Circadian gene expression is suppressed during sevoflurane anesthesia and the suppression persists after awakening

Hippocampal gene expression patterns in Sevoflurane anesthesia associated neurocognitive disorders: A bioinformatic analysis

Background

Several studies indicate general anesthetics can produce lasting effects on cognitive function. The commonly utilized anesthetic agent Sevoflurane has been implicated in neurodegenerative processes. The present study aimed to identify molecular underpinnings of Sevoflurane anesthesia linked neurocognitive changes by leveraging publically available datasets for bioinformatics analysis.

Methods

A Sevoflurane anesthesia related gene expression dataset was obtained. Sevoflurane related genes were obtained from the CTD database. Neurocognitive disorders (NCD) related genes were downloaded from DisGeNET and CTD. Intersecting differentially expressed genes between Sevoflurane and NCD were identified as cross-talk genes. A protein-protein interaction (PPI) network was constructed. Hub genes were selected using LASSO regression. Single sample gene set enrichment analysis; functional network analysis, pathway correlations, composite network analysis and drug sensitivity analysis were performed.

Results

Fourteen intersecting cross-talk genes potentially were identified. These were mainly involved in biological processes including peptidyl-serine phosphorylation, cellular response to starvation, and response to gamma radiation, regulation of p53 signaling pathway, AGE-RAGE signaling pathway and FoxO signaling. Egr1 showed a central role in the PPI network. Cdkn1a, Egr1, Gadd45a, Slc2a1, and Slc3a2 were identified as important or hub cross-talk genes. Among the interacting pathways, Interleukin-10 signaling and NF-kappa B signaling enriched among Sevoflurane-related DEGs were highly correlated with HIF-1 signaling enriched in NCD-related genes. Composite network analysis showed Egr1 interacted with AGE-RAGE signaling and Apelin signaling pathways, Cdkn1a, and Gadd45a. Cdkn1a was implicated in in FoxO signaling, PI3K-Akt signaling, ErbB signaling, and Oxytocin signaling pathways, and Gadd45a. Gadd45a was involved in NF-kappa B signaling and FoxO signaling pathways. Drug sensitivity analysis showed Egr1 was highly sensitive to GENIPIN.

Conclusion

A suite of bioinformatics analysis revealed several key candidate hippocampal genes and associated functional signaling pathways that could underlie Sevoflurane associated neurodegenerative processes.

Anesthetics and Long Term Cancer Outcomes: May Epigenetics Be the Key for Pancreatic Cancer?

Knowledge shows a divergence of results between preclinical and clinical studies regarding anesthesia and postoperative progression of cancer. While laboratory and animal data from then 2000s onwards raised much enthusiasm in this field of research leading to several clinical investigations worldwide, data from randomized trials seem to have killed off hope for many scientists. However several aspects of the actual knowledge should be reevaluated and there is space for new strategies of investigation. In this paper, we perform a critical review of actual knowledge and propose new research strategies with a special focus on anesthetic management and repurposed anesthetic adjuvants for pancreatic cancer.

Glibenclamide ameliorates the expression of neurotrophic factors in sevoflurane anaesthesia-induced oxidative stress and cognitive impairment in hippocampal neurons of old rats

Introduction

Several antidiabetic medications have been proposed as prospective treatments for cognitive impairments in type 2 diabetes patients, glibenclamide (GBC) among them. Our research aimed to evaluate the impact of GBC on hippocampal learning memory and inflammation due to enhanced neurotrophic signals induced by inhalation of sevoflurane.

Material and Methods

Rats (Sprague Dawley, both sexes) were assigned to four groups: a control (vehicle, p.o.), GBC (10 mg/kg b.w.; p.o.), low-dose sevoflurane and low-dose sevoflurane + GBC (10 mg/kg b.w.; p.o.) for 23 days. Terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) staining was performed to analyse the count of apoptotic cells and ELISA was conducted to assess the protein signals. A Western blot, a Y-maze test, and a Morris maze test were performed, and the results analysed. Blood and tissues were collected, and isolation of RNA was performed with qRT-PCR.

Results

The Morris maze test results revealed an improvement in the length of the escape latency on days 1 (P < 0.05), 2 (P < 0.01), 3, and 4 in the low-dose Sevo group. Time spent in the quadrant and crossing axis and the percentage of spontaneous alterations showed a substantial decrease in the low-dose Sevo group which received GBC at 10 mg/kg b.w. Significant increases were shown in IL-6 and TNF-α levels in the low-dose Sevo group, whereas a decrease was evident in the GBC group.

Conclusion

Our results indicate that glibenclamide may be a novel drug to prevent sevoflurane inhalation-induced impaired learning and reduce brain-derived neurotrophic factor release, which may be a vital target for the development of potential therapies for cognitive deficits and neurodegeneration.

Anesthetics may modulate cancer surgical outcome: a possible role of miRNAs regulation

Background

microRNAs (miRNAs) are single-stranded and noncoding RNA molecules that control post-transcriptional gene regulation. miRNAs can be tumor suppressors or oncogenes through various mechanism including cancer cell biology, cell-to-cell communication, and anti-cancer immunity.

Main Body

Anesthetics can affect cell biology through miRNA-mediated regulation of messenger RNA (mRNA). Indeed, sevoflurane was reported to upregulate miR-203 and suppresses breast cancer cell proliferation. Propofol reduces matrix metalloproteinase expression through its impact on miRNAs, leading to anti-cancer microenvironmental changes. Propofol also modifies miRNA expression profile in circulating extracellular vesicles with their subsequent anti-cancer effects via modulating cell-to-cell communication.

Conclusion

Inhalational and intravenous anesthetics can alter cancer cell biology through various cellular signaling pathways induced by miRNAs’ modification. However, this area of research is insufficient and further study is needed to figure out optimal anesthesia regimens for cancer patients.

A Novel Application of Ketamine for Improving Perioperative Sleep Disturbances

Perioperative sleep disturbances are commonly observed before, during, and after surgery and can be caused by several factors, such as preoperative negative moods, general anesthetics, surgery trauma, and pain. Over the past decade, the fast-acting antidepressant effects of the N-methyl-D-aspartate (NMDA) receptor antagonist ketamine represent one of the most attractive discoveries in the field of psychiatry, such as antidepressant and anxiolytic effects. It is also widely used as a short-acting anesthetic and analgesic. Recent research has revealed new possible applications for ketamine, such as for perioperative sleep disorders and circadian rhythm disorders. Here, we summarize the risk factors for perioperative sleep disturbances, outcomes of perioperative sleep disturbances, and mechanism of action of ketamine in improving perioperative sleep quality.

Internal clock and the surgical ICU patient

PURPOSE OF REVIEW

The alteration of circadian rhythms in the postoperative period has been demonstrated to influence the outcomes. With this narrative review we would revise how anesthesia, surgery and intensive care can interfere with the circadian clock, how this could impact on the postsurgical period and how to limit the disruption of the internal clock.

RECENT FINDINGS

Anesthesia affects the clock in relation to the day-time administration and the type of anesthetics, N-methyl-D-aspartate receptor antagonists or gamma-aminobutyric acid receptors agonists. Surgery causes stress and trauma with consequent alteration in the circadian release of cortisol, cytokines and melatonin. ICU represents a further challenge for the patient internal clock because of sedation, immobility, mechanical ventilation and alarms noise.

SUMMARY

The synergic effect of anesthesia, surgery and postoperative intensive care on circadian rhythms require a careful approach to the patient considering a role for therapies and interventions aimed to re-establish the normal circadian rhythms. Over time, approach like the Awakening and Breathing Coordination, Delirium Monitoring and Management, Early Mobility and Family engagement and empowerment bundle can implement the clinical practice.

Sevoflurane anesthesia-mediated oxidative stress and cognitive impairment in hippocampal neurons of old rats can be ameliorated by expression of brain derived neurotrophic factor

Postoperative cognitive dysfunction in elderly patients has been related to neurodegenerative disorders and mortality. Sevoflurane anesthesia has been implicated in both postoperative cognitive dysfunction and neurotoxicity. Given the advantages of using inhaled anesthetics like sevoflurane, it is important to understand how their usage results in neurotoxicity and subsequently devise ways to circumvent or attenuate the anesthetic-mediated induction in neurotoxicity. We have used an aged rat model to investigate the molecular mechanisms by which sevoflurane inhalation results in neurotoxicity and whether modulation of these molecular mechanisms can inhibit or attenuate neurotoxicity and cognitive learning and memory impairment in these animals. Low- or high-dose of sevoflurane resulted in reactive oxygen species generation, increased NADPH oxidase protein expression, apoptosis and autophagy. Sevoflurane inhalation resulted in significant inhibition of brain derived neurotrophic factor (BDNF) and cognitive impairment. And the activation of PI3K/Akt/mTOR signaling pathways are attenuated in sevoflurane-mediated anesthesia. Adeno-associated virus (AAV)-mediated expression of Bdnf, but not controls EGFP, attenuated sevoflurane-induced oxidative stress and cognitive impairment in the rats. Our results highlight that AAV-mediated gene therapy might offer a potential therapeutic opportunity to treat post-operative cognitive impairment resulting from inhaled anesthetics.

Minimum Information in In Vivo Research

Data quality, reproducibility and reliability are a matter of concern in many scientific fields including biomedical research. Robust, reproducible data and scientific rigour form the foundation on which future studies are built and determine the pace of knowledge gain and the time needed to develop new and innovative drugs that provide benefit to patients. Critical to the attainment of this is the precise and transparent reporting of data. In the current chapter, we will describe literature highlighting factors that constitute the minimum information that is needed to be included in the reporting of in vivo research. The main part of the chapter will focus on the minimum information that is essential for reporting in a scientific publication. In addition, we will present a table distinguishing information necessary to be recorded in a laboratory notebook or another form of internal protocols versus information that should be reported in a paper. We will use examples from the behavioural literature, in vivo studies where the use of anaesthetics and analgesics are used and finally ex vivo studies including histological evaluations and biochemical assays.

REM sleep deprivation-induced circadian clock gene abnormalities participate in hippocampal-dependent memory impairment by enhancing inflammation in rats undergoing sevoflurane inhalation

Sleep disturbance can result in memory impairment, and both sleep and hippocampal memory formation are maintained by circadian clock genes. Although preoperative sleep deprivation is known to be an independent risk factor for postoperative cognitive dysfunction (POCD) after inhalation anesthesia, the circadian mechanisms involved are currently unclear. To examine this issue, we constructed models of rapid eye movement sleep deprivation (RSD) and POCD after sevoflurane inhalation, to evaluate the circadian mechanisms underlying preoperative sleep deprivation-induced POCD after sevoflurane inhalation. Morris water maze probe test performance revealed that RSD aggravated the hippocampal-dependent memory impairment induced by sevoflurane anesthesia, and the recovery period of memory impairment was prolonged for more than a week by sleep deprivation. Western blot analysis revealed that sleep deprivation inhibited hippocampal Bmal1 and Egr1 expression for more than 7 days after sevoflurane inhalation. Importantly, hippocampal Per2 expression levels were first decreased by sevoflurane inhalation then increased from the third day by sleep deprivation. Sleep deprivation enhanced the expression of hippocampal inflammatory factors IL-1β and IL-6 after sevoflurane inhalation. In addition, sevoflurane inhalation activated the plasma expression of S100β and IL-6, particularly after sleep deprivation. Sleep deprivation aggravated pathogenic impairment of pyramidal neurons and activated astrocytes in CA1 after sevoflurane inhalation. These results suggest that preoperative RSD aggravates hippocampal memory impairment by enhancing neuroinflammatory injuries after sevoflurane inhalation, which is related to hippocampal clock gene abnormalities.

Effect of Sevoflurane Anesthesia on Brain Is Mediated by lncRNA HOTAIR

Postoperative cognitive dysfunction in elderly patients has been related to neurodegenerative disorders and mortality. Sevoflurane anesthesia has been implicated in both postoperative cognitive dysfunction and neurotoxicity. Given the advantages of using inhaled anesthetics like sevoflurane, it is important to understand how their usage results in neurotoxicity and subsequently devise ways to circumvent or attenuate the anesthetic-mediated induction in neurotoxicity. Long noncoding RNAs (LncRNAs) are a group of > 200 bp long RNAs and show specific spatiotemporal expression profiles. Several recent reports suggest that lncRNAs are involved in responses of the central nervous system (CNS) following acute injuries. However, their role in sevoflurane anesthesia-mediated cognitive dysfunction has not been studied. RNA immunoprecipitation (RIP) combined with qRT-PCR detection of six different lncRNAs showed that the HOTAIR lncRNAs were significantly more bound to both Sin3A and coREST, both corepressors of the RE-1 silencing transcription factor, within rat hippocampus following sevoflurane anesthesia compared with sham. Sevoflurane inhalation resulted in significant inhibition of brain-derived neurotrophic factor (BDNF) and cognitive impairment. Treatment with a combination of siRNAs targeting HOTAIR rescued BDNF expression and improved cognitive responses. Taken together, our results suggest that sevoflurane-mediated brain function impairment is at least in part mediated by the HOTAIR lncRNA.

Day-Time Isoflurane Administration Suppresses Circadian Gene Expressions in Both the Brain and a Peripheral Organ, Liver

OBJECTIVE

The aim of this study is to investigate the effects of light and administration time of isoflurane on circadian gene expression in the brains and liver tissues of rats kept in light-dark cycle.

METHODS

Seventy two 15-days-old rats pups were divided into four groups. All animals were exposed to 1.5% concentration of isoflurane or to 6 L min^-1 O₂ for six hours between Zeitgeber Time (ZT) 0-ZT06 (day-time administration) or ZT12-ZT18 (night-time administration). Rats were sacrificed after six hours of anaesthesia with four-hour time intervals. Total RNA was isolated from brains and liver tissues. Circadian gene expression was examined using quantitative real-time Reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

BMAL1, CLOCK, PER2 and CRY2 gene expression levels were markedly suppressed after day-time anaesthesia in the both brain and liver, but night-time administration caused only temporary suppression of gene expression.

CONCLUSION

The effect of isoflurane on the circadian clock is time-dependent, and administered isoflurane anaesthesia at night had minimal effect on clock gene expression. Additionally, when the treated animals were kept in a regular light-dark cycle, isoflurane-induced phase shift was not observed, possibly because of the light.

Effect of day/night administration of three different inhalational anesthetics on melatonin levels in rats

The nocturnal peak of melatonin can be altered after anesthesia and surgery. We aimed to examine the melatonin levels during the day and night after anesthesia with three commonly used inhalational anesthetics. Forty-eight male Wistar albino rats were randomized into eight groups. Rats were administered anesthesia between 7:00 am and 1:00 pm (day groups) or 7:00 pm and 1:00 am (night groups) for 6 hours. At the end of the anesthesia, blood samples were collected for assessing melatonin levels. Mean values of melatonin levels after 6 hours of anesthesia during daytime were 43.17±12.95 for control, 59.79±27.83 for isoflurane, 50.75±34.28 for sevoflurane and 212.20±49.56 pg/mL for desflurane groups. The night groups' mean melatonin levels were 136.12±33.20 for control, 139.85±56.29 for isoflurane, 117.48±82.39 for sevoflurane and 128.70±44.63 pg/mL for desflurane groups. Desflurane anesthesia between 7:00 am and 1:00 pm significantly increased melatonin levels (p<0.001). Sevoflurane and desflurane anesthesia between 7:00 pm and 1:00 am decreased the melatonin levels but there were no significant differences (p=0.904 and p>0.99, respectively). Isoflurane anesthesia did not significantly change melatonin levels during day or night (p=0.718 and p>0.99, respectively). Our results demonstrate that during daytime desflurane anesthesia can alter melatonin levels. Altered melatonin rhythm following inhalational anesthesia can be related to sleep disorders observed after anesthesia.

Anesthesia-induced hypothermia mediates decreased ARC gene and protein expression through ERK/MAPK inactivation

Several anesthetics have been reported to suppress the transcription of a number of genes, including Arc, also known as Arg3.1, an immediate early gene that plays a significant role in memory consolidation. The purpose of this study was to explore the mechanism of anesthesia-mediated depression in Arc gene and protein expression. Here, we demonstrate that isoflurane or propofol anesthesia decreases hippocampal Arc protein expression in rats and mice. Surprisingly, this change was secondary to anesthesia-induced hypothermia. Furthermore, we confirm in vivo and in vitro that hypothermia per se is directly responsible for decreased Arc protein levels. This effect was the result of the decline of Arc mRNA basal levels following inhibition of ERK/MAPK by hypothermia. Overall, our results suggest that anesthesia-induced hypothermia leads to ERK inhibition, which in turns decreases Arc levels. These data give new mechanistic insights on the regulation of immediate early genes by anesthesia and hypothermia.

Changes in the gene expression levels of microRNAs in the rat hippocampus by sevoflurane and propofol anesthesia

General anesthesia is commonly used in the surgical arena, but little is known regarding its influence at the genomic and molecular levels. MicroRNAs (miRNAs) belong to a new class of non-coding RNA molecules which influence cell biology. In the present study, it was hypothesized that miRNAs alter gene expression levels under general anesthesia. The aim was to compare the miRNA expression profiles in the rat hippocampus in response to anesthesia with representative volatile (sevoflurane) and intravenous (propofol) anesthetics. Wistar Rats were randomly assigned to either a 2.4% sevoflurane, 600 µg/kg/min propofol or control (without anesthetics) group. Total RNA from hippocampal samples which contained miRNA was subjected to quantitative reverse transcription-polymerase chain reaction and Taqman Low-Density Arrays (TLDA). A total of 373 miRNAs are associated with rats and the TLDA analysis revealed that 279 expressed miRNAs (74.8%) were expressed in all three groups. Significant differences in the levels of 33 of the 279 expressed miRNAs (11.8%) were observed among the three groups in response to the anesthetic agents, and when compared with the control group, significant differences were found in 26 of the 279 expressed miRNAs (9.3%). Following sevoflurane anesthesia, the levels of four miRNAs were significantly increased and those of 12 were significantly reduced. By contrast, following propofol anesthesia, the levels of 11 miRNAs were significantly reduced but no miRNAs exhibited significantly elevated levels. One miRNA was common between the two anesthesia groups, whereas 14 miRNAs were significantly differentially expressed. In conclusion, sevoflurane and propofol exerted different effects on miRNA expression in the rat hippocampus.

2,2,2-Tribromoethanol phase-shifts the circadian rhythm of the liver clock in Per2::Luciferase knockin mice: lack of dependence on anesthetic activity

Comprehensive gene expression profiling in mice in response to the inhalation of sevoflurane has revealed that circadian clock gene expression is affected strongly in the liver, heart, lung, and kidney, in this order, but moderately in the spleen and slightly in the brain. Therefore, we examined whether the administration of general anesthetics at different times of the day induces phase shifts of the liver clock in Per2::Luciferase knockin mice. One to 4 days of intraperitoneal injection of 2,2,2-tribromoethanol (240 mg/kg, anesthetic time 60 min) or 2,2,2-trichloroethanol (240 mg/kg, 60 min), common anesthetics in veterinary surgery, caused phase delays when injected during the daytime and phase advances when injected during the nighttime. Inhalation administration of isoflurane for 30 or 60 min during the daytime did not induce a phase delay. Injection of propofol (300 mg/kg, 17 min) during the daytime induced an insignificant phase delay of the Per2 bioluminescence rhythm. Injection of 2,2,2-tribromoethanol did not induce a phase shift in the suprachiasmatic nucleus, the main oscillator, or in behavioral locomotor rhythms, suggesting that 2,2,2-tribromoethanol induced phase shifts of the liver clock independent of the main suprachiasmatic clock. The expression of clock genes, such as Bmal1 and Clock, in mouse liver was decreased strongly 1 and 4 h after a single injection of 2,2,2-tribromoethanol. These results demonstrate that 2,2,2-tribromoethanol or 2,2,2-trichloroethanol produce phase shifts of the peripheral clock, independent of anesthetic activity. These anesthetics may cause circadian rhythm disorders in peripheral organs when administered as general anesthetics several times during the day.

Propofol anaesthesia alters the cerebral proteome differently from sevoflurane anaesthesia

Previous studies suggest that propofol and sevoflurane anaesthesia in rats may have variable effects on the proteome. Brains from untreated rats and rats anaesthetised with intravenous propofol infusion or inhaled sevoflurane were collected at various time points post-anaesthesia and subjected to global protein expression profiling using two-dimensional gel electrophoresis. Significant changes in protein spot intensity (i.e. expression) between the propofol and sevoflurane groups demonstrated clear similarities and differences in proteomic regulation by these anaesthetics. The proteins regulated were broadly classified into groups involved in cytoskeletal/neuronal growth, cellular metabolism, signalling, and cell stress/death responses. Proteins concerned with cell death and stress responses were down-regulated by both agents, but the anaesthetics had variable effects on proteins in the other groups. Importantly, proteins such as Ulip2 and dihydropyrimidinase-like-2 were regulated in opposite directions by propofol and sevoflurane. Moreover, the time-course of regulation of proteins varied depending on the agent used. These data suggest different underlying mechanisms of proteomic regulation. We found that sevoflurane anaesthesia had more pronounced effects, on a wider range of proteins, and over an apparently longer duration than propofol. Thus, sevoflurane could be considered a more disruptive anaesthetic agent. Our findings show that protein expression is regulated differentially according to the anaesthetic agent and the method of delivery support and extend our previous observations of differential genomic regulation by anaesthetics in the brain. This study highlights the power of proteomic studies in assessing the effects of certain anaesthetics on the integrity of neuronal structure and function.

Circadian rhythms and their development in children: implications for pharmacokinetics and pharmacodynamics in anesthesia

The influence of time-of-day on the action and toxicity of drugs may be an important factor in the design of pharmacokinetic (PK) and pharmacodynamic (PD) studies, and the interpretation of data resulting from these studies. Time-of-day can have a profound influence on the action of drugs. In some settings (e.g. cancer chemotherapy), the timing of drug administration has been utilized to maximize therapeutic effect and minimize toxicity. Time-of-day variation in the action of anesthetic drugs has been clearly demonstrated in adults. For example, local anesthetic action is longest during the afternoon, and neuromuscular blockade by rocuronium lasts one-third longer in the morning than the afternoon. Circadian rhythms develop over the first months and years of life. Robust rhythms in hormone production (e.g. melatonin and cortisol) are seen at approximately 3 months of age, but it remains unclear as to when daily rhythms in drug PK and PD first appear. Here, we review the evidence for time-of-day effects in anesthetic drugs in adults and children and outline the potential influence this has on pediatric anesthesia.

The general anesthetic sevoflurane affects the expression of clock gene mPer2 accompanying the change of NAD+ level in the suprachiasmatic nucleus of mice

Sevoflurane is an anesthetic for the general anesthesia. In this study, we showed that sevoflurane anesthesia affects the expression of mouse Per2 (mPer2), which is a clock gene in the brain which is considered the organ where the anesthetics act in. 64.5% of mPer2 circadian expression was repressed under anesthesia in the suprachiasmatic nucleus (SCN) of the brain. After recovering from the anesthesia, the repressed mPer2 expression was restored to the same level as in non anesthesia-treated mice. This repression pattern was also observed in the subsequent phases of diurnal mPer2 expression. However, obvious phase-shift in the mPer2 expression was not showed in this study. On the other hand, the behavior analysis in this experiment exhibited that the phases in the circadian behavioral rhythm were shifted backwards. We also measured the NAD(+) level in the SCN, which was a mediator regulating the mPer2 expression. Then, significant increase of NAD(+) was detected under the anesthesia. These results indicate that the anesthesia induces the increase of NAD(+), and consequently leads to the repression of mPer2 expression and modifies the circadian expression pattern and diurnal behavioral rhythm of mice. Furthermore, the modification of mPer2 expression by the anesthesia is considered to affect various gene expressions.

[Biological rhythms for anaesthesia and intensive care]

Knowledge of biological rhythms has led to better understanding of the time-of-day dependent effects of anaesthetic drugs. These chronopharmacological effects are currently explained by the biological rhythms modulating the pharmacokinetic, toxic and pharmacodynamic parameters of these substances. Such effect has been described for general anesthetics, local anaesthetics, analgesics as well as for antibiotics. But recent data also highlight that general anaesthetics, probably part of their brain effects, also alter the regulation of biological rhythms, including the sleep-wake or the endogenous circadian temperature rhythms. This desynchronization of biological rhythms can led to disturbance of the circadian secretion of many substances, including hormones. Finally, biological rhythms have been also described with regard to physiology of pain and cardiovascular physiopathology. The concept of biological rhythm should be present in mind not only for the clinical management of patients but also for setting studies in the field of anaesthesia, pain and intensive care.

Pattern recognition analysis of proton nuclear magnetic resonance spectra of brain tissue extracts from rats anesthetized with propofol or isoflurane

BACKGROUND

General anesthesia is routinely used as a surgical procedure and its safety has been endorsed by clinical outcomes; however, its effects at the molecular level have not been elucidated. General anesthetics influence glucose metabolism in the brain. However, the effects of anesthetics on brain metabolites other than those related to glucose have not been well characterized. We used a pattern recognition analysis of proton nuclear magnetic resonance spectra to visualize the changes in holistic brain metabolic phenotypes in response to the widely used intravenous anesthetic propofol and the volatile anesthetic isoflurane.

METHODOLOGY/PRINCIPAL FINDINGS

Rats were randomized into five groups (n = 7 each group). Propofol and isoflurane were administered to two groups each, for 2 or 6 h. The control group received no anesthesia. Brains were removed directly after anesthesia. Hydrophilic compounds were extracted from excised whole brains and measured by proton nuclear magnetic resonance spectroscopy. All spectral data were processed and analyzed by principal component analysis for comparison of the metabolite profiles. Data were visualized by plotting principal component (PC) scores. In the plots, each point represents an individual sample. The propofol and isoflurane groups were clustered separately on the plots, and this separation was especially pronounced when comparing the 6-h groups. The PC scores of the propofol group were clearly distinct from those of the control group, particularly in the 6-h group, whereas the difference in PC scores was more subtle in the isoflurane group and control groups.

CONCLUSIONS/SIGNIFICANCE

The results of the present study showed that propofol and isoflurane exerted differential effects on holistic brain metabolism under anesthesia.

A transient inflammatory reaction in the lung after experimental hemorrhagic shock and resuscitation with a hemoglobin-vesicles solution compared with rat RBC transfusion

Transfusion for hemorrhagic shock can improve oxygenation, but immunoreactions may induce inflammation. Artificial oxygen carriers have been developed to address clinical concerns of infection and stability, but whether an artificial oxygen carrier might induce inflammation is not well known. To address this question, we compared inflammatory reactions after resuscitation with hemoglobin vesicles (HbVs) or red blood cells (RBCs) in a hemorrhagic shock rat model. Both HbVs and the stored and irradiated rat RBCs deprived of buffy coat were suspended in recombinant human serum albumin [(Hb) = 8.6 g/dL]. Under anesthesia, hemorrhagic shock was induced for 30 min, followed by resuscitation by 20 min transfusion of HbVs or rat RBCs in a volume equivalent to the volume of withdrawn blood. Lungs were excised 2 or 24 h after resuscitation, and mRNA levels of tumor necrosis factor alpha (TNF-alpha), intercellular adhesion molecule-1 (ICAM-1), nitric oxide synthase 2 (iNOS), nitric oxide synthase 3, hypoxia-inducible factor 1 alpha, and heme oxygenase 1 (HO-1) were measured. In rats resuscitated with HbVs, mRNA levels of TNF-alpha and HO-1 2 h after resuscitation were significantly higher than those in the rat RBC group, but the levels at 24 h were similar in both groups. The expression of iNOS and ICAM-1, second messengers of inflammation, was not affected, and inflammatory levels after 24 h with HbVs are similar to rat RBC transfusion. The rat RBC group did not show an expected inflammatory reaction related to a transfusion-induced lung injury, and a clinical relevance concerning this level of transient inflammatory reaction induced by HbVs is not known; however, attention to the early stage of resuscitation in ongoing studies of HbV is required.