In Vivo Evaluation of Brain [18F]F-FDG Uptake Pattern Under Different Anaesthesia Protocols.

BACKGROUND/AIM: Since the use of anaesthetics has the drawback of altering radiotracer distribution, preclinical positron emission tomography (PET) imaging findings of anaesthetised animals must be carefully handled. This study aimed at assessing the cerebral [18F]F-FDG uptake pattern in healthy Wistar rats under four different anaesthesia protocols using microPET/magnetic resonance imaging (MRI) examinations. MATERIALS AND METHODS: Post-injection of 15±1.2 MBq of [18F]F-FDG, either while awake or during the isoflurane-induced incubation phase was applied. Prior to microPET/MRI imaging, one group of the rats was subjected to forane-only anaesthesia while the other group was anaesthetised with the co-administration of forane and dexmedetomidine/Dexdor® Results: While as for the whole brain it was the addition of dexmedetomidine/Dexdor® to the anaesthesia protocol that generated the differences between the radiotracer concentrations of the investigated groups, regarding the cortex, the [18F]F-FDG accumulation was rather affected by the way of incubation. To ensure the most consistent and highest uptake, forane-induced anaesthesia coupled with an awake uptake condition seemed to be most suitable method of anaesthetisation for cerebral metabolic assessment. Diminished whole brain and cortical tracer accumulation detected upon dexmedetomidine/Dexdor® administration highlights the significance of the mechanism of action of different anaesthetics on radiotracer pharmacokinetics. CONCLUSION: Overall, the standardization of PET protocols is of utmost importance to avoid the confounding factors derived from anaesthesia.

A chromosome-level genome assembly of anesthetic drug-producing Anisodus acutangulus provides insights into its evolution and the biosynthesis of tropane alkaloids.

Tropane alkaloids (TAs), which are anticholinergic agents, are an essential class of natural compounds, and there is a growing demand for TAs with anesthetic, analgesic, and spasmolytic effects. Anisodus acutangulus (Solanaceae) is a TA-producing plant that was used as an anesthetic in ancient China. In this study, we assembled a high-quality, chromosome-scale genome of A. acutangulus with a contig N50 of 7.4 Mb. A recent whole-genome duplication occurred in A. acutangulus after its divergence from other Solanaceae species, which resulted in the duplication of ADC1 and UGT genes involved in TA biosynthesis. The catalytic activities of H6H enzymes were determined for three Solanaceae plants. On the basis of evolution and co-expressed genes, AaWRKY11 was selected for further analyses, which revealed that its encoded transcription factor promotes TA biosynthesis by activating AaH6H1 expression. These findings provide useful insights into genome evolution related to TA biosynthesis and have potential implications for genetic manipulation of TA-producing plants.

Microglia modulate general anesthesia through P2Y12 receptor.

General anesthesia (GA) is an unconscious state produced by anesthetic drugs, which act on neurons to cause overall suppression of neuronal activity in the brain. Recent studies have revealed that GA also substantially enhances the dynamics of microglia, the primary brain immune cells, with increased process motility and territory surveillance. However, whether microglia are actively involved in GA modulation remains unknown. Here, we report a previously unrecognized role for microglia engaging in multiple GA processes. We found that microglial ablation reduced the sensitivity of mice to anesthetics and substantially shortened duration of loss of righting reflex (LORR) or unconsciousness induced by multiple anesthetics, thereby promoting earlier emergence from GA. Microglial repopulation restored the regular anesthetic recovery, and chemogenetic activation of microglia prolonged the duration of LORR. In addition, anesthesia-accompanying analgesia and hypothermia were also attenuated after microglial depletion. Single-cell RNA sequencing analyses showed that anesthesia prominently affected the transcriptional levels of chemotaxis and migration-related genes in microglia. By pharmacologically targeting different microglial motility pathways, we found that blocking P2Y12 receptor (P2Y12R) reduced the duration of LORR of mice. Moreover, genetic ablation of P2Y12R in microglia also promoted quicker recovery in mice from anesthesia, verifying the importance of microglial P2Y12R in anesthetic regulation. Our work presents the first evidence that microglia actively participate in multiple processes of GA through P2Y12R-mediated signaling and expands the non-immune roles of microglia in the brain.

The neuroendocrine stress response compensates for suppression of insulin secretion by volatile anesthetic agents: An observational study.

Alterations in perioperative metabolic function, particularly hyperglycemia, are associated with increased post-operative complications, even in patients without preexisting metabolic abnormalities. Anesthetic medications and the neuroendocrine stress response to surgery may both contribute to altered energy metabolism through impaired glucose and insulin homeostasis but the discrete pathways involved are unclear. Prior human studies, though informative, have been limited by analytic sensitivity or technique, preventing resolution of underlying mechanisms. We hypothesized that general anesthesia with a volatile agent would suppress basal insulin secretion without altering hepatic insulin extraction, and that surgical stress would promote hyperglycemia through gluconeogenesis, lipid oxidation, and insulin resistance. In order to address these hypotheses, we conducted an observational study of subjects undergoing multi-level lumbar surgery with an inhaled anesthetic agent. We measured circulating glucose, insulin, c-peptide, and cortisol frequently throughout the perioperative period and analyzed the circulating metabolome in a subset of these samples. We found volatile anesthetic agents suppress basal insulin secretion and uncouple glucose-stimulated insulin secretion. Following surgical stimulus, this inhibition disappeared and there was gluconeogenesis with selective amino acid metabolism. No robust evidence of lipid metabolism or insulin resistance was observed. These results show that volatile anesthetic agents suppress basal insulin secretion, which results in reduced glucose metabolism. The neuroendocrine stress response to surgery ameliorates the inhibitory effect of the volatile agent on insulin secretion and glucose metabolism, promoting catabolic gluconeogenesis. A better understanding of the complex metabolic interaction between anesthetic medications and surgical stress is needed to inform design of clinical pathways aimed at improving perioperative metabolic function.

Integrated Excitatory/Inhibitory Imbalance and Transcriptomic Analysis Reveals the Association between Dysregulated Synaptic Genes and Anesthetic-Induced Cognitive Dysfunction.

Emerging evidence from human epidemiologic and animal studies has demonstrated that developmental anesthesia neurotoxicity could cause long-term cognitive deficits and behavioral problems. However, the underlying mechanisms remain largely unknown. We conducted an electrophysiological analysis of synapse activity and a transcriptomic assay of 24,881 mRNA expression on hippocampal tissues from postnatal day 60 (P60) mice receiving propofol exposure at postnatal day 7 (P7). We found that developmentally propofol-exposed P60 mouse hippocampal neurons displayed an E/I imbalance, compared with control mice as evidenced by the decreased excitation and increased inhibition. We found that propofol exposure at P7 led to the abnormal expression of 317 mRNAs in the hippocampus of P60 mice, including 23 synapse-related genes. Various bioinformatic analyses revealed that these abnormally expressed synaptic genes were associated with the function and development of synapse activity and plasticity, E/I balance, behavior, and cognitive impairment. Our findings suggest that the altered E/I balance may constitute a mechanism for propofol-induced long-term impaired learning and memory in mice. The transcriptomic and bioinformatic analysis of these dysregulated genes related to synaptic function paves the way for development of therapeutic strategies against anesthetic neurodegeneration through the restoration of E/I balance and the modification of synaptic gene expression.

Insights into the interaction dynamics between volatile anesthetics and tubulin through computational molecular modelling.

General anesthetics, able to reversibly suppress all conscious brain activity, have baffled medical science for decades, and little is known about their exact molecular mechanism of action. Given the recent scientific interest in the exploration of microtubules as putative functional targets of anesthetics, and the involvement thereof in neurodegenerative disorders, the present work focuses on the investigation of the interaction between human tubulin and four volatile anesthetics: ethylene, desflurane, halothane and methoxyflurane. Interaction sites on different tubulin isotypes are predicted through docking, along with an estimate of the binding affinity ranking. The analysis is expanded by Molecular Dynamics simulations, where the dimers are allowed to freely interact with anesthetics in the surrounding medium. This allowed for the determination of interaction hotspots on tubulin dimers, which could be linked to different functional consequences on the microtubule architecture, and confirmed the weak, Van der Waals-type interaction, occurring within hydrophobic pockets on the dimer. Both docking and MD simulations highlighted significantly weaker interactions of ethylene, consistent with its far lower potency as a general anesthetic. Overall, simulations suggest a transient interaction between anesthetics and microtubules in general anesthesia, and contact probability analysis shows interaction strengths consistent with the potencies of the four compounds.Communicated by Ramaswamy H. Sarma.

Mechanisms underlying neonate-specific metabolic effects of volatile anesthetics.

Volatile anesthetics (VAs) are widely used in medicine, but the mechanisms underlying their effects remain ill-defined. Though routine anesthesia is safe in healthy individuals, instances of sensitivity are well documented, and there has been significant concern regarding the impact of VAs on neonatal brain development. Evidence indicates that VAs have multiple targets, with anesthetic and non-anesthetic effects mediated by neuroreceptors, ion channels, and the mitochondrial electron transport chain. Here, we characterize an unexpected metabolic effect of VAs in neonatal mice. Neonatal blood ß-hydroxybutarate (ß-HB) is rapidly depleted by VAs at concentrations well below those necessary for anesthesia. ß-HB in adults, including animals in dietary ketosis, is unaffected. Depletion of ß-HB is mediated by citrate accumulation, malonyl-CoA production by acetyl-CoA carboxylase, and inhibition of fatty acid oxidation. Adults show similar significant changes to citrate and malonyl-CoA, but are insensitive to malonyl-CoA, displaying reduced metabolic flexibility compared to younger animals.

Malformations and mortality in zebrafish early stages associated with elevated caspase activity after 24 h exposure to MS-222.

Tricaine methanesulfonate (MS-222) is a commonly used anaesthetic agent for immobilization of aquatic species. However, delayed development and malformations have been observed in 24 hpf (hours post-fertilization) zebrafish embryos after long-term immobilization. Still, no comprehensive study has been described regarding zebrafish exposure to MS-222 during the first hours of development, which are one of the most sensitive life stages to toxicants. Therefore, this research aimed to assess the toxicity of a 24 h exposure to MS-222 on zebrafish embryonic development. Based on the MS-222 LC50, early blastula stage embryos (~2 hpf) were exposed to 0, 12.5, 25 and 50 mg L-1 for 24 h and then allowed to develop up to 144 hpf. The chromatographic analysis showed that this anaesthetic agent bioaccumulates in 26 hpf zebrafish larvae in a concentration-dependent manner. In addition, increased mortalities and skeletal abnormalities were observed at 144 hpf, namely in the highest tested concentration. Yet, no craniofacial anomalies were observed either by alcian blue or calcein staining methods. Independently of the tested concentration, decreased speed and distance travelled were perceived in 144 hpf larvae. At the biochemical level, decreased in vivo reactive oxygen species (ROS) generation and apoptosis was observed. Additionally, catalase activity was increased at 26 hpf while results of mRNA expression showed a decreased gclc transcript content at the same time-point. Overall, data obtained highlight the toxicological risk of MS-222 and support ROS-mediated cell death signalling changes through the elevation of catalase activity as an adaptative or protective response.

Drug Development in Channelopathies: Allosteric Modulation of Ligand-Gated and Voltage-Gated Ion Channels.

Ion channels have been characterized as promising drug targets for treatment of numerous human diseases. Functions of ion channels can be fine-tuned by allosteric modulators, which interact with channels and modulate their activities by binding to sites spatially discrete from those of orthosteric ligands. Positive and negative allosteric modulators have presented a plethora of potential therapeutic advantages over traditionally orthosteric agonists and antagonists in terms of selectivity and safety. This thematic review highlights the discovery of representative allosteric modulators for ligand-gated and voltage-gated ion channels, discussing in particular their identifications, locations, and therapeutic uses in the treatment of a range of channelopathies. Additionally, structures and functions of selected ion channels are briefly described to aid in the rational design of channel modulators. Overall, allosteric modulation represents an innovative targeting approach, and the corresponding modulators provide an abundant but challenging landscape for novel therapeutics targeting ligand-gated and voltage-gated ion channels.

A Structural Analysis of the FDA Green Book-Approved Veterinary Drugs and Roles in Human Medicine.

The FDA Green Book is a list of all drug products that have been approved by the FDA for use in veterinary medicine. The Green Book, as published, lacks structural information corresponding to approved drugs. To address this gap, we have compiled the structural data for all FDA Green Book drugs approved through the end of 2019. Herein we discuss the relevance of this data set to human drugs in the context of structural classes and physicochemical properties. Analysis reveals that physicochemical properties are highly optimized and consistent with a high probability of favorable drug metabolism and pharmacokinetic properties, including good oral bioavailability for most compounds. We provide a detailed analysis of this data set organized on the basis of structure and function. Slightly over half (51%) of vet drugs are also approved in human medicine. Combination drugs are biologics are also discussed.

POTENTIAL FOR ELECTROENCEPHALOGRAPHIC MONITORING OF ANESTHETIC DEPTH IN CAPTIVE CHIMPANZEES (PAN TROGLODYTES) USING A NOVEL BRAIN FUNCTION MONITOR.

The electroencephalogram (EEG) waveform can predictably change with depth of anesthesia, and algorithms such as the Patient State index (PSi) have been developed to convert the waveform into a user-friendly objective reading of anesthetic depth. In this study, PSi values were measured in 10 captive chimpanzees (Pan troglodytes) during three phases of an anesthetic event. Phase 1 included sedation with dexmedetomidine, midazolam, and ketamine. Phase 2 started with administration of an α-2 antagonist and isoflurane. Phase 3 started with discontinuing isoflurane and ended with spontaneous movement and extubation. Initial PSi readings for phase 1 were high at 74.5 ± 12.2 (mean ± SD), before declining to 24.1 ± 5.3 for the remainder of the phase. Phase 2 PSi values were recorded as 21.4 ± 5.4 and then climbed during phase 3. Spontaneous movement was recorded at PSi values of 72 to 79. Electroencephalographic monitoring via PSi was successfully performed during three phases of anesthesia in the chimpanzees and was consistent with human values reported during general anesthesia. This paper serves as a preliminary investigation into EEG monitoring of chimpanzees, and further work is needed for its validation.

Development of photo-magnetic drug delivery system by facile-designed dual stimuli-responsive modified biopolymeric chitosan capped nano-vesicle to improve efficiency in the anesthetic effect and its biological investigations.

Though anesthetic drug delivery system and drug vehicles is generally applied for pain relief, there are have many difficulties and issues due to its short duration carrier and low biocompatibility, effectiveness at the conditions of inflammation at acidic pH. To resolve this issue, we have designed and developed the dual (pH and temperature) responsive bio-nanomaterial to improve the efficiency anesthetic drug delivery system. Chitosan is a unique class of biomaterials that is widely used in medical devices. The surface engineering of ZnFe2O4 nanoparticles was performed by coating with chitosan using simple precipitation method. Then, multi-active anesthetic drug (Lidocaine) was loaded into nano-ferrite to form a drug delivery vehicle. The prepared drug-vesicle was characterized by using XRD, FTIR, SEM, XPS and TGA analysis. XRD analysis proved the face center cubic structure of zinc nanoferrite. The sustained delivery of Lidocaine (LDC) from CS coated nanoferrite (CS/ZnFe2O4) was stimulated by pH and temperature responsive characteristics of vesicles. The in vitro cytotoxicity of the CS/ZnFe2O4 particles towards fibroblast cells was analyzed by using MTT assay. The drug loaded CS/ZnFe2O4 particles exhibit high biocompatibility and sustained drug release in the physiological pH environment (4.8, 5.5 and 7.4) and temperature responsive (25 and 37 °C) of normal tissues and also drug loading efficiency was measured.

Embedment of liposomes into chitosan physical hydrogel for the delayed release of antibiotics or anaesthetics, and its first ESEM characterization.

This work describes the characterization of an original liposomes/hydrogel assembly, and its application as a delayed-release system of antibiotics and anaesthetics. This system corresponds to drug-loaded liposomes entrapped within a chitosan (CS) physical hydrogel. To this end, a suspension of pre-formed 1,2-dipalmitoyl-sn-glycero-3-phosphocoline liposomes loaded with an antibiotic (rifampicin, RIF), an anaesthetic (lidocaine, LID), or a model fluorescent molecule (carboxyfluorescein, CF), was added to a CS solution. The CS gelation was subsequently carried out without any trace of chemical cross-linking agent or organic solvent in the final system. Liposomes within the resulting gelled CS matrix were characterized for the first time by environmental scanning electron microscopy. The release of drugs from the assembly was investigated by fluorescence or UV spectroscopy. The cumulative release profiles of RIF and LID (and also CF for comparison) were found to be lower from the "drug-in-liposomes-in-hydrogel" (DLH) assembly in comparison to "drug-in-hydrogel" (DH) system.

A Rationale for Allopregnanolone Treatment of Alcohol Use Disorders: Basic and Clinical Studies.

For many years, research from around the world has suggested that the neuroactive steroid (3α,5α)-3-hydroxypregnan-20-one (allopregnanolone or 3α,5α-THP) may have therapeutic potential for treatment of various symptoms of alcohol use disorders (AUDs). In this critical review, we systematically address all the evidence that supports such a suggestion, delineate the etiologies of AUDs that are addressed by treatment with allopregnanolone or its precursor pregnenolone, and the rationale for treatment of various components of the disease based on basic science and clinical evidence. This review presents a theoretical framework for understanding how endogenous steroids that regulate the effects of stress, alcohol, and the innate immune system could play a key role in both the prevention and the treatment of AUDs. We further discuss cautions and limitations of allopregnanolone or pregnenolone therapy with suggestions regarding the management of risk and the potential for helping millions who suffer from AUDs.

The Biology of General Anesthesia from Paramecium to Primate.

General anesthesia serves a critically important function in the clinical care of human patients. However, the anesthetized state has foundational implications for biology because anesthetic drugs are effective in organisms ranging from paramecia, to plants, to primates. Although unconsciousness is typically considered the cardinal feature of general anesthesia, this endpoint is only strictly applicable to a select subset of organisms that are susceptible to being anesthetized. We review the behavioral endpoints of general anesthetics across species and propose the isolation of an organism from its environment - both in terms of the afferent arm of sensation and the efferent arm of action - as a generalizable definition. We also consider the various targets and putative mechanisms of general anesthetics across biology and identify key substrates that are conserved, including cytoskeletal elements, ion channels, mitochondria, and functionally coupled electrical or neural activity. We conclude with a unifying framework related to network function and suggest that general anesthetics - from single cells to complex brains - create inefficiency and enhance modularity, leading to the dissociation of functions both within an organism and between the organism and its surroundings. Collectively, we demonstrate that general anesthesia is not restricted to the domain of modern medicine but has broad biological relevance with wide-ranging implications for a diverse array of species.

[Determination of 5 kinds of fish anesthetics residues in fish by ultra-high performance liquid chromatography-tandem mass spectrometry].

OBJECTIVE: A method for the simultaneous determination of 5 kinds of fish anesthetics residues in fish has been developed by ultra-high performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS). Eugenol, methyl-eugenol, methyl-isoeugenol, acetyl-isoeugenol and tricaine methanesulfonate(MS-222) were concerned. METHODS: After homogenization fish samples were extracted by acetonitrile-water(80↿0, V/V), purified by Oasis PRiME HLB solid-phase extraction column. Then after centrifuged and concentrated, the samples were separated by Waters ACQUITY UPLC BEH Phenyl column(2. 1 mm×100 mm, 1. 7 µm). The detection was confirmed and quantified by mass spectrum of triple quadrupole in the multiple reaction monitoring(MRM) mode. RESULTS: The calibration curves showed good linearity in each range with correlation coefficients greater than 0. 995. Three levels spiked recovery experiments were carried out using blank fish mud extraction as substrate, the recoveries ranged from 72. 6% to 106. 0%, the relative standard deviations(RSDs) ranged from 2. 2% to 20. 1%(n=6). The qualitative limits of detections(S/N>3) were 0. 14-0. 30 µg/kg and the quantitative limits(S/N>10) were 0. 5-1. 0 µg/kg. CONSLUSION: The method is simple and easy to operate, with less organic reagent, high sensitivity and good stability. The isomers of methyl eugenol and methyl isoeugenol were successfully separated. It is suitable for the detection of 5 kinds of fish anesthetics in fish.

(R)-Ketamine exerts antidepressant actions partly via conversion to (2R,6R)-hydroxynorketamine, while causing adverse effects at sub-anaesthetic doses.

BACKGROUND AND PURPOSE: (R)-Ketamine (arketamine) may have utility as a rapidly acting antidepressant. While (R)-ketamine has lower potency than (R,S)-ketamine to inhibit NMDA receptors in vitro, the extent to which (R)-ketamine shares the NMDA receptor-mediated adverse effects of (R,S)-ketamine in vivo has not been fully characterised. Furthermore, (R)-ketamine is metabolised to (2R,6R)-hydroxynorketamine (HNK), which may contribute to its antidepressant-relevant actions. EXPERIMENTAL APPROACH: Using mice, we compared (R)-ketamine with a deuterated form of the drug (6,6-dideutero-(R)-ketamine, (R)-d2 -ketamine), which hinders its metabolism to (2R,6R)-HNK, in behavioural tests predicting antidepressant responses. We also examined the actions of intracerebroventricularly infused (2R,6R)-HNK. Further, we quantified putative NMDA receptor inhibition-mediated adverse effects of (R)-ketamine. KEY RESULTS: (R)-d2 -Ketamine was identical to (R)-ketamine in binding to and functionally inhibiting NMDA receptors but hindered (R)-ketamine's metabolism to (2R,6R)-HNK. (R)-Ketamine exerted greater potency than (R)-d2 -ketamine in several antidepressant-sensitive behavioural measures, consistent with a role of (2R,6R)-HNK in the actions of (R)-ketamine. There were dose-dependent sustained antidepressant-relevant actions of (2R,6R)-HNK following intracerebroventricular administration. (R)-Ketamine exerted NMDA receptor inhibition-mediated behaviours similar to (R,S)-ketamine, including locomotor stimulation, conditioned-place preference, prepulse inhibition deficits, and motor incoordination, with approximately half the potency of the racemic drug. CONCLUSIONS AND IMPLICATIONS: Metabolism of (R)-ketamine to (2R,6R)-HNK increases the potency of (R)-ketamine to exert antidepressant-relevant actions in mice. Adverse effects of (R)-ketamine require higher doses than those necessary for antidepressant-sensitive behavioural changes in mice. However, our data revealing that (R)-ketamine's adverse effects are elicited at sub-anaesthetic doses indicate a potential risk for sensory dissociation and abuse liability.

[Reduction the risk in pediatric anesthesia-what should we know-what should we do]. / Risikominimierung in der Kinderanästhesie ­ was sollten wir wissen ­ was sollten wir tun.

Pediatric anesthesia has always been conjuncted with higher risk than anesthesia for adults (JP Morray; Pediatric Anesthesia 2011;21:722-9). Not only the imminent critical events, but also, caused by recently published data, the theoretical neurotoxicity of anesthetic agents and a potencial negative influence of anesthetics on braindevelopement, are in the spotlight.Concerns about the neurodevelopement and the general warnings from the U.S. Food and Drug Administration (FDA) for anesthesia in young children led to a worldwide discussion about safety in pediatric anesthesia (FDA Safety Anouncement 2017).Beside these theoretical risks, which are based only on animal research, we have to pay much more attention to the widely spread out poor quality of anesthesia in children.The following article should summarize the state of science about the risks and the opportunities to minimize them.

Noninvasive Ultrasonic Drug Uncaging Maps Whole-Brain Functional Networks.

Being able to noninvasively modulate brain activity, where and when an experimenter desires, with an immediate path toward human translation is a long-standing goal for neuroscience. To enable robust perturbation of brain activity while leveraging the ability of focused ultrasound to deliver energy to any point of the brain noninvasively, we have developed biocompatible and clinically translatable nanoparticles that allow ultrasound-induced uncaging of neuromodulatory drugs. Utilizing the anesthetic propofol, together with electrophysiological and imaging assays, we show that the neuromodulatory effect of ultrasonic drug uncaging is limited spatially and temporally by the size of the ultrasound focus, the sonication timing, and the pharmacokinetics of the uncaged drug. Moreover, we see secondary effects in brain regions anatomically distinct from and functionally connected to the sonicated region, indicating that ultrasonic drug uncaging could noninvasively map the changes in functional network connectivity associated with pharmacologic action at a particular brain target.