Ketamine-induced hepatoprotection: the role of heme oxygenase-1

Pharmacological prevention of postoperative delirium in patients undergoing cardiac surgery: a bayesian network meta-analysis

The incidence of postoperative delirium in patients undergoing cardiac surgery is very high and increases morbidity and mortality. The possibility of pharmacological means to reduce its incidence is very attractive. At present, there is still no clear demonstration that any drug can prevent postoperative delirium in these patients. The aim of this Bayesian network meta-analysis (NMA) was to evaluate whether there is evidence that a drug is effective in reducing the incidence of POD in cardiac surgical patients. Our NMA showed that preoperative ketamine at subanesthetic doses can significantly reduce the incidence of POD. Risperidone also decreases the incidence of POD, but not significantly.

S-ketamine alleviates carbon tetrachloride-induced hepatic injury and oxidative stress by targeting the Nrf2/HO-1 signaling pathway

The aim of the present study was to investigate the protective effect of S-ketamine (S-KET) against carbon tetrachloride (CCl4) - induced liver damage and oxidative stress, as well as to elucidate the related underlying mechanisms. Blood was collected to measure biochemical parameters (alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), total bilirubin (TB) and γ-glutamyltransferase (γ-GT)) and the liver was harvested for histopathological analysis of enzymes related to the antioxidant response (malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and glutathione peroxidase (GSH-PX)). Liver cell apoptosis was evaluated using the TUNEL assay. In addition, the expression levels of apoptosis-related proteins and the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway were detected by Western blot analysis to explore potential mechanisms. S-KET protected the liver from CCl4-induced damage. The changes to the liver biochemical parameters (increased ALT, AST, ALP, TB, and γ-GT) and oxidative stress-related indicators (increased MDA; depleted SOD, GSH, and GSH-PX) induced by CCl4 were inhibited by S-KET. S-Ket also inhibited CCl4-induced cell apoptosis, the changes in expression of related proteins, and blocked CCl4-induced liver injury and oxidative stress via activation of the Nrf2/HO-1 signaling pathway. S-KET effectively protected the liver by inhibition of CCl4-induced damage via upregulation the Nrf2/HO-1 signaling pathway.

Ketamine reduces LPS-induced HMGB1 via activation of the Nrf2/HO-1 pathway and NF-κB suppression

BACKGROUND

Ketamine, as an anesthetic agent, has an anti-inflammatory effect. In the present study, we investigated whether ketamine inhibits release of high mobility group box 1 (HMGB1), a late-phase cytokine of sepsis, in lipopolysaccharide (LPS)-stimulated macrophages through heme oxygenase-1 (HO-1) induction.

METHODS

Macrophages were preincubated with various concentrations of ketamine and then treated with LPS (1 μg/mL). The cell culture supernatants were collected to measure inflammatory mediators (HMGB1, nitric oxide, tumor necrosis factor-α, and interleukin 1β) by enzyme-linked immunosorbent assay. Moreover, HO-1 protein expression, the phosphorylation and degradation of IκB-α, and the nuclear translocation of nuclear factor E2-related factor 2 and nuclear factor κB (NF-κB) p65 were tested by Western blot analysis. In addition, to further identify the role of HO-1 in this process, tin protoporphyrin (SnPP), an HO-1 inhibitor, was used.

RESULTS

Ketamine treatment dose-dependently attenuated the increased levels of proinflammatory mediators (HMGB1, nitric oxide, tumor necrosis factor α, and interleukin 1β) and increased the HO-1 protein expression in LPS-activated macrophages. Furthermore, ketamine suppressed the phosphorylation and degradation of IκB-α as well as the LPS-stimulated nuclear translocation of NF-κB p65 in macrophages. In addition, the present study also demonstrated that ketamine induced HO-1 expression through the nuclear translocation of nuclear factor E2-related factor 2 in macrophages. The effects of ketamine on LPS-induced proinflammatory cytokines production were partially reversed by the HO inhibitor tin protoporphyrin (SnPP).

CONCLUSION

Ketamine inhibits the release of HMGB1 in LPS-stimulated macrophages, and this effect is at least partly mediated by the activation of the Nrf2/HO-1 pathway and NF-κB suppression.

Glycyrrhizin reduces HMGB1 secretion in lipopolysaccharide-activated RAW 264.7 cells and endotoxemic mice by p38/Nrf2-dependent induction of HO-1

High mobility group box 1 (HMGB1) is now recognized as a late mediator of sepsis. Although glycyrrhizin was known as inhibitor of HMGB1, it is not yet clear underlying mechanism(s). We found that glycyrrhizin activates translocation of Nrf2 from cytosol to nucleus and induces heme oxygenase (HO)-1 expression in RAW 264.7 cells. In addition, deletion of Nrf2 by siRNA significantly reduced mRNA expression of NQO1 and HO-1 suggesting that glycyrrhizin targets Nrf2 gene. The expression of iNOS protein and release of HMGB1 in LPS activated cells were significantly reduced by glycyrrhizin and cells transfected with mouse HO-1 expression vector. The p38MAPK inhibitor (SB203580) but not JNK inhibitor (SP600125) or ERK inhibitor (PD98059) significantly inhibited HO-1 induction by glycyrrhizin, which was confirmed by showing that siP38 transfected cells significantly reduced HO-1 induction. Pretreatment with SB203580 significantly reversed the expression of iNOS and release of NO and HMGB1 in LPS-activated cells. Most importantly, administration of glycyrrhizin (200mg/kg, i.p) significantly reduced hepatic injury and serum HMGB1 in a ZnPPIX-sensitive manner. Thus, it is concluded that glycyrrhizin reduces HMGB1 secretion in lipopolysaccharide-activated RAW 264.7 cells and endotoxemic mice by p38/Nrf2-dependent induction of HO-1.

Antidepressant-like effect of ascorbic acid is associated with the modulation of mammalian target of rapamycin pathway

The present study investigated the involvement of the PI3K, GSK-3β, heme oxygenase-1 (HO-1) and mTOR in the antidepressant-like effect of ascorbic acid in the tail suspension test (TST). Male Swiss mice were pretreated with ascorbic acid (1 mg/kg, p.o.) or vehicle and 45 min after, LY294002 (10 μg/site, i.c.v., reversible PI3K inhibitor), rapamycin (0.2 nmol/site, i.c.v., selective mTOR inhibitor), zinc protoporphyrin (ZnPP - 10 ng/site, i.c.v., HO-1 inhibitor) or vehicle was administered. We also investigated the synergistic effect of ascorbic acid (0.1 mg/kg, p.o., sub-effective dose in the TST) with lithium chloride (10 mg/kg, p.o., non-selective GSK-3β inhibitor), AR-A014418 (0.01 μg/site, i.c.v., selective GSK-3β inhibitor) or cobalt protoporphyrin (CoPP - 0.01 μg/site, i.c.v., HO-1 inducer) in the TST. The antidepressant-like effect of ascorbic acid (1 mg/kg, p.o.) was prevented by the treatment of mice with LY294002, rapamycin or ZnPP. In addition, sub-effective doses of lithium chloride, AR-A014418 or CoPP, combined with a sub-effective dose of ascorbic acid produced a synergistic antidepressant-like effect. We also demonstrated that 1 h after its administration, ascorbic acid increased the phosphorylation of p70S6K and the immunocontent of PSD-95 in the hippocampus of mice. These results indicate that the antidepressant-like effect of ascorbic acid in the TST might be dependent on the activation of PI3K and mTOR, inhibition of GSK-3β as well as induction of HO-1, reinforcing the notion that these are important targets for antidepressant activity and contributing to better elucidate the mechanisms underlying the antidepressant-like effect of ascorbic acid.

Ketamine and peripheral inflammation

The old anesthetic ketamine has demonstrated interactions with the inflammatory response. This review intends to qualify the nature and the mechanism underlying this interaction. For this purpose, preclinical data will be presented starting with the initial works, and then, the probable mechanisms will be discussed. A summary of the most relevant clinical data will be presented. In conclusion, ketamine appears as a unique "homeostatic regulator" of the acute inflammatory reaction and the stress-induced immune disturbances. This is of some interest at a moment when the short- and long-term deleterious consequences of inadequate inflammatory reactions are increasingly reported. Large-scale studies showing improved patient's outcome are, however, required before to definitively assert the clinical reality of this positive effect.

Long-term ketamine and ketamine plus alcohol treatments produced damages in liver and kidney

Ketamine is one of the common recreational drugs used in rave parties and it is frequently taken with alcohol. In spite of this, the potential toxicity of ketamine in liver and kidney has not been fully documented. In this study, ICR mice were treated for periods of 6, 16 and 28 weeks with 30 mg/kg ketamine injected daily intraperitoneally, and together with alcohol (0.5 ml of 10% alcohol for each mouse) during the last 4 weeks of the treatment periods. Our experimental results showed significant damage in liver, including fatty degeneration of liver cells, fibrosis and increase in liver glutamic oxaloacetic transaminase, proliferative cell nuclear antigen and lactate dehydrogenase after 16 weeks of treatment with ketamine. Hydropic degenerations of the kidney tubules were observed as early as 6 weeks of treatment. Long-term ketamine administration (28 weeks) led to atresia of glomeruli in the kidney. Proteinuria was confirmed in the 67% of the ketamine-treated animals after 28 weeks of treatment. It was apparent that ketamine when taken chronically (16 weeks of treatment and thereafter) affected both liver and kidney definitively. The damages in both liver and kidney of these mice were more severe when the animals were treated with both ketamine and alcohol.

Xylazine-/diazepam-ketamine and isoflurane differentially affect hemodynamics and organ injury under hemorrhagic/traumatic shock and resuscitation in rats

Most experimental studies on hemorrhage and trauma are performed under anesthesia. We determined the effects of three commonly used anesthetic regimens on hemodynamics and organ damage under normal and hemorrhagic/traumatic shock (HTS) conditions in rats. Animals were anesthetized with ketamine/diazepam (K/D), ketamine/xylazine (K/X), or isoflurane (ISO). Hemorrhagic/traumatic shock was induced by a midline laparotomy, bleeding to a mean arterial pressure of 30 to 35 mmHg until decompensation, followed by restrictive and adequate phases of resuscitation. The experiment was terminated 120 min after the completion of resuscitation. Under normal conditions, K/D anesthesia resulted in higher mean arterial pressure and heart rate than K/X and higher systemic vascular resistance index (SVRI) than ISO. Stroke volume was significantly lower in K/D group than in K/X and ISO groups. Under normal conditions, ISO anesthesia was accompanied by the highest cardiac index. During shock and resuscitation, heart rate remained higher in the K/D than K/X. During shock, SVRI decreased in the K/D group but increased in K/X and ISO groups. After resuscitation, SVRI was lower, and cardiac index was higher in the ISO group than in the K/D group. Despite higher shed blood volume, the rats anesthetized with ISO did not decompensate within the time frame compared with other groups. Cellular damage (plasma creatine kinase, lactate dehydrogenase, uric acid) was more pronounced with K/D compared with ISO. Histological examinations revealed frequent HTS-induced damage to adrenals, kidney, and liver of animals anesthetized with K/D and K/X but not with ISO. Anesthetics differentially affect HTS-induced hemodynamic alterations and organ injury. Thus, when interpreting data from HTS models, the individual effect of anesthetics should be considered.

Lack of effect of oral administration of resveratrol in LPS-induced systemic inflammation

PURPOSE

The high mortality index due to sepsis and the lack of an effective treatment requires the search for new compounds that can serve as therapy for this disease. Resveratrol, a well-known anti-inflammatory natural compound, might be a good candidate for the treatment of sepsis. The aim of this work was to study the effects of oral administration of resveratrol, before and after sepsis initiation, on inflammation markers in a murine model of endotoxin-induced sepsis.

METHODS

Sprague-Dawley male rats were treated with resveratrol the 3 days prior to LPS administration and 45 min later. Hematological parameters, TNF-α, IL-1β and CINC-1, FRAP and TBARS levels were determined. Resveratrol and resveratrol-derived metabolites profile in plasma was compared after oral and intraperitoneal administration.

RESULTS

Oral treatment with resveratrol had no apparent systemic protective effects. However, resveratrol reduced the levels of lipid peroxidation in the small intestine and colon. Importantly, the administration of LPS caused a decrease in resveratrol absorption. When resveratrol bioavailability after i.p. administration was compared to that observed after oral administration, a different profile of resveratrol metabolites was found in plasma.

CONCLUSION

These results highlight the importance of studying the bioavailability of the assayed compounds in the experimental models used to be able to choose the best route of administration depending on the target organ and to determine which compounds or derived metabolites are effective treating the studied disease.

Critical care "normality": individualized versus protocolized care

Patients with critical illness are heterogeneous, with differing physiologic requirements over time. Goal-directed therapy in the emergency room demonstrates that protocolized care could result in improved outcomes. Subsequent studies have confirmed benefit with such a "bundle-based approach" in the emergency room and in preoperative and postoperative scenarios. However, this cannot be necessarily extrapolated to the medium-term and long-term care pathway of the critically ill patient. It is likely that the development of mitochondrial dysfunction could result in goal-directed types of approaches being detrimental. Equally, arterial pressure aims are likely to be considerably different as the patient's physiology moves toward "hibernation." The agents we utilize as sedative and pressor agents have considerable effects on immune function and the inflammatory profile, and should be considered as part of the total clinical picture. The role of gut failure in driving inflammation is considerable, and the drive to feed enterally, regardless of aspirate volume, may be detrimental in those with degrees of ileus, which is often a difficult diagnosis in the critically ill. The pathogenesis of liver dysfunction may be, at least in part, related to venous engorgement that will contribute toward portal hypertension and gut edema. This, in association with loss of the hepatosplanchnic buffer response, it is likely to contribute to venous pooling in the abdominal cavity, impaired venous return, and decreased central blood volumes. Therapies such as those used in "small-for-size syndrome" may have a role in the chronic stages of septic vascular failure.