Propofol compared with isoflurane inhibits mitochondrial metabolism in immature swine cerebral cortex

Ganglioside GM1 Alleviates Propofol-Induced Pyroptosis in the Hippocampus of Developing Rats via the PI3K/AKT/NF-κB Signaling Cascade

In pediatric and intensive care units, propofol is widely used for general anesthesia and sedation procedures as a short-acting anesthetic. Multiple studies have revealed that propofol causes hippocampal injury and cognitive dysfunction in developing animals. As is known, GM1, a type of ganglioside, plays a crucial role in promoting nervous system development. Consequently, this study explored whether GM1 mitigated neurological injury caused by propofol during developmental stages and investigated its underlying mechanisms. Seven-day-old SD rats or PC12 cells were used in this study for histopathological analyses, a Morris water maze test, a lactate dehydrogenase release assay, Western blotting, and an ELISA. Furthermore, LY294002 was employed to explore the potential neuroprotective effect of GM1 via the PI3K/AKT signaling cascade. The results indicated that GM1 exerted a protective effect against hippocampal morphological damage and pyroptosis as well as behavioral abnormalities following propofol exposure by increasing p-PI3K and p-AKT expression while decreasing p-p65 expression in developing rats. Nevertheless, the inhibitor LY294002, which targets the PI3K/AKT cascade, attenuated the beneficial effects of GM1. Our study provides evidence that GM1 confers neuroprotection and attenuates propofol-induced developmental neurotoxicity, potentially involving the PI3K/AKT/NF-κB signaling cascade.

Propofol-Related Infusion Syndrome: A Bibliometric Analysis of the 100 Most-Cited Articles

Propofol-related infusion syndrome (PRIS) is a rare, yet life-threatening sequelae to prolonged administration of the anesthetic propofol in mechanically intubated patients. The condition is characterized by progressive multi-system organ failure and eventual mortality; of note, the predominant characteristics of PRIS involve but are not limited to cardiovascular impairment and collapse, metabolic and lactic acidosis, rhabdomyolysis, hyperkalemia, and acute renal failure. While potent or extended doses of propofol have been found to be the primary precipitating factor of this condition, others such as age, critical illness, steroid therapy, and hyperlipidemia have been discovered to play a role as well. This bibliometric analysis was done to reflect the current relevance and understanding of PRIS in recent literature. The SCOPUS database was utilized to conduct a search for articles with keywords "propofol infusion syndrome" and "propofol syndrome" from February 24, 2001, until April 16, 2023, with parameters for article title, citation number, citation per year, author, institution, publishing journal, and country of origin. PRIS was first defined in 1990, just a year after its approval by the Food and Drug Administration for use as a sedative-hypnotic. Since then, interest in PRIS slowly rose up to 13 publications per year in 2013. Seven papers on the topic were published in Critical Care Medicine, six in Neurocritical Care, and four in Anesthesia. The most common institutions were Mayo Clinic, Northeastern University, and Tufts Medical Center. To our knowledge, this is the first bibliometric analysis to evaluate the most influential publications about PRIS. A majority of the research is case-based, possibly owing to the rarity of the condition. Our research suggests that confounding factors outside the precipitating dosage of propofol may be implicated in the onset and progression of PRIS. This study could therefore bring renewed interest to the topic and lead to additional research focused on fully understanding the pathophysiology of PRIS in order to promote the development of novel diagnostics and treatment.

The effects of general anesthetics on mitochondrial structure and function in the developing brain

The use of general anesthetics in modern clinical practice is commonly regarded as safe for healthy individuals, but exposures at the extreme ends of the age spectrum have been linked to chronic cognitive impairments and persistent functional and structural alterations to the nervous system. The accumulation of evidence at both the epidemiological and experimental level prompted the addition of a warning label to inhaled anesthetics by the Food and Drug Administration cautioning their use in children under 3  years of age. Though the mechanism by which anesthetics may induce these detrimental changes remains to be fully elucidated, increasing evidence implicates mitochondria as a potential primary target of anesthetic damage, meditating many of the associated neurotoxic effects. Along with their commonly cited role in energy production via oxidative phosphorylation, mitochondria also play a central role in other critical cellular processes including calcium buffering, cell death pathways, and metabolite synthesis. In addition to meeting their immense energy demands, neurons are particularly dependent on the proper function and spatial organization of mitochondria to mediate specialized functions including neurotransmitter trafficking and release. Mitochondrial dependence is further highlighted in the developing brain, requiring spatiotemporally complex and metabolically expensive processes such as neurogenesis, synaptogenesis, and synaptic pruning, making the consequence of functional alterations potentially impactful. To this end, we explore and summarize the current mechanistic understanding of the effects of anesthetic exposure on mitochondria in the developing nervous system. We will specifically focus on the impact of anesthetic agents on mitochondrial dynamics, apoptosis, bioenergetics, stress pathways, and redox homeostasis. In addition, we will highlight critical knowledge gaps, pertinent challenges, and potential therapeutic targets warranting future exploration to guide mechanistic and outcomes research.

Propofol-Induced Developmental Neurotoxicity: From Mechanisms to Therapeutic Strategies

Propofol is the most commonly used intravenous general anesthetic in clinical anesthesia, and it is also widely used in general anesthesia for pregnant women and infants. Some clinical and preclinical studies have found that propofol causes damage to the immature nervous system, which may lead to neurodevelopmental disorders and cognitive dysfunction in infants and children. However, its potential molecular mechanism has not been fully elucidated. Recent in vivo and in vitro studies have found that some exogenous drugs and interventions can effectively alleviate propofol-induced neurotoxicity. In this review, we focus on the relevant preclinical studies and summarize the latest findings on the potential mechanisms and therapeutic strategies of propofol-induced developmental neurotoxicity.

Inhibition of mitochondrial respiration by general anesthetic drugs

General anesthetic drugs have been associated with various unwanted effects including an interference with mitochondrial function. We had previously observed increases of lactate formation in the mouse brain during anesthesia with volatile anesthetic agents. In the present work, we used mitochondria that were freshly isolated from mouse brain to test mitochondrial respiration and ATP synthesis in the presence of six common anesthetic drugs. The volatile anesthetics isoflurane, halothane, and (to a lesser extent) sevoflurane caused an inhibition of complex I of the electron transport chain in a dose-dependent manner. Significant effects were seen at concentrations that are reached under clinical conditions (< 0.5 mM). Pentobarbital and propofol also inhibited complex I but at concentrations that were two-fold higher than clinical EC50 values. Only propofol caused an inhibition of complex II. Complex IV respiration was not affected by either agent. Ketamine did not affect mitochondrial respiration. Similarly, all anesthetic agents except ketamine suppressed ATP production at high concentrations. Only halothane increased cytochrome c release indicating damage of the mitochondrial membrane. In summary, volatile general anesthetic agents as well as pentobarbital and propofol dose-dependently inhibit mitochondrial respiration. This action may contribute to depressive actions of the drugs in the brain.

Lawrence K. Assessing the relationship between the cerebral metabolic rate of oxygen and the oxidation state of cytochrome-c-oxidase

Significance: Hyperspectral near-infrared spectroscopy (hsNIRS) combined with diffuse correlation spectroscopy (DCS) provides a noninvasive approach for monitoring cerebral blood flow (CBF), the cerebral metabolic rate of oxygen ( CMRO 2 ) and the oxidation state of cytochrome-c-oxidase (oxCCO). CMRO 2 is calculated by combining tissue oxygen saturation ( S t O 2 ) with CBF, whereas oxCCO can be measured directly by hsNIRS. Although both reflect oxygen metabolism, a direct comparison has yet to be studied. Aim: We aim to investigate the relationship between CMRO 2 and oxCCO during periods of restricted oxygen delivery and lower metabolic demand. Approach: A hybrid hsNIRS/DCS system was used to measure hemodynamic and metabolic responses in piglets exposed to cerebral ischemia and anesthetic-induced reductions in brain activity. Results: Although a linear relationship was observed between CMRO 2 and oxCCO during ischemia, both exhibited a nonlinear relationship with respect to CBF. In contrast, linear correlation was sufficient to characterize the relationships between CMRO 2 and CBF and between the two metabolic markers during reduced metabolic demand. Conclusions: The observed relationship between CMRO 2 and oxCCO during periods of restricted oxygen delivery and lower metabolic demand indicates that the two metabolic markers are strongly correlated.

Sevoflurane Effects on Neuronal Energy Metabolism Correlate with Activity States While Mitochondrial Function Remains Intact

During general anesthesia, alterations in neuronal metabolism may induce neurotoxicity and/or neuroprotection depending on the dose and type of the applied anesthetic. In this study, we investigate the effects of clinically relevant concentrations of sevoflurane (2% and 4%, i.e., 1 and 2 MAC) on different activity states in hippocampal slices of young Wistar rats. We combine electrophysiological recordings, partial tissue oxygen (p_tiO₂) measurements, and flavin adenine dinucleotide (FAD) imaging with computational modeling. Sevoflurane minimally decreased the cerebral metabolic rate of oxygen (CMRO₂) while decreasing synaptic transmission in naive slices. During pharmacologically induced gamma oscillations, sevoflurane impaired network activity, thereby decreasing CMRO₂. During stimulus-induced neuronal activation, sevoflurane decreased CMRO₂ and excitability while basal metabolism remained constant. In this line, stimulus-induced FAD transients decreased without changes in basal mitochondrial redox state. Integration of experimental data and computer modeling revealed no evidence for a direct effect of sevoflurane on key enzymes of the citric acid cycle or oxidative phosphorylation. Clinically relevant concentrations of sevoflurane generated a decent decrease in energy metabolism, which was proportional to the present neuronal activity. Mitochondrial function remained intact under sevoflurane, suggesting a better metabolic profile than isoflurane or propofol.

Low neuronal metabolism during isoflurane-induced burst suppression is related to synaptic inhibition while neurovascular coupling and mitochondrial function remain intact

Deep anaesthesia may impair neuronal, vascular and mitochondrial function facilitating neurological complications, such as delirium and stroke. On the other hand, deep anaesthesia is performed for neuroprotection in critical brain diseases such as status epilepticus or traumatic brain injury. Since the commonly used anaesthetic propofol causes mitochondrial dysfunction, we investigated the impact of the alternative anaesthetic isoflurane on neuro-metabolism. In deeply anaesthetised Wistar rats (burst suppression pattern), we measured increased cortical tissue oxygen pressure (p_tiO₂), a ∼35% drop in regional cerebral blood flow (rCBF) and burst-associated neurovascular responses. In vitro, 3% isoflurane blocked synaptic transmission and impaired network oscillations, thereby decreasing the cerebral metabolic rate of oxygen (CMRO₂). Concerning mitochondrial function, isoflurane induced a reductive shift in flavin adenine dinucleotide (FAD) and decreased stimulus-induced FAD transients as Ca²⁺ influx was reduced by ∼50%. Computer simulations based on experimental results predicted no direct effects of isoflurane on mitochondrial complexes or ATP-synthesis. We found that isoflurane-induced burst suppression is related to decreased ATP consumption due to inhibition of synaptic activity while neurovascular coupling and mitochondrial function remain intact. The neurometabolic profile of isoflurane thus appears to be superior to that of propofol which has been shown to impair the mitochondrial respiratory chain.

Emerging Role of Long Noncoding RNAs in Perioperative Neurocognitive Disorders and Anesthetic-Induced Developmental Neurotoxicity

Preclinical investigations in animal models have consistently demonstrated neurobiological changes and life-long cognitive deficits following exposure to widely used anesthetics early in life. However, the mechanisms by which these exposures affect brain function remain poorly understood, therefore, limiting the efficacy of current diagnostic and therapeutic options in human studies. The human brain exhibits an abundant expression of long noncoding RNAs (lncRNAs). These biologically active transcripts play critical roles in a diverse array of functions, including epigenetic regulation. Changes in lncRNA expression have been linked with brain development, normal CNS processes, brain injuries, and the development of neurodegenerative diseases, and many lncRNAs are known to have brain-specific expression. Aberrant lncRNA expression has also been implicated in areas of growing importance in anesthesia-related research, including anesthetic-induced developmental neurotoxicity (AIDN), a condition defined by neurological changes occurring in patients repeatedly exposed to anesthesia, and the related condition of perioperative neurocognitive disorder (PND). In this review, we detail recent advances in PND and AIDN research and summarize the evidence supporting roles for lncRNAs in the brain under both normal and pathologic conditions. We also discuss lncRNAs that have been linked with PND and AIDN, and conclude with a discussion of the clinical potential for lncRNAs to serve as diagnostic and therapeutic targets for the prevention of these neurocognitive disorders and the challenges facing the identification and characterization of associated lncRNAs.

The Neonatal and Juvenile Pig in Pediatric Drug Discovery and Development

Pharmacotherapy in pediatric patients is challenging in view of the maturation of organ systems and processes that affect pharmacokinetics and pharmacodynamics. Especially for the youngest age groups and for pediatric-only indications, neonatal and juvenile animal models can be useful to assess drug safety and to better understand the mechanisms of diseases or conditions. In this respect, the use of neonatal and juvenile pigs in the field of pediatric drug discovery and development is promising, although still limited at this point. This review summarizes the comparative postnatal development of pigs and humans and discusses the advantages of the juvenile pig in view of developmental pharmacology, pediatric diseases, drug discovery and drug safety testing. Furthermore, limitations and unexplored aspects of this large animal model are covered. At this point in time, the potential of the neonatal and juvenile pig as nonclinical safety models for pediatric drug development is underexplored.

Anesthesia-Sepsis-Associated Alterations in Liver Gene Expression Profiles and Mitochondrial Oxidative Phosphorylation Complexes

Background: Hepatic dysfunction plays a major role in adverse outcomes in sepsis. Volatile anesthetic agents may protect against organ dysfunction in the setting of critical illness and infection. The goal of this study was to study the impact of Sepsis-inflammation on hepatic subcellular energetics in animals anesthetized with both Propofol (intravenous anesthetic agent and GABA agonist) and Isoflurane (volatile anesthetic i.e., VAA).

Methods: Sprague-Dawley rats were anesthetized with Propofol or isoflurane. Rats in each group were randomized to celiotomy and closure (control) or cecal ligation and puncture “CLP” (Sepsis-inflammation) for 8 h.

Results: Inflammation led to upregulation in hepatic hypoxia-inducible factor-1 in both groups. Rats anesthetized with isoflurane also exhibited increases in bcl-2, inducible nitric oxide synthase, and heme oxygenase-1(HO-1) during inflammation, whereas rats anesthetized with Propofol did not. In rats anesthetized with isoflurane, decreased mRNA, protein (Complex II, IV, V), and activity levels (Complex II/III,IV,V) were identified for all components of the electron transport chain, leading to a decrease in mitochondrial ATP. In contrast, in rats anesthetized with Propofol, these changes were not identified after exposure to inflammation. RNA-Seq and real-time quantitative PCR (qPCR) expression analysis identified a substantial difference between groups (isoflurane vs. Propofol) in mitogen-activated protein kinase (MAPK) related gene expression following exposure to Sepsis-inflammation.

Conclusions: Compared to rats anesthetized with Propofol, those anesthetized with isoflurane exhibit more oxidative stress, decreased oxidative phosphorylation protein expression, and electron transport chain activity and increased expression of organ-protective proteins.

Inhaled nitric oxide reduces injury and microglia activation in porcine hippocampus after deep hypothermic circulatory arrest

OBJECTIVE

Dysregulation of local nitric oxide (NO) synthetases occurs during ischemia and reperfusion associated with cardiopulmonary bypass, deep hypothermic circulatory arrest (DHCA), and reperfusion. Rapid fluctuations in local NO occurring in neonates and infants probably contribute to inflammation-induced microglial activation and neuronal degeneration after these procedures, eventually impairing neurodevelopment. We evaluated the anti-inflammatory efficacy of inhaled NO (iNO) in a piglet model emulating conditions during pediatric open-heart surgery with DHCA.

METHODS

Infant Yorkshire piglets underwent DHCA (18°C) for 30 minutes, followed by reperfusion and rewarming either with or without iNO (20 ppm) in the ventilator at the onset of reperfusion for 3 hours (n = 5 per group, DHCA-iNO and DHCA). Through craniotomy, brains were extracted after perfusion fixation for histology.

RESULTS

Plasma NO metabolites were elevated 2.5 times baseline data before DHCA by iNO. Fluoro-Jade C staining identified significantly lower number of degenerating neurons in the hippocampus of the DHCA-iNO group (P = .02) compared with the DHCA group. Morphologic analyses of ionized calcium-binding adapter molecule-1 stained microglia, evaluating cell body and dendritic process geometry with Imaris imaging software, revealed subjectively less microglial activation in the hippocampus of pigs receiving iNO.

CONCLUSIONS

Using DHCA for 30 minutes, consistent with clinical exposure, we noted that iNO reduces neuronal degeneration in the hippocampus. In addition, iNO reduces microglial activation in the hippocampus after DHCA. The data suggest that iNO reduces neuronal degeneration by ameliorating inflammation and may be a practical mode of neuroprotection for infants undergoing DHCA.

Potential role of the cAMP/PKA/CREB signalling pathway in hypoxic preconditioning and effect on propofol‑induced neurotoxicity in the hippocampus of neonatal rats

Hypoxic preconditioning (HPC) is neuroprotective against ischaemic brain injury; however, the roles of potential anti‑apoptotic signals in this process have not been assessed. To elucidate the molecular mechanisms involved in HPC‑induced neuroprotection, the effects of HPC on the cyclic adenosine monophosphate (cAMP)/protein kinase A (PKA)/cAMP response element‑binding protein (CREB) signalling pathway and apoptosis in Sprague‑Dawley pups (postnatal day 7) treated with propofol were investigated. Western blot and histological analyses demonstrated that HPC exerts multiple effects on the hippocampus, including the upregulation of cAMP and phosphorylation of CREB. These effects were partially blocked by intracerebroventricular injection of the protein kinase antagonist H89 (5 µmol/5 µl). Notably, the level of cleaved caspase‑3 was significantly downregulated by treatment with the cAMP agonist Sp‑cAMP (20 nmol/5 µl). The results indicate that propofol increased the level of cleaved caspase‑3 and Bax by suppressing the activity of cAMP‑dependent proteins and Bcl‑2; thus, HPC prevents propofol from triggering apoptosis via the cAMP/PKA/CREB signalling pathway.

Impact of inflammation on brain subcellular energetics in anesthetized rats

Background

Emerging data suggests that volatile anesthetic agents may have organ protection properties in the setting of critical illness. The purpose of this study was to better understand the effect of inflammation on cerebral subcellular energetics in animals exposed to two different anesthetic agents—a GABA agonist (propofol) and a volatile agent (isoflurane).

Results

Forty-eight Sprague–Dawley rats were anesthetized with isoflurane or propofol. In each group, rats were randomized to celiotomy and closure (sham) or cecal ligation and puncture (inflammation [sepsis model]) for 8 h. Brain tissue oxygen saturation and the oxidation state of cytochrome aa₃ were measured. Brain tissue was extracted using the freeze-blow technique. All rats experienced progressive increases in tissue oxygenation and cytochrome aa₃ reduction over time. Inflammation had no impact on cytochrome aa₃, but isoflurane caused significant cytochrome aa₃ reduction. During isoflurane (not propofol) anesthesia, inflammation led to an increase in lactate (+ 0.64 vs. − 0.80 mEq/L, p = 0.0061). There were no differences in ADP:ATP ratios between groups. In the isoflurane (not propofol) group, inflammation increased the expression of hypoxia-inducible factor-1α (62%, p = 0.0012), heme oxygenase-1 (67%, p = 0.0011), and inducible nitric oxide synthase (31%, p = 0.023) in the brain. Animals exposed to inflammation and isoflurane (but not propofol) exhibited increased expression of protein carbonyls (9.2 vs. 7.0 nM/mg protein, p = 0.0050) and S-nitrosylation (49%, p = 0.045) in the brain. RNA sequencing identified an increase in heat shock protein 90 and NF-κβ inhibitor mRNA in the inflammation/isoflurane group.

Conclusions

In the setting of inflammation, rats exposed to isoflurane show increased hypoxia-inducible factor-1α expression despite a lack of hypoxia, increased oxidative stress in the brain, and increased serum lactate, all of which suggest a relative increase in anaerobic metabolism compared to propofol. Differences in oxidative stress as well as heat shock protein 90 and NF-κβ inhibitor may account for the differential expression of cerebral hypoxia-inducible factor-1α during inflammation.

Electronic supplementary material

The online version of this article (10.1186/s12868-019-0514-8) contains supplementary material, which is available to authorized users.

Propofol induces impairment of mitochondrial biogenesis through inhibiting the expression of peroxisome proliferator-activated receptor-γ coactivator-1α

Propofol is a commonly used general anesthetic in patient care. Recent studies have shown that propofol has neurological side effects especially in young children, which raises a concern regarding the safety of its use. We explored the effects of the molecular mechanism of propofol on neuronal mitochondrial function in SH-SY5Y cells. Our results demonstrate that clinically relevant doses of propofol reduce the expression of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) in a dose- and time-dependent manner. At a concentration of 2%, propofol suppresses the mitochondrial regulator nuclear respiratory factor 1 and mitochondrial transcription factor A and impairs neuronal mitochondrial biogenesis. These impairments involve reduction of mitochondrial mass and reduction of the ratio of mitochondrial to nuclear DNA as well as reduction of cytochrome C oxidase activity. Propofol treatment reduces intracellular adenosine triphosphate (ATP) production, the mitochondrial respiratory rate, and increases mitochondrial reactive oxygen species production, implying that it disturbs neuronal mitochondrial function. Overexpression of PGC-1α rescued propofol-induced reduced mitochondrial mass, ATP production, and respiratory rate, indicating that PGC-1α is the mediator of the effect of propofol on mitochondrial function. Finally, we demonstrate that propofol suppresses PGC-1α by inhibiting cAMP-response element binding protein (CREB) activation and promoting PKA RI expression, and the addition of cyclic adenosine monophosphate rescues propofol-mediated reduced PGC-1α. In conclusion, PGC-1α is the central mediator of propofol-induced impairment of mitochondrial biogenesis and neuronal mitochondrial dysfunction. Our study demonstrates the molecular mechanism behind propofol-induced neurotoxicity and provides valuable information regarding its side effects in clinical practice.

Cdh1-Mediated Metabolic Switch from Pentose Phosphate Pathway to Glycolysis Contributes to Sevoflurane-Induced Neuronal Apoptosis in Developing Brain

Cdh1 is a regulatory subunit of the anaphase promoting complex/cyclosome (APC/C), known to be involved in regulating neuronal survival. The role of Cdh1 in volatile anesthetics-induced neuronal apoptosis in the developing brain is unknown. In this study, we used postnatal day 7 (P7) and day 21 (P21) mice exposed to 2.3% sevoflurane for 6 h to investigate at which age and duration of exposure sevoflurane affects the expression of Cdh1 and glycolytic enzyme 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) and that of the pentose phosphate pathway (PPP) enzyme, glucose-6-phosphate dehydrogenase (G6PD). Furthermore, we tested whether the cyclin-dependent kinases (cdks) inhibitor roscovatine could counteract the effects caused by exposure to sevoflurane. Finally, we applied the glycolysis inhibitor 3-(3-pyridinyl)-1-(4-pyridinyl)-2-propen-1-one (3-PO), G6PD inhibitor dehydroepiandrosterone (DHEA), and exogenous reduced glutathione to examine the contribution of the glycolysis pathway and PPP to sevoflurane-induced neuroapoptosis. We found that prolonged sevoflurane anesthesia significantly reduces the Cdh1 level in P7 mice compared to in the P21 ones; moreover, the decrease in Cdh1 level results in a switch in glucose metabolism from the PPP to neuronal glycolysis. This leads to an imbalance between reactive oxygen species production and reduced glutathione level in the developing brain, which is more susceptible to oxidative stress. As a result, sevoflurane induces neuroapoptosis through Cdh1-mediated glucose metabolism reprogramming. Our study demonstrates a critical role of Cdh1 in sevoflurane-induced neuroapoptosis by shifting PPP to the glycolytic pathway in the developing brain. These findings suggest that Cdh1 may be a novel target for preventing volatile anesthetics-induced neurotoxicity and memory impairment.

Propofol Alters Long Non-Coding RNA Profiles in the Neonatal Mouse Hippocampus: Implication of Novel Mechanisms in Anesthetic-Induced Developmental Neurotoxicity

BACKGROUND

Propofol induces acute neurotoxicity (e.g., neuroapoptosis) followed by impairment of long-term memory and learning in animals. However, underlying mechanisms remain largely unknown. Long non-coding RNAs (lncRNAs) are found to participate in various pathological processes. We hypothesized that lncRNA profile and the associated signaling pathways were altered, and these changes might be related to the neurotoxicity observed in the neonatal mouse hippocampus following propofol exposure.

METHODS

In this laboratory experiment, 7-day-old mice were exposed to a subanesthetic dose of propofol for 3 hours, with 4 animals per group. Hippocampal tissues were harvested 3 hours after propofol administration. Neuroapoptosis was analyzed based on caspase 3 activity using a colorimetric assay. A microarray was performed to investigate the profiles of 35,923 lncRNAs and 24,881 messenger RNAs (mRNAs). Representative differentially expressed lncRNAs and mRNAs were validated using reverse transcription quantitative polymerase chain reaction. All mRNAs dysregulated by propofol and the 50 top-ranked, significantly dysregulated lncRNAs were subject to bioinformatics analysis for exploring the potential mechanisms and signaling network of propofol-induced neurotoxicity.

RESULTS

Propofol induced neuroapoptosis in the hippocampus, with differential expression of 159 lncRNAs and 100 mRNAs (fold change ± 2.0, P< 0.05). Bioinformatics analysis demonstrated that these lncRNAs and their associated mRNAs might participate in neurodegenerative pathways (e.g., calcium handling, apoptosis, autophagy, and synaptogenesis).

CONCLUSION

This novel report emphasizes that propofol alters profiles of lncRNAs, mRNAs, and their cooperative signaling network, which provides novel insights into molecular mechanisms of anesthetic-induced developmental neurodegeneration and preventive targets against the neurotoxicity.

Possible neurotoxicity of the anesthetic propofol: evidence for the inhibition of complex II of the respiratory chain in area CA3 of rat hippocampal slices

Propofol is the most frequently used intravenous anesthetic for induction and maintenance of anesthesia. Propofol acts first and formost as a GABA_A-agonist, but effects on other neuronal receptors and voltage-gated ion channels have been described. Besides its direct effect on neurotransmission, propofol-dependent impairment of mitochondrial function in neurons has been suggested to be responsible for neurotoxicity and postoperative brain dysfunction. To clarify the potential neurotoxic effect in more detail, we investigated the effects of propofol on neuronal energy metabolism of hippocampal slices of the stratum pyramidale of area CA3 at different activity states. We combined oxygen-measurements, electrophysiology and flavin adenine dinucleotide (FAD)-imaging with computational modeling to uncover molecular targets in mitochondrial energy metabolism that are directly inhibited by propofol. We found that high concentrations of propofol (100 µM) significantly decrease population spikes, paired pulse ratio, the cerebral metabolic rate of oxygen consumption (CMRO₂), frequency and power of gamma oscillations and increase FAD-oxidation. Model-based simulation of mitochondrial FAD redox state at inhibition of different respiratory chain (RC) complexes and the pyruvate-dehydrogenase show that the alterations in FAD-autofluorescence during propofol administration can be explained with a strong direct inhibition of the complex II (cxII) of the RC. While this inhibition may not affect ATP availability under normal conditions, it may have an impact at high energy demand. Our data support the notion that propofol may lead to neurotoxicity and neuronal dysfunction by directly affecting the energy metabolism in neurons.

Propofol induces a metabolic switch to glycolysis and cell death in a mitochondrial electron transport chain-dependent manner

The intravenous anesthetic propofol (2,6-diisopropylphenol) has been used for the induction and maintenance of anesthesia and sedation in critical patient care. However, the rare but severe complication propofol infusion syndrome (PRIS) can occur, especially in patients receiving high doses of propofol for prolonged periods. In vivo and in vitro evidence suggests that the propofol toxicity is related to the impaired mitochondrial function. However, underlying molecular mechanisms remain unknown. Therefore, we investigated effects of propofol on cell metabolism and death using a series of established cell lines of various origins, including neurons, myocytes, and trans-mitochondrial cybrids, with defined mitochondrial DNA deficits. We demonstrated that supraclinical concentrations of propofol in not less than 50 μM disturbed the mitochondrial function and induced a metabolic switch, from oxidative phosphorylation to glycolysis, by targeting mitochondrial complexes I, II and III. This disturbance in mitochondrial electron transport caused the generation of reactive oxygen species, resulting in apoptosis. We also found that a predisposition to mitochondrial dysfunction, caused by a genetic mutation or pharmacological suppression of the electron transport chain by biguanides such as metformin and phenformin, promoted propofol-induced caspase activation and cell death induced by clinical relevant concentrations of propofol in not more than 25 μM. With further experiments with appropriate in vivo model, it is possible that the processes to constitute the molecular basis of PRIS are identified.

Recent Insights Into Molecular Mechanisms of Propofol-Induced Developmental Neurotoxicity: Implications for the Protective Strategies

Mounting evidence has demonstrated that general anesthetics could induce developmental neurotoxicity, including acute widespread neuronal cell death, followed by long-term memory and learning abnormalities. Propofol is a commonly used intravenous anesthetic agent for the induction and maintenance of anesthesia and procedural and critical care sedation in children. Compared with other anesthetic drugs, little information is available on its potential contributions to neurotoxicity. Growing evidence from multiple experimental models showed a similar neurotoxic effect of propofol as observed in other anesthetic drugs, raising serious concerns regarding pediatric propofol anesthesia. The aim of this review is to summarize the current findings of propofol-induced developmental neurotoxicity. We first present the evidence of neurotoxicity from animal models, animal cell culture, and human stem cell-derived neuron culture studies. We then discuss the mechanism of propofol-induced developmental neurotoxicity, such as increased cell death in neurons and oligodendrocytes, dysregulation of neurogenesis, abnormal dendritic development, and decreases in neurotrophic factor expression. Recent findings of complex mechanisms of propofol action, including alterations in microRNAs and mitochondrial fission, are discussed as well. An understanding of the toxic effect of propofol and the underlying mechanisms may help to develop effective novel protective or therapeutic strategies for avoiding the neurotoxicity in the developing human brain.

Behavioral regression in 2 patients with autism spectrum disorder and attention-deficit/hyperactivity disorder after oral surgery performed with a general anesthetic

BACKGROUND AND OVERVIEW

Routine dental care for people with autism spectrum disorders can be complex. There is little published on postoperative behavioral changes associated with use of general anesthetics in this population.

CASE DESCRIPTION

The authors describe postoperative behavioral changes in 2 patients with autism spectrum disorder and attention deficit hyperactivity disorder that the patients' caretakers described as regression. In both cases, behaviors representative of autism spectrum disorder and attention deficit hyperactivity disorder worsened after uncomplicated oral surgery after receipt of a general anesthetic in the operating room. In both cases, behavioral changes caused great difficulties for the patients and caretakers and were difficult to address.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

With little in the scientific literature, these 2 cases have a great importance for the dental care practitioner. Awareness must be raised so that further investigation can occur regarding this phenomenon.

Inhibition of the mitochondrial pyruvate carrier protects from excitotoxic neuronal death

In cortical neurons and hippocampal slice cultures, blocking mitochondrial pyruvate uptake rewires metabolism to increase reliance on glutamate to fuel the TCA cycle. This diminishes the readily releasable pool of neuronal glutamate and minimizes the positive-feedback cascade of excitotoxic injury.

Glutamate is the dominant excitatory neurotransmitter in the brain, but under conditions of metabolic stress it can accumulate to excitotoxic levels. Although pharmacologic modulation of excitatory amino acid receptors is well studied, minimal consideration has been given to targeting mitochondrial glutamate metabolism to control neurotransmitter levels. Here we demonstrate that chemical inhibition of the mitochondrial pyruvate carrier (MPC) protects primary cortical neurons from excitotoxic death. Reductions in mitochondrial pyruvate uptake do not compromise cellular energy metabolism, suggesting neuronal metabolic flexibility. Rather, MPC inhibition rewires mitochondrial substrate metabolism to preferentially increase reliance on glutamate to fuel energetics and anaplerosis. Mobilizing the neuronal glutamate pool for oxidation decreases the quantity of glutamate released upon depolarization and, in turn, limits the positive-feedback cascade of excitotoxic neuronal injury. The finding links mitochondrial pyruvate metabolism to glutamatergic neurotransmission and establishes the MPC as a therapeutic target to treat neurodegenerative diseases characterized by excitotoxicity.

Drug induced mitochondrial dysfunction: Mechanisms and adverse clinical consequences

Several commonly used medications impair mitochondrial function resulting in adverse effects or toxicities. Drug induced mitochondrial dysfunction may be a consequence of increased production of reactive oxygen species, altered mitochondrial permeability transition, impaired mitochondrial respiration, mitochondrial DNA damage or inhibition of beta-oxidation of fatty acids. The clinical manifestation depends on the specific drug and its effect on mitochondria. Given the ubiquitous presence of mitochondria and its central role in cellular metabolism, drug-mitochondrial interactions may manifest clinically as hepatotoxicity, enteropathy, myelosuppression, lipodystrophy syndrome or neuropsychiatric adverse effects, to name a few. The current review focuses on specific drug groups which adversely affect mitochondria, the mechanisms involved and the clinical consequences based on the data available from experimental and clinical studies. Knowledge of these adverse drug-mitochondrial interactions may help the clinicians foresee potential issues in individual patients, prevent adverse drug reactions or alter drug regimens to enhance patient safety.

Selective cerebral perfusion prevents abnormalities in glutamate cycling and neuronal apoptosis in a model of infant deep hypothermic circulatory arrest and reperfusion

Deep hypothermic circulatory arrest is often required for the repair of complex congenital cardiac defects in infants. However, deep hypothermic circulatory arrest induces neuroapoptosis associated with later development of neurocognitive abnormalities. Selective cerebral perfusion theoretically provides superior neural protection possibly through modifications in cerebral substrate oxidation and closely integrated glutamate cycling. We tested the hypothesis that selective cerebral perfusion modulates glucose utilization, and ameliorates abnormalities in glutamate flux, which occur in association with neuroapoptosis during deep hypothermic circulatory arrest. Eighteen infant male Yorkshire piglets were assigned randomly to two groups of seven (deep hypothermic circulatory arrest or deep hypothermic circulatory arrest with selective cerebral perfusion for 60 minutes at 18℃) and four control pigs without cardiopulmonary bypass support. Carbon-13-labeled glucose as a metabolic tracer was infused, and gas chromatography-mass spectrometry and nuclear magnetic resonance were used for metabolic analysis in the frontal cortex. Following 2.5 h of cerebral reperfusion, we observed similar cerebral adenosine triphosphate levels, absolute levels of lactate and citric acid cycle intermediates, and carbon-13 enrichment among three groups. However, deep hypothermic circulatory arrest induced significant abnormalities in glutamate cycling resulting in reduced glutamate/glutamine and elevated γ-aminobutyric acid/glutamate along with neuroapoptosis, which were all prevented by selective cerebral perfusion. The data suggest that selective cerebral perfusion prevents these modifications in glutamate/glutamine/γ-aminobutyric acid cycling and protects the cerebral cortex from apoptosis.

In vivo study of hepatic oxidative stress and mitochondrial function in rabbits with severe hypotension after propofol prolonged infusion

In humans, prolonged sedations with propofol or using high doses have been associated with propofol infusion syndrome. The main objective of this study was to evaluate the effects of prolonged high-dose administration of a specific propofol emulsion (Propofol Lipuro) and an improved lipid formulation (SMOFlipid) in liver mitochondrial bioenergetics and oxidative stress of rabbits, comparatively to a saline control. Twenty-one male New Zealand white rabbits were randomly allocated in three groups that were continuously treated for 20 h. Each group of seven animals received separately: NaCl 0.9 % (saline), SMOFlipid (lipid-based emulsion without propofol) and Lipuro 2 % (propofol lipid emulsion). An intravenous propofol bolus of 20 mg kg⁻¹ was given to the propofol Lipuro group to allow blind orotracheal intubation and mechanical ventilation. Anesthesia was maintained using infusion rates of: 20, 30, 40, 50 and 60 mg kg⁻¹ h⁻¹, according to the clinical scale of anesthetic depth and the index of consciousness values. The SMOFlipid and saline groups received the same infusion rate as the propofol Lipuro group, which were infused during 20 consecutive hours. At the end, the animals were euthanized, livers collected and mitochondria isolated by standard differential centrifugation. Mitochondrial respiration, membrane potential, swelling and oxidative stress were evaluated. Data were processed using one-way ANOVA (p < 0.05). The animals revealed a significant decrease in cardiovascular parameters showing bradycardia and severe hypotension. No statistical differences were observed when using pyruvate as substrate, however, when using succinate as respiratory substrate, significant decrease in ADP-stimulated respiration rate was observed for SMOFlipid group (p = 0.002). Lipid peroxides (p < 0.01) and protein carbonyls (p = 0.01) showed a statistically significant difference between propofol Lipuro and the SMOFlipid groups. These results suggest that lipid-based emulsions can be involved in the regulation of different pathways that ultimately lead to a decrease of state 3 mitochondrial respiration rate. The infusion of propofol Lipuro during prolonged periods, in addition to marked hypotension and hypoperfusion, also showed to have higher anti-oxidant activity and lower impairment of the mitochondrial function comparatively to the improved lipid formulation, SMOFlipid, using the rabbit as animal model.

Effect of propofol and remifentanil on cerebral perfusion and oxygenation in pigs: a systematic review

The objective of this review is to evaluate the existing literature with regard to the influence of propofol and remifentanil total intravenous anaesthesia (TIVA) on cerebral perfusion and oxygenation in healthy pigs. Anaesthesia has influence on cerebral haemodynamics and it is important not only in human but also in veterinary anaesthesia to preserve optimal regulation of cerebral haemodynamics. Propofol and remifentanil are widely used in neuroanaesthesia and are increasingly used in experimental animal studies. In translational models, the pig has advantages compared to small laboratory animals because of brain anatomy, metabolism, neurophysiological maturation, and cerebral haemodynamics. However, reported effects of propofol and remifentanil on cerebral perfusion and oxygenation in pigs have not been reviewed. An electronic search identified 99 articles in English. Title and abstract screening selected 29 articles for full-text evaluation of which 19 were excluded with reasons. Of the 10 peer-reviewed articles included for review, only three had propofol or remifentanil anaesthesia as the primary study objective and only two directly investigated the effect of anaesthesia on cerebral perfusion and oxygenation (CPO). The evidence evaluated in this systematic review is limited, not focused on propofol and remifentanil and possibly influenced by factors of potential importance for CPO assessment. In one study of healthy pigs, CPO measures were within normal ranges following propofol-remifentanil anaesthesia, and addition of a single remifentanil bolus did not affect regional cerebral oxygen saturation (rSO2). Even though the pool of evidence suggests that propofol and remifentanil alone or in combination have limited effects on CPO in healthy pigs, confirmative evidence is lacking.

Ischemia reperfusion injury as a modifiable therapeutic target for cardioprotection or neuroprotection in patients undergoing cardiopulmonary resuscitation

AIMS

We sought to review cellular changes that occur with reperfusion to try to understand whether ischemia-reperfusion injury (RI) is a potentially modifiable therapeutic target for cardioprotection or neuroprotection in patients undergoing cardiopulmonary resuscitation.

DATA SOURCES

Articles written in English and published in PubMed.

RESULTS

Remote ischemic conditioning (RIC) involves brief episodes of non-lethal ischemia and reperfusion applied to an organ or limb distal to the heart and brain. Induction of hypothermia involves cooling an ischemic organ or body. Both have pluripotent effects that reduce the potential harm associated with RI in the heart and brain by reduced opening of the mitochondrial permeability transition pore. Recent trials of RIC and induced hypothermia did not demonstrate these treatments to be effective. Assessment of the effect of these interventions in humans to date may have been modified by use of concurrent medications including propofol.

CONCLUSIONS

Ongoing research is necessary to assess whether reduction of RI improves patient outcomes.

Melatonin pretreatment prevents isoflurane-induced cognitive dysfunction by modulating sleep-wake rhythm in mice

BACKGROUND

Sleep plays an important role in memory processing. However, its role in anesthesia-induced cognitive dysfunction was not revealed. Our study sought to investigate the connection between the cognition decline and sleep-wake rhythm disorders after long-term isoflurane anesthesia in mice. Also, we examined the effect of exogenous melatonin pretreatment on both cognitive function and circadian rhythm. Furthermore, we discussed whether NR2B (N-methyl-D-aspartate receptor 2B subunit)-CREB (cAMP-response element binding protein) signaling pathway was involved in this course.

METHODS

2-month-old male C57/BL-6J mice were submitted to long-term anesthesia using 1% isoflurane from CT (Circadian Time) 14 to CT20. Melatonin pretreatment were conducted before anesthesia for 7 Days. Intellicage for mice and Mini-Mitter were applied to monitor spatial memory and gross motor activity which can reflect cognition and sleep-wake rhythm. Messenger RNA and protein expression of right hippocampus NR2B and CREB were examined by RT-PCR and Western blot.

RESULTS

6h isoflurane anesthesia led to impaired spatial memory from Day 3 to Day 10 in mice accompanied by the disruption of sleep-wake rhythm. Meanwhile, the hippocampus CREB and NR2B expression declined in step. Melatonin pretreatment ameliorated disturbed sleep-wake cycle, improved isoflurane-induced cognitive dysfunction, and reversed the down-regulation of CREB and NR2B expression.

CONCLUSIONS

Our data demonstrate that sleep-wake rhythm is involved in the isoflurane-induced cognition impairment and pretreatment of melatonin has a positive effect on circadian normalization and cognition reversal. Also, NR2B-CREB signaling pathway has a critical role in this process. This study provides us a new strategy for anesthesia-induced cognitive dysfunction therapy.

Differential influence of propofol and isoflurane anesthesia in a non-human primate on the brain kinetics and binding of [(18)F]DPA-714, a positron emission tomography imaging marker of glial activation

Translocator protein 18 kDa (TSPO) expression at the mitochondrial membrane of glial cells is related to glial activation. TSPO radioligands such as [(18)F]DPA-714 are useful for the non-invasive study of neuroimmune processes using positron emission tomography (PET). Anesthetic agents were shown to impact mitochondrial function and may influence [(18)F]DPA-714 binding parameters and PET kinetics. [(18) F]DPA-714 PET imaging was performed in Papio anubis baboons anesthetized using either intravenous propofol (n = 3) or inhaled isoflurane (n = 3). Brain kinetics and metabolite-corrected input function were measured to estimate [(18) F]DPA-714 brain distribution (VT). Displacement experiments were performed using PK11195 (1.5 mg/kg). In vitro [(18)F]DPA-714 binding experiments were performed using baboon brain tissue in the absence and presence of tested anesthetics. Brain radioactivity peaked higher in isoflurane-anesthetized animals compared with propofol (SUVmax = 2.7 ± 0.5 vs. 1.3 ± 0.2, respectively) but was not different after 30 min. Brain VT was not different under propofol and isoflurane. Displacement resulted in a 35.8 ± 8.4% decrease of brain radioactivity under propofol but not under isoflurane (0.1 ± 7.0%). In vitro, the presence of propofol increased TSPO density and dramatically reduced its affinity for [(18)F]DPA-714 compared with control. This in vitro effect was not significant with isoflurane. Exposure to propofol and isoflurane differentially influences TSPO interaction with its specific radioligand [(18)F]DPA-714 with subsequent impact on its tissue kinetics and specific binding estimated in vivo using PET. Therefore, the choice of anesthetics and their potential influence on PET data should be considered for the design of imaging studies using TSPO radioligands, especially in a translational research context.

Pten Inhibitor-bpV Ameliorates Early Postnatal Propofol Exposure-Induced Memory Deficit and Impairment of Hippocampal LTP

Early postnatal propofol administration has potential detrimental effects on hippocampal synaptic development and memory. Therapeutic method is still lack due to unknown mechanisms. In this study, a 7-day propofol protocol was applied to model anesthesia in neonatal mice. Phosphatase and tensin homolog deleted on chromosome ten (Pten) inhibitor bisperoxovanadium (bpV) was pre-applied before propofol to study its potential protection. After propofol application, Pten level increased while phospho-AKT (p-AKT) (Ser473) decreased in dorsal hippocampus. Interestingly, i.p. injection of Pten inhibitor reversed the decrease of p-AKT. Two months after administration, basal synaptic transmission, hippocampal long-term potentiation (LTP) and long-term memory were reduced in propofol-administrated mice. By contrast, i.p. injection of Pten inhibitor at a dose of 0.2 mg/kg/day before propofol reversed the detrimental effects due to propofol application. Consistently, bpV injection also reversed propofol application-induced decrease of synaptic plasticity-related proteins, including p-CamKIIα, p-PKA and postsynaptic density protein 95. Taken together, our results demonstrate that bpV injection could reverse early propofol exposure-induced decrease of memory and hippocampal LTP. bpV might be a potential therapeutic for memory impairment after early propofol postnatal application.

Measurement of the acute metabolic response to hypoxia in rat tumours in vivo using magnetic resonance spectroscopy and hyperpolarised pyruvate

Purpose

To estimate the rate constant for pyruvate to lactate conversion in tumours in response to a hypoxic challenge, using hyperpolarised ¹³C₁-pyruvate and magnetic resonance spectroscopy.

Methods and materials

Hypoxic inspired gas was used to manipulate rat P22 fibrosarcoma oxygen tension (pO₂), confirmed by luminescence decay of oxygen-sensitive probes. Hyperpolarised ¹³C₁-pyruvate was injected into the femoral vein of anaesthetised rats and slice-localised ¹³C magnetic resonance (MR) spectra acquired. Spectral integral versus time curves for pyruvate and lactate were fitted to a precursor-product model to estimate the rate constant for tumour conversion of pyruvate to lactate (k_pl). Mean arterial blood pressure (MABP) and oxygen tension (ArtpO₂) were monitored. Pyruvate and lactate concentrations were measured in freeze-clamped tumours.

Results

MABP, ArtpO₂ and tumour pO₂ decreased significantly during hypoxia. k_pl increased significantly (p < 0.01) from 0.029 ± 0.002 s⁻¹ to 0.049 ± 0.006 s⁻¹ (mean ± SEM) when animals breathing air were switched to hypoxic conditions, whereas pyruvate and lactate concentrations were minimally affected by hypoxia. Both ArtpO₂ and MABP influenced the estimate of k_pl, with a strong negative correlation between k_pl and the product of ArtpO₂ and MABP under hypoxia.

Conclusion

The rate constant for pyruvate to lactate conversion, k_pl, responds significantly to a rapid reduction in tumour oxygenation.