Propofol scavenges reactive oxygen species and inhibits the protein nitration induced by activated polymorphonuclear neutrophils

Propofol Downregulates lncRNA MALAT1 to Alleviate Cerebral Ischemia-Reperfusion Injury

Propofol (PPF) is reported to play a protective role in ischemia/reperfusion (I/R) injury, including cerebral ischemia-reperfusion injury (CIRI). This study aims to investigate the mechanism by which PPF ameliorates CIRI. Kunming mice were used to establish the middle cerebral artery occlusion (MCAO)/reperfusion mouse model in vivo. PPF pre-treatment was performed before CIRI. Lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) levels were detected to evaluate the tissue injury. PC12 cells were exposed to hypoxia/reoxygenation (H/R) to construct the in vitro CIRI model, and PC12 cells were pre-treated with PPF before H/R. Quantitative real-time polymerase chain reaction (qRT-PCR) was employed to detect the expression of lncRNA MALAT1 and miR-182-5p. Flow cytometry was used to detect the apoptosis of PC12 cells. Bioinformatics analysis, qRT-PCR, dual-luciferase reporter gene experiments, and RNA immunoprecipitation (RIP) experiments were performed to predict and validate the targeting relationship between MALAT1 and miR-182-5p. Western blot was used to detect Toll-like receptor 4 (TLR4) expression at protein level. PPF pre-treatment remarkably inhibited LDH and CPK levels in the serum of the mice with CIRI, and reduced the apoptosis of PC12 cells exposed to H/R. Besides, PPF pre-treatment markedly suppressed MALAT1 expression in both in vivo and in vitro models and upregulated miR-182-5p expression. MiR-182-5p was validated to be a downstream target gene of MALAT1, and MALAT1 could increase the expression of TLR4 by suppressing miR-182-5p. The effects of PPF on the injury of the mice brain and PC12 cells were partly counteracted by the restoration of MALAT1. PPF protects the brain against I/R-induced injury by regulating MALAT1/miR-182-5p/TLR4 axis.

The analgesic effect of propofol associated with the inhibition of hypoxia inducible factor and inflammasome in complex regional pain syndrome

BACKGROUND

Complex regional pain syndrome (CRPS) is related to microcirculation impairment caused by tissue hypoxia and peripheral cytokine overproduction in the affected human limb and chronic post-ischemic pain (CPIP) is considered as an animal model for this intractable disease. Previous studies suggest that the pathogenesis of CPIP involves the hypoxia inducible factor-1α (HIF-1α) and an exaggerated regional inflammatory and free radical response. The inhibition of HIF-1α is known to relieve CPIP. So, propofol, as a free radical scavenger, is very likely to be beneficial in terms of relieving CPIP.

METHODS

We set up a CPIP model using the hindpaw of mice. We administered propofol (10 mg/kg) just after the reperfusion period (early stage) and also on the second day (late stage), as treatment. The analysis evaluated the expression of HIF-1α, free radicals, and inflammasome.

RESULTS

Propofol administration produced obvious analgesia in both mechanical and thermal evaluation in the early stage of CPIP (2 h after reperfusion). Only a mild analgesic effect was found in the late stage (48 h later after reperfusion). In the early stage, the expression of HIF-1α and the inflammasome marker (NALP1) along with caspase-1 were suppressed by propofol. The free radical level also decreased in the propofol group. But those molecular changes were not founded in the late stage of CPIP.

CONCLUSION

Our data demonstrated that propofol produces mice analgesia in the early stage of CPIP and this effect is associated with inhibition of free radical, hypoxia inducible factor and inflammasome.

The effect of total intravenous anaesthesia with propofol on postoperative pain after third molar surgery: A double-blind randomized controlled trial

BACKGROUND

Total intravenous anaesthesia (TIVA) with propofol may reduce pain after surgery compared with inhalational anaesthetic techniques. Whether propofol provides analgesic benefit may be influenced by the surgical procedure and anaesthetic/analgesic regime. Third molar surgery is a consistent and fairly standard surgical technique that provides a good model for postoperative pain. We investigated whether propofol TIVA or sevoflurane (SEVO) inhalational anaesthesia would produce better quality pain relief after third molar surgery.

METHODS

In this double-blind, randomized controlled trial, patients scheduled for bilateral third molar surgery received propofol TIVA or SEVO inhalational anaesthesia. Postoperative numerical rating pain scores, analgesic consumption, adverse effects and global pain satisfaction were assessed.

RESULTS

Data from 48 patients in each group were analysed. The area under curves for numerical rating scale pain scores were significantly lower in the propofol TIVA group at rest and during mouth opening between 1 and 72 hr after surgery (p = 0.013 at rest, p = 0.021 with mouth opening). There was no difference in postoperative analgesic consumption. Propofol TIVA was associated with less postoperative headache (p = 0.041 in the postoperative anaesthetic care unit, p = 0.036 in ward). There were no differences in other adverse effects including postoperative nausea and vomiting. Global pain satisfaction and level of postoperative discomfort at 24 hr after surgery were significantly better in the propofol TIVA group (p = 0.008 and p = 0.009, respectively).

CONCLUSION

Propofol TIVA was associated with reduced postoperative pain after bilateral third molar surgery, but did not reduce postoperative analgesic consumption.

SIGNIFICANCE

Choice of general anaesthetic technique can affect postoperative analgesia. The results of this study suggest that propofol TIVA improves postoperative pain and patient satisfaction after third molar surgery compared to inhalational anaesthesia.

Serial perioperative cell-free DNA levels in donors and recipients undergoing living donor liver transplantation

BACKGROUND

Effect of anaesthesia and surgery on cell-free DNA (cfDNA) is not known. Given that surgical stress augments inflammation and injury, we hypothesized that levels of cfDNA will fluctuate during perioperative period. Therefore, in this study serial perioperative cfDNA concentration was measured in donors and recipients undergoing living donor liver transplantation (LDLT).

METHODS

Baseline, post-induction, intraoperative and post-operative plasma cfDNA levels were evaluated in 21 donors and recipients each, by Sytox green method. In addition, qPCR was performed in a subset of samples.

RESULTS

Baseline cfDNA levels were higher in recipients (37.62 ng/ml) than in donors (25.49 ng/ml). A decrease in cfDNA was observed following anaesthesia induction in both recipients (11.90 ng/ml) and donors (10.75 ng/ml). When the kinetics of the cfDNA was monitored further, an increase was noted intraoperatively in donors (46.18 ng/ml) and recipients (anhepatic phase: 56.25 ng/ml, reperfusion phase: 54.36 ng/ml). cfDNA levels remained high post-operatively. One recipient who developed post-operative sepsis had the highest cfDNA level (94.72 ng/ml).

CONCLUSION

Plasma cfDNA levels are high in recipients indicative of liver injury. Lower cfDNA levels following induction may be attributed to the subduing effect of anaesthetic agents on cell death. High cfDNA levels seen in intra- and post-operative phases reflect cellular trauma and inflammation. This similar pattern of fluctuation of cfDNA level in donors and recipients is suggestive of its possible utility as a surgical stress marker. In addition, comparable cfDNA levels in anhepatic and reperfusion phase reflect less ischemia reperfusion injury during LDLT.

Effect of propofol on generation of inflammatory mediator of monocytes

OBJECTIVE

To evaluate the effect of propofol with different concentrations on the expression of inflammatory mediators of interleukin and tumor-necrosis factor-α (TNF-α) by stimulating the mouse primary monocytes and human monocytic cell line with lipopolysaccharide (LPS) and also discuss the effect of propofol on the secretion of inflammatory mediator and its possible molecular mechanism.

METHODS

The mononuclear cells of mouse spleen were separated and then purified to obtain the primary monocytes. The dose-effect relationship of production of pro-inflammatory cytokines by monocytes which were stimulated by LPS, namely the monocytes were stimulated by the dose of 0-500 ng/mL for 24 h. ELISA was employed to detect the concentration of IL-6, IL-8 and TNF-α. The effect of propofol on the secretion of above pro-inflammatory cytokines by the monocytes was observed. Cells were divided into the control group, the 0.1% DMSO group, the LPS group and the treatment group with LPS + different dose of propofol (propofol 1-100 μg/mL). ELISA was employed to detect the concentration of IL-6, IL-8 and TNF-α. The change in the expression of important signaling molecules in Toll-like receptor and NF-κB signaling pathway was detected after THP-1 cells were treated with propofol.

RESULTS

The concentration of TNF-α was (3863 ± 153) pg/mL after 12 h of stimulation by LPS and then its concentration was decreased gradually. But the concentration of IL-6 and IL-8 was relatively high after 24 h of stimulation by LPS, (5627 ± 330) pg/mL and (1626 ± 200) pg/mL, respectively. The propofol could inhibit the expression of IL-6, IL-8 and TNF-α caused by LPS. After the intervention treatment of 50 μg/mL propofol, the concentration of IL-6, IL-8 and TNF-α was significantly decreased (P < 0.01).

CONCLUSIONS

The propofol can inhibit the expression of TLR-4 and NF-κB to inhibit the activation of p38 and the expression of pro-inflammatory cytokines.

Propofol Limits Microglial Activation after Experimental Brain Trauma through Inhibition of Nicotinamide Adenine Dinucleotide Phosphate Oxidase

Background:

Microglial activation is implicated in delayed tissue damage after traumatic brain injury (TBI). Activation of microglia causes up-regulation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, with the release of reactive oxygen species and cytotoxicity. Propofol appears to have antiinflammatory actions. The authors evaluated the neuroprotective effects of propofol after TBI and examined in vivo and in vitro whether such actions reflected modulation of NADPH oxidase.

Methods:

Adult male rats were subjected to moderate lateral fluid percussion TBI. Effect of propofol on brain microglial activation and functional recovery was assessed up to 28 days postinjury. By using primary microglial and BV2 cell cultures, the authors examined propofol modulation of lipopolysaccharide and interferon-γ–induced microglial reactivity and neurotoxicity.

Results:

Propofol improved cognitive recovery after TBI in novel object recognition test (48 ± 6% for propofol [n = 15] vs. 30 ± 4% for isoflurane [n = 14]; P = 0.005). The functional improvement with propofol was associated with limited microglial activation and decreased cortical lesion volume and neuronal loss. Propofol also attenuated lipopolysaccharide- and interferon-γ–induced microglial activation in vitro, with reduced expression of inducible nitric oxide synthase, nitric oxide, tumor necrosis factor-α, interlukin-1β, reactive oxygen species, and NADPH oxidase. Microglial-induced neurotoxicity in vitro was also markedly reduced by propofol. The protective effect of propofol was attenuated when the NADPH oxidase subunit p22phox was knocked down by small interfering RNA. Moreover, propofol reduced the expression of p22phox and gp91phox, two key components of NADPH oxidase, after TBI.

Conclusion:

The neuroprotective effects of propofol after TBI appear to be mediated, in part, through the inhibition of NADPH oxidase.

Effect of propofol on proliferation and apoptosis of gastric mucosal cells in gastric ischemia-reperfusion injury in mice

AIM: To observe the changes in proliferation and apoptosis of gastric mucosal cells in gastric ischemia-reperfusion (I/R) injury, and to clarify whether propofol has a gastric protection effect and the possible mechanisms involved.

METHODS: Seventy-two Kunming mice were randomly divided into four groups: sham operation group, I/R injury group, fat emulsion group, and propofol group. Except the sham operation group, I/R injury was induced in other groups by clamping the celiac artery for 30 min and allowing reperfusion for 1h. The mice were finally sacrificed to observe morphological changes and investigate gastric mucosal damage index (GMDI). The histological changes of the stomach were observed using light microscopy. The content of malondialdehyde (MDA) and activity of superoxide dismutas (SOD) in gastric mucosal cells were measured by colorimetry analysis. Immunohistochemistry and TdT-mediated d-UTP-biotin nick end-labeling (TUNEL) assay were used to observe PCNA expression and apoptosis in gastric mucosa, and the expression of Bax and Bcl-2 proteins was determined by Western blot.

RESULTS: Severe mucosal lesions induced by gastric I/R were considerably reduced following administration of propofol (25 mg/kg); mucosal and submueosal hyperemia, edema, and deep erosion were improved significantly. Compared to the I/R group, treatment with propofol significantly reduced gastric mucosal MDA content and cell apoptosis (33.9% ± 1.3% vs 60.8% ± 6.9%, P < 0.01), enhanced SOD activity, promoted cell proliferation (16.0% ± 1.8% vs 6.4% ± 1.2%, P < 0.01), and regulated Bax (0.453 ± 0.025 vs 0.268 ± 0.023, P < 0.01) and Bcl-2 (0.513 ± 0.014 vs 0.752 ± 0.015, P < 0.01) protein expression.

CONCLUSION: Propofol protects against gastric gastric I/R injury possibly by promoting gastric mucosal cell proliferation and inhibiting apoptosis.

Propofol protects against high glucose-induced endothelial dysfunction in human umbilical vein endothelial cells

BACKGROUND

Hyperglycemia, via peroxynitrite-mediated endothelial nitric oxide synthase (eNOS) enzymatic uncoupling, induced endothelial dysfunction. Propofol has been reported to improve high glucose-induced endothelial dysfunction. However, its mechanisms of action remain unclear. We hypothesized that propofol could improve hyperglycemia-induced endothelial dysfunction by decreasing the peroxynitrite level and thus restoring eNOS coupling.

METHODS

At the end of 3 days of incubation in medium with 30 mM glucose, human umbilical vein endothelial cells were treated with different concentrations (0.2, 1, 5, and 25 μM) of propofol for different times (0.5, 1, 2, and 4 hours). In parallel experiments, cells were cultured in 5 mM glucose for 3 days as a control. Nitric oxide (NO) production was measured with a nitrate reductase assay. Superoxide anion (O(2)(·-)) accumulation was measured with the reduction of ferricytochrome c and dihydroethidine fluorescence assay. The treatment that had maximal effect on 30 mM glucose-induced NO production and O(2)(·-) accumulation was applied in the following studies to examine the underlying signaling pathways. eNOS total protein, eNOS dimer and monomer expression, eNOS phosphorylation at Ser(1177), inducible NO synthase total protein, inducible NO synthase dimer and monomer expression, peroxynitrite, and guanosine triphosphate cyclohydrolase I expression were measured by Western blot. Tetrahydrobiopterin (BH(4)) level was measured with liquid chromatography-mass spectrometry.

RESULTS

Compared with 5 mM glucose treatment, 30 mM glucose significantly decreased NO production by 60% (P < 0.001) and increased O(2)(·-) accumulation by 175% (P = 0.0026), which were both attenuated by propofol in a concentration- and time-dependent manner. Compared with 5 mM glucose treatment, total eNOS protein expression was increased by 30 mM glucose (P < 0.001), whereas the ratio of eNOS dimer/monomer (P = 0.0001) and eNOS phosphorylation (P < 0.001) were decreased by 30 mM glucose. Propofol did not affect 30 mM glucose-induced total eNOS protein expression, but restored the ratio of eNOS dimer/monomer (P = 0.0005) and increased eNOS phosphorylation (P < 0.001). 30 mM glucose-induced O(2)(·-) accumulation was inhibited by the eNOS inhibitor hydrochloride. Furthermore, compared with 5 mM glucose treatment, 30 mM glucose decreased the BH(4) level (P = 0.0001) and guanosine triphosphate cyclohydrolase I expression (P < 0.001), whereas it increased peroxynitrite level (P = 0.0003), which could all be reversed by propofol (P = 0.0045, P < 0.001, P = 0.0001 vs 30 mM glucose treatment, respectively).

CONCLUSIONS

Propofol has beneficial effects on 30 mM glucose-induced NO reduction and O(2)(·-) accumulation in human umbilical vein endothelial cells. This may be mediated through inhibiting peroxynitrite-mediated BH(4) reduction, and restoring eNOS coupling.

L-arginine enhances nitrative stress and exacerbates tumor necrosis factor-alpha toxicity to human endothelial cells in culture: prevention by propofol

Supplementation of L-arginine, a nitric oxide precursor, during the late phase of myocardial ischemia/reperfusion increases myocyte apoptosis and exacerbates myocardial injury, but the underlying mechanism is unclear. During myocardial ischemia/reperfusion, apoptosis of endothelial cells precedes that of cardiomyocyte. Tumor necrosis factor-alpha (TNF) production is increased during myocardial ischemia/reperfusion, which may exacerbate myocardial injury by inducing endothelial cell apoptosis. We postulated that L-arginine may exacerbate TNF-induced endothelial cell apoptosis by enhancing peroxynitrite-mediated nitrative stress. Cultured human umbilical vein endothelial cells were either not treated (control) or treated with TNF alone or with TNF in the presence of L-arginine, the nonselective nitric oxide synthase inhibitor N (omega)-nitro-L-arginine (L-NNA), propofol (an anesthetic that scavenges peroxynitrite), or L-arginine plus propofol, respectively, for 24 hours. TNF increased intracellular superoxide and hydrogen peroxide production accompanied by increases of inducible nitric oxide synthase (iNOS) protein expression and nitric oxide production. This was accompanied by increased protein expression of nitrotyrosine, a fingerprint of peroxynitrite and an index of nitrative stress, and increased endothelial cell apoptosis. L-arginine did not enhance TNF-induced increases of superoxide and peroxynitrite production but further increased TNF-induced increase of nitrotyrosine production and exacerbated TNF-mediated cell apoptosis. L-NNA and propofol, respectively, reduced TNF-induced nitrative stress and attenuated TNF cellular toxicity. The L-arginine-mediated enhancement of nitrative stress and TNF toxicity was attenuated by propofol. Thus, under pathological conditions associated with increased TNF production, L-arginine supplementation may further exacerbate TNF cellular toxicity by enhancing nitrative stress.

Propofol pretreatment reduces ceramide production and attenuates intestinal mucosal apoptosis induced by intestinal ischemia/reperfusion in rats

BACKGROUND

Apoptosis has been shown to be a major mode of intestinal epithelial cell death caused by intestinal ischemia/reperfusion (II/R), a condition that is associated with increased oxidative stress. Ceramide has been proposed as a messenger of apoptosis. We investigated if pretreatment with propofol, an anesthetic with antioxidant properties, could reduce ceramide production, and consequently, mucosal epithelial apoptosis induced by II/R in rats.

METHODS

Rat II/R injury was produced by clamping the superior mesenteric artery for 1 h followed by 3 h of reperfusion. Thirty rats were randomly allocated into control, injury (II/R) and propofol (pretreatment) groups (n = 10 per group). In the propofol group, propofol 50 mg/kg, a dose that has been shown to cause the loss of reflex responses to a painful stimulus while remaining sensitive to skin incision in rats, was administered intraperitoneally 30 min before inducing intestinal ischemia, while animals in control and untreated injury groups received an equal volume of intralipid. Intestinal mucosal epithelial apoptosis was detected via electron microscopy and TUNEL analysis. Lipid oxidation product malondialdehyde and the activities of superoxide dismutase were assessed by colorimetric analyses. Ceramide generation and sphingomyelinase mRNA expression in intestinal mucosa were determined by high performance thin layer chromatography and reverse transcriptase polymerase chain reaction, respectively.

RESULTS

II/R caused intestinal mucosal epithelial apoptosis and over-production of ceramide accompanied by up-regulation of sphingomyelinase mRNA expression and increases in lipid oxidation (all P < 0.01 versus control). Propofol pretreatment significantly attenuated these changes (all P < 0.01, propofol versus injury).

CONCLUSION

The findings indicate that propofol pretreatment attenuates II/R-induced intestinal epithelial apoptosis, which might be attributable to its antioxidant property modulating the ceramide pathway.

Why we still use intravenous drugs as the basic regimen for neurosurgical anaesthesia

PURPOSE OF REVIEW

Evolution of neurosurgery mainly trends towards minimally invasive and functional procedures including endoscopies, small-size craniotomies, intraoperative imaging and stereotactic interventions. Consequently, new adjustments of anaesthesia should aim at providing brain relaxation, minimal interference with electrophysiological monitoring, rapid recovery, patients' cooperation during surgery and neuroprotection.

RECENT FINDINGS

In brain tumour patients undergoing craniotomy, propofol anaesthesia is associated with lower intracranial pressure and cerebral swelling than volatile anaesthesia. Hyperventilation used to improve brain relaxation may decrease jugular venous oxygen saturation below the critical threshold. It decreases the cerebral perfusion pressure in patients receiving sevoflurane, but not in those receiving propofol. The advantage of propofol over volatile agents has also been confirmed regarding interference with somatosensory, auditory and motor evoked potentials. Excellent and predictable recovery conditions as well as minimal postoperative side-effects make propofol particularly suitable in awake craniotomies. Finally, the potential neuroprotective effect of this drug could be mediated by its antioxidant properties which can play a role in apoptosis, ischaemia-reperfusion injury and inflammatory-induced neuronal damage.

SUMMARY

Although all the objectives of neurosurgical anaesthesia cannot be met by one single anaesthetic agent or technique, propofol-based intravenous anaesthesia appears as the first choice to challenge the evolution of neurosurgery in the third millennium.

Comparison of spectrophotometric, HPLC and chemilumines-cence methods for 3-nitrotyrosine and peroxynitrite interaction

We have studied the interaction of 3-nitrotyrosine with peroxynitrite using three different methods; chemiluminescence, spectrophotometry and HPLC. Peroxynitrite-induced luminol or lucigenin chemiluminescence were significantly decreased by 3-nitrotyrosine, in concentration-dependent manners. The intensity of the peroxynitrite spectrum was also markedly reduced in the presence of 3-nitrotyrosine in the spectrophometric assay. However, there was no attenuation of the 3-nitrotyrosine signal in the HPLC assay after mixing with peroxynitrite. The interaction of 3-nitrotyrosine and hypochlorous acid (HOCl) was also studied via the chemiluminescence assay, where the HOCl-induced responses were markedly inhibited by 3-nitrotyrosine. These results suggest that caution should be taken when studying the levels or interactions of 3-nitrotyrosine.