Effect of basal forebrain somatostatin and parvalbumin neurons in propofol and isoflurane anesthesia

A ventral pallidum-locus coeruleus-lateral hypothalamus pathway modulates brain arousal in freely behaving and isoflurane-anesthetized male mice

Much progress has been made in the understanding of the neural circuits associated with sleep and anesthesia. As an important component among these circuits, the forebrain nuclei have been frequently interrogated. This study demonstrates that glutamatergic (Glu) neurons in the ventral pallidum (VP) enhance activity upon salient stimuli and state-dependently modulate brain arousal and motor activity in freely behaving male mice, and bidirectionally regulate the induction of and emergence from isoflurane general anesthesia. We delineate a neural pathway, consisting of VP Glu neurons→ noradrenergic (NA) neurons in the locus coeruleus (LC)→the lateral hypothalamus (LH) in male mice, controlling the release of noradrenaline in the LH and state-dependently modulated brain arousal, motor activity, and isoflurane general anesthesia through α2a receptors in the LH. Therefore, the VPGlu-LCNA-LH pathway and α2a receptors in the LH may be promising state-dependent regulators of brain arousal in both freely behaving and anesthetized states.

Somatostatin-expressing Neurons in the Medial Prefrontal Cortex Promote Sevoflurane Anesthesia in Mice

BACKGROUND

The medial prefrontal cortex plays a crucial role in regulating consciousness. However, the specific functions of its excitatory and inhibitory networks during anesthesia remain uncertain. Here, the authors explored the hypothesis that somatostatin interneurons in the medial prefrontal cortex enhance the effects of sevoflurane anesthesia by increasing γ-aminobutyric acid (GABA) transmission to pyramidal neurons.

METHODS

Electroencephalography was utilized to reflect the depth of anesthesia. Immunostaining and fiber photometry were employed to assess neuronal activities and GABA delivery. The regulation of neuronal activity was achieved by chemogenetics and optogenetics.

RESULTS

The expression of c-Fos was increased in somatostatin neurons of the medial prefrontal cortex during sevoflurane anesthesia (air vs. sevoflurane: 26.4 ± 6.5% vs. 48 ± 6.2%; P = 0.0007; n = 5 mice). Chemogenetic inhibition or activation of somatostatin neurons in the medial prefrontal cortex reduced (from 84 ± 24 s to 51 ± 18 s; P = 0.008; n = 7 mice) or prolonged (from 97 ± 31 s to 140 ± 30 s; P = 0.006; n = 7 mice) the sevoflurane anesthesia recovery time. Increased GABA input to pyramidal neurons in the medial prefrontal cortex precedes sevoflurane-induced loss of consciousness (baseline vs . pre-loss of the righting reflex: from 0.46 ± 0.57% to 2.25 ± 1.42%; P = 0.031; n = 10 mice). Activation of somatostatin neurons in the medial prefrontal cortex leads to a significant reduction in calcium signals within local pyramidal neurons (baseline vs . 20 Hz stimulation: from -0.14 ± 0.52% to -10.08 ± 4.44%; P = 0.002; n = 10 mice). Additionally,GABA input on pyramidal neurons increased (baseline vs . 20 Hz stimulation: from -0.001 ± 0.001% to 0.28 ± 0.03%; P = 0.002; n = 7 mice) in a time-locked manner. Chemogenetic inhibition of pyramidal neurons prolonged the recovery from sevoflurane anesthesia in mice (from 101 ± 46 s to 136 ± 54 s; P = 0.017; n = 19 mice).

CONCLUSIONS

Cortical somatostatin neurons may inhibit local pyramidal neurons by enhancing GABA transmission, which increases the effectiveness of sevoflurane anesthesia.

Impact of Sevoflurane and Propofol on Perioperative Respiratory Adverse Events in Pediatrics: A Systematic Review and Meta-analysis

PURPOSE

Perioperative respiratory adverse events continue to pose significant challenges in pediatric anesthesia. Research has hinted at a lower incidence of these complications in children anesthetized with propofol than sevoflurane. This study aimed to assess and compare respiratory complications in children undergoing general anesthesia with either sevoflurane or propofol during surgery.

DESIGN

Systematic review and meta-analysis.

METHODS

We conducted comprehensive searches of the PubMed, Embase, and Cochrane Library databases and manual searches to identify pertinent randomized controlled trials (RCTs) published up to August 19, 2023. The Cochrane risk assessment tool was employed to evaluate the risk of bias in the selected studies. The pooled analysis of relevant data compared respiratory complications, vomiting, agitation, anesthesia duration, extubation time, and recovery time in pediatric patients undergoing anesthesia with sevoflurane and propofol.

FINDINGS

A total of 17 RCTs, containing 1,758 pediatric participants, were included and analyzed. Respiratory adverse events were examined, encompassing laryngospasm, apnea, cough, and SpO2. In comparison to sevoflurane, children subjected to propofol anesthesia demonstrated a significant reduction in the risk of laryngospasm (P = .001), vomiting (P < .001), and agitation (P = .029). Especially in patients receiving laryngeal mask airway, propofol anesthesia significantly reduced the incidence of laryngospasm (P = .003) and agitation (P < .001). At the same time, they exhibited an increased risk of apnea (P = .039). Notably, no statistically significant disparities were observed between sevoflurane and propofol concerning cough, SpO2 < 95%, anesthesia time, extubation time, and recovery time. Administration of propofol following sevoflurane anesthesia did not significantly impact the occurrence of vomiting or the recovery time.

CONCLUSIONS

While propofol presents an elevated risk of apnea, it concurrently yields a significant reduction in laryngospasm, vomiting, and agitation. Consequently, propofol emerges as a favorable anesthetic option for pediatric patients.

GABAergic Neurons in the Central Amygdala Promote Emergence from Isoflurane Anesthesia in Mice

BACKGROUND

Recent evidence indicates that general anesthesia and sleep-wake behavior share some overlapping neural substrates. γ-Aminobutyric acid-mediated (GABAergic) neurons in the central amygdala have a high firing rate during wakefulness and play a role in regulating arousal-related behaviors. The objective of this study was to investigate whether central amygdala GABAergic neurons participate in the regulation of isoflurane general anesthesia and uncover the underlying neural circuitry.

METHODS

Fiber photometry recording was used to determine the changes in calcium signals of central amygdala GABAergic neurons during isoflurane anesthesia in Vgat-Cre mice. Chemogenetic and optogenetic approaches were used to manipulate the activity of central amygdala GABAergic neurons, and a righting reflex test was used to determine the induction and emergence from isoflurane anesthesia. Cortical electroencephalogram (EEG) recording was used to assess the changes in EEG spectral power and burst-suppression ratio during 0.8% and 1.4% isoflurane anesthesia, respectively. Both male and female mice were used in this study.

RESULTS

The calcium signals of central amygdala GABAergic neurons decreased during the induction of isoflurane anesthesia and were restored during the emergence. Chemogenetic activation of central amygdala GABAergic neurons delayed induction time (mean ± SD, vehicle vs . clozapine-N-oxide: 58.75 ± 5.42 s vs . 67.63 ± 5.01 s; n = 8; P = 0.0017) and shortened emergence time (385.50 ± 66.26 s vs . 214.60 ± 40.21 s; n = 8; P = 0.0017) from isoflurane anesthesia. Optogenetic activation of central amygdala GABAergic neurons produced a similar effect. Furthermore, optogenetic activation decreased EEG delta power (prestimulation vs . stimulation: 46.63 ± 4.40% vs . 34.16 ± 6.47%; n = 8; P = 0.0195) and burst-suppression ratio (83.39 ± 5.15% vs . 52.60 ± 12.98%; n = 8; P = 0.0003). Moreover, optogenetic stimulation of terminals of central amygdala GABAergic neurons in the basal forebrain also promoted cortical activation and accelerated behavioral emergence from isoflurane anesthesia.

CONCLUSIONS

The results suggest that central amygdala GABAergic neurons play a role in general anesthesia regulation, which facilitates behavioral and cortical emergence from isoflurane anesthesia through the GABAergic central amygdala-basal forebrain pathway.

Zona Incerta GABAergic Neurons Facilitate Emergence from Isoflurane Anesthesia in Mice

The zona incerta (ZI) predominantly consists of gamma-aminobutyric acid (GABAergic) neurons, located adjacent to the lateral hypothalamus. GABA, acting on GABAA receptors, serves as a crucial neuromodulator in the initiation and maintenance of general anesthesia. In this study, we aimed to investigate the involvement of ZI GABAergic neurons in the general anesthesia process. Utilizing in-vivo calcium signal optical fiber recording, we observed a decrease in the activity of ZI GABAergic neurons during isoflurane anesthesia, followed by a significant increase during the recovery phase. Subsequently, we selectively ablated ZI GABAergic neurons to explore their role in general anesthesia, revealing no impact on the induction of isoflurane anesthesia but a prolonged recovery time, accompanied by a reduction in delta-band power in mice under isoflurane anesthesia. Finally, through optogenetic activation/inhibition of ZI GABAergic neurons during isoflurane anesthesia, we discovered that activation of these neurons facilitated emergence without affecting the induction process, while inhibition delayed emergence, leading to fluctuations in delta band activity. In summary, these findings highlight the involvement of ZI GABAergic neurons in modulating the emergence of isoflurane anesthesia.

Regulating the activity of GABAergic neurons in the ventral pallidum alters the general anesthesia effect of propofol

The full mechanism of action of propofol, a commonly administered intravenous anesthetic drug in clinical practice, remains elusive. The focus of this study was the role of GABAergic neurons which are the main neuron group in the ventral pallidum (VP) closely associated with anesthetic effects in propofol anesthesia. The activity of VP GABAergic neurons following propofol anesthesia in Vgat-Cre mice was observed via detecting c-Fos immunoreactivity by immunofluorescence and western blotting. Subsequently, chemogenetic techniques were employed in Vgat-Cre mice to regulate the activity of VP GABAergic neurons. The role of VP GABAergic neurons in generating the effects of general anesthesia induced by intravenous propofol was further explored through behavioral tests of the righting reflex. The results revealed that c-Fos expression in VP GABAergic neurons in Vgat-Cre mice dramatically decreased after propofol injection. Further studies demonstrated that chemogenetic activation of VP GABAergic neurons during propofol anesthesia shortened the duration of anesthesia and promoted wakefulness. Conversely, the inhibition of VP GABAergic neurons extended the duration of anesthesia and facilitated the effects of anesthesia. The results obtained in this study suggested that regulating the activity of GABAergic neurons in the ventral pallidum altered the effect of propofol on general anesthesia.

A hypothalamus-lateral periaqueductal gray GABAergic neural projection facilitates arousal following sevoflurane anesthesia in mice

BACKGROUND

The lateral hypothalamus (LHA) is an evolutionarily conserved structure that regulates basic functions of an organism, particularly wakefulness. To clarify the function of LHAGABA neurons and their projections on regulating general anesthesia is crucial for understanding the excitatory and inhibitory effects of anesthetics on the brain. The aim of the present study is to investigate whether LHAGABA neurons play either an inhibitory or a facilitatory role in sevoflurane-induced anesthetic arousal regulation.

METHODS

We used fiber photometry and immunofluorescence staining to monitor changes in neuronal activity during sevoflurane anesthesia. Opto-/chemogenetic modulations were employed to study the effect of neurocircuit modulations during the anesthesia. Anterograde tracing was used to identify a GABAergic projection from the LHA to a periaqueductal gray (PAG) subregion.

RESULTS

c-Fos staining showed that LHAGABA activity was inhibited by induction of sevoflurane anesthesia. Anterograde tracing revealed that LHAGABA neurons project to multiple arousal-associated brain areas, with the lateral periaqueductal gray (LPAG) being one of the dense projection areas. Optogenetic experiments showed that activation of LHAGABA neurons and their downstream target LPAG reduced the burst suppression ratio (BSR) during continuous sevoflurane anesthesia. Chemogenetic experiments showed that activation of LHAGABA and its projection to LPAG neurons prolonged the anesthetic induction time and promoted wakefulness.

CONCLUSIONS

In summary, we show that an inhibitory projection from LHAGABA to LPAGGABA neurons promotes arousal from sevoflurane-induced loss of consciousness, suggesting a complex control of wakefulness through intimate interactions between long-range connections.

Study on the preventive effect of dexmedetomidine on anesthetic associated sleep disturbance in young to middle-aged female patients undergoing hysteroscopy: a study protocol for a crossover randomized controlled trial

BACKGROUND

Postoperative sleep disturbance has a potentially detrimental effect on postoperative recovery. Perioperative patients are affected by several factors. General anesthesia induces a non-physiological state that does not resemble natural sleep. Exposure to propofol/sevoflurane can lead to desynchronization of the circadian rhythm, which may result in postoperative sleep disturbance characterized by mid-cycle advancement of sleep and daytime sleepiness. Dexmedetomidine is a highly selective α2-adrenoceptor agonist with a unique sedative effect that facilitates the transition from sleep to wakefulness. Basic research has shown that dexmedetomidine induces deep sedation, similar to physical sleep, and helps maintain forebrain connectivity, which is likely to reduce delirium after surgery. The aim of this study is to evaluate the influence of exposure to the mono-anesthetic propofol on the development of postoperative sleep disturbance in young and middle-aged female patients undergoing hysteroscopy and whether prophylactic administration of dexmedetomidine influences reducing postoperative sleep disturbance.

METHODS

This prospective randomized controlled trial (RCT) will include 150 patients undergoing hysteroscopy at the First Affiliated Hospital of Xiamen University. Participants will be randomly assigned to three groups in a 1:1:1 ratio. The dexmedetomidine group will have two subgroups and will receive a nasal spray of 0.2 µg/kg or 0.5 µg/kg 25 min before surgery, while the control group will receive a saline nasal spray. Three groups will undergo hysteroscopy with propofol-based TIVA according to the same scheme. Sleep quality will be measured using a wearable device and double-blind sleep assessments will be performed before surgery and 1, 3, and 7 days after surgery. SPSS 2.0 is used for statistical analysis. A χ2 test is used to compare groups, and t-test is used to determine statistical the significance of continuous variables.

DISCUSSION

The purpose of this study is to investigate the incidence of propofol-associated sleep disorders and to test a combination of dexmedetomidine anesthesia regimen for the prevention of postoperative sleep disorders. This study will help to improve patients' postoperative satisfaction and provide a new strategy for comfortable perioperative medical treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06281561. Registered on February 24, 2024.

Distinct Neural Mechanisms Between Anesthesia Induction and Emergence: A Narrative Review

Anesthesia induction and emergence are critical periods for perioperative safety in the clinic. Traditionally, the emergence from general anesthesia has been recognized as a simple inverse process of induction resulting from the elimination of general anesthetics from the central nervous system. However, accumulated evidence has indicated that anesthesia induction and emergence are not mirror-image processes because of the occurrence of hysteresis/neural inertia in both animals and humans. An increasing number of studies have highlighted the critical role of orexinergic neurons and their involved circuits in the selective regulation of emergence but not the induction of general anesthesia. Moreover, additional brain regions have also been implicated in distinct neural mechanisms for anesthesia induction and emergence, which extends the concept that anesthetic induction and emergence are not antiparallel processes. Here, we reviewed the current literature and summarized the evidence regarding the differential mechanism of neural modulation in anesthesia induction and emergence, which will facilitate the understanding of the underlying neural mechanism for emergence from general anesthesia.

Melatonin attenuates sevoflurane-induced hippocampal damage and cognitive deficits in neonatal mice by suppressing CypD in parvalbumin neurons

BACKGROUND

Sevoflurane, a commonly administered inhaled anesthetic, is found to induce synaptic and mitochondrial damage in neonatal mice. Mitochondrial membrane potential (MMP) changes, mediated by Cyclophilin D (CypD), are implicated in mitochondrial function. Melatonin, known for its significant neuroprotective properties, was investigated in this study to elucidate its mechanisms in mitigating the cognitive impairment caused by sevoflurane.

METHODS

The mice were categorized into several groups, including the control, vehicle, sevoflurane, vehicle plus sevoflurane, and melatonin plus sevoflurane groups. From postnatal day 6 to day 8, the mice were administered inhaled sevoflurane or intraperitoneal melatonin. MMP and reactive oxygen species (ROS) were measured using appropriate detection kits. The protein expression levels of PSD95, Synapsin Ⅰ, and CypD in the hippocampus were analyzed through western blotting in acute and prolonged terms. Immunofluorescence staining was used to assess the co-localizations of PSD95 or CypD in parvalbumin (PV) neurons. Cognitive ability was evaluated through novel object recognition, social interaction experiment, and the Morris water maze.

RESULTS

The findings revealed that repeated exposure to sevoflurane in neonatal mice resulted in cognitive and synaptic impairment. Furthermore, melatonin administration suppressed the ROS and CypD protein expression, enhanced the MMP in mitochondria and synaptic protein expression in PV neurons, and ameliorated cognitive deficits.

CONCLUSION

Melatonin alleviated sevoflurane-induced cognitive deficits by suppressing CypD and promoting synaptic development in hippocampal PV neurons. These results provide valuable insights into a promising therapeutic approach for preventing neurotoxic injuries caused by general anesthetics.

Activation of astrocytes in the basal forebrain in mice facilitates isoflurane-induced loss of consciousness and prolongs recovery

OBJECTIVES

General anesthesia results in a state of unconsciousness that is similar to sleep. In recent years, increasing evidence has reported that astrocytes play a crucial role in regulating sleep. However, whether astrocytes are involved in general anesthesia is unknown.

METHODS

In the present study, the designer receptors exclusively activated by designer drugs (DREADDs) approach was utilized to specifically activate astrocytes in the basal forebrain (BF) and observed its effect on isoflurane anesthesia. One the other side, L-α-aminoadipic acid was used to selectively inhibit astrocytes in the BF and investigated its influence on isoflurane-induced hypnotic effect. During the anesthesia experiment, cortical electroencephalography (EEG) signals were recorded as well.

RESULTS

The chemogenetic activation group had a significantly shorter isoflurane induction time, longer recovery time, and higher delta power of EEG during anesthesia maintenance and recovery periods than the control group. Inhibition of astrocytes in the BF delayed isoflurane-induced loss of consciousness, promoted recovery, decreased delta power and increased beta and gamma power during maintenance and recovery periods.

CONCLUSIONS

The present study suggests that astrocytes in the BF region are involved in isoflurane anesthesia and may be a potential target for regulating the consciousness state of anesthesia.

Understanding the Neural Mechanisms of General Anesthesia from Interaction with Sleep-Wake State: A Decade of Discovery

The development of cutting-edge techniques to study specific brain regions and neural circuits that regulate sleep-wake brain states and general anesthesia (GA), has increased our understanding of these states that exhibit similar neurophysiologic traits. This review summarizes current knowledge focusing on cell subtypes and neural circuits that control wakefulness, rapid eye movement (REM) sleep, non-REM sleep, and GA. We also review novel insights into their interactions and raise unresolved questions and challenges in this field. Comparisons of the overlapping neural substrates of sleep-wake and GA regulation will help us to understand sleep-wake transitions and how anesthetics cause reversible loss of consciousness. SIGNIFICANCE STATEMENT: General anesthesia (GA), sharing numerous neurophysiologic traits with the process of natural sleep, is administered to millions of surgical patients annually. In the past decade, studies exploring the neural mechanisms underlying sleep-wake and GA have advanced our understanding of their interactions and how anesthetics cause reversible loss of consciousness. Pharmacotherapies targeting the neural substrates associated with sleep-wake and GA regulations have significance for clinical practice in GA and sleep medicine.

Paraventricular thalamus controls consciousness transitions during propofol anaesthesia in mice

BACKGROUND

The neuronal mechanisms underlying propofol-induced modulation of consciousness are poorly understood. Neuroimaging studies suggest a potential role for non-specific thalamic nuclei in propofol-induced loss of consciousness. We investigated the contribution of the paraventricular thalamus (PVT), a midline thalamic nucleus that has been implicated in arousal control and general anaesthesia with inhaled anaesthetics, to loss and recovery of consciousness during propofol anaesthesia.

METHODS

Polysomnographic recordings and righting reflex test were used to determine the transitions of loss and recovery of righting reflex, used as a measure of consciousness in mice, during propofol anaesthesia in mice under conditions mimicking clinical propofol administration. PVT neuronal activities were monitored using fibre photometry and regulated using optogenetic and chemogenetic methods.

RESULTS

Population activities of PVT glutamatergic neurones began to decrease before propofol-induced loss of consciousness and rapidly increased to a peak at the onset of recovery of consciousness. Chemogenetic inhibition of PVT calretinin-expressing (PVT^CR) neurones shortened onset (from 176 [35] to 127 [26] s; P=0.001) and prolonged return (from 1568 [611] to 3126 [1616] s; P=0.002) of righting reflex. Conversely, chemogenetic activation of PVT^CR neurones exerted opposite effects. Furthermore, optogenetic silencing of PVT^CR neurones accelerated transitions to loss of consciousness (from 205 [35] to 158 [44] s; P=0.027) and slowed transitions to recovery of consciousness (from 230 [78] to 370 [99] s; P=0.041). During a steady period of unconsciousness maintained with continuous propofol infusion, brief optical activation of PVT^CR neurones restored cortical activity and arousal with a latency of about 5 s.

CONCLUSIONS

The paraventricular thalamus contributes to the control of consciousness transitions in propofol anaesthesia in mice. This provides a potential neuroanatomical target for controlling consciousness to reduce anaesthetic dose requirements and side effects.

The role of the basal forebrain in general anesthesia

The basal forebrain is a group of nerve nuclei on the ventral side of the ventral ganglion, composed of γ-aminobutyric acid neurons, glutamatergic neurons, cholinergic neurons, and orexigenic neurons. Previous studies have focused on the involvement of the basal forebrain in regulating reward, learning, movement, sleep-awakening, and other neurobiological behaviors, but its role in the regulation of general anesthesia has not been systematically elucidated. Therefore, the different neuronal subtypes in the basal forebrain and projection pathways in general anesthesia will be discussed in this paper. In this paper, we aim to determine and elaborate on the role of the basal forebrain in general anesthesia and the development of theoretical research and provide a new theory.

Efficacy of propofol for the prevention of emergence agitation after sevoflurane anaesthesia in children: A meta-analysis

Background

Emergence agitation (EA) is a common postoperative behavioral disorder, predominantly in pediatric patients, after sevoflurane general anesthesia. This study was aimed at assessing propofol's efficacy and clinical conditions established for preventing EA in children under sevoflurane anesthesia.

Methods

Randomized controlled trials (RCTs) that comparatively investigated propofol and control treatment in terms of efficacy and safety on administration at the end of surgery and examinations to prevent EA in children under sevoflurane anesthesia were searched. The sources accessed included PubMed, Embase, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov. Furthermore, manual searches were performed to identify studies; the last review was conducted on March 21, 2022. When the risk of bias assessment of trials was performed with the Cochrane Risk of Bias Tool, we calculated risk ratios (RRs) with 95% confidence intervals (CIs) for EA incidence and mean differences (MDs) with 95% CI for continuous data.

Results

We included 12 RCTs with 1103 children. EA incidence (RR: 0.51, 95% CI: 0.39 to 0.67) and Pediatric Anesthesia Emergence Delirium scores (MD: −3.14, 95% CI: −4.37 to −1.92) were lower in the propofol group. Subgroup analyses showed lower EA incidences with 3 mg/kg propofol (RR: 0.22, 95% CI: 0.13 to 0.38) without extension of the PACU time (MD: 4.97, 95% CI: −0.84 to 10.78) in the laryngeal mask airway (LMA; RR: 0.52, 95% CI: 0.36 to 0.77) and spontaneous breathing (RR: 0.36, 95% CI: 0.21 to 0.62) groups.

Discussion

We confirmed that a prophylactic dose of propofol prevented EA and decreased its severity in children under sevoflurane anesthesia. Furthermore, several conditions such as 3 mg/kg propofol, LMA, and spontaneous breathing, potentially contributed to EA prevention.

Systematic Review Registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=274692, identifier: PROSPERO (No. CRD42021274692).

Janus Kinase Mediates Faster Recovery From Sevoflurane Anesthesia Than Isoflurane Anesthesia in the Migratory Locusts

Inhalation anesthetics isoflurane and sevoflurane have been widely used in clinical practice for anesthesia. However, the molecular mechanisms underlying the faster recovery from sevoflurane anesthesia than isoflurane anesthesia remain largely undetermined. Herein, we use RNA-seq, RNA interference, quantitative real-time PCR and western blotting to explore the mechanisms of recovery from isoflurane and sevoflurane anesthesia in the migratory locusts. Although the migratory locusts show similar anesthetic responses to these two chemicals in corresponding half-maximal effective concentrations (EC50s), the recovery from sevoflurane anesthesia is significantly faster than that for isoflurane anesthesia after 30 min of anesthetic exposure. Transcriptome analysis shows that those transcripts involved in cytoskeletal components, Janus kinase (JAK) pathway and cuticle protein are differentially expressed in locust brains in response to isoflurane and sevoflurane. RNAi knockdown confirms that Actin, Myosin-like protein 84B (Mlp84B), JAK and cuticle protein NCP56 do not affect anesthetic response of the locusts to these two chemical anesthetics. Moreover, actin, Mlp84B and NCP56 do not affect differential recovery from isoflurane and sevoflurane anesthesia, whereas RNAi knockdown of JAK and its partner STAT5B does not affect anesthetic recovery from isoflurane but elongates recovery duration from sevoflurane anesthesia. Thus, JAK may mediate faster recovery from sevoflurane anesthesia than from isoflurane anesthesia in the migratory locust. This finding provides novel insights into the molecular mechanism underlying faster recovery from sevoflurane anesthesia than isoflurane anesthesia.

Effects of different injection methods of propofol anesthesia on the behavior and electroencephalography recording in mice

Propofol is commonly used in mice studies on the mechanism of general anesthesia. The administration routes of propofol include intraperitoneal injection, single tail vein injection, and continuous tail vein pumping. The aim of this study is to compare the effects of the three injection methods on the behavior and electroencephalography (EEG) recording in mice. Mice were divided into an intraperitoneal injection group, a single tail vein injection group, and a continuous tail vein pumping group according to the propofol administration route. The indexes for observation were: time of loss of righting reflex (LORR), time of resumption of righting reflex (RORR), and change in the number of EEG spindle waves during anesthesia. The LORR and RORR were detected again after 1 week to determine the repeatability of the three administration routes. Death and behavioral change after anesthesia recovery in mice were recorded in the three groups. For propofol administration in mice, intraperitoneal injection induced long-duration anesthesia, but the depth of anesthesia was shallow and there was a risk of anesthesia accidents. A small dose of propofol administered through a single tail vein can induce loss of consciousness but the LORR time was not recorded, hence the metrics during induction of anesthesia were not investigated. Continuous tail vein pumping produced stable behavior and EEG recording during anesthesia induction and recovery in mice, and the individual difference was small. Continuous tail vein pumping is an ideal administration route for studying the mechanism of loss of consciousness of propofol anesthesia in mice, which could provide reference data for future mice experiments using propofol.

HC. Relevance of Cortical and Hippocampal Interneuron Functional Diversity to General Anesthetic Mechanisms: A Narrative Review

General anesthetics disrupt brain processes involved in consciousness by altering synaptic patterns of excitation and inhibition. In the cerebral cortex and hippocampus, GABAergic inhibition is largely mediated by inhibitory interneurons, a heterogeneous group of specialized neuronal subtypes that form characteristic microcircuits with excitatory neurons. Distinct interneuron subtypes regulate specific excitatory neuron networks during normal behavior, but how these interneuron subtypes are affected by general anesthetics is unclear. This narrative review summarizes current principles of the synaptic architecture of cortical and interneuron subtypes, their contributions to different forms of inhibition, and their roles in distinct neuronal microcircuits. The molecular and cellular targets in these circuits that are sensitive to anesthetics are reviewed in the context of how anesthetics impact interneuron function in a subtype-specific manner. The implications of this functional interneuron diversity for mechanisms of anesthesia are discussed, as are their implications for anesthetic-induced changes in neural plasticity and overall brain function.