Perioperative neurocognitive disorders (PNDs) are a spectrum of cognitive impairments that can occur after anaesthesia and surgery, most often in older adults. They are linked to worse outcomes and higher mortality. Despite several proposed mechanisms, effective prevention and treatment remain limited, suggesting that key triggers of PNDs remain unknown or that our understanding of PND pathophysiology is incomplete. The review article by Ba and colleagues highlights the role of extrasynaptic γ-aminobutyric acid type A (GABAA) receptors in PNDs, including their structure, function, and potential roles in PNDs after exposure to anaesthesia and surgery. Current experimental approaches focus on PND contributors in isolation. Further advances in understanding the complex systemic neurobehavioural interactions required to perform cognitive tasks, including integration of the known exposures and risk factors for PNDs with age- and pathology-related changes in the neural circuits underlying cognition, will facilitate development of mechanism-based treatments for PNDs.

ABSTRACT Establishment of electrical potentials across biological membranes is a universal feature of all cells. Tandem pore domain (K2P) potassium ion channels play pivotal roles in maintaining cellular membrane potentials, shaping physiological responses across a diverse range of cell types. With only a limited repertoire of high-aAinity and subtype-selective K2P modulators available for experimental or therapeutic use, we devised a strategy to genetically engineer K2P channels that are potently activated by rapamycin or non-immunomodulatory rapamycin analogs. Insertion of the FRB domain of mTOR into a short flexible cytoplasmic loop between the second and third transmembrane (TM) domains of the TREK1 K2P channel yielded fusion channels that are activated by nanomolar concentrations of rapamycin. Rapamycin-induced potentiation requires recruitment of an FKBP binding partner, from either the endogenous pool of FKBP within the cell or through fusion of FKBP to the C-terminus of TREK1. Formation of an FRB/rapamycin/FKBP ternary complex within the core of the TREK1 channel leads to an increase in TREK1 single-channel open probability and unitary current, mimicking positive modulatory eAects of conventional TREK1 activating cues. Cryo-EM structures demonstrate that rapamycin-induced ternary complex formation rigidifies the position of the FRB and stabilizes the TM2/TM3 loop in an active channel conformation. We demonstrate that FRB fusion can be employed to successfully activate several K2P channel isoforms, providing chemogenetically targetable tools for direct manipulation of cellular membrane potential.

Major depressive disorder is associated with deficits in hippocampal synaptic plasticity that depend on brain-derived neurotrophic factor (BDNF) release from both axonal and dendritic compartments. Antidepressant efficacy requires enhanced BDNF signaling, thought to be mediated by drug-induced BDNF release from postsynaptic dendritic spines. Here, we show that fast-acting antidepressants rapidly trigger BDNF secretion from presynaptic terminals in hippocampal area CA3. At antidepressant-relevant concentrations, ketamine and its metabolite (2R,6R)-hydroxynorketamine (HNK) induced BDNF release within minutes from mossy fiber terminals of dentate granule neurons in rat hippocampal cultures, with no detectable secretion from dendritic spines. This antidepressant-evoked BDNF release required presynaptic NMDA receptors (preNMDARs). Conditional genetic deletion of preNMDARs from granule neurons abolished ketamine- and HNK-induced BDNF exocytosis in acute mouse hippocampal slices, establishing a presynaptic receptor mechanism for antidepressant-induced neurotrophin release. In CA3 pyramidal neurons that receive mossy fiber input, both compounds induced rapid remodeling of dendritic spines, resulting in increased spine density. Together, these findings identify presynaptic terminals as a previously unrecognized source of antidepressant-evoked BDNF release and establish a new cellular mechanism for the rapid synaptic effects of fast-acting antidepressants.

Neuronal hyperexcitability is an early and pervasive feature of Alzheimers disease (AD) that both predicts and accelerates subsequent cognitive decline. Persistent excitability depends on activation of voltage-gated sodium channels (Nav), yet most work has focused on the Nav subtypes expressed in the mature brain. Here, we show that Nav1.3, a subtype normally confined to early development, shows aberrantly increased expression in the dentate gyrus (DG)-CA3 circuit in early-stage 5xFAD mice. Using in vivo fiber photometry, three-month-old 5xFAD mice exhibited greater CA3 neuron population activity than seven-month-old 5xFAD mice or wildtype littermates. Oligomeric Aβ expression, assessed by immunolabeling, was sparse at three months and rose significantly by seven months, indicating that CA3 hyperactivity emerges before substantial oligomeric Aβ accumulates. This early activity increase coincided with elevated Nav1.3 expression at the DG-CA3 mossy fiber synapse, localized by immuno-electron microscopy to presynaptic mossy fiber terminals, where it exceeded levels in age-matched controls. Lentiviral shRNA-mediated knockdown of Nav1.3 expression in CA3 normalized CA3 network activity in early-stage 5xFAD mice. These findings identify Nav1.3 expression at DG-CA3 mossy fiber synapses as a driver of early hippocampal network dysfunction in AD and suggest Nav1.3 modulation as a potential target for circuit-level intervention.

This article presents a Delphi consensus developed by a panel of editors-in-chief of anaesthesiology and pain medicine journals to guide the responsible use of large language models (LLMs) in academic publishing. LLMs offer potential benefits for scientific writing, including language editing, summarisation, translation, information organisation, and support for non-native English speakers, but their misuse raises concerns about accuracy, transparency, confidentiality, and research integrity. Through a three-round modified Delphi process involving 53 editors-in-chief or their delegates, 59 statements were generated and categorised into guidance for authors, editors, reviewers, and publishers with a particular attention to LLM disclosure practices and perceived risks. The consensus recognises that LLMs are useful tools in academic publishing for authors, reviewers, and editors. However, their use must be guided by ethics, legality, and principles of transparency and accountability. LLMs may assist with limited editorial and authorial tasks provided that their use is fully disclosed and all outputs are verified by humans. The consensus also emphasises the inappropriateness of using LLMs to generate original or ideative content, which should remain a strictly human responsibility. Moreover, LLMs must not generate data, references, conclusions, or entire manuscripts, nor be used for editorial decisions or peer-review reports. Editors expressed concerns about 'hallucinations', erosion of critical skills, confidentiality breaches, and the proliferation of low-quality LLM-generated manuscripts. The resulting guidance highlights transparency, human accountability, and careful verification as essential principles for integrating LLMs into scholarly workflows while preserving the integrity of scientific publishing.

Perioperative neurocognitive disorders may arise from three complementary mechanisms that, together, cause excessive inhibitory neurotransmission. Sustained accumulation of type A γ-aminobutyric acid (GABAA) receptors on the surface of neurones, aberrant release of GABA from astrocytes, and increased production of hydrogen peroxide (H2O2) can all enhance the amplitude of tonic inhibitory conductance, and in concert could disrupt network synchrony and impair cognition after anaesthesia and surgery. The report by Wan and colleagues identifies a key pathway by which sevoflurane activates calcium (Ca2+)/calmodulin-dependent protein kinase II (CaMKII), which impairs GABAA receptor internalisation and thereby promotes receptor accumulation on the neuronal surface. The accumulation of GABAA receptors is expected to interact synergistically with increased concentrations of GABA and H2O2 to drive excess inhibitory neurotransmission. Targeting even one of these three factors might be sufficient to preserve cognition after anaesthesia and surgery.

Voltage-gated sodium channels (VGSCs) mediate neuronal excitability and synaptic transmission and are functionally relevant targets for volatile anaesthetic (VA) actions. Here, we show that multiple VAs at clinically relevant concentrations share binding sites on NavMs, a prokaryotic VGSC. Sevoflurane, a representative VA, interacts with NavMs and NaChBac with functional effects paralleling those on human VGSCs, including modulation of channel inactivation. X-ray crystallography of purified NavMs reveals an atomic-resolution VA binding site in a VGSC, in which sevoflurane displaces lipid to occupy a membrane-embedded hydrophobic pocket. Alanine substitution of an invariant tyrosine within this binding pocket abolishes sevoflurane binding and eliminates the sevoflurane-induced hyperpolarising shift of steady-state inactivation. Sevoflurane modulates both fast and slow inactivation of human Nav1.1, demonstrating VA modulation of steady-state slow inactivation in a neuronal VGSC. Supporting evidence shows that VAs interact with homologous sites in human VGSCs. These findings define a VA binding site in VGSCs that supports a membrane-assisted pathway for modulating channel gating and neuronal activity in general anaesthesia.

Enhancement of neuronal plasticity is a key determinant of the onset of antidepressant responses. Because brain-derived neurotrophic factor (BDNF)-dependent synaptic plasticity is essential for antidepressant efficacy, we examined whether fast-acting antidepressants directly trigger BDNF release. At antidepressant-relevant concentrations, ketamine and its metabolite (2R,6R)-hydroxynorketamine (HNK) induced BDNF secretion from mossy fiber terminals of granule neurons within minutes of application in rat hippocampal cultures. BDNF release required selective NMDAR signaling, as conditional genetic deletion of presynaptic NMDARs from granule neurons or from postsynaptic NMDARs from CA3 pyramidal neurons in acute mouse hippocampal slices, abolished BDNF exocytosis in response to both ketamine and HNK or selectively to HNK, respectively. Both compounds produced acute synaptic plasticity, reflected by gains and losses of CA3 dendritic spines without a net change in overall spine density. These findings reveal distinct, drug-specific NMDAR mechanisms at mossy fiber terminal–CA3 synapses that drive rapid BDNF release by fast-acting antidepressants.

BACKGROUND:The mechanisms underlying volatile anaesthetic-induced unconsciousness remain unclear. Glutamatergic pyramidal neurones and fast-spiking interneurones in cerebral cortex circuits play distinct roles in cortical network dynamics under volatile anaesthesia. We investigated the roles of medial prefrontal cortex (mPFC) pyramidal and fast-spiking interneurones in volatile anaesthetic-induced hypnosis. METHODS:The electrophysiological properties of pyramidal and fast-spiking parvalbumin (PV+) neurones were explored by in vivo multichannel recordings and in vitro patch-clamp electrophysiological recordings. Chemogenetic manipulation was used to test the role of pyramidal neurones in the mPFC in volatile anaesthetic-induced unconsciousness. Nav1.1 knockdown in PV+ neurones was used to regulate activities of pyramidal neurones by PV+-dependent disinhibition and to investigate the role of pyramidal neurone activation in volatile anaesthetic-induced unconsciousness. RESULTS:Regular-spiking pyramidal neurones and fast-spiking PV+ neurones in the mPFC were identified with distinct spiking properties. Sevoflurane suppressed pyramidal neurone firing frequency and action potential characteristics. Chemogenetic inhibition of pyramidal neurones in the mPFC enhanced the potency of volatile anaesthetics, whereas chemogenetic activation produced the opposite results. Sevoflurane also suppressed the firing of fast-spiking PV+ neurones, with a greater inhibition ratio than that in regular pyramidal neurones; however, sevoflurane did not affect the action potential properties of PV+ neurones. Nav1.1 knockdown in PV+ neurones enhanced sevoflurane-mediated suppression of PV+ neurone activity, leading to pyramidal neurone disinhibition and reduced hypnotic potency. CONCLUSION:The excitability of pyramidal neurones in the mPFC primarily determines the sedative potency of volatile anaesthetics in mice.

Neuronal hyperexcitability is a prevalent feature in early stages of Alzheimer's Disease (AD), hastening cognitive decline and neurodegeneration. However, despite the immense clinical significance, the underlying molecular mechanisms are not fully understood. Variable expression of voltage‐gated sodium channel (Na v ) subtypes in specific neuronal populations influence sensitivity of network excitability. Heterogeneity of Na v expression also differs with cell maturity, as subtypes with distinct activation kinetics render developing neurons more susceptible to hyperexcitability when compared to established neurons. Interestingly, mature excitatory neurons, following injury or disease, augment their high‐frequency firing by reverting to an Na v profile indicative of an earlier developmental window, but have yet to be explored in AD hyperexcitability. Here, we hypothesize that developmentally dominant Na v 1.3 is re‐expressed in glutamatergic mossy fiber terminals and potentiates hippocampal CA3 hyperexcitability. Subtype‐specific expression of Na v 1.3 was quantified in mossy fiber terminals by immunogold labeling and electron microscopy from hippocampal tissue of 3‐mo (early stage) and 7‐mo (late stage) old male and female wildtype and 5xFAD mice. Real‐time measurements of neuronal activity from pyramidal CA3 neurons, synapsing with mossy terminals, were determined using fiber photometry in same mouse models and developmental stages. Neurophysiological properties of Na v 1.3 were assayed using electrophysiology. Here, we show that early AD mice have increased mossy terminal Na v 1.3 labeling and hippocampal CA3 neuronal activity compared to wildtype or older AD mice. Higher neuronal activation was also found to be more prevalent in female mice at early stages of AD compared to male mice. Our findings identify a novel Na v subtype (Na v 1.3) re‐expressed in early stages of AD coinciding with sex dependent hippocampal CA3 hyperexcitability.

The antiparasitic drug ivermectin was proposed as a repurposed drug for the treatment of SARS-CoV-2 infection based on in vitro studies, but proved ineffective in high-quality clinical trials. When exploring possible reasons for this disconnect, we found that ivermectin interferes with AlphaScreen assays by quenching singlet oxygen transmission, calling into question the original justifications for pursuing ivermectin as an antiviral agent. Furthermore, at the low micromolar concentrations where ivermectin reduced SARS-CoV-2 viral burden in vitro, ivermectin decreased cell viability, modified membrane bilayer properties, and nonspecifically dysregulated membrane protein functions. In this Perspective, we provide molecular-level rationale for why ivermectin, an effective and safe antiparasitic drug at low nanomolar concentrations, becomes cytotoxic at low micromolar concentrations and, in turn, why ivermectin has not translated into an effective antiviral agent. We highlight lessons learned from the failed ivermectin repurposing effort and provide a workflow for identifying membrane-perturbing bioactivity early in drug development.

Voltage-gated sodium channels (VGSCs), key mediators of excitability and synaptic transmission, are established and functionally relevant targets for volatile anaesthetic (VA) action. Using the structurally homologous prokaryotic VGSCs NavMs and NaChBac as models, we present a structure-function analysis of VGSC-VA interactions. We report that multiple VAs compete for binding sites on NavMs, and that these direct interactions mediate functional effects of sevoflurane on NavMs that mirror those attributed to VA effects in eukaryotic VGSCs, including human isoforms. Using X-ray crystallography, we determined the first atomic-resolution structure of a VA bound to a VGSC, showing sevoflurane displacing lipids to bind in an intramembranous hydrophobic pocket of NavMs. A conserved tyrosine residue within this binding site is critical for channel gating, and its substitution with alanine abolishes sevoflurane binding and selectively eliminates the characteristic anaesthetic-induced hyperpolarising shift of steady-state inactivation that reduces neuronal excitability at physiological membrane potentials. Finally, we provide evidence supporting VA action at the conserved sites in human VGSC isoforms. These findings define the first VA binding site in a VGSC. A membrane-mediated access pathway to the binding site leads to negative modulation of channel function that reduces neuronal activity and excitatory synaptic transmission in general anaesthesia.

Neuronal voltage-gated sodium channels (Nav) are major targets for the neurophysiological actions of general anesthetics. In the adult brain, cell type-specific effects on synaptic transmission are attributed to the differential sensitivity to volatile anesthetics of specific Nav subtypes preferentially expressed in mature neurons (Nav1.1, Nav1.2, Nav1.6). Comparatively, developing neurons are more excitable than mature neurons. We determined volatile anesthetic effects on Na+ currents mediated by Nav1.3, the principal Nav subtype expressed in developing neurons. Sevoflurane at clinical concentrations inhibited peak Na+ current of human Nav1.3 heterologously expressed in HEK293T cells in a voltage-dependent manner, induced a - 6.1 mV hyperpolarizing shift in the voltage dependence of steady-state inactivation, and slowed recovery from fast inactivation. Nav1.3-mediated Na+ currents also exhibited distinct activation properties associated with hyperexcitability, including prominent persistent currents and ramp currents, both of which were significantly reduced by sevoflurane. Nav1.3 showed a more depolarized voltage dependence of steady-state inactivation than Nav1.2, consistent with its higher propensity for sustained repetitive firing. Nav1.2 exhibited minimal persistent and ramp currents, and these were unaffected by sevoflurane. These findings identify subtype-specific effects of sevoflurane on neuronal Nav subtype electrophysiological properties, and suggest a mechanistic basis for increased anesthetic sensitivity and toxicity in early neuronal differentiation and maturation.

Current anesthetic theory is mostly based on neurons and/or neuronal circuits. A role for astrocytes also has been shown in promoting recovery from volatile anesthesia, while the exact modulatory mechanism and/or the molecular target in astrocytes is still unknown. In this study by animal models in male mice and electrophysiological recordings in vivo and in vitro, we found that activating astrocytes of the paraventricular thalamus (PVT) and/or knocking down PVT astrocytic Kir4.1 promoted the consciousness recovery from sevoflurane anesthesia. Single-cell RNA sequencing of the PVT reveals two distinct cellular subtypes of glutamatergic neurons: PVTGRMand PVTChATneurons. Patch-clamp recording results proved astrocytic Kir4.1-mediated modulation of sevoflurane on the PVT mainly worked on PVTChATneurons, which projected mainly to the mPFC. In summary, our findings support the novel conception that there is a specific PVT→prefrontal cortex projection involved in consciousness recovery from sevoflurane anesthesia, which is mediated by the inhibition of sevoflurane on PVT astrocytic Kir4.1 conductance.

Editor—There are >100 million global refugees according to the United Nations, 44% of whom have experienced torture.1 The USA is the highest recipient of asylum applications,2 and healthcare providers there and in other resource-rich nations are increasingly likely to see refugee patients in their clinical practices. We previously found that 85% of torture survivors experience chronic somatic pain, such as brachial plexopathy from upper extremity suspension or lumbosacral plexus injury from leg hyperextension; however, this pain was most frequently misdiagnosed by providers as a manifestation of post-traumatic stress disorder (PTSD), major depressive disorder (MDD), or psychosomatisation.

Volatile anesthetics reduce excitatory synaptic transmission by both presynaptic and postsynaptic mechanisms which include inhibition of depolarization-evoked increases in presynaptic Ca 2+ concentration and blockade of postsynaptic excitatory glutamate receptors. The presynaptic sites of action leading to reduced electrically evoked increases in presynaptic Ca 2+ concentration and Ca 2+ -dependent exocytosis are unknown. Endoplasmic reticulum (ER) of Ca 2+ release via ryanodine receptor 1 (RyR1) and uptake by SERCA are essential for regulation intracellular Ca 2+ and are potential targets for anesthetic action. Mutations in sarcoplasmic reticulum (SR) release channels mediate volatile anesthetic-induced malignant hyperthermia (MH), a potentially fatal pharmacogenetic condition characterized by unregulated Ca 2+ release and muscle hypermetabolism. However, the impact of MH mutations on neuronal function are unknown. We used primary cultures of postnatal hippocampal neurons to analyze volatile anesthetic-induced changes in ER Ca 2+ dynamics using a genetically encoded ER-targeted fluorescent Ca 2+ sensor in both rat and mouse wild-type (WT) neurons and in mouse mutant neurons harboring the RYR1 T4826I MH-susceptibility mutation. The volatile anesthetic isoflurane reduced both baseline and electrical stimulation-evoked increases in ER Ca 2+ concentration in neurons independent of its depression of presynaptic cytoplasmic Ca 2+ concentrations. Isoflurane and sevoflurane, but not propofol, depressed depolarization-evoked increases in ER Ca 2+ concentration significantly more in mouse RYR1 T4826I mutant neurons than in wild-type neurons. The RYR1 T4826I mutant neurons also showed markedly greater isoflurane-induced reductions in presynaptic cytosolic Ca 2+ concentration and synaptic vesicle (SV) exocytosis. These findings implicate RyR1 as a molecular target for the effects of isoflurane on presynaptic Ca 2+ handling.