those of the LPS + Levo group (all P < 0.05). In contrast, neuronal cell viability of the LPS + Levo group was significantly higher than those of the LPS and LPS + Levo + Bz-ATP groups (P = 0.012 and 0.002). Moreover, levels of P2X7 receptor activation of the LPS and LPS + Levo + Bz-ATP groups were significantly higher than that of the LPS + Levo group (P = 0.003 and 0.006).

CONCLUSIONS

P2X7 receptor is involved in the effects of levobupivacaine on inhibiting microglial activation.

High-lipid enteral nutrition could partially mitigate inflammation but not lung injury in hemorrhagic shock rats

BACKGROUND

Loss of gut barrier function is crucial in mediating lung injury induced by hemorrhagic shock/resuscitation (HS). High-lipid enteral nutrition (HL) can preserve gut barrier function. We hypothesized that HL could also mitigate HS-induced lung injury.

MATERIALS AND METHODS

Forty-eight adult male rats were randomly assigned to one of four experimental groups: HS; HS-HL; Sham; Sham-HL. HS was induced by blood drawing and mean blood pressure was maintained at 40-45 mmHg for 120 min followed by resuscitation with re-infusion of exsanguinated blood/saline mixtures. HL gavage was performed at 45 min before blood drawing and at the end of resuscitation.

RESULTS

Intestinal permeability of the HS group was significantly higher than that of the Sham group (P < 0.001). Pulmonary concentrations of malondialdehyde (lipid peroxidation) and inflammatory molecules, including prostaglandin E2, tumor necrosis factor-α, interleukin-6, and macrophage inflammatory protein-2, of the HS group were significantly higher than those of the Sham group. Histologic analyses, including histopathology, wet/dry weight ratio, and neutrophil infiltration revealed moderate lung injury in the HS group. In contrast, intestinal permeability (P < 0.001) and pulmonary concentrations of tumor necrosis factor-α and macrophage inflammatory protein-2 (P = 0.021 and 0.01) of the HS-HL group were significantly lower than those of the HS group. However, pulmonary concentrations of malondialdehyde, prostaglandin E2, and interleukin-6 of the HS-HL and HS groups were comparable. Moreover, histologic analyses also revealed moderate lung injury in the HS-HL group.

CONCLUSIONS

High-lipid enteral nutrition significantly mitigated gut barrier loss and partially mitigated lung inflammation but not oxidation and lung injury in hemorrhagic shock/resuscitation rats.

Platonin mitigates lung injury in a two-hit model of hemorrhage/resuscitation and endotoxemia in rats

BACKGROUND

Traumatic hemorrhagic shock and subsequent resuscitation may promote bacteria translocation and cause endotoxemia, a two-hit process that will induce severe lung injury. The pathogenesis involves oxidative stress, neutrophil infiltration, and inflammatory response. Platonin, a potent antioxidant, possesses potent anti-inflammation capacity. We sought to elucidate whether platonin could mitigate acute lung injury in a two-hit model of traumatic hemorrhage/resuscitation and subsequent endotoxemia.

METHODS

Adult male rats were randomized to receive traumatic hemorrhage/resuscitation plus lipopolysaccharide (HS/L) alone or HS/L plus platonin (200 μg/kg; n = 12 in each group). Sham groups were used simultaneously. At 6 hours after resuscitation, rats were killed and the levels of lung injury were assayed.

RESULTS

Rats treated with HS/L alone had severe lung injury as evidenced by significant alterations in lung function (i.e., arterial blood gas and alveolar-arterial oxygen difference) and histology. Significant increases in polymorphonuclear leukocytes/alveoli ratio (neutrophil infiltration index) and significant increases in the concentrations of inflammatory molecules (including chemokine, cytokine, and prostaglandin E2) and malondialdehyde (lipid peroxidation index) revealed that HS/L caused significant oxidative stress, neutrophil infiltration, and inflammatory response in rat lungs. Moreover, our data revealed that the levels of functional and histologic alteration as well as polymorphonuclear leukocytes/alveoli ratio and the concentrations of inflammatory molecules and malondialdehyde in rats treated with HS/L plus platonin (200 μg/kg) were significantly lower than those treated with HR/L alone.

CONCLUSIONS

Platonin mitigates lung injury in a two-hit model of traumatic hemorrhage/resuscitation and endotoxemia in rats.

Lidocaine attenuates the development of diabetic-induced tactile allodynia by inhibiting microglial activation

BACKGROUND

Lidocaine is used clinically for tactile allodynia associated with diabetes-induced neuropathy. Although the analgesic effect of lidocaine through suppression of microglial activation has been implicated in the development of injury-induced neuropathic pain, its mechanism of action in diabetes-induced tactile allodynia has not yet been completely elucidated.

METHODS

To evaluate the effects of lidocaine on microglial response in diabetic neuropathy, streptozotocin (STZ)-injected mice received a continuous infusion of lidocaine (vehicle, 2, or 10%) from day 14 to day 21 after STZ injection. On day 21, microglial accumulation and p38 mitogen-activated protein kinase activation in the dorsal horn were evaluated. In vitro, the effects of lidocaine on cell viability, chemotactic response to monocyte chemotactic protein-1, and induction of proinflammatory mediators were examined in interferon (IFN)-γ-stimulated primary microglial cells.

RESULTS

Continuous systemic administration of lidocaine in the early progression of tactile allodynia produced long-lasting analgesic effects in STZ-treated mice. Lidocaine significantly reduced accumulation and p38 phosphorylation of microglial cells in the dorsal horn. In vitro, lidocaine down-regulated IFN-γ-induced gene induction of inducible oxide synthase and interleukin-1β. Pretreatment with lidocaine significantly reduced chemotactic response to monocyte chemotactic protein-1 of IFN-γ-activated microglial cells.

CONCLUSION

Lidocaine alleviates STZ-induced tactile allodynia, possibly by modulating the p38 pathway in spinal microglial cells. Inhibiting microglial activation by lidocaine treatment early in the course of diabetes-induced neuropathy represents a potential therapeutic strategy for tactile allodynia.

Magnesium sulfate mitigates lung injury induced by bilateral lower limb ischemia-reperfusion in rats

BACKGROUND

Lower limb ischemia-reperfusion (I/R) elicits oxidative stress and causes inflammation in lung tissues that may lead to lung injury. Magnesium sulfate (MgSO(4)) possesses potent anti-oxidation and anti-inflammation capacity. We sought to elucidate whether MgSO(4) could mitigate I/R-induced lung injury. As MgSO(4) is an L-type calcium channel inhibitor, the role of the L-type calcium channels was elucidated.

MATERIALS AND METHODS

Adult male rats were allocated to receive I/R, I/R plus MgSO(4) (10, 50, or 100 mg/kg), or I/R plus MgSO(4) (100 mg/kg) plus the L-type calcium channels activator BAY-K8644 (20 μg/kg) (n = 12 in each group). Control groups were run simultaneously. I/R was induced by applying rubber band tourniquets high around each thigh for 3 h followed by reperfusion for 3 h. After euthanization, degrees of lung injury, oxidative stress, and inflammation were determined.

RESULTS

Arterial blood gas and histologic assays, including histopathology, leukocyte infiltration (polymorphonuclear leukocytes/alveoli ratio and myeloperoxidase activity), and lung water content, confirmed that I/R caused significant lung injury. Significant increases in inflammatory molecules (chemokine, cytokine, and prostaglandin E(2) concentrations) and lipid peroxidation (malondialdehyde concentration) confirmed that I/R caused significant inflammation and oxidative stress in rat lungs. MgSO(4), at the dosages of 50 and 100 mg/kg but not 10 mg/kg, attenuated the oxidative stress, inflammation, and lung injury induced by I/R. Moreover, BAY-K8644 reversed the protective effects of MgSO(4).

CONCLUSIONS

MgSO(4) mitigates lung injury induced by bilateral lower limb I/R in rats. The mechanisms may involve inhibiting the L-type calcium channels.

Heme oxygenase-1 mediates the protective effects of ischemic preconditioning on mitigating lung injury induced by lower limb ischemia-reperfusion in rats

BACKGROUND

Lower limb ischemia-reperfusion (I/R) imposes oxidative stress, elicits inflammatory response, and subsequently induces acute lung injury. Ischemic preconditioning (IP), a process of transient I/R, mitigates the acute lung injury induced by I/R. We sought to elucidate whether the protective effects of IP involve heme oxygenase-1 (HO-1).

METHODS

Adult male rats were randomized to receive I/R, I/R plus IP, I/R plus IP plus the HO-1 inhibitor tin protoporphyrin (SnPP) (n = 12 in each group). Control groups were run simultaneously. I/R was induced by applying rubber band tourniquet high around each thigh for 3 h followed by reperfusion for 3 h. To achieve IP, three cycles of bilateral lower limb I/R (i.e., ischemia for 10 min followed by reperfusion for 10 min) were performed. IP was performed immediately before I/R. After sacrifice, degree of lung injury was determined.

RESULTS

Histologic findings, together with assays of leukocyte infiltration (polymorphonuclear leukocytes/alveoli ratio and myeloperoxidase activity) and lung water content (wet/dry weight ratio), confirmed that I/R induced acute lung injury. I/R also caused significant inflammatory response (increases in chemokine, cytokine, and prostaglandin E(2) concentrations), imposed significant oxidative stress (increases in nitric oxide and malondialdehyde concentrations), and up-regulated HO-1 expression in lung tissues. IP significantly enhanced HO-1 up-regulation and, in turn, mitigated oxidative stress, inflammatory response, and acute lung injury induced by I/R. In addition, the protective effects of IP were counteracted by SnPP.

CONCLUSIONS

The protective effects of IP on mitigating acute lung injury induced by lower limb I/R are mediated by HO-1.

Platonin mitigates acute lung injury induced by bilateral lower limb ischemia-reperfusion in rats

BACKGROUND

Oxidative stress and inflammatory response are crucial in mediating the development of acute lung injury induced by bilateral lower limb ischemia-reperfusion (I/R). Platonin, a potent antioxidant, possesses anti-inflammation capacity. We sought to elucidate whether platonin could mitigate acute lung injury induced by lower limb I/R.

MATERIALS AND METHODS

Forty-eight adult male rats were allocated to receive I/R, I/R plus platonin (100 μg/kg intravenous injection immediately after reperfusion), sham instrumentation, or sham instrumentation plus platonin (denoted as the I/R, I/R-platonin, Sham, or Sham-platonin group, respectively; n = 12 in each group). Bilateral hind limb I/R was induced by applying rubber band tourniquets high around each thigh for 3 h followed by reperfusion for 3 h. After sacrifice, the degree of lung injury was determined.

RESULTS

Histologic findings revealed moderate inflammation in lung tissues of the I/R group and mild inflammation in those of the I/R-platonin group. Total cell number and protein concentration in bronchoalveolar lavage fluid as well as the leukocyte infiltration and myeloperoxidase activity in lung tissues of the I/R group were significantly higher than those of the I/R-platonin group. The pulmonary concentrations of macrophage inflammatory protein-2, interleukin-6, and prostaglandin E(2) of the I/R group were significantly higher than those of the I/R-platonin group. Moreover, the plasma nitric oxide concentration as well as the nitric oxide and malondialdehyde concentrations in lung tissues of the I/R group were significantly higher than those of the I/R-platonin group.

CONCLUSIONS

Platonin mitigates acute lung injury induced by bilateral lower limb I/R in rats.

Toll-like receptor 4 modulation as a strategy to treat sepsis

Despite a decrease in mortality over the last decade, sepsis remains the tenth leading causes of death in western countries and one of the most common cause of death in intensive care units. The recent discovery of Toll-like receptors and their downstream signalling pathways allowed us to better understand the pathophysiology of sepsis-related disorders. Particular attention has been paid to Toll-like receptor 4, the receptor for Gram-negative bacteria outer membrane lipopolysaccharide or endotoxin. Since most of the clinical trial targeting single inflammatory cytokine in the treatment of sepsis failed, therapeutic targeting of Toll-like receptor 4, because of its central role, looks promising. The purpose of this paper is to focus on the recent data of various drugs targeting TLR4 expression and pathway and their potential role as adjunctive therapy in severe sepsis and septic shock.

Dexmedetomidine-ketamine combination mitigates acute lung injury in haemorrhagic shock rats

AIM OF THE STUDY

Upregulation of pulmonary inflammatory molecules is crucial in mediating the development of acute lung injury induced by haemorrhagic shock. Dexmedetomidine and ketamine possess potent anti-inflammatory capacity. We sought to elucidate whether dexmedetomidine, ketamine, or dexmedetomidine-ketamine combination could mitigate acute lung injury in haemorrhagic shock rats.

METHODS

Fifty adult male Sprague-Dawley rats were randomized to the sham-instrumented, haemorrhagic shock (HS), HS plus dexmedetomidine (HS-D), HS plus ketamine (HS-K), or HS plus dexmedetomidine-ketamine (HS-D+K) group (n=10 in each group). Haemorrhagic shock was induced by blood withdrawing and the mean blood pressure was maintained at 40-45mmHg for 120min. Resuscitation was then performed by infusion of shed blood/saline mixtures. After monitoring for another 8h, rats were sacrificed.

RESULTS

Histology findings and lung injury score analysis revealed moderate lung injury in rats of the HS, HS-D, and HS-K groups, whereas those of the HS-D+K group revealed mild lung injury. The effects of haemorrhagic shock on increasing cell number and protein concentration in bronchoalveolar lavage fluid as well as water content, leukocyte infiltration, and myeloperoxidase activity of lung tissues were significantly attenuated by dexmedetomidine-ketamine combination but not by dexmedetomidine or ketamine alone. Dexmedetomidine-ketamine combination, but not dexmedetomidine or ketamine alone, also significantly inhibited haemorrhagic shock-induced upregulation of pulmonary inflammatory molecules, including nitric oxide, prostaglandin E(2), chemokine (e.g., macrophage inflammatory protein-2), and cytokines [e.g., interleukin (IL)-1beta, and IL-6].

CONCLUSIONS

Dexmedetomidine-ketamine combination mitigates acute lung injury in haemorrhagic shock rats.

Effects of dexmedetomidine on regulating pulmonary inflammation in a rat model of ventilator-induced lung injury

BACKGROUND

We sought to elucidate the effects of dexmedetomidine, a selective alpha2-adrenergic receptor agonist, on the regulation of pulmonary inflammation in ventilator-induced lung injury (VILI) in a rat model.

METHODS

A total of 64 adult male Sprague-Dawley rats were assigned to receive either standard ventilation (tidal volume 10 mL/kg; respiratory rate 50 breaths/minute), high-tidal volume ventilation (HVT: tidal volume 20 mL/kg; respiratory rate 50 breaths/minute), HVT plus dexmedetomidine (0.5, 2.5 or 5.0 microg/kg per hour), or HVT plus dexmedetomidine (0.5, 2.5 or 5.0 microg/kg per hour) and yohimbine (the alpha2-adrenergic receptor antagonist) (n = 8 in each group). The doses of dexmedetomidine were chosen to correspond to 1, 5 and 10 times the clinical dose (0.5 microg/kg per hour). After maintaining ventilation for 4 hours, rats were sacrificed and pulmonary inflammatory changes as well as the upregulation of pulmonary inflammatory molecules were evaluated.

RESULTS

Histological and arterial blood gas analyses confirmed that HVT induced significant lung injury. HVT also significantly increased the pulmonary concentrations of chemokines (e.g. macrophage inflammatory protein-2), cytokines (e.g. tumor necrosis factor-alpha, interleukin [IL]-1beta, and IL-6), inducible nitric oxide synthase/nitric oxide, cyclooxygenase-2/prostaglandin E2. Dexmedetomidine at the dose of 5.0 microg/kg per hour, but not at 0.5 and 2.5 microg/kg per hour, significantly attenuated the effects of HVT. Moreover, these effects of dexmedetomidine were significantly attenuated by yohimbine.

CONCLUSION

Dexmedetomidine at clinically relevant doses had no significant effect in attenuating VILI. In contrast, dexmedetomidine at a dose approximately 10 times higher than the clinical dose significantly attenuated VILI. These effects of dexmedetomidine were mediated, at least in part, by the alpha2-adrenergic receptor.

Anesthetic modulation of immune reactions mediated by nitric oxide

Nitric oxide (NO), when produced via inducible NO synthase (iNOS) in excess under pathological conditions (e.g., inflammation, endotoxemia, and septic shock), may lead to tissue injury and organ dysfunction. The bioavailability of NO and the activity and expression of iNOS are regulated by anesthetic agents. Volatile anesthetics mostly suppress, but in some instances may upregulate, the lipopolysaccharide-and cytokine-induced expression of iNOS in blood vessels and macrophages. Intravenous anesthetics inhibit iNOS expression in macrophages and the liver. Local anesthetics decrease the production of NO by inhibiting iNOS expression in macrophages and increase NO production in glial cells. Based on the literature reported so far, the effects of anesthetics on iNOS expression and activity under conditions of inflammation are controversial, with the observed effects depending on the experimental methods and animal species used. On the other hand, it has been shown that volatile and intravenous anesthetics consistently prevent the development of multiple organ failure elicited by endotoxemia or septic shock. Information, although still insufficient, regarding the interactions between anesthetic agents and the detrimental effects of NO formed during inflammatory processes may help us to construct advanced strategies for anesthetizing and sedating patients with inflammation and sepsis and for anesthetic preconditioning against ischemic injury.